2AM Day 3 Convective Outlook for Wednesday, September 3. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS
SUMMARY
Isolated severe storms are possible over portions of the central Plains on Wednesday.
Synopsis
A mid-level trough will deepen while also taken on a more neutral tilt over the Midwest as upper ridging persists west of the Rockies on Wednesday. The deepening mid-level trough will encourage the continued southward progression of a surface cold front over the central Plains into the OH Valley. Seasonal low-level moisture ahead of the front will promote buoyancy to support thunderstorms, which should develop with the aid of low-level frontal convergence. Since stronger northwesterly flow aloft will begin to overspread the pre-frontal airmass and support adequate vertical wind shear aloft, isolated severe thunderstorms are possible across parts of the central Plains.
Portions of the Central Plains
By afternoon, surface temperatures should warm well into the 70s F amid mid 60s F dewpoints, which when overspread by 7+ C/km mid-level lapse rates, will yield over 2000 J/kg MLCAPE, especially over eastern KS. Winds will gradually veer with height, from southwest to northwest through the boundary layer, then increase from 20 kts around 700 mb, to about 40 kts in the 500-300 mb layer. This profile will support modestly elongated and curved hodographs and 40-50 kts of effective bulk shear. The stronger storms that develop ahead of the cold front will likely be mixed modal between multicells and supercells, capable of at least isolated severe hail and wind. Category 1/Marginal Risk severe probabilities have been introduced, though higher probabilities may be needed if it becomes clear that more sustained supercells can materialize over eastern KS.