The graphic above shows how La Niña has been behaving since the middle of August. To be classified a La Niña, that dotted blue line needs to be at or below -0.5 for three consecutive months. Technically, we have briefly achieved that threshold, however, you can see that since the end of October, it has been weakening a bit. As of now, we are barely hanging on to weak La Niña status.
Also, we need the atmosphere to respond and couple to the ocean for this La Niña to truly have a meaningful impact. Is that happening? Not yet.
The graphic above is a measure of the Southern Oscillation Index (SOI). When it is around +10 or above, we are in La Niña. You can see back in 2022 how positive it was and we were certainly in a La Niña at that time. Recently, you can see that we briefly went positive in September, but then have been hovering in neutral territory with no major move to positive territory. The big question is, will that continue?
The graphic below is a equatorial trade wind forecast for the next couple of weeks. As I write this, there looks to be a solid surge in the easterly trade winds along the equator. This shows up as green and blue on the graphic below:
In order for La Niña to start developing again, those easterly trade winds not only have to be strong, but also have to persist. For right now, it looks like that will occur. So, I would expect us to see this weak La Niña intensify a bit. Do I expect this La Niña to become a moderate or strong event? No, I do not.
On another note, westerly wind bursts show up as orange and red, and will likely remain confined to the Indian Ocean and far western Pacific. This configuration also keeps the MJO focused across the Indian Ocean and far western Pacific. That's usually not a good spot for the MJO to favor, if you like big storms east of the mountains. We'll see.
The graphics below show the various models and how strong and long they think this La Niña event will become.
December ENSO Forecast
February ENSO Forecast
April ENSO Forecast
A couple of takeaways…
What does this mean for the next few months? The model forecasts for December/January/February are shown below.
EURO Seasonal Model Precipitation Anomaly Forecast Dec/Jan/Feb
EURO Seasonal Model Temperature Anomaly Forecast Dec/Jan/Feb
NMME Model Precipitation Anomaly Forecast Dec/Jan/Feb
NMME Model Temperature Anomaly Forecast Dec/Jan/Feb
IRI Multi-Model Precipitation Anomaly Forecast Dec/Jan/Feb
IRI Multi-Model Precipitation Anomaly Forecast Dec/Jan/Feb
The model consensus would show a average to drier than average conditions for Colorado. The more robust dry signal does show up across the southern tier of the state. We usually don't give a lot of credence to the temperature forecast from the seasonal models, as they are notoriously bad on picking up any cold temperature signal. However, it is interesting to note that the IRI bucks the trend of the EURO and NMME, and shows a colder than average winter for most of Colorado and the adjacent Plains.
What does history show? Since 2000, we have had 11 La Niña events. Of those, six have been classified as weak. The precipitation anomalies that occurred for those winters are shown below.
As you can see, there is some variability. That is usually the case when we don't have a strong La Niña signal. However, it is interesting to note that the northern part of the state didn't show up drier than average in any of those winters! While there is not definitive tip toward wetter or drier than average for the southern part of the state, two of those winters showed up drier than average. Areas east of the mountains and south of the Palmer Divide have the greatest chance of being drier than average. That is somewhat reflected in the models too... That being said, there is no strong evidence suggesting a dry winter is in the cards for the northern tier of the state.
A big question many are asking... "Was the recent big snowstorm a harbinger of an active winter?" In one word, no. There is really no correlation one way or the other. However, it is important to note that this La Niña will be weak and short lived. That should make for much more weather variability versus if we were locked into a stronger La Niña event. Plus, this "event" should be gone by spring. While that is not a guarantee for a wet spring or a dry spring, it is better than being locked into a La Niña weather regime. In our next update, I will dig into that further.
]]>Here's an hourly look at the timeline for Denver with temperatures on top and chances for precipitation on the bottom.
We can expand on that chance for snow with this animation showing a few areas of snow, mostly in the central and northern mountains for tonight through Tuesday.
Snowfall totals are shown here.
Sure, most of that snow is in the mountains but that is not to say we can't see snow around the metro areas. The odds are slim, but the Palmer Divide has the best chance.
The Palmer Divide will also have stronger wind, as many of us will, on Tuesday. Here's a look at wind speeds/gusts for Colorado Springs showing some of the stronger gusts during the morning through midday.
All in all a relatively minor system, but one that will catch your attention for how chilly the day will be. For those headed to the high country, driving may have some slick spots to deal with, as shown here on the impact map.
After Tuesday, warmer weather returns with lighter wind. We are watching a potential change for next week with a significant storm possible across the Western U.S. with impact on our mountains into Thanksgiving. More on that later.
]]>First, more on the snow. The white stuff will be falling in parts of the mountains Monday and Tuesday, albeit not that much. Some of those showers will try to sneak into the metro areas Tuesday.
Here are the totals expected:
There's a hint of snow possible on the Palmer Divide and north/west sides of Colorado Springs.
All in all, though, that's not much water. If we look at just total precipitation, it's a dry system, relatively speaking, with exception for some spots in the mountains that may come away with 0.25-0.5" of water.
With the passage of this little ripple, there may be some gustier wind to add a cold bite to the air Tuesday. Right now, it looks like Tuesday morning will be the windiest and may be stronger on and south of the Palmer Divide for Colorado Springs versus Denver here on the north side.
As this system exits, we likely warm to well-above normal temperatures - some 60s later this week. Here is the daily breakdown for highs/lows expected.
Beyond this week, we clearly enter a busy holiday period for Thanksgiving. There is currently a slight chance of receiving heavy snowfall in the region between the 23rd and 27th. History suggests that moisture will stay in the mountains as analogous weather patterns usually leave the Front Range drier, but we will be watching that for you and will pass along updates later this week so you can begin travel adjustments if needed.
]]>Snowfall totals
For Denver, the official total for the duration of the storm: 20.0" at Denver International Airport. The last 20"+ storm in November came when 22.4" of snow fell near the end of the month in 1983. If we see no more snow for the duration of the month, this will go down as Denver's 10th snowiest November on record, toppling 1972 when the city picked up 19.4" during the month.
While hard to measure given melting, compaction, and multi-day event, the overall picture is nothing short of impressive. NOAA's NOHRSC analysis shows just how much of Eastern Colorado was absolutely buried in heavy, wet snow last week:
CoCoRaHS observations mostly confirm these totals, with yes some 30"+ totals south and east of Denver. In the city proper, the 5-day totals were more in the 1o - 15" range, with slightly lesser amounts north, and plentiful 2o"+ totals to Denver's south and west.
Up north we never quite got off the struggle bus for cashing in on the snow. Five day totals show just a Trace to 3" for areas up around Loveland and Fort Collins, with placement of the low and ultimately temperature issues really limited snowfall potential for these areas.
In Colorado Springs, however, also a pretty epic snow event. Totals here from 15 to 24", with 19.3" at the airport landing it in the top spot for largest November snowfall on record for the city! Checkout this list of records from COS and Pueblo:
Not just snow, but lots of water too!
The drought picture through November 5th (right before the storm started) shows really much of the CONUS experiencing drier than average or drought conditions, including much of Eastern Colorado:
This system will be HUGE in combating that trend, with copius amounts of moisture received in the last week:
Zoomed in to Colorado we see most of Eastern Colorado picked up 2 or more inches of precipitation over the last 7 days, with upwards of 4" of liquid for some locals. Can't stress enough how big that is, especially for November!
The week ahead looks much quieter across eastern Colorado, with highes mostly in the 50s along the urban corridor. The next system to impact that state arrives mid week, but at this point looks like it'll keep most of the rain and snow in the high country – let's keep an eye on things just in case!
]]>As of 10:00am Friday, the radar is lit up across most of eastern Colorado. You can see the moisture pinwheeling around the upper-level low... fantastic upslope setup for pretty much everyone.
And it looks like Weld and Larimer counties are finally starting to get their share!
