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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.

Monday, October 25, 2021

SPC Oct 25, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Oct 25 2021 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTH CENTRAL NORTH CAROLINA INTO CENTRAL AND EASTERN VIRGINIA... ...SUMMARY... Threat for mainly a few strong to damaging wind gusts and possibly a tornado or two exists this afternoon and evening from central North Carolina into Virginia. ...Discussion... Only modest adjustments have been made to previous outlook, primarily to trim on western end of SLGT to reflect current trends. See swomcd 1899 for more information. ..Dial.. 10/25/2021 .PREV DISCUSSION... /ISSUED 1127 AM CDT Mon Oct 25 2021/ ...Eastern KY/OH to NC/VA this afternoon/evening... A midlevel shortwave trough over IN/KY/TN this morning will progress eastward to the Appalachians this evening and VA/NC overnight. An associated surface cyclone will move eastward from northeast IN across northern OH today while slowly weakening, and a trailing cold front will likewise move eastward across TN/KY/WV/OH through this evening. A band of convection will be possible along the cold front this afternoon in conjunction with a narrow zone of cloud breaks/surface heating and modest low-level moisture (surface dewpoints of 56-60 F) across OH/KY. Buoyancy will remain weak (MLCAPE < 500 J/kg) and wind profiles will be only modestly favorable for organized severe storms (effective bulk shear near 30 kt) suggest that any severe threat with to storms along the cold front should remain marginal. Farther east, low-level moisture is increasing from eastern NC into VA, on the west side of a separate shortwave trough ejecting northeastward near the southeast Atlantic coast. The moisture should be able to spread far enough west and north to support thunderstorm development later this afternoon near the Blue Ridge, as the primary cloud/ascent band (now across eastern KY into WV) reaches the west edge of the richer low-level moisture. Wind profiles will be sufficient for supercells with effective bulk shear of 40-50 kt, given MLCAPE up to 1000 J/kg. Occasional damaging gusts will be the main concern, though a tornado or two may also occur near the NC/VA border where effective SRH of 100-150 m2/s2 is expected by late afternoon. Otherwise, convection is expected to grow upscale into clusters/line segments, with an attendant threat for damaging winds through late evening. Read more LIVE: