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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.


Friday, August 25, 2023

SPC Aug 25, 2023 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Fri Aug 25 2023 Valid 251300Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MIDWEST... ...SUMMARY... Isolated to scattered thunderstorms associated with strong wind gusts and hail are possible this afternoon and evening especially across parts of the the Midwest, and more broadly from the central Plains eastward to the Ohio Valley and Mid-Atlantic States. ...Midwest... With the prominent upper high centered over the southern Plains, a shortwave trough (and related speed max) over northern Minnesota and nearby Ontario will continue to modestly amplify and spread southeastward over the Great Lakes through tonight. While forcing for ascent and stronger winds aloft will exist to the north, some of these influences will partially overlap a frontal zone across the Midwest and Middle Mississippi Valley/Lower Ohio Valley, with the easternmost portion of the front convectively modified and more southward progressive across the Appalachians/Mid-Atlantic region. The aforementioned disturbance appears to be influencing widely scattered thunderstorms across Iowa early today. This forcing for ascent may interface with the frontal zone later today, where a very unstable air mass will reside particularly across southeast Iowa into central Illinois and southern Indiana. Even with some capping-related uncertainties, concern exists for the possibility of at least isolated intense thunderstorm development this afternoon into early evening, with the high degree of instability and ~30 kt of effective shear potentially supportive of upscale growing/east-southeastward-moving clusters capable of wind damage. ...Appalachians/Mid-Atlantic States... A southward-moving MCS continues to spread generally southward across parts of West Virginia/western Virginia as it has tended to weaken through the early morning hours. Some later-day thermodynamic uncertainties exist related to this MCS, but zones of differential heating/terrain influences and lee trough development should lead to additional thunderstorm development this afternoon as the boundary layer recovers/destabilizes. Some strong to severe thunderstorms capable of wind damage will be possible, even while deep-layer shear will remain weak. ...Central Plains... A front will sag southward across the region, with low-level moisture and buoyancy maximized later today near and north of the front including eastern Colorado into western/northern Kansas and southern Nebraska. As the airmass diurnally destabilizes, an increase in thunderstorms is expected across the region into mid/late afternoon, with more prevalent thunderstorms this evening. Steep lapse rates, moderate buoyancy, and modest strength deep-layer shear will support some severe storms capable of hail and severe-caliber wind gusts, mostly late this afternoon and evening across parts of eastern Colorado, western/northern Kansas, and southern Nebraska. ..Guyer/Goss.. 08/25/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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