We continue the cool down of SST anomalies across the ENSO region of the Pacific, with El Niño quickly fading and La Niña on the way by late summer if not before. El Niño has weakened a lot over the last several weeks, with some indicators suggesting we are already at a neutral or near-neutral ENSO state. The ENSO 3.4 region which was 1+ degrees C above average all winter has neutralized quite a bit since April 1st, and is nearing that zero line: You can see the cooler than average SSTs real

We've been locked into El Niño conditions since last spring. Sea surface temperature anomalies have been much above average in the equatorial Pacific Ocean, but have recently really started to cool off. The El Niño peaked in late December and early January, and continues to weaken. Here is the equatorial sea surface temperature anomaly animation, during the past 90 days. This graphic represents the depth (0-450 meters) and east (120 degrees E) to west ( 80 degrees west) across the equatorial P

Feels like fall today, cloudy and light rain at our headquarters with football on the tv so that must mean that fall is in the air. For the week ahead, Denver and the Front Range will be considerably cooler with 60s and 70s versus the 80s and 90s, which will be 5 to 15 degrees cooler than normal from day to day this week. No, that low of 48 for Saturday isn't the first of the "season," we've had a couple temperatures that cool in the past month. The last time the city had a high temperature i

Earlier this year, we were still in the grip of La Niña, but from April through August, we saw a transition toward El Niño. El Niño began to develop in the spring and by summer had a more powerful grip on the atmosphere. There are multiple ways of measuring how strong the grip is, whether that be in the atmosphere, ocean or a combination of those two. The atmosphere's behavior is shown here, by one such metric called the SOI, where positive values are La Niña characteristics and negative valu

It has been a little over a month since we last looked at our old friend , so it's time to see what the (incoming?) El Niño is up to. The graphic below shows current sea surface temperature anomalies, where yellows/reds indicate above average surface temperatures and blues below average. A few things to note, before I show you what it looked like earlier this year: 1. The warmest water in the ENSO region is centere

Obviously, it's way too early to create a specific winter forecast, but as we sit in the heat, there is value in looking at where this current Niño sits, its forecast, and how that forecast can be compared to past years. Let's have that discussion - video: For additional reading about El Niño and Colorado: A Closer look at What El Niño Means for Rain and Snow in ColoradoThere has been a great deal of interest in El Niño recently, following multiple authoritative statements that it is on track

Just a short update on the current status, and where we are likely heading with El Niño. First, here is a look at the current sea surface temperature anomalies: Very  warm water just off the west coast of South America, and that warmer  than average water extends westward across the equatorial Pacific Ocean. Overall, the Pacific Ocean continues to warm, despite a few spots that  are currently cooler than average. All of the  forecast models continue to develop this episode further, during th

June is upon us and is off to a wet start across parts of the plains and mountain west where scattered to numerous thunderstorms impacted day-to-day operations. As of Friday June 2nd, a number of flood alerts paint the map from Montana to Wyoming and Nebraska, and from New Mexico through Texas into Oklahoma. This is following a month of wet weather in the same zones. May 2023 was an impressive month for precipitation along the Rockies and adjacent plains. Sadly, however, deficits grew for much

The past 30 days have proved to be wetter than recent times in some areas, but not for everyone. Folks in far Southeast Colorado, Southwest Kansas, southward into the Texas Panhandle really benefited from a late April storm. While it was by no means a drought buster, it was certainly a big help. You can see that in the map below, with greens indicating above average precipitation over the last 30 days, and browns below average. The Pacific Ocean has been warming up too. The equatorial Pacific

Good morning, La Niña is done! Now onto a neutral pattern before El Niño likely establishes itself. This may come with cheers or jeers depending on your perspective and how each affects your operations. Let's walk through some brief details about where we are and where we are headed. La Niña is gone in the sea surface conditions – the ENSO region has warmed quite a lot. Right now, the westernmost region (4) is the coolest and the easternmost region, (1.2) is warmest. Moments of La Niña contin

It's increasingly likely that La Niña is very near the end of this latest phase as the likelihood of La Niña conditions this spring falls to 14% in the latest CPC forecast released this week. Here is that forecast, shown as the probability of ENSO phase going forward through three-month seasons. For March-April-May we have an 82% probability of neutral conditions. That forecast is based on multiple model and statistical projections for sea surface temperatures (SSTs) within the ENSO 3.4 regio

The weather we have experienced for the past several weeks lines up very well with what we thought winter would be like... a more active finish than start and middle. During the past 60 days, areas along the Palmer Divide / I-70 Corridor have benefited the most –– running well above average for precipitation during this time: Most areas of Colorado have received at least average moisture, with a few small exceptions. Mountain areas have also been doing well, especially the parched San Juans a

