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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.

Saturday, December 11, 2021

SPC Dec 11, 2021 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Sat Dec 11 2021 Valid 111630Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FROM SOUTHERN AL INTO THE SOUTHERN APPALACHIANS... ...SUMMARY... A few damaging gusts are expected this afternoon in the vicinity of the southern Appalachians. Isolated strong/damaging gusts will also be possible from eastern Ohio to western New York, and late evening/early tonight into parts of the Mid Atlantic. ...AL into the Southern Appalachians this afternoon... A pre-frontal band of convection will continue to move eastward/southeastward across the southern Appalachians to the northern Gulf coast through this afternoon. Forcing for ascent will gradually diminish along this pre-frontal band, given little in the way of height falls as the primary shortwave trough moves over the OH Valley and Great Lakes. However, lingering strong southwesterly wind profiles and modest destabilization during the afternoon will support occasional damaging gusts before the convection weakens this evening. Also, a few discrete cells will form ahead of the front from southeast MS to southern AL, where deep-layer shear will remain favorable for supercells capable of producing isolated damaging gusts and an isolated tornado or two. ...Lower Great Lakes area this afternoon... The deepening synoptic cyclone will develop northeastward from northern Lower MI across ON/QC, as a trailing cold front progresses eastward from the OH Valley to PA/NY in conjunction with the primary midlevel trough. Filtered surface heating through high clouds, and in a narrow zone of cloud breaks now across northern OH, will support low-topped convection along the cold front through the afternoon. The band of convection will cross OH, northwest PA, and western NY, where a couple hundred J/kg of SBCAPE and strong wind profiles suggest at least low potential for convectively augmented gusts capable of producing some wind damage this afternoon. ...Mid Atlantic this evening into early tonight... Some form of the shallow convective band crossing the Appalachians may persist into early tonight to the east of the higher terrain (from eastern PA into VA), though only isolated strong/damaging gusts are expected due to minimal surface-based buoyancy and weakening low-level lapse rates tonight. ..Thompson/Mosier.. 12/11/2021 Read more LIVE: