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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, August 29, 2022

SPC Aug 29, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0254 PM CDT Mon Aug 29 2022 Valid 292000Z - 301200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN INDIANA...FAR SOUTHERN LOWER MICHIGAN...AND NORTHWESTERN OHIO... ...SUMMARY... Scattered to numerous severe thunderstorm winds should continue through this evening across parts of the mid Mississippi Valley into Lower Michigan. ...20Z Update... The main change with this update was to adjust severe wind probabilities across the Midwest and Lower MI to account for an ongoing cluster of thunderstorms extending across Lower MI into IN. With a moist and rather unstable airmass present ahead of it, scattered to numerous severe/damaging winds should continue to be the main threat with this MCS as it moves eastward through the rest of the afternoon and into the early evening. The potential for additional robust convective development later this afternoon and evening along/ahead of the surface cold front in northern MO and central IL remains unclear. If thunderstorms can develop across this region, then both damaging winds and isolated severe hail may occur given the strong buoyancy and moderate deep-layer shear present. The Marginal Risk has been expanded into western NY based on an ongoing cluster of thunderstorms moving from western PA into this region. Occasional damaging winds appear possible with this convection through the early evening as it moves northeastward into a moderately unstable airmass with modest deep-layer shear. ..Gleason.. 08/29/2022 .PREV DISCUSSION... /ISSUED 1123 AM CDT Mon Aug 29 2022/ ...Northeast MO across IL to Lower MI through late evening... A midlevel trough will move eastward from the upper MS Valley to the Great Lakes, with some modest amplification expected from IA to IL as an embedded mid-upper speed max digs southeastward from the northern Plains. An associated surface cold front will likewise move eastward/southeastward from IA/WI to MO/IL/Lower MI by tonight. Convective clusters are ongoing this morning across northwest IL, apparently in conjunction with an undular bore ahead of the surface cold front. Given an environment with MLCAPE near 3000 J/kg, midlevel lapse rates at or above 8 C/km, DCAPE > 1000 J/kg and 35-45 kt midlevel flow, the ongoing storms should eventually produce a stronger cold pool and there will be and attendant increase in the threat for damaging winds by early afternoon. The ongoing convection will modulate the severe threat area later this afternoon, with potential stabilization across northern IL in the wake of the storms, and outflow to focus the threat a bit farther south by mid-late afternoon. Additional storms that form this afternoon along the front/outflow will have the potential to produce occasional damaging outflow gusts and isolated large hail from northeast MO across central IL into northern IN and southern Lower MI. ...West TX to the OH Valley this afternoon/evening... A few thunderstorm clusters are ongoing from northern OK to southern IL and northern OH in association with subtle midlevel vorticity maxima and within a moisture plume with PW > 1.75 inches. Mid-upper flow weakens with southward and westward extent, but precipitation loading within multicell clusters will support the potential for isolated wind damage this afternoon. Additional storms will likely form along the surface cold front in KS, and in the area of strong surface heating east of a subtle midlevel trough over northeast NM. Relatively deep mixing and moderate-strong buoyancy will support downburst potential this afternoon/evening from west TX into KS. Read more CHECK UPDATE ZOOM GRAPHIC
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