WEATHERAmerica Newsletter, Saturday, May 7, 2022 at 8:00 PM CT; Medium Range Discussion

[Larry Cosgrove]

MEDIUM RANGE OUTLOOK

(Four To Ten Days From Now)

Trough, Cold Front May Dent The Heat In Northern Great Plains, Mississippi Valley

ECMWF (4)

PivotalWeather.Com (4)

As strong as the heat ridge complex is over Texas and the Mississippi Valley, the erosion of the warmth from the cold air mass is virtually assured. As can be seen on the maps above, the forward edge of the frontal structure will be along an arc from Amarillo TX to International Falls MN on May 12. As the heat ridge complex weakens and retrogresses toward northwestern Mexico, the front will start to shift into Appalachia and the Mid-South. Temperature changes by that time will be modest, but enough lift and force elements will be present to spread significant, if not intense, convection into the Mississippi Valley and Great Lakes while sections of the West start to warm up.

Gale Center, Incoming Trough Likely To Bring Showers, Thunderstorms To Eastern Seaboard Next Weekend

UQAM Meteocentre (4)

TwisterData.Com (4)

TrueWx.Com (4)

College Of DuPage Weather Laboratory

Once thunderstorms start to fire east of the Mississippi River, it may be a while before any type of meaningful drying returns. What appears to be happening is that the western system and the remnants of the upper low off of the East Coast (which may turn into a gale center of subtropical depression before working inland around Jacksonville FL) will merge/phase into a negative tilt trough or 500MB weakness that lodges over the Great Lakes into Appalachia. Most forecast guidance shows heavy rain and chances for strong or severe thunderstorms, repeatedly, over the eastern third of the U.S. May 14 - 17. The hot and dry regime will by that point be rebuilding in an arc from California to Texas.