Brian Bledsoe

Last week, we talked about the current weak El Niño and how it may not only
stick around but actually strengthen later this year
[https://www.weather5280.com/blog/2019/03/21/el-nino-has-reestablished-and-might-stick-around-for-awhile/]
. Now it is time to discuss a bit further what we think the next several months
will hold.

Soil Moisture
Right now, most of the Plains are running at or above average when it comes to
soil moisture.



This is something we think will be key during the thunderstorm season. If you
put moisture in the ground during late winter and early spring, this usually
bodes well for an active thunderstorm season. Why? Well, when we start to
warm-up, that moisture evaporates from the ground adding humidity (thunderstorm
fuel) to the air. That fuel can serve to create thunderstorms during warm days
or to enhance activity as part of a system moving through. The resultant rain
charges the ground and air with moisture, so that moisture can then be used the
next day and beyond. This is a classic positive feedback mechanism. The exact
opposite occurs during a drought, with a strong and similar positive feedback
mechanism. Wet begets wet, and dry begets dry. Also, wet soil heats up less than
dry soil. So where the soil is wetter, the daytime high temperatures are cooler
and nighttime temperatures are warmer.

Let's look at a couple of models and see what they have to say.

Euro Seasonal Model

Precipitation Forecast

April


May


June


Temperature Forecast

April


May


June


The Euro Seasonal Model is our favorite long-range model, and it has been very
consistent with our forecast calling for a wet spring for many areas in the
nation's midsection. You can see it matches up well with where the soil moisture
is at or above average.

As we said, wet breeds wet. It also breeds cooler than average temperatures for
some of those areas. Likely the areas that end up the wettest.

NMME Model

Precipitation Forecast

April-June


Again, you can see that many of the same areas that are wet now remain wet
through the spring.

If we look at our latest analog package (similar years), we see good agreement
with what the models are showing above. For precipitation, a lot of positive
anomalies with most of the eastern two thirds of the country experiencing above
average precipitation in this years. 2015 remains our top analog year for now.



For temperatures, not a huge "cold" signal by any means, but temperatures near
average across the heartland, with temperatures above average on each coast:



With all this in mind, we have a couple of concerns for the next couple of
months:

 1. Flooding
 2. Enhanced severe thunderstorm risk

The added available moisture that will be utilized by thunderstorms will likely
make thunderstorms not only more frequent but also stronger. This means a
greater risk for flash flooding, large/damaging hail, and yes, tornadoes. Again,
our thinking on this is based on the fact that the available fuel for
thunderstorms will be greater this year.

Based on the current soil moisture, the forecast trend, the model forecasts, and
good analog agreement, we have pretty high confidence in our forecast below.

Weather5280 Outlook

Outlook for April through June, 2019