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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, March 5, 2022

SPC Mar 5, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Sat Mar 05 2022 Valid 052000Z - 061200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHERN IA AND FAR NORTHERN MO... ...SUMMARY... Severe thunderstorms are expected this afternoon through tonight across the lower Missouri Valley into southern portions of the Great Lakes region. A few tornadoes, damaging winds, and large hail will be likely in portions of Iowa and northern Missouri. Isolated damaging gusts will be possible through tonight toward the Great Lakes. ...Midwest/Lower MO Valley to Great Lakes... Previous forecast reasoning remains largely on-track with somewhat greater confidence in the number of discrete supercells developing along and just east of the MO River into southern IA and northern MO. Increasingly agitated CU/CB development is ongoing near the surface cyclone across southeast NE and northeast KS with around 100 miles of clearing immediately east. Further destabilization through boundary-layer heating and cooling mid-level temperatures will support a narrow corridor of MLCAPE reaching 1000 J/kg. Despite boundary-layer dew points only in the mid to locally upper 50s, low to mid-level lapse rates greater than 8 C/km and enlarging low-level hodographs suggests a few tornadoes appear likely. See MCD 194 for additional near-term discussion. Only other change is to expand lower tornado probabilities eastward across northern IL to southern Lower MI. Environment should remain favorable for a conditional tornado threat in addition to damaging winds, although the bulk of CAMs still suggest convection should nocturnally weaken later this evening. ..Grams.. 03/05/2022 .PREV DISCUSSION... /ISSUED 1029 AM CST Sat Mar 05 2022/ ...Midwest/Lower Missouri Valley to Great Lakes... A negatively tilted shortwave trough and attendant 70-80 kt H5 jet streak visible across the central High Plains on morning water vapor imagery are forecast to rapidly eject northeastward reaching the upper Midwest/Great Lakes over the next 12-16 hours. Strong dynamic lift associated with this trough/jet and a 40-50 kt low-level jet have advected modest (50-55 F) dewpoints across eastern KS, northern MO and far southern IA. As the trough continues northeastward during the day, a deepening surface cyclone will continue pulling moisture northward, toward a slowly advancing warm front stretching from the low northeastward into central IA. North of the warm front, a band of elevated convection is ongoing within the strong warm advection regime at the nose of the low-level jet. Modest buoyancy aloft may favor some potential for isolated severe hail trough the morning, before these storms move far enough north and eastward away from the jet and into more stable conditions. Behind the initial convection, strong dynamic lifting from the approaching trough and isolated cloud breaks should work to destabilize the boundary-layer ahead of a fast moving cold front/dryline near the low across northeastern KS and southeastern NE. With the modest surface moisture in place, destabilization should remain mostly weak to moderate, with regional model soundings showing between 500 and 1000 J/kg of MLCAPE developing beneath -20 C 500 mb temps by early afternoon. Some uncertainty exists regarding destabilization in the wake of early-day convection, though clearing evident across northeastern KS this morning lends some confidence to at least patchy sunshine through the early afternoon. Strong convection appears likely to initiate near the triple point in vicinity to the Missouri River between 19 and 21z, and track northeastward across south-central IA and northern MO. Wind profiles near and southeast of the low and the warm front strongly favor supercells with enhanced low-level curvature (200-250 0-1km SRH) evident on model hodographs. Aloft, more straight line structure suggests some potential for left splits and upscale growth resulting in a mixed storm mode of broken/semi discrete bands of convection. Fast storm motions and the potential development of small but moderately strong low-level mesocyclones will support all severe hazards including a few tornadoes. Steep lapse rates, both low and in the mid-levels will facilitate efficient transfer of strong winds aloft to the surface with scattered damaging gusts likely, especially after the initial cellular development. Some potential for damaging gusts will also extended farther south along the cold front across eastern KS and southwestern MO and into the western Great Lakes later tonight. Displaced from the stronger ascent, convective organization is less certain, but the strong wind fields suggests some threat for damaging wind gusts and small hail. Read more CHECK UPDATE ZOOM GRAPHIC
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