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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, December 3, 2021

SPC Dec 3, 2021 0830 UTC Day 3 Severe Thunderstorm Outlook

SPC 0830Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0222 AM CST Fri Dec 03 2021 Valid 051200Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF COASTAL/EAST TEXAS TO THE MID-SOUTH... ...SUMMARY... Isolated strong to severe thunderstorms may occur Sunday from parts of coastal/east Texas to the Mid-South. ...Coastal/East Texas to the Mid-South... The mid-latitude westerlies extending across the northern CONUS are expected to undergo substantial amplification Sunday as a shortwave trough digs from the northern Plains across the Upper Midwest and Great Lakes. Phasing of this feature with a low-amplitude, southern-stream perturbation may also encourage further amplification of the large-scale upper trough across much of the MS Valley by late Sunday night. At the surface, a low associated with the primary shortwave trough is forecast to develop from the northern Plains to the Upper Great Lakes vicinity by Sunday evening, while an attendant cold front sweeps southeastward across the much of the Plains and upper/mid MS Valley. Modest low-level moisture return from the western Gulf of Mexico should occur ahead of the front from parts of central/east TX into the lower MS Valley and Mid-South. There is still a fair amount of variability in model guidance regarding the northward extent of at least upper 50s to low 60s surface dewpoints, which will probably be needed to support surface-based convection. Still, the latest GFS and ECMWF are in general agreement that at least weak instability should develop across these regions by late Sunday afternoon. Convective initiation will probably delayed until Sunday evening and the arrival of the cold front, by which point stronger mid-level westerly winds associated with the southern-stream shortwave trough will likely have overspread the warm sector. The forecast combination of weak instability and strong low- and deep-layer shear should prove sufficient for isolated strong to severe thunderstorms. The convection that forms along the front will likely become linear fairly quickly, with mainly a threat for strong to damaging wind gusts Sunday evening and overnight as thunderstorms move east-southeastward. There also appears to be some potential for open warm-sector development across parts of east/coastal TX and southeastern OK Sunday evening/night as a southwesterly low-level jet strengthens. Modestly steepened mid-level lapse rates across this region may support an isolated threat for severe hail in addition to damaging winds with any discrete storms that can form. The thunderstorms that develop along/ahead of the front should eventually outpace the low-level moisture return and slowly weaken with eastward extent across the Mid-South and lower MS Valley late Sunday night into early Monday morning. ..Gleason.. 12/03/2021 Read more LIVE:
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)