At look at mid level water vapor imagery shows our low continuing its gradual track east this morning, soon to begin its turn north/northeast through tonight. The blues and whites are indicative of lots of water being thrown up against the hills with great upslope in place at this hour:
We'll see snow most of the day. A bit of dry slow may work through the area through early afternoon, but if it does – it'll be relatively short-lived, with most guidance promising some heavy snowfall across the urban corridor for that evening commute.
HRRR depiction for snowfall looks like it's being handled well. Snow will continue to progress northward as the low scoots north along the Kansas/Colorado border. As it does so, the storm will likely puff up in intensity through mid-afternoon, before slowly relaxing and weakening as we progress into early Saturday morning. As the low wraps up more today, we're likely to see winds increase to 25-35 mph, especially over the plains leading to blizzard-like conditions at times.
It's likely the accumulating snowfall will taper off once we get to sunrise Saturday if not before for some, but lingering snow showers and wind are likely to continue through lunchtime. Blowing snow could be an issue trying to get out the door tomorrow, especially if you live further east.
WSSI impacts show worst conditions expected along and south of I-76, but if we can keep rates up this evening, look for trouble along the northern urban corridor as well for that evening commute. While yellow, let's not sleep on it!
As for snowfall totals... we aren't going to adjust from what we put out yesterday. Most areas should have no problem hitting low-end projections (if you haven't already) with good bet on some boom snowfall totals.
Here's our quick list from yesterday:
And the post:
A quick check on our friends up north near Fort Collins shows that rates have been heavy enough so far today to overcome and temperature issues, and we've got snow on the ground up there! Could be we see some precipitation mixing for northern communities today if and rates decrease in any given area.
The European ensemble showed this for totals in its early morning run, and looks pretty on target, even even a bit low in spots. Overall, a snow-filled finish to a snow-filled week across Eastern Colorado.
And FWIW, here's the latest HRRR snowfall forecast through early Saturday morning hot off the press. It shows about 8" more for Denver, a bit more for higher terrain south and west, and 3 - 5" up north:
It seems likely most are in line for at LEAST 6". This would put many locations above 20" for the weekly totals. Great stuff all around.
Please keep us posted in the comments below! Feel free to share pics as well, we love the ❄️ ☃️!
]]>Further north – we hear you – frustrating to be left out of the action, but it actually looks like you've got some hope getting in the action with this final push, we'll see.
How much snow so far?
Through early this morning Denver has record 6.2" of snow officially (at DIA), with more for many of us, especially on the western and southern portions of the city. What a flip from October!
Three day snowfall totals shows who's seen how much, with much of the state picking up measurable snowfall over the last couple of days, and plenty more is on the way!
The setup
Despite the snow we are seeing today, the main feature (low) is still well to our southwest. After the initial energy dropped through Tuesday night, things haven't progressed much – and won't until we move into the day Friday and Friday night into Saturday.
You can see in current water vapor the low (red L) sitting over Arizona this morning. It'll gradually creep east then turn northeast through tonight, eventually tracking along the Colorado/Kansas border Friday night into Saturday.
You can see that in the animation below, which the the positioning of the circles/blue as they track from our south, to east, and eventually eject northeast.
This is beautiful setup for a lot of snow across eastern Colorado.
While the energy might favor areas further south and east (vs Loveland, Fort Collins), I'd argue the trend today would include more of those southern cities in getting some measurable snow before things are said and done on Saturday.
If we look at forecast QPF (precipitation) between now and Saturday night, we see just a tremendous amount of water forecast for Southeast Colorado. Upwards of 2" for a good chunk of this area on this particular model. You'll note, lesser totals up toward Denver and points north... but not dry!
Snowfall forecast
As mentioned above, a Winter Storm Warning goes into effect for the Denver metro area tomorrow morning and extends through Saturday morning:
WINTER STORM WARNING IN EFFECT FROM 5 AM FRIDAY TO NOON MST SATURDAY...
* WHAT...Heavy snow expected. Total snow accumulations between 7 and 14 inches, with the heaviest amounts south of I-70. Lighter totals of just 1 to 4 inches north of Boulder.
* WHERE...The Southern Front Range Foothills, Boulder and the western suburbs of Denver, and Denver.
* WHEN...From 5 AM Friday to noon MST Saturday.
* IMPACTS...Travel could be very difficult. The hazardous conditions could impact the Friday late morning and evening commutes.
For totals we're thinking the following, with room to adjust as we head into Friday.
Modeled forecasts:
The European ensemble mean is probably a good place to start, though is at the high end of what we think is potential in Denver. Still, overall hard to argue much here, and shows that some of our northern communities could see several inches before things are through:
The HRRR (below) is closest to our forecast right now. Note the heaviest totals across southern and eastern Denver metro, with less upslope north and west:
And the 3km NAM showing high-end potential across the entire area – would no doubt be a boom scenario!
Greatest boom and bust potential
Eventual track and to a lesser degree temperatures will impact eventual snowfall totals. A slightly further east track would limit snow up into Denver and points northwest, while a more westerly track would bring "boom" snowfall totals to these areas. Also worth noting, some guidance shows snow mixing with rain at times at lower elevations, which obviously would hurt snowfall forecasts!
For greatest boom we think Denver's southern and eastern suburbs could end up under an impressive band as things get going in earnest later Friday which could over deliver in these areas again. Think Southeast Aurora on this.
For greatest bust potential, likely Denver and points north, where temperatures and or track could rob us of upslope and high end snow totals.
All this to say, greatest confidence across the plains where BIG totals are expected, with Denver on the edge – a foot of snow almost as likely as 4". Yikes!
Planning and impacts
This has been an impactful event, and will continue to be one through the end of the week and into the early part of the weekend. There will also be a substantial increase in the wind through the day on Friday through early Saturday for some areas. Those areas at greatest risk for blizzard conditions will be in the following areas: Elbert County, east/northeast El Paso County, Lincoln County, Kit Carson County, Cheyenne County and the majority of the southeast corner of Colorado where snow has occurred or will occur. Gusts of 30-45 mph will likely occur in these areas. Considerable blowing and drifting snow will occur making for a dangerous scenario, especially Friday night. Below is a look at where the greatest impacts are expected through the remainder of the storm, which could be adjusted as we head into Friday, stay tuned.
As for timing, look for snow showers to taper off today, with low snow chances through most of tonight.
Snow chances increase from south to north on Friday, with Denver's best window for accumulating snow coming between 6am Friday and 9am Saturday.
Temperatures gradually moderate as the storm exits on Saturday, but will remain chilly.
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]]>What we've seen so far
For many along and south of I-70, this has been a high-impact snow event, with closures of major roadways including HWY 24 east of Colorado Springs and HWY 287 in far southeast Colorado. For the immediate Denver metro area, this storm has produced mostly moderate impacts, with heavier snowfall totals on the south side of town near the Palmer Divide.
Here were the totals through this morning, and we added to this today:
Reports from 7AM: areas around Colorado Springs overachieved the most with the first wave of this system as a powerful mesoscale band dumped 6-12" between Tuesday night and Wednesday morning.
Meanwhile most of the Denver metro area saw totals between 4-9".
Light snow has been on and off for much of Wednesday, with most locations seeing minor additional accumulations.
That will change tonight into Thursday morning. Below is a look at simulated radar from Wednesday evening through Thursday evening. Snow will increase over far southern Colorado overnight, spreading north into the morning commute and throughout the day on Thursday.
We'll likely see that shield of snow slowly break apart by Thursday night before another wave of energy spins up and takes a similar path into Friday morning. That following wave looks to last all of Friday and linger into Saturday morning before the system as a whole finally begins to taper in strength and move east.
You can see the light at the end of the tunnel after we get past midnight into early Saturday morning. But the damage will be done... especially for folks over southern Colorado.
How much more snow can we expect?
For southern Colorado quite a bit of more snow on the way, and that's not to say some of that won't make its way north. For places like Trinidad, however, several feet between now and Saturday will be possible.
As you get closer to Denver, the heavier snowfall is again expected along and south of I-76, with the greatest totals between now and Saturday over the Palmer Divide.
Still, several more inches of snow for the Mile High City looks doable, on top of what's already fallen. Good stuff.
Look for snow showers on Thursday, a brief lull, and then increase snow coverage again Friday into Saturday before this system finally kicks east. Timeline below.
We'll keep an eye on the trends, and pass along updates as needed!
]]>We've obviously added to that total since then, and will continue to put a bit more snow on top of current totals today, with on and off snow expected to continue most of the day – especially for communities along and south of I-76.
Here are the latest winter weather alerts from the NWS in Boulder. The heaviest snow will be from Denver's southern and southeast suburbs through east-central Colorado, where a Winter Storm Warning remains in effect through 5am Thursday.
Below is what to expect for additional snowfall through tonight. Look for an additional 1 - 4" or so for Denver, with upwards of an additional 4" possible further south and southeast as you head out of the city.
Thursday forecast
Thursday we'll be a bit between the two waves we've been talking about for some time now. Still, we'll be under the influence of the trough to our south, which means a rather chilly and possibly unsettled – rain and snow showers are possible – day is on tap Thursday.
This is evident in the hourly planner. Look for snow chances upwards of 60% all day today, and about 30% chance for those rain/snow showers on Thursday across the metro areas.
Friday into Saturday
The big question here remains how far west the trough tracks as it finally begins to eject northeast. The trend recently has been a bit further west again, which would increase snow chances for the Denver metro area. A wobble southeast, however, and those chances go back down again. A bit of a wait and see.
The latest European ensemble mean 24 hour precipitation forecast ending Saturday morning shows another 0.5" of liquid across the the area, with more to the east. If this pans out, we'd see another accumulating snowfall event for the metro area to kick off the weekend.
For now, plan on the chance of snow ramping up again later in the day Friday, particularly across the eastern plains, with the best chance of snow for Denver looking to come Friday night into Saturday morning.
Temperatures
No surprise here, but we'll remain chilly until the trough finally moves out for the latter half of the weekend.
The blend of models shows gradual warming through Saturday, but that warming will be overdone if some of the models are correct with the western track of the low.
In any event, highs in the 30s today and tomorrow, near 40F on Friday, and perhaps a bit cooler-than-advertised here Friday night into Saturday, but we'll see.
We'll continue to watch things for you, stay warm, stay safe, and post those snow reports and photos!
As the atmosphere tries to remain in balance, if you place a strong system over the Four Corner and a tropical cyclone over the Gulf, a strong ridge needs to develop somewhere to offset those features. The stronger one gets, impacts the others. We have yet to see how each of these features will impact the other, but there is increased clarity in data that arrived through this morning.
During the next few hours, a cold front will barrel through the area which will switch wind direction, increase potential for snowfall, and keep temperatures cold enough to discuss snow rather than rain or even a rain/snow mix for the Front Range. Most of the state has snow chances, except parts of the plains which will have some rain in addition to snow.
Here's an animation from Tuesday through later Wednesday:
From that animation, we see chances of snow increase and stick around from later Tuesday through much of Wednesday. In hourly form, the chance in Denver looks like this:
Snowfall forecast through Wednesday
From first snow chance, we can see the following totals as most probable, although there are totals much higher and some much lower across the northern metro locations.
The biggest question mark at this point is how much snow to drop onto the Palmer Divide and how far into the metro area to pull that snowfall. Guidance is about split on just a dusting to 1" for Denver and higher end amounts of 3 - 5". Generally speaking, the further south and southwest you go from downtown Denver, the greater your odds are for accumulating snow between tonight and Wednesday.
Here is the statewide view. Should be some spots of pretty good snowfall for the foothills west of Denver, the Palmer Divide, and east-central Plains:
For now, we remain watching this first wave of snowfall to see how it plays with terrain and where the forecast is potentially too low, or high if the case may be.
I was asked this morning at school drop-off to give the forecast... 0-18" I said... tongue-in-cheek obviously, but we are playing with the difference of less than 100 miles to see this thing crank up a lot of snow or waking up to very little Wednesday morning.
The NWS remains watchful also, and has parts of the Palmer Divide in a Winter Storm Advisory, meaning:
...WINTER WEATHER ADVISORY IN EFFECT FROM 8 PM THIS EVENING TO 8 PM MST WEDNESDAY...
* WHAT...Snow expected. Total snow accumulations between 2 and 7 inches. Winds gusting as high as 35 mph.
* WHERE...The Southern Front Range Foothills, and Castle Rock.
* WHEN...From 8 PM this evening to 8 PM MST Wednesday.
* IMPACTS...Plan on slippery road conditions. The hazardous conditions could impact the Tuesday evening and Wednesday morning commutes.
What happens beyond Wednesday?
What happens beyond Wednesday hinges on a lot of factors, as mentioned way up at the top of this post. The parent storm system will drift over and stall out on the Four Corners region. Leaving this energy in place will continue snow chances for several days until this system exits. When, how quickly, and the path it chooses to exit will either keep us with trivial snowfall totals or grabbing the snowshovels.
Under any scenario, it looks like the biggest impact will be across the Plains where a lot of water will fall. The question remaining to be answered, how close to Denver will that system exit later this week, and if we're watching it pass us by or talking another round of snow.
That's for our next discussion. Stay tuned.
]]>And, there's another waiting in the wings...
Our current system gets on out by Monday night, but it may end up merging with a storm already beginning to impact the Pacific Northwest. Check out the 500mb anomalies stepping you through the weather pattern the rest of the week (remember, blues = cold and stormy, orange = warm and drier)
A few key things to note:
Southerly track to burn us?
Lots of excitement around this incoming system, and you'll see in the snowfall map below why... but take it with caution. There's a lot at play here, and getting multiple waves of snow to line up right is hard to do!
Perhaps the biggest risk to the heaviest snowfall potential we see out there right now is the secondary wave late in the week ending up too far south, then east for that heavier snow to wrap up west along the Front Range. If it stays a bit further north and west... well, we should be in good shape to get some good snow.
At 500mb – the Euro ensemble takes a pretty good track for us on Friday, moving it into the panhandles then ejecting northeast:
At the surface, some disagreement between the members is evident though... with quite a spread for the placement of the low (indicated by the red numbers over southeast Colorado into Kansas).
And then the deterministic models have a spread too... The GFS is largely a MISS for snow in Denver, and you can see what, lots of energy really digging too far southeast of us Friday night:
And it's that southerly bias in the GFS we will be watching closely today. The operational (above) is scary if you want snow in Denver later this week, but the ensemble had a pretty big shift southeast from yesterday too. Below (left) is yesterday's run (with upwards of 1" of liquid for Denver), and blow (right) is todays – a big time shift southeast.
Does the trend show in other modeling today? We'll see.
How we're handling snowfall totals right now:
The trend: some have a chance for higher end snowfall, especially with the second wave mid to late week. That "higher end" of the snowfall is a bit up in the air at this point. Like, maybe way up in the air.
We've seen guidance produce everything from a several inches, to a foot, to two feet and in some cases over 2 feet for some along the Front Range.
The blend of models shows lackluster snow potential for Denver (remember this is a combo of both waves) with the heaviest snow south of the city. But still, some snow.
Here's what the (trusty?) EURO ensemble is printing (a combination of all the various waves through Saturday)... a solid potential this far out!
If we break down by 24 hour totals... There's a couple of things to note. We see maybe 2 - 4" for Denver from round one in the ensemble mean, and 4 - 5" in the means for round two. But if you look at the individual members (along the y axis) you see some produce as little as 0.1" of snow through the period, and some upwards of 20"! That's HUGE spread, and therein lies the uncertainty.
GFS and Canadian ensembles have similar snowfall potentials across the state... however some have different flavors of track/strength, leading to variable totals for the front range.
To pair, we should get pretty cold during this stretch of potential snowfall, with highs in the 20s and 30s.
Clearly a lot to track... we'll have all the latest on Weather5280 through the week. The big question today will be, does the GFS remain alone in its southerly shift? Or do other models follow?
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]]>The Advisory closest to the metro areas calls for 3 - 8" of snow, which fits pretty well with our forecast. This includes western Douglas County, western Jefferson County, and western Boulder county, mainly above 6,000 feet.
For lower elevations this continues to not look like a huge deal (theoretically, but a wet road in the metro area can throw the whole city into a tizzy). Chilly? Yes. Some rain, snow, and everything in between? Probably. Accumulating snow? Maybe not so much. Most guidance suggests only a Trace to 1/2" for Denver (if that) with perhaps 1 - 4" for the western Palmer Divide and southern/southeast metro area suburbs at the high-end.
With that, our snowfall forecast hasn't moved much since yesterday's update either.
Timing and impacts
As for timing and impacts... look for precipitation to be on the increase later this afternoon, with the best chance of those rain/snow showers moving through the Denver area overnight into early Monday morning.
In the cities, not a huge impact expected, though under the colder/snowier scenarios even a 1/2" in spots could lead to some icing on the roadways – so maybe give yourself some extra time for your Monday morning commute just in case.
West of Denver, and south between Denver and Colorado Springs a bit more of a concern, especially given water on the roadways and freeze potential.
As for temperatures, the blend of models shows highs in the mid 40s in Denver on Monday, with overnight lows tonight near freezing. Briefly warmer on Tuesday, before another shot of cold air arrives Tuesday night into Wednesday.
Looking at the timelines above you'll note two additional important things.
If you manage some snow tonight, let us know!
]]>While we haven't seen a storm quite get its act together yet for those of us along the urban corridor and Front Range, it's hard to look at this pattern and not at least like our chances for our first measurable snow during the next week.
In fact, the entire region and really the central third of the U.S. is expected to receive above average precipitation over the next two weeks – Colorado included. This big blob of green and blue represents a much wetter than average couple of weeks:
The animation below is from the latest GFS model, showing a series of troughs (blues) digging into the western U.S. and through Colorado over the next 15 days. One of this will have to hit, right?
We'll see. There certainly is a social media buzz about the second system to come through our area this week (Wednesday-ish).
For now, we focus on the next weather-maker that is set to bring rain, snow, and another shot of cold air to the state later this weekend.
Temperatures will be quite nice this afternoon, cooling to seasonal or just below seasonal average highs Sunday, ahead of a cold front that knocks us into the low 40s for highs on Monday. We get a quick break on Election Day Tuesday, before more chilly air will push into the state for the middle and latter half of the week.
Snowfall forecast
No winter weather highlights in effect for Colorado at this time, but that could change as we head into this evening. Some close-to advisory level snowfall for the higher terrain looks possible from Sunday morning through lunch time Monday, with perhaps some nice 5"+ totals for the Front Range mountains west of Denver!
At lower elevations... This still might not be the one, though a bit better chance than the last round, especially for communities at higher elevations south, west, and southwest of Denver. We've got about a Trace to 3" in the forecast for those areas, with perhaps some upside potential we'll need to watch for. If you live in western Lakewood, Golden, Black Hawk, Estes Park... well, several inches are possible Sunday into Monday.
Will this system deliver Denver's first official snowfall of the season? We'll see. Not a super convincing look for areas further east of the hills and lower in elevation, but not out of the realm of possibility either. We'll see if anything looks more convincing in the data as we had into Sunday and update accordingly as well. Remember, technically Denver has to receive at least 0.10" at DIA for it to be the city's first official snowfall.
For Monday morning drivers, this could be an impactor depending on your commute. Folks from the western and southern burbs may have their first wintry drive of the season. Around here, you know how the first couple of snows seemingly shock drivers into an inability to get around smoothly, so here goes...
Even if this Sunday night/Monday storm doesn't deliver snow to you, there's another chance quickly on its heels.
Midweek
Once we get Sunday/Monday's system out of the way, our focus turns toward the middle part of the week. Guidance is a bit more excited around this system's potential for lower elevations, with some models keeping us under an active pattern of on-again-off-again snow through the end of the week without much forward progression of the trough.
There lacks consistency here in the data, so hard to get super excited just yet, but definitely something to watch as we head into the latter half of the weekend and early next week. And, this system is the one that is inflated on social media.
While the European deterministic model has been maybe the most bullish on snow with this event, its ensemble model doesn't look too bad either. If we look at probabilities for 3" of snow or more, hard not to like our odds for Denver to see its first measurable snow of the season by the time we get through the next week.
Here are odds through Monday, with good odds west and south of Denver, but not really registering for the city:
If we pull that through next Saturday we see upwards of about 70% odds for the city:
No doubt an active time ahead!
Get out and enjoy the day today and look for those changes to arrive Sunday afternoon to our area. We'll keep an eye on the sky and pass along updates as needed – stay tuned!
]]>We are seeing rain and snow across the western half of the state early this morning. This will eventually move east over the urban corridor and plains as we head toward the latter half of the morning and early afternoon hours.
Precipitation may start as drizzle, even freezing drizzle for some, before transitioning to rain and snow. Worth mentioning, that while we don't see a whole lot of potential for accumulating snow below about ~6,000 due to temperatures, it could be some of us see our first real flakes of the season here later this morning, if even briefly.
The hourly precipitation forecast for the urban corridor shows the best chance of showers coming around midday, with the system scooting east of us this evening.
For lower elevations, temperatures will be marginal. So rain, or mixed precipitation is possible. And, if we do transition to snow, it's not likely to stack up... we don't think, though some of the snow showers peeling off the hills today could at least briefly bring moderate snowfall with them, that's from Fort Collins south through Elbert County.
For higher elevations west of Denver, and along the Palmer Divide south and southeast of Denver, perhaps a bit more upside potential with the passing snow showers today, with some models bringing a quick dusting to 4" of snow under the heaviest showers. We'll see.
Here's our latest snowfall forecast through tonight:
Cold tonight!
A reminder that it'll be cold tonight! The first hard freeze for many locations.
From the NWS:
...FREEZE WARNING IN EFFECT FROM 10 PM WEDNESDAY TO 9 AM MDT THURSDAY...
* WHAT...Sub-freezing temperatures as low as 22 expected.
* WHERE...Fort Collins, Boulder and the western suburbs of Denver, Denver, Castle Rock, Greeley, and Byers.
* WHEN...From 10 PM Wednesday to 9 AM MDT Thursday.
* IMPACTS...Frost and freeze conditions are expected kill unprotected sensitive vegetation and possibly damage unprotected outdoor plumbing.
And our latest hazard map:
Enjoy this chilly day, and hopefully it gets you in the mood for a spooky Halloween! We hope everyone stays safe out there with the kiddos tomorrow evening, and as always – let us know if you see any ... snow(!) today!
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]]>1. When will Denver see its first freeze of the season?
Denver officially hit 32°F on October 25th, marking its first freeze of the season. This is about two weeks later than the average first freeze date for the city. However, that was DIA and many locations in the area have yet to experience a freeze, with some potentially setting records for the latest first freeze in decades.
For those locations that have yet to freeze, this is pushing the limit in decades. We ran the numbers through 10/27 and here are those locations that have set a record latest freeze or potentially will this week in two different timesteps: Since 1990 and since 1970. Blue marks indicate 2024 set a new record. Red marks indicate 2024 is threatening the record.
2. What kind of weather can we expect for Halloween week?
After a mild start to the week, temperatures will drop significantly beginning Tuesday, with the coldest day expected to be Wednesday. Wind will be annoyingly strong for many of us. A storm system moving in will bring rain and snow to the state, along with much cooler temperatures. We expect the first widespread freeze for the metro areas/Front Range by Thursday morning.
