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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, February 27, 2023

SPC Feb 27, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1153 PM CST Sun Feb 26 2023 Valid 271200Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE OHIO VALLEY... ...SUMMARY... Thunderstorms may produce damaging gusts across the Ohio Valley today. At least a few tornadoes are also possible, especially across Ohio this afternoon. ...Synopsis... A potent mid-level trough will quickly overspread the OH Valley as a 986 mb surface low traverses the Great Lakes region today. A narrow line of thunderstorms should be ongoing at the start of the period along the cold front near the MS River and is poised to rapidly progress eastward through the day. During the first half of the period, a 50+ kt low-level jet will advect a marginally moist/buoyant airmass into the OH Valley ahead of the surface low/line of storms. Strong westerly flow atop the southerly low-level jet will promote strong vertical wind shear, that in tandem with the marginal buoyancy will promote a risk for severe thunderstorms across the OH Valley during the afternoon. ...OH Valley... Widespread clouds and at least scattered thunderstorms are anticipated across the warm-sector in association with the warm-air advection regime, hampering more robust low-level instability from materializing through at least early afternoon. Nonetheless, latest guidance consensus shows a brief period of diurnal heating across the OH Valley in advance of an approaching band of low-topped storms. Ahead of the storms, temperatures may warm to 60 F amid upper 50s F surface dewpoints, contributing to short, thin MLCAPE profiles. However 850 mb southwesterly winds at 50+ kts overspread by 60-70 kts of west-southwesterly flow will contribute to relatively long and curved hodographs, suggesting that both deep-layer and low-level shear will be abundant. As the low-topped line of storms progresses eastward through the afternoon, small bowing segments and transient supercell structures may develop, with damaging gusts possible. The best chance for low-topped supercells and associated tornadoes would be across OH during the mid to late afternoon hours, where an optimal overlap of strong low-level shear/moisture may take place. Should greater than expected diurnal heating and moisture return occur, a locally higher tornado threat may materialize. Storms should weaken by early evening as they approach the Appalachians and outpace any surface-based buoyancy. ..Squitieri.. 02/27/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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