Brian Bledsoe

Current La Niña Status
The map below shows the current sea surface temperature anomalies as relative to
the global mean sea surface temperature anomaly. It is a metric that better
represents the current strength of the particular ENSO (El Niño/La Niña) phase. 

The blue shading along the equator clearly shows the presence of a La Niña. The
graphic below shows the sea surface temperature anomaly trend since November.


Since mid-November, you can see that this La Niña event maxed out around
Christmas and then again late in January. Since late January, this event has
been steadily weakening. This is pretty much right on target with how a La Niña
event behaves. It typically maxes out in late December or January, and then
weakens steadily during late winter and early spring. However, that doesn't
necessarily mean that it will completely go away by spring or during spring. The
forecast graphic below from the Bureau of Meteorology out of Australia shows the
forecast trend through spring and summer.



The one thing that bugs me a bit in the above graphic is the "sidestep" that the
trend is forecast to do from March through April. That could offer some trouble
for some of us... Beyond that time, the upward trend in sea surface temperature
anomalies is forecast to resume. Remember, the green trend line is the mean
forecast of all those gray lines. By summer, we are forecast to have warmer that
average sea surface temperature anomalies in the main ENSO region. I also
received the latest ENSO forecast probabilities from the Climate Prediction
Center. 


The graphic above shows La Niña probabilities shrinking from 95% right now, to
less than 30% by late spring and summer. Neutral probability maxes out at 70% in
April/May/June, and El Niño probability maxes out at 20% in the fall. The one
bit of worry I have is that the La Niña probability increases to 35% again by
the fall. I am not sure exactly how the back half of the year will play out, as
it is a bit too early to say. So, let's just focus on the short-term trend which
weakens this La Niña considerably as we finish winter and enter spring.

Current PDO (Pacific Decadal Oscillation) Status

The graphic above shows the PDO trend for the past year. Interesting to see that
our current value is the same as what we had in January. The current state of
the PDO is cold and will likely remain cold. For now, I am just going with the
current trend, as I see no pivot toward a warm/positive PDO in the immediate
future. While it is good that we are not seeing the tremendously cold/negative
values of 2024, the current value is still quite negative. While La Niña is
weakening and LIKELY to go away, the PDO is still cold/negative. A cold/negative
PDO is rarely ever a good thing for folks that live in the Plains. It doesn't
mean we can't see some good storms and moisture from time to time, but it
certainly stacks the deck against a "normal" pattern. Anyway, just something I
will continue to monitor closely for you...


EURO Seasonal Model Precipitation Anomaly Forecast March - August

NMME Model Precipitation Anomaly Forecast March - August

You can see from the model graphics above that there is a tendency for the
Plains to be drier than average from late winter through early summer. This
doesn't mean that there won't be storms or moisture, but the flavor of the
forecast for those brown shaded areas is drier than average. Also, I feel as
though the farther southwest you go, the stouter the dry signal will be. This
just piggybacks on the fact that those areas have been the driest for the past
couple of months. The dry signal does relax as we get deeper into summer, but
that dry signal does shift north and northeast into the northern Plains and
Midwest. Right now, it's a bit early to determine just how stout that part of
the dry signal will be. That is something I will resolve in the coming months.
However, it is something I have been watching now for quite some time. 

A quick note on the monsoon potential for this summer... Historically, if the
southwest part of the country is drier and warmer than average during the winter
and spring, the monsoonal flow from Mexico usually starts up earlier than
average. The monsoonal signal is also typically stronger than usual too. While
it is a bit early to determine if this will be the case, you can see some hints
of that in the EURO seasonal model's June forecast. Certainly something we'll be
watching for...

Seasonal Forecast Update