Temperature timeline for the Front Range:
3. Will the cold weather bring snow to Denver?
While the mountains are expected to receive significant snowfall, with some areas potentially seeing over a foot, just a bit of precipitation is forecast for Denver. There is a slight chance of showers today through Wednesday - a brief snow burst on Wednesday morning, with possible accumulation and some slick areas for the commute and morning. We'll watch for trends related to this closely today, and pass along an update on Wednesday's snowfall potential for the urban corridor if need be.
A timeline for Denver:
A timeline for Colorado:
Potential snowfall totals for Colorado:
We'll watch for trends related to this closely today, and pass along an update on Wednesday's snowfall potential for the urban corridor if need be.
4. What will the weather be like for trick-or-treating on Halloween?
Halloween is currently looking cool and mostly dry across the state. Highs will be in the 50s and 40s, so plan for chilly temperatures, especially as the sun sets Thursday evening.
5. How cold will it get overnight during Halloween week?
Overnight lows are forecast to dip into the mid to upper 20s for Halloween morning, with some models predicting below-freezing temperatures through the weekend. This will be the first freeze for many areas.
6. What is causing the sudden drop in temperatures?
A strong trough is moving into the Four Corners region, bringing with it a significant mass of cold air. This will result in below-average temperatures across the state, particularly Wednesday through Thursday morning.
7. Is there any more snow in the forecast after Halloween?
Another storm system is possible early next week, but the details are still uncertain. We are monitoring its development and encourage you to stay updated on the forecast, which leads us to...
8. Where can I get more information and updates on the Denver weather forecast?
We'll watch for trends related to this closely today, and pass along an update on Wednesday's snowfall potential for the urban corridor if need be. For the most up-to-date information and detailed forecasts, you can subscribe to Weather5280 and sign up for our email alerts.
Many locations have yet to freeze and this is pushing the limit for some stations in decades. We ran the numbers through 10/27 and here are those locations that have set a record latest freeze or potentially will this week in two different timesteps: Since 1990 and since 1970.
For today, another mild one on tap for the Front Range before we cool off about 1o to 15-degrees on Tuesday, then further yet Wednesday. This is thanks to an incoming storm system that will bring rain, snow, and cooler temperatures to the state for much of your Halloween week. We discussed this for Insiders last week.
The ridge in place over the weekend stays in place today, at least for the early part of the day, particularly for Eastern Colorado. For Western Colorado, expect to start feeling the impacts of this change later in the day today, with a Winter Weather Advisory going up for the high country west of the Divide this evening, extending through Wednesday morning.
Here is the placement of the trough Monday morning:
By Wednesday we see that trough centered over the Four Corners region, ushering in quite a bit of chilly air, and of course some rain and snow for the state.
Surface temperature anomalies for Wednesday morning show temperatures well below average across the state, with the warmer than average anomalies parked on the ridge that builds in across the East:
The forecast calls for a high of just 45°F on Wednesday in Denver, dipping into the mid to upper 20s for Halloween morning – bundle up! Some models keep overnight lows below freezing clear through the weekend, so we'll see how these current forecast lows hold up as we move through the week.
Of course everyone wonders if that midweek chill will bring with it rain or snow, and how much of that would linger into Trick-or-Treating on Thursday.
We'll answer the second question first. That is, it looks like whatever wet weather we manage this week east of the hills should be wrapped up by Thursday. Highs will be in the 50s, so a chilly day, particularly as the sun sets Thursday evening, so plan accordingly!
As for the first question... well, the track will be pretty good for some snow at higher elevations over the next few days. As we mentioned above, a Winter Weather Advisory goes into effect this evening, with some locales likely to see upwards of a foot of snow before all is said and done Wednesday evening.
As you can see below, only minimal precipitation makes it east of the hills, mainly Wednesday morning. A few models show at least a brief burst of snow pushing across the urban corridor Wednesday morning, we'll need to keep an eye on that potential. The greatest potential to see some flakes looks to be along the foothills adjecent to Denver, and the Palmer Divide. Little accumulation, if any, is expected at this time.
Here is the snowfall forecast through Wednesday:
In short
Much cooler weather on the way after today, with the coldest day being Wednesday. High country snow kicks in tonight, and continues through Wednesday, with upwards of a foot possible for the highest terrain.
Halloween is looking cool, but mostly dry across the state.
Long range
As we discussed last week, this system will be followed by another as we move into the first days of November. There's a lot to come together for this next system, so plan to keep an eye on the forecast as we head later in this week (sign up for email alerts) in case we finally manage to piece together a storm. Not convinced just yet, but about as much potential as we've seen yet this fall. I know that doesn't mean much! 😆
Here is a look at the city's average temperature from September 1st through October 22nd with the peak being 2024.
From that, here is a list of the top-10 warmest periods on record for fall to date.
The warmth ahead is up to 17° warmer than average for the time of year. Here is a look at those temperatures - the daily highs and lows.
For Sunday and Monday, we near record territory. Those records are 83° and 82° respectively.
You may also see that there is a temperature dip coming to end this week. That's a little wave moving overhead that will switch wind enough (gusty at times, too) to push in slightly cooler temperatures but without much of a chance for moisture. In fact, here's the precipitation map for the next three days.
Now, go back to that temperature forecast and look at next Tuesday. See that temperature drop? Well, we have a (as of data through this morning) substantial trough to dig in across the Western U.S. This means colder weather and moisture can spread throughout the area - fitting for a Colorado Halloween, eh?
Luke writes more about next week's snowy impact for our Insiders here:
We are running stats on the latest freeze dates in the last 35 years, and we'll be back with a new post to talk through those later this week. For now, these are the stations that have already set their latest freeze since 1990 and many more stations, including the metro area, will likely be added to this before our first freeze hits.
This map represents data since 1990.
That data and an update on possible snow before Halloween coming your way next. Make sure you are on our list to get emails as we publish new content.
]]>Wind gusts may top 50mph with this energy as it scoots overhead. The same energy that has dropped up to 11 inches of snow on parts of the high country.
This is Winter Park this morning:
The winter weather advisory calling for slick travel will expire midday.
No advisories in place for the metro area, just some wind and a few thundershowers (perhaps some hail in the strongest cells). As far as rainfall chances, they are mostly until the early afternoon.
Here's a series of images showing the progression of the showers today.
As the sky clears, it does remain a chilly day but warmer and drier days are ahead of us. Some details are below...70s return quickly!
The next snow/rain maker may arrive just before Halloween...how fitting. Don't miss out on those updates and subscribe today, we email you when we publish something new.
]]>The layman's summary: A cold front is about to hit, meaning it'll be much colder today through tomorrow. With this system comes widespread rain and snow to Colorado this evening through Sunday morning, with the snow staying in the mountains for the most part. Heavy snowfall, talking feet, will hit the southwestern mountains. Then, we get warmer with drier conditions returning early next week. Here's a timeline of the shower activity:
If you are worried about the potential frost or freeze for your area, here's a quick look at the possible frost vs freeze zones.
In the weeds
The trough responsible for delivering this change to our weather has dug its way into the Great Basin this morning and is already delivering rain and snow to parts of the state this morning.
Its not forecast to make much eastward progress over the next 48 hours as it drops into Arizona tonight and stalls. Eventually it will move northeast as we head toward the latter half of the weekend/early next week, but much weaker.
The position of this trough through Saturday looks just a bit too far southwest for Northeast Colorado to really capitalize on moisture. For Southern Colorado, a much different story, with some really good beneficial moisture on the way it appears.
The blend of models (below) shows from 0.5 to upwards of 2.0" of liquid for parts of southern Colorado through early next week! Some of that will make it into the Denver area, but unless things change, totals will be much lower north of I-76 or so.
Of course some of that's going to fall in the form of snow. And in some cases, a lot of it! For the mountains of southwest Colorado a Winter Storm Warning is in effect already, and extends through noon Sunday. Places like Wolf Creek Pass could see 1 to 2 feet of early season snow over the next couple of days.
...WINTER STORM WARNING REMAINS IN EFFECT FROM 6 AM THIS MORNING TO NOON MDT SUNDAY...
WHAT...Heavy snow expected. Total snow accumulations between 1 and 2 Feet. Winds gusting as high as 45 mph.
WHERE...La Garita Mountains Above 10000 Feet and Eastern San Juan Mountains Above 10000 Feet.
WHEN...From 6 AM this morning to noon MDT Sunday. *
IMPACTS...Travel could be very difficult to impossible, especially over Wolf Creek Pass.
And here's a look at our snowfall forecast:
For the northern urban corridor... the biggest impact may be the temperatures. Highs in the 50s today and tomorrow with overnight lows in the 30s, before we begin a warming trend into next week.
As for precipitation, not a horrible look if you live along the Palmer and south. Places like Colorado Springs could eke out some good moisture before things are said and done later this weekend. The blend of models shown above has 0.5 to 1.1" of precipitation along and south of the Palmer Divide, with totals generally less than 0.3" north and in some cases, no appreciable moisture.
It's worth noting that some high-resolution data is a bit more bullish on snow potential for the foothills southwest of Denver and the higher terrain of the Palmer Divide.
The snowfall gamblers are not picking up on much of a chance for the metro areas, but we did filter down to Castle Rock and Monument, two spots that have at least low-end snowfall chances.
The latest HRRR shows good snow for the Pikes Peak region, with perhaps some sneaky totals as you get southwest of Denver and up in elevation.
Similar to nearly all guidance, however, it shows the bulk of the precipitation for Eastern Colorado falling along and south of I-76, with not much for Denver, but upwards of 1.0" as you move southeast of the Mile High City, through the Colorado Springs area, and the – always dry? – southeast plains of Colorado. We'll take it!
Keep an eye on the sky this weekend. If your travel plans take you south, consider delaying or plan for rain and snow over the next couple of days. Here's the travel impact for this storm.
While it's not looking like a widespread hard freeze for lower elevations at this point, certainly some of the coldest air of the season over the next couple of days, and perhaps some frosty mornings from select locations Saturday and/or Sunday. Let us know how cold (or lack of cold) you manage to get this weekend!
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]]>We've still got a significant pattern change loading up as we close out the work week. A powerful trough looks to dig into the four corners region, bringing widespread rain, snow and much colder air starting Friday.
Key messages for this storm
1) The trend has been to keep the core of this system's cold air too far west for significant Front Range snow.
2) It's still far enough east to provide beneficial rainfall places like Denver, Colorado Springs and parts of the eastern plains.
3) Mountain travel will be tough and potentially dangerous this weekend, ESPECIALLY over the San Juans.
4) It will be much colder, especially Saturday where highs may only get into the 40s for many along the Front Range
Timing the storm
Colorado will begin to see the influence of this storm as early as Thursday with rain and snow beginning to fly in the mountains. As the storm begins to pivot east, we'll begin to see moisture move into eastern Colorado, especially Friday night and through the day on Saturday.
If you have plans this weekend, Saturday is likely going to be a cold, raw day to be out and about, especially for areas south of the Palmer Divide. Lingering moisture is expected on Sunday with mountain travel slowly improving.
From Friday night through Sunday, upwards of 0.5" to 1"+ worth of liquid is possible across much of the state. Areas over southern Colorado looked to be favored for more moisture due to the track of the low-pressure system.
Will there be any snow out of this system for Denver?
It will be tough... but some flakes aren't out of the question. As it stands now, the best chance for snow will be in the mountains Friday into Saturday, with some slushy accumulations possible on the Palmer Divide and on the west side of Colorado Springs.
Low temperatures on Saturday and Sunday are most likely to hover in the mid to upper 30s and low 40s at the lower elevations. Shifts in track/strength of this system could certainly influence snow chances at this range, and with the system still 3-4 days out, some changes are still possible.
We'll have more specific details about this system in the next few days... for now, let's keep fingers crossed that moisture prospects remain good! Subscribe now and we email you our updates...easy peasy.
]]>We briefly discussed a possible pattern change around the 18th in one of our posts earlier this month -- and like clockwork, looking upstream is at least going to try to pay potential dividends.
Breaking down the large scale pattern: for now, we stay under the influence of high pressure, keeping things dry and warm for most of this week. By Friday and Saturday, we will start to see changes to our weather.
A strong push from the pacific jet stream will crash onshore of the northwest US, bringing cold air to most of the western states. Models are a bit back and forth on how much (if at all) that energy is able to spin up a low pressure system in the Rockies. If you've been weather model watching, you'll know the global models (GFS, GEM, and EURO) have been printing out everything from heavy rain, heavy snow, our coldest air so far this season, to at times not much of anything at all, and everything in between that.
We're still quite a ways out but we're attempting to get a clearer image of what might play out later this week.
The most important aspect will be the placement of the potential trough.
The three images above are possible outcomes of this trough Friday into Saturday. The GFS (American), GEM (Canadian) and EURO (European) all show a big "bowling ball" type trough that spins itself out between Arizona, California and Nevada... never quite getting the worst of the system into our backyards in Colorado.
The data above is just one sample from each of those models.
We've talked about ensemble modeling before, which takes an average of a data set from these models. The latest from the Euro's ensemble members shows the center of troughing further north towards the four corners. That indicates that there still is some background data skewing the average further north.
Regardless... the data are going to see big shifts this week as the models try to pin down an end product.
Now, let's say the ensemble has a good idea on the track of this storm... what is it printing out in terms of snow/cold potential? Well, for a first potential snow, it's not too shabby. At this range, this seems like a storm that would slow down mountain travel for sure... and potentially lead to a coating of snow for the front range. Some rough estimates on timing would put this storm in our area some time between Friday evening and through the day Saturday.
The GEFS is particularly bullish:
The Euro is less so, and perhaps a bit more in line with its deterministic as of today – showing about a 30 to 40% chance of 1" of snow in Denver this weekend, which isn't epic, but would count for the first snow event of the season if we could pull it off!
We shall see! Friday is Denver's average first snowfall, so if we can pull it off it'd be right on time!
As for those low temperatures this weekend, depending on strength/placement of the low, frost/freeze potential will need to be monitored. Above is the "most likely* scenario as of now for coldest temperatures by Saturday morning. Plenty of 10s and 20s in the mountains, with 20s and 30s along the front range by Saturday morning.
So, quite a bit to figure out still, but at least the weather is trying to be interesting... We'll continue to update throughout the week as this storm approaches the region! Subscribe to the e-mail list to get the next article as soon as it comes out!
]]>Satellite imagery this evening is stunning, to say the least.
After undergoing an eyewall replacement cycle earlier today Milton has again strengthened into a category 5 monster in the the Gulf of Mexico.
While it's expected to weaken slightly Wednesday before landfall, Milton is forecast to remain a major hurricane as it slams the west coast of Florida Wednesday night.
This evening's key takeaways from the NHC:
1. A large area of destructive storm surge, with highest inundations of 10 ft or greater, is expected along a portion of the west-central coast of the Florida Peninsula. If you are in the Storm Surge Warning area, this is an extremely life-threatening situation, and you should evacuate today if ordered by local officials. There will likely not be enough time to wait to leave on Wednesday.
2. Devastating hurricane-force winds are expected along portions of the west coast of Florida, where a Hurricane Warning is in effect. Milton is forecast to remain a hurricane as it crosses the Florida Peninsula and life-threatening hurricane-force winds, especially in gusts, are expected to spread inland across the peninsula. Preparations to protect life and property, including being ready for long-duration power outages, should be complete by tonight.
3. Heavy rainfall across the Florida Peninsula through Thursday brings the risk of catastrophic and life-threatening flash and urban flooding along with moderate to major river flooding, especially in areas where coastal and inland flooding combine to increase the overall flood threat.
While all eyes are on Milton in the Gulf, and Florida over the coming days, our weather remains mostly unremarkable, but warm.
The average high for this time of year in Denver is just about 70-degrees, and we'll be a good 10 to 15 degrees warmer than that in the Mile High City through the end of the week. Here's a look at forecast highs departure from average from across the region:
You'll notice by the second half of the weekend we start to get closer to those average daily highs (woo!) with even a few cooler-than-average values showing up by next Monday across Nebraska and Kansas.
I'm cautiously optimistic this really means cooler weather for us. The European model certainly agrees with this idea, dropping highs into the 50s and 60s by early next week (and hey, evening a FREEZING overnight low!), but the brunt of the trough may try to pull east of our area, so definitely not a done deal.
Nevertheless, here is the European model forecast for Denver through next Thursday:
With the ridge we've been cooking under retrograding a bit as a large trough carves itself out over the eastern U.S.:
Perhaps pulling some cold (cool? near average?) air down along the Front Range as it does.
Thoughts to all those in the path of Milton over the next several days, and we'll check in soon.
]]>Both cities have a chance to see record high temperatures broken for the date tomorrow. For Colorado Springs, a high of 85 would break the record of 83 (2020). In Denver, 86 is the record, set back in 1997.
The ridge looks to flex to start this weekend, with a weak trough passing overhead Monday, with the ridge strengthening again late next week. Getting into October, we tend to dry out the atmosphere and kick up a bit more wind.
With that, we're going to see fire danger ramp up on Saturday. Gusty winds between 20-30 mph, with relative humidity values in the single digits combined with drying vegetation will create conditions for rapid fire spread and growth. We're also seeing this threat extend all the way up to the eastern flank of the continental divide.
The latest drought monitor is starting to get a bit bleak for us too. A large chunk of the Denver Metro and foothills are now considered to be under "severe drought".
WHEN WILL WE FINALLY SEE THAT BIG PATTERN CHANGE?...
It may very well be another 2 weeks of mostly above normal, dry weather for the state. The main storm track looks to stay locked up north in Canada with the ridge holding strong through mid-October.
That loop above isn't just the next 7 days either. That's a 46-day loop! We see the ridge finally begin to buckle by late October and especially into November. At some point, growing snowpack and shorter, cooler days to the north will allow the weather pattern to moderate down a bit... but it seems like it will take its sweet time this year.
Some other indices are showing some signs of life too. We've shown you an MJO chart before. Essentially, you want all those lines to cycle into the upper-left quadrant of that chart (zone 7 and 8) for Colorado to have a better chance at active weather.
Translating that mess of lines above, we're basically seeing the MJO cycle towards 7 and 8 around October 18th, which means we could potentially see activity ramp up around the 3rd week of October.
No weather data is ever a total guarantee, but we'll take whatever we can get at this point! We'll walk you through changes going forward... but for right now, plan on hot, dry October weather sticking around.
]]>Record-setting on a number of tallies: Sunday's high hit 92°, which ties the daily record high for September 29th, first set in 1892. We've had the 4th most 90° days this year, with the tally now at 64 days; the most on record is 2020 with 75. This also marks the hottest temperature ever recorded this late in the year. Here are the record-latest 90° days.
It appears that the city is not quite done with 90s as it will make a run at another one this Wednesday. If we hit 90°, that'll be the latest occurrence on record and will set a daily record by two degrees. Our WeatherBoard shows how far from records select cities will be this week.
Check out Grand Junction, possibly setting records every single day. Denver has a chance to set Wednesday and Saturday's records.
Cold Front Arrives Today: Although today cools off leaving tomorrow one of the coolest days this week, it clearly doesn't last long. Plus, with very little moisture in the outlook we may catch some wind to further increase the fire danger across the region.
The forecast for the week:
Sure, we've been teased with model data that suggests a cool off is coming with rain and snow but that has remained just a tease; no viable signs of a major weather change anytime soon. Soon, as in within the next seven to ten days.
]]>That record for the latest 90° days in a calendar year since the 1800s may see a very late 90° arrival this Sunday and perhaps the middle parts of next week, too.
Although Sunday's forecast high of 90° will put us on the list for the fourth-latest occurrence, we may be able to hit 90°+ next Wednesday, which would be the latest 90° day on Denver's climate record.
We'll see if we can actually record that 90 next week; it'll be close. Here are the daily highs and lows throughout the week.
Although we stay mild across this stretch, it may not be totally dry for a few of us. There is a bit of rainfall coming today to the high country. Here is an animation of those thundershowers/storms.
Beyond this weekend, perhaps a hint of another fall-like weather producer next weekend, the 5th/6th, that can produce rain and snow and perhaps our first frost and/or freeze for many—probably not the city itself, although something to watch.
Just for kicks and giggles, here is the snowfall outlook way out there...
We know, we know...
We will keep you posted next week. In the meantime, have a great weekend - it'll be a beauty.
]]>Here's a quick recap of the weekend moisture, for Denver it was the wettest day since April and nearly set a daily record.
Statewide, the totals observed are shown. There's a clear pocket of heavy moisture across northeastern Colorado, and some heavy pockets in the mountains, too.
Of that moisture in the high country, we have seen some awesome snow pictures. Here are some from Loveland Ski Area.
Okay, let's look forward. For the rest of this week, temperatures warm. We are likely to hit 90° by Thursday. This will threaten the existing record, which is 90° from 2010.
Should we indeed hit 90, how late is this historically? Denver's latest 90° day is October 1st, which happened in 1892. This will be the 8th latest 90-degree day on record.
With the warmth, we have dry days too. There is a hint of a change in the first week of October but we can focus on those changes in future posts. For now, enjoy the week.
]]>Ensemble guidance still looks healthy enough (relatively), but even here the trend has been drier. And frankly, with the drying showing up in the operational models this morning, I'm not sure this will be enough to save us. What's new?
The European ensemble model's QPF dropped from roughly 0.9" for Denver yesterday to 0.6" overnight, with high-end potential now much more reasonable looking (1 - 1.5" rather than 2"+).
The shift in the operational models has been even more dramatic.
Take a look at the European operational model from yesterday morning's run (right) to last night (left). A notable drop in QPF, and a notable southern shift as well – the more recent run nearly dry up north of Denver, and only 0.3 - 0.4" of precipitation for Denver vs over an inch!
A similar trend is evident in the GFS. First, here's the GFS from yesterday morning. It shows roughly 0.8" of water across the Denver area, with a swath of 1"+ totals from southeast of Denver extending northeast across the plains:
This morning's run has just a very narrow swath of heavy precipitation from south of Colorado Springs extending northeast, with just 0.1" to 0.3" of precipitation for the Denver area!
And the trend from the last 6 runs from the GFS showing QPF pretty systematically being cut across the northern extent, with the focus of heaviest precipitation setting up across the Texas/Oklahoma panhandles and extending east/northeast:
The high-resolution HRRR shows roughly 0.1" to 0.5" for the northern urban corridor, with a notable dry slot hurting totals over Denver and points southeast. We again see the southern bias of the heaviest precipitation from this event across extreme southern Colorado and the Panhandles, but someone across northeast Colorado still in the running for some meaningful QPF. This 0.1" to 0.5" may ultimately be the best forecast range for most communities along the I-25 corridor.
A wait and see
Trends aside, we are right up against this thing so let's see how it all plays out. The drying trend in the modeling, and a rather potent dry slot pushing into the state now definitely has us concerned, with a very real bust potential on the table.
As our system moves in later today we'll have quite a bit of dry air to overcome before rain gets going across the region as evident by the most recent water vapor imagery showing a lot of dry air wrapping around the low. With any luck at all we can saturate things in earnest this evening and take advantage of our upslope flow before it's too late for some better-than-currently-advertised precipitation along the urban corridor!
As for timing, not much change there. It still looks like our best precipitation chances are from late this afternoon (perhaps evening if dry air is stubborn!) through the overnight hours. We dry our Sunday afternoon through most of Monday before the next system swings through:
Snowfall
Still some good mountain snowfall on the table, especially for the higher peaks southwest of Denver. A lack of heavier precipitation would hurt snowfall potential for the northern Front Range mountains, but again, let's see how this all plays out.
And FINALLY, enjoy the nice cool fall weather, moisture or a lack there of! Sunday should see highs in the 50s to low 60s (cooler end of range if we get heavier rain, warmer if we don't) with 70s in the forecast through Wednesday for the Denver area!
As always, let us know how things shake out in your neck of the woods as things get going later today!
]]>Overall no huge shifts in the overall look of things we've been tracking all week. We still see, broadly speaking, a good early fall cool down on the way for the weekend and widespread moisture across the region. The devil is in the details, and some of those details remain a bit fuzzy.
In brief: We have a wet system to move through this weekend, giving heavy rain and snow to much of the region along with cooler temperatures. You will notice these changes progressively Saturday into Sunday with the first fall-like system to hit. All the details, including timing is below.
The latest ensemble guidance continues to show above average precipitation for our area through the middle of next week:
With the 5-day average temperature anomaly (in Celsius) ending next Wednesday evening showing the core of the colder-than-average temperatures across the CONUS focused over Eastern Colorado:
While large-scale features have been generally steady, we've seen some pretty wild swings in potential QPF (precipitation) between models and model runs which leads to a continued medium to higher uncertainty with regard to how much moisture we ultimately end up picking up. We'll discuss this further below.
Temperatures
Temperatures will again be warm today, with highs in the upper 80s for Denver. While today's high will be about 10-degrees above average for the date, tomorrow's high in the upper 60s will be about 10-degrees below average for the date. Not exactly frigid temperatures on the way, but a notable cool down for sure!
Here's the latest temperature forecast for Denver, with all cities along the urban corridor looking to see a similar temperature profile over the next couple of days:
This system shouldn't bring freezing temperatures to lower elevations, but lows in the 40s Sunday and Monday, combined with the anticipated rain Saturday night into Sunday, will make things feel quite brisk and fall-like!
Rainfall forecast
I wish confidence around how much water to expect this weekend were higher, given it is Friday morning already. While the setup supports a good amount of water, there's still some guidance hedging on the dry side and perhaps even some concern that the greatest QPF misses us to the south tomorrow. We'll see.
Ensemble guidance shows roughly 0.8" to 1" of precipitation from Colorado Springs north through Fort Collins this weekend, with perhaps a bit more added to that early next week. You'll see in each of the charts below, however, a pretty good spread in the ensemble members (0.3" to 2.3" for Denver for example), with a healthy number of those members favoring the lower-end totals. The mean for Denver is 0.9".
A similar idea for Colorado Springs, with a mean of 0.8":
And a bit lower in the means further north across the Fort Collins area:
So, a widespread possibilities of outcomes, but a healthy rain event is possible should things align right, with even some high-end potential (more then 1.5" in spots) still on the table. As for bust potential? I think it's highest the further north you go, you see that a bit in the means for Fort Collins, but some models are pretty dry up that way...
Here is our latest precipitation forecast map, we'll see how today goes and adjust as needed. Keep in mind this represents the most likely total in the event you get the heavier showers:
Snowfall forecast
We have some Winter Weather Advisories posted for the highest terrain of west-central Colorado. Pretty exciting! Places like Pikes Peak, the Western Mosquito Range, and the Sawatch Mountains could pick up from 5 - 10" of snow, mainly above about 10,500 feet.
Closer to the metro areas we could see snow as low as about 8,500 feet Saturday night, especially if the heavier precipitation sets up as we see on some modeling. Should that happen, many Front Range foothill communities will see their first snow of the season this weekend!
Some of the high-res models that are coming into range are hinting at this as well. We see the HRRR below through early Sunday morning with some accumulating snow west of Denver and Boulder, with precipitation still falling at this hour. Should this trend continue, look for potential winter weather alerts to be posted by the NWS in Boulder.
Here's our latest snowfall forecast:
Timing and impacts
Cooler air arrives for your Saturday, but the best chance for rain will hold of until later in the day and overnight into Sunday. Here's the timeline for precipitation along the I-25 northern urban corridor, with rain getting going a bit earlier across the Colorado Springs vacinity.
Here is the HRRR at 2pm Saturday:
With widespread rain and snow across the high country by 7pm:
And this model not really filling in along the urban corridor until closer to sunrise on Sunday (though it might be a bit slow on that):
This will be the first snow event of the season for many areas, so if your travels take you west this weekend consider delaying or getting a jump start today or early Saturday. The wet weather will work its way east of us Sunday afternoon, with a quieter Sunday evening on tap as things look today.
]]>The way things look to shake out right now: There will be an initial wave that passes through Colorado Saturday night into Sunday which has the potential to bring an inch or more of water content from the foothills to the eastern plains.
Folks above 8,000 ft could see snow, which could be significant in spots if the moisture lines up properly.
As that wave exits, another northern stream wave could follow, leading to additional moisture early next week. (Both parts of this equation are still pretty uncertain given we're still early, but at the very least, the weekend part is starting to become a bit more clear).
Taking the deterministic EURO at face value, it doesn't seem like a completely unreasonable scenario. A slow-moving pacific system can do work around here, even if it's out of the norm for this time of year.
Below are the solutions from the EURO and GFS ensembles. Both are showing similar solutions with significant moisture across eastern Colorado.
And overall a healthy looking above-average swath of precipitation from central Colorado east across the central plains into early next week. Yes, please!
The track of this system will be important in determining if this is more of a north or south of the Palmer Divide type-storm. The track this time of year can be a little less volatile since the jet stream is not quite as active just yet.
This also means that this system won't have a ton of cold air to work with – so for lower elevations, this is almost certainly a rain in the 40s and 50s type of event. However, areas above 8,000 feet could see some heavy wet snow. EURO ensemble and deterministic models show snow totals of 4-12"+ for our higher elevations.
Temp trends for Denver and Colorado Springs do a good job of telling the story. We look to completely flip the script with a nearly 40 degree temp drop between Friday and Sunday.
There's not a whole lot of other detail to get into with this upcoming system... While ensembles are in reasonable agreement that some good moisture is on the way, the devil of course in details. Given how much movement we've seen in the operational modeled storm track the last couple of days, this could turn into a headache to forecast as we move towards the end of the week. As mentioned above, a few focus the moisture north, some south, and placement of course has big impacts on who sees how much water this weekend. Bottom line: We'll definitely have more updates for you in the next few days.
]]>Here's a look at the timing and placement of showers and thunderstorms in the next two days.
Here is how that will look hourly for Denver:
For the metro area, the peak in rain chances happens from Tuesday's lunch through dinner.
The days will be gustier anyway, but nearby storms will add to the wind gusts - don't forget your patio umbrella you may have left open this weekend.
I'll show you total moisture in a moment, but it should be noted that we do need to watch for potentially strong and damaging thunderstorms - wind mostly. This is more likely over the state's northeastern corner.
Okay, onto potential rainfall totals. IF IF IF you get the rain, you could be looking at more than 2" for the Southwest, more than 0.5" for parts of the West and East, and not likely to exceed a tenth in the metro areas...that's quite a doughnut hole there on the city.
And for snow lovers we have a hint of snow for the peaks.
Again, per yesterday's post we are moving into a more active period of weather. Look for more moisture, snow chances, and much cooler weather to arrive into the state throughout the next week.
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