Welcome to my 9th annual US summer forecast. As always, when compiling this forecast for the upcoming June-August period there are multiple factors which have been taken into consideration which could influence the summer pattern. These include global and regional sea surface temperature anomalies, El Nino, MJO and rainfall distribution over the last 6 months.
Wettest Winter
Winter 2018-19 turned out to be America’s wettest winter in recorded history.
As a result of the excessive and widespread rain/snow during the winter and spring, we have only 2.33% of the US is in a drought.
Credit: weather.com
With a considerable amount of water in the ground, I expect a ground to atmosphere feedback which on the whole promotes a wetter, less hot summer.
However, more water doesn’t necessarily mean cool. Sometimes what you don’t get with air temperature, you can make up for with the combination of heat and humidity. More moisture during the summer months can lead to more oppressive days thanks to higher humidity and this could influence particularly overnight temperatures.
Yes, there will be hot spells and some could be significant. The fire season could be long and devastating due higher concentrations of flammable brush
El Nino
Wet winters followed by a developing summer El Nino can too aid a cooler, wetter summer. I believe the central US could see some unusually cool days and these cool spells could affect a broad area of the country at times.
The below graphics are a month by month breakdown of 500mb height, precipitation and temperature anomalies. The effects of a greater release of water from ground to atmosphere can promote lower pressure aloft just like dry ground can enhance higher pressure and warmer temperatures.
So, overall I believe the US has a near average to slighter below average summer with coolest compared to normal from N Plains, Great Lakes to Southern Plains. Warmer than normal for Southeast as well as West and East Coasts.
CFSv2
June 500mb height anomaly
Credit: Tropical Tidbits
June Precipitation anomaly
Credit: Tropical Tidbits
June temperature anomaly
Credit: Tropical Tidbits
July 500mb height anomaly
Credit: Tropical Tidbits
July precipitation anomaly
Credit: Tropical Tidbits
July temperature anomaly
Credit: Tropical Tidbits
August 500mb height anomaly
Credit: Tropical Tidbits
August precipitation anomaly
Credit: Tropical Tidbits
Credit: Tropical Tidbits
FEATURED IMAGE CREDIT: vikwaters
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