WEATHERAmerica Newsletter, Sunday, June 16, 2024; MEDIUM RANGE OUTLOOK

[Larry Cosgrove]

How Long Will The Gulf Of Mexico Disturbance Hang On? And What About The Midwest Thunderstorms?

UQAM Meteocentre (4)

TwisterData.Com (4)

TrueWx.Com (4)

College Of DuPage Weather Laboratory

The potential torrential rain threat for Texas may interact with the storm and frontal structure in the Midwest, which vastly complicates the forecast. There is a ton of unstable mTw air in the Gulf of Mexico, but most of the numerical models are slow to advance the feature while a low pressure and trough makes its move into South Texas. The sheared profiles of winds above argue against tropical cyclone development. Surface steering indicates that the unstable regime will disperse from The Lone Star State through the Great Plains, and begin to interact with the colder system as it tracks through the Upper Midwest into the Great Lakes. Whereas there is some uncertainty with respect to severe weather and extreme rains along the Interstate 10 corridor, there is none in the Corn Belt. Prolonged threats for hail and tornadoes will lurk in places like Omaha NE and Chicago IL, perhaps translating into Ohio and Pennsylvania next weekend. The warm character of the feature aimed toward the Rio Grande Valley will mean waterspouts along the Gulf Coast.

Needless to say, this is a difficult outlook, likely to change during the next 48 hours or so. But one thing that can be said is that by next Saturday, dewpoints and relative humidity in the south central states will feel like Venezuela. Because that is where the air mass will be originating!

The Heat Will Subside In The East, Slowly

ECMWF (4)

PivotalWeather.Com (4)

The heat ridge complex looks to linger off of the Atlantic shoreline. Splitting apart from the Sonoran counterpart anticyclone, the Eastern Seaboard will maintain a hot, humid atmosphere which may or may not be punctuated by thunderstorms. The convection, you see, will remain mostly in the Midwest and lower Great Lakes, as the frontal structure there gets some reinforcement by a deep 500MB shortwave that closes off in Wisconsin and Michigan. Note also the comeback of the searing heat from california and the Southwest into Texas and the lower Great Plains. The longer term, you see, will surely see another widespread expansion of hot air.