The recent weak La Niña episode that prevailed since last fall, has been all but erased. The animation below shows the sea surface temperature anomaly trend during the past several weeks. Blue colors mean colder than average sea surface temperature anomalies, while orange/red means warmer than average sea surface temperature anomalies. Notice how all of the blue color in the ENSO regions has pretty much disappeared. At the same time, we have seen some much warmer than average water build off

In a good year, August can be one of the wetter months of the year for many of us in Colorado. Right on schedule, we've had a recent surge of monsoon moisture. This is always a good thing, especially when the amount of flash flooding we've seen of late has been relatively low. Below is a look at rainfall totals for the past three weeks. Overall, a pretty good look for the state. Northwest Colorado is hurting the most, with those of us living along the northern I-25 urban corridor also missing o

La Niña Transition Let's see how our transition from El Niño to La Niña is going. We've talked about this a lot during the past several months , and here is a look at the current sea surface temperature anomalies: The blue shading that you see extending off the west coast of South America represents cooling taking place in that part of the Pacific Ocean. However, while that is happening the rest of the Pacific Ocean is still quite warm. This is especia

If you frequent Weather5280 this the title of this post is not breaking news. In fact, we've been talking about this transition for several months. Today I wanted to provide an update for those that are interested, and show what history and various computer models are suggesting. First, let's look at the recent sea surface temperature anomaly changes over the tropical Pacific Ocean: The animation above shows the changes that have taken place at the surface since early February. Notice th

The USDA announced Friday that Colorado's mountains experienced the driest February in 30 years. The data was measured from the Natural Resources Conservation Service Snow Telemetry (SNOTEL) network of weather stations. There are 114 such SNOTEL sites that mostly span the mountains; only a handful are at the lower elevations. At the combined San Miguel, Dolores, Animas & San Juan river basins the stations only received 35% of the average February precipitation. Statewide mountain precipitation

As we've discussed for some time now, the western ridge will finally begin to break down this weekend and allow for a much stormier weather pattern to set up across the west. Take a look at the 500mb pattern across the United States today: Compared with early next week: Quite an impressive flip, and one we've been waiting for for some time. What this will equate to is a period of very wet weather across California and the Pacific Northwest. And, unlike some of the more active periods earl

Ah El Niño, the winter is closing in on you my so-often misrepresented phenomena. All those media headlines promising that you'll do this, that, and the other, and for what? Yes, that's right, you never promised one thing or another, other than to be a warm area of ocean in the central and southern Pacific and that you will attempt to shift seasonal areas of heavy versus light precipitation. That you have. No two El Niños are alike For the current winter, December and January (February's data

Let the great meltdown begin! After a great snowstorm this past week, many folks are wanting some warmer weather. Well, if you are one of those people that wants warmer weather, this is certainly going to be the weather pattern for you. In fact, it is likely going to be one of those weather patterns that produces some of the nicest weather we've seen in a while. Why do I think this? Let's take a look... GEFS Ensemble Mean 500mb Maps: Tuesday: Thursday: Saturday: Monday: Wednesday: Fri

JAMSTEC Update It has been a while since we have chatted about the JAMSTEC model and its forecast for the next several months. There is a reason for this. During the past several months, it has been forecasting colder than normal temperatures for Eastern Colorado. We've lamented in the past about why we didn't think this would happen (current strong El Niño and positive PDO), but figure the model was worth a look again. Why? Because some of what the model has been spitting out may be spot on...

I am not going to spend much time on the main drivers with this update. We have talked about them at length in previous posts , and I think you pretty much know what they are. We've touched on analogs in previous posts too, but not in a lengthy fashion. The main reason for that is that there really isn't a "perfect" analog when it comes to referencing the next several months. Of the analogs chosen, those years with a strong El Niño, a positive PDO, and a positive AMO

As of September, El Niño remained as the second strongest recorded since 1950. The strongest September El Niño occurred in 1997. In the grand scheme of things, 65 years of data is not all that long, so comparing our current El Niños to previous ones is not necessarily a good idea for the basis of a forecast. However, let's compare the El Niño events simply to show just how different each one of them can be. Here are the winter precipitation m

Before we move into October, here is a thought on the late summer: I have to admit that there were a lot of things I thought would happen this year with the warm Pacific and subsequent El Niño, but a failing monsoon wasn't one of them. Historically, an El Niño will enhance the monsoon season for Colorado and certainly doesn't scream drought. However, I attribute the "monsoon fail" to a very weak MJO (Madden Julian Oscillation ) signal and one that simply got stuck in a rut that perpetu

I was ready to hit publish on one post with the aim of beginning work on another. I quickly realized that perhaps the two were connected, so here is the joint post. The first blog was to add some historical perspective on a recent article published by The Denver Post regarding El Niño. The second was a bit of a reactionary agreement piece to this article in Forbes [http://www.forbes.com/sites/marshallsh