Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 24 2024 19:59:22 ACUS01 KWNS 241959 SWODY1 SPC AC 241957 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Wed Jul 24 2024 Valid 242000Z - 251200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR WESTERN/CENTRAL NY INTO NORTHWESTERN PA...AND SOUTHERN ARIZONA... ....SUMMARY... Strong to severe thunderstorms may produce damaging wind gusts across western/central New York and vicinity, the northern Rockies, and across southern Arizona this afternoon/evening. ....20z Update... The current D1 Outlook remains on track with no changes needed with this update. Several clusters of thunderstorms are ongoing along a cold front extending from the Great Lakes region northeastward into portions of New York. In this region, daytime heating has yielded around 1000-1500 J/kg of MLCAPE with 30-40 kts of deep layer shear. In this regime, some more organized cells have produced wind damage across portions of New York and Pennsylvania. The threat for strong to severe gusts will continue through the afternoon and evening, shifting eastward with the front. Farther west, two areas of potential continue with a Marginal Risk across the Northern Rockies and a Slight Risk across southern Arizona. Within these regions, damaging wind will be possible with thunderstorm activity this afternoon. See MCD #1701 for more information on the threat across southern Arizona. ...Thornton/Thompson.. 07/24/2024 ..PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Jul 24 2024/ ....Western/central NY and northwest PA this afternoon/evening... A midlevel trough will progress eastward from the upper Great Lakes toward NY as an associated surface cold front likewise moves eastward into western NY and southeastward into OH/northwest PA through this evening. Surface heating is underway in a corridor ahead of the cold front from northern OH into western NY where boundary-layer dewpoints are in the mid-upper 60s with surface temperatures warming into the lower 80s, and a band of convection has already developed from Lake Erie to western Lake Ontario. These storms may persist into the afternoon while spreading eastward, with additional development possible along convective outflow, a pre-frontal confluence zone and/or local lake breeze boundaries. Midlevel lapse rates will remain modest (roughly 6.5 C/km), but the low-level moisture/warming temperatures will drive MLCAPE in the 1000-1500 J/kg range. Deep-layer vertical shear/hodograph length will be on the lower margins for organized clusters/cells per local VWPs now sampling 30-40 kt midlevel flow, while steepening low-level lapse rates will support the potential for occasional wind damage with strong thunderstorm outflow in the 50-60 mph range. ....Southern AZ this afternoon/evening... Strong surface heating is underway near and south of the Rim, and late afternoon temperatures will peak near or above 110 F across the lower deserts into southern AZ. Moisture will be sufficient for thunderstorm development this afternoon along the Rim and the mountains in southeast AZ, while northeasterly midlevel flow of 15-20 kt will steer outflows southwestward toward the lower deserts. MLCAPE will increase to the 1000-1500 J/kg with deep inverted-V profiles favoring strong downdrafts and outflow winds of 60-75 mph capable of producing wind damage and substantial blowing dust. The relatively greater severe threat will be with the stronger/deeper convection driven by outflow mergers. ....Northern Rockies area this afternoon/evening... A plume of mainly midlevel moisture with PW values of 0.75-1 inch (per BOI and LKN 12z soundings) will persist around the northern periphery of a midlevel high over the Great Basin, and southeast of a midlevel trough approaching WA. High-based thunderstorms are expected in a few loosely organized clusters within this plume, where deep inverted-V profiles will support the potential for a few strong-severe outflow gusts 50-65 mph. ....Mid-Atlantic into NC this afternoon... Modest surface heating within small cloud breaks and boundary-layer dewpoints of 72-74 F will contribute MLCAPE approaching 1500 J/kg to the east of the Blue Ridge, though midlevel lapse rates will remain poor. Still, the southern extent of 30-40 kt midlevel flow will support a low-end wind damage threat with the stronger storm clusters this afternoon. $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .