Weather Wise
published: April 5th 2019
by: Brian Bledsoe
April-May
outlook
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. Our top analog year for now continues to be 2015.
For temperatures, not a huge "cold" signal by any means, but temperatures near average across the heartland, with temperatures above average on each coast: