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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, September 3, 2021

SPC Sep 3, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0246 PM CDT Fri Sep 03 2021 Valid 032000Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/SOUTHERN HIGH PLAINS INTO SOUTHERN KANSAS AND NORTHERN OKLAHOMA... ...SUMMARY... Isolated severe storms with large hail as the primary hazard may occur across parts of the central High Plains to Black Hills vicinity. Isolated damaging wind gusts are also possible from the south-central High Plains across southern Kansas, northern Oklahoma, and southwest Missouri. ...20Z Update... A small adjustment has been made to the Marginal Risk across CO based on ongoing convection, with previous forecast reasoning remaining valid. See Mesoscale Discussion 1690 for more information on the short-term severe threat across the central High Plains. ..Gleason.. 09/03/2021 .PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Sep 03 2021/ ...Black Hills and Central High Plains... A low-amplitude shortwave trough over central MT will shift east into the Upper Midwest tonight. The combination of forcing for ascent from this wave and a weak upslope-flow regime should support scattered thunderstorm development this afternoon across eastern WY, spreading into western SD and the NE Panhandle through early evening. With mostly broken cloud coverage and leading ascent overspreading the region at present, the degree of destabilization is uncertain. Some clearing might occur by late afternoon before the shortwave trough entirely passes to yield a confined corridor of MLCAPE to 500-1000 J/kg. Should this occur, an elongated hodograph would support a couple supercells with large hail as the primary hazard. The severe threat will likely remain spatially confined owing to a dearth of surface-based instability farther east into the lower plains in SD/NE. ...South-central High Plains across south KS north OK... Robust boundary-layer heating is underway across much of OK and the TX Panhandle to the south of a slowly sagging cold front bisecting KS from southwest to northeast and leading outflow from decaying convection across southeast KS. This should support a plume of moderate buoyancy with MLCAPE of 1500-2500 J/kg despite relatively warm mid-level temperatures around -4 C at 500 mb. Scattered thunderstorms are expected to initiate towards late afternoon in the southwest KS/northwest OK/northeast TX Panhandle vicinity and spread east along and south of the baroclinic zone in south KS and north OK this evening. Along the periphery of 15-25 kt 500-mb flow, loosely organized multicells should support a primary threat of isolated severe wind gusts. Farther west, a lone supercell may develop off the Palmer Divide within a weak upslope flow regime and spread southeast towards greater buoyancy across southeast CO into southwest KS this evening. Poor upper-level lapse rates should temper hail magnitudes and overall updraft intensity, but a low-probability threat for all hazards remains warranted. Read more LIVE: spc.noaa.gov