12AM Day 1 Convective Outlook for Wednesday, August 27. NO SEVERE THUNDERSTORM AREAS FORECAST
SUMMARY
The potential for severe storms appears to be low across the continental U.S. today, though a few stronger storms are possible across parts of the Upper Midwest and Colorado Front Range where locally gusty winds and small hail are possible.
Synopsis
A broad upper-level trough will be present across the eastern CONUS today with weak ridging across the western CONUS. Surface high pressure will weaken slightly and shift east across the Appalachians into the Mid-Atlantic/Carolinas. A cold front along the Gulf Coast will extend into the Central Plains.
Upper Midwest
A region of moderate instability and shear is forecast to develop across southern Minnesota this afternoon. A lead shortwave trough (currently across north Dakota) is expected to move through southern Minnesota around mid-day with weak height rises and subsidence in its wake. However, by the evening, an additional shortwave trough (traversing the western edge of the broader trough) may result in isolated storm development by late afternoon/early evening. Some forecast sounding, particularly the NAM, would support a few strong to isolated severe storms with a threat for large hail. However, consensus guidance is not as unstable and therefore, any severe threat may remain mostly isolated. Therefore, no severe weather probabilities will be included at this time.
Central High Plains into western Kansas
Thunderstorms across the central High Plains may congeal into a cluster as they move into western Kansas this evening. A belt of stronger mid-level flow (35 to 45 knots) on the southwest periphery of the large-scale trough will provide favorable deep-layer shear across the region. However, despite the favorable shear, weak mid-level lapse rates will limit overall instability. A few stronger storms capable of damaging winds will be possible, but this threat is expected to be too low/limited to warrant severe weather probabilities.