SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Wed Apr 07 2021 Valid 072000Z - 081200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF ARKANSAS...NORTHERN LOUISIANA...CENTRAL AND NORTHERN MISSISSIPPI...AND SOUTHWEST TENNESSEE... ...SUMMARY... Scattered severe thunderstorms are expected from this afternoon into the evening across parts of the lower Mississippi Valley, Mid-South, Arklatex and Ozarks. Wind damage, hail and tornadoes will be possible. ...Discussion... The forecast appears on track. Strong to severe storms have developed along and ahead of the cold front from northern Missouri to east Texas. Large hail, damaging winds and tornadoes remain the primary threat which is expected to continue through the afternoon and into the evening hours. ..Bentley/Dial.. 04/07/2021 .PREV DISCUSSION... /ISSUED 1105 AM CDT Wed Apr 07 2021/ ...Lower MS Valley... An upper low is evident this morning over central KS, with a shortwave trough rotating through the base of the low into parts of OK/TX. Strong forcing for ascent ahead of this trough will overspread a cold front currently over eastern OK, leading to thunderstorm development by early afternoon. Abundant clouds have limited daytime heating ahead of the front over parts of AR/LA, but dewpoints in the 60s and rather steep lapse rates will yield afternoon MLCAPE values of 1500+ J/kg. South-southwesterly low-level winds of 40+ knots will result in favorable vertical shear profiles (0-3km SRH values of 150-300 m2/s2) for supercell storms capable of large hail, damaging winds, and tornadoes. Messy storm modes are likely to evolve through the afternoon, but a continued risk of damaging winds and tornadoes will persist into parts of west TN and much of MS before storms move out of primary moisture/instability axis this evening. ...Mid MS Valley... A surface low is currently analyzed over eastern KS, with a cold front extending southeastward into western MO. An area of precipitation has affected much of MO during the morning, but is moving away and allowing some air mass recovery. Present indications are that scattered thunderstorms will form early this afternoon along the front and move across much of MO before weakening as they track into more stable air over IL this evening. The strongest cells will be capable of hail, damaging winds, and isolated tornadoes. Please refer to recent MCD #321 for further details. ...MN/WI... Most 12z CAM solutions suggest the development of a cluster of thunderstorms this afternoon over parts of eastern MN/western WI. This would be in vicinity of a retreating warm front, where broken cloudiness and dewpoints in the 50s will result in MLCAPE values around 1000 J/kg. A strong storm or two is possible for a few hours this afternoon, capable mainly of hail.
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