Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 21 2024 19:28:41 ACUS01 KWNS 211928 SWODY1 SPC AC 211927 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Wed Aug 21 2024 Valid 212000Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN HIGH PLAINS... ....SUMMARY... Severe hail and thunderstorm gusts are most probable today over parts of eastern Montana and the western Dakotas. ....20Z Update... The previous forecast remains on track for the northern and central High Plains based on recent observed trends and latest forecast guidance. The Marginal risk area across south-central AZ has been modified to remove areas that have seen little diurnal destabilization owing to persistent stratiform rain and/or cirrus emanating from a broken line of weak convection. Additionally, wind risk probabilities have been expanded slightly east to account for recent thunderstorm development within a similarly buoyant and deeply-mixed environment as the remainder of the risk area. See the previous discussion for additional details. ...Moore.. 08/21/2024 ..PREV DISCUSSION... /ISSUED 1120 AM CDT Wed Aug 21 2024/ ....Northern High Plains... Morning water vapor imagery shows a fast-moving shortwave trough over ID/NV tracking northeastward. Lift associated with this system will overspread parts of MT/WY/Dakotas later this afternoon and evening. This will help to initiate scattered thunderstorms over the higher terrain of southern MT and WY, building eastward into the Plains during the evening. Instability in the mountains is quite weak with dewpoints only in the 40s, but with steep low/mid level lapse rates and moderately strong westerly flow aloft posing a risk of gusty winds. Storms will eventually move/develop eastward into a more moist/unstable air mass across eastern MT and western SD/ND where more robust/severe storms are expected, capable of damaging winds and large hail. ....CO/NE/KS... Ample mid-level moisture will result in scattered afternoon thunderstorms over the mountains of central CO and southern WY. This area will be on the fringe of the stronger westerly flow aloft, and with pockets of strong daytime heating helping to steepen low-level lapse rates. This will promote a risk of gusty/damaging winds in the strongest cells. As the activity spreads eastward into the Plains, further intensification is possible with a few cells continuing a risk of gusty winds and hail during the evening. ....Southeast AZ... Afternoon thunderstorms have been occurring daily over southeast AZ, with isolated strong cells capable of gusty winds. Today will be similar as daytime heating dewpoints in the 60s promote storms over the higher terrain that track slowly northwestward during the late afternoon and early evening. $$ = = = 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) .