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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 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Oct 25 2021 Valid 251300Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/SOUTHERN APPALACHIANS AND MID-ATLANTIC STATES... ...SUMMARY... Thunderstorms capable of damaging winds and possibly a tornado risk are expected from the southern and central Appalachians into the Carolinas and Mid-Atlantic region, mainly this afternoon and evening. ...Upper Ohio Valley to the Mid-Atlantic States/Carolinas... The remnants of last evening's severe storms across the Ozarks/Middle Mississippi Valley grew upscale and persist early this morning in a diminished intensity from Ohio south-southwestward into eastern portions of Kentucky and middle/eastern Tennessee, parallel to but ahead of an eastward-moving cold front. The parent shortwave trough will continue eastward over the Midwest/Ohio Valley toward the central/northern Appalachians through tonight, with height falls and the exit region of a strong mid/upper jet overspreading the southern Appalachians and Carolinas/Virginia. The aforementioned bands of convection and related cloud cover will tend to hinder pre-frontal destabilization across the Upper Ohio Valley and windward side of the Appalachians, but a few strong/severe low-topped storms could occur pending weak but sufficient destabilization this afternoon in those areas. A more certain/probable severe-weather risk is expected this afternoon east of the Appalachians spine, perhaps initially near/just east of the Blue Ridge across Virginia and nearby Maryland/North Carolina. This is where cloud breaks ahead of the upstream cold front and lingering overnight convection should allow for modest destabilization, with upwards of 1000 J/kg MLCAPE possible from the North Carolina/Virginia Blue Ridge and Piedmont vicinities toward the Delmarva by late afternoon. Strong deep-layer shear will support some well-organized storms including linear bands aside from the possibility of some initial/embedded supercells, particularly across the Piedmont of Virginia and northern North Carolina. Although low-level shear will not be overly strong and details of convective mode are a bit uncertain, the potential for a tornado or two could somewhat increase late this afternoon/early evening. This would particularly be across southern Virginia/northern North Carolina pending weak lee-side low/trough development and a related increase in low-level shear/SRH. Damaging winds will otherwise be the most probable hazard across the region this afternoon and evening, with a few instances of marginally severe hail also a possibility. ...Florida... A couple of stronger storms may persist toward and across the central/southern Florida Peninsula and Keys vicinity today. However, the potential for severe-caliber storms should be limited by relatively poor mid-level lapse rates, weak vertical shear, and weakening low-level convergence. ..Guyer/Kerr.. 10/25/2021 Read more LIVE: