Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Aug 28 2023 06:02:23 ACUS02 KWNS 280602 SWODY2 SPC AC 280600 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Aug 28 2023 Valid 291200Z - 301200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FLORIDA... ....SUMMARY... The potential for a few tornadoes should gradually increase along/near parts of the Florida Gulf Coast and into north Florida through Tuesday night as Tropical Cyclone Idalia approaches. ....Florida into Southeast Georgia... TC Idalia is forecast by the NHC to strengthen into a hurricane over the eastern Gulf of Mexico Tuesday. Given the latest forecast track and model consensus, 50+ kt of southerly low-level flow will likely overspread much of the central/northern FL Peninsula Tuesday afternoon through Tuesday night. Increasingly elongated and curved low-level hodographs are anticipated as this occurs, with 0-1 km SRH quickly strengthening to 200+ m2/s2. This ample low-level shear will foster updraft rotation with any low-topped supercells that can form in outer rain bands. The corresponding threat for isolated tornadoes is expected to increase Tuesday evening through early Wednesday morning as TC Idalia approaches and eventually moves onshore along parts of the FL Gulf Coast. Even though instability should remain fairly weak across much of FL owing to poor lapse rates and a nearly saturated profile, various NAM/GFS forecast soundings along the FL Gulf Coast show sufficient boundary-layer instability and a very rich/moist low-level airmass to support surface-based thunderstorms. A Slight Risk has been introduced across parts of north/central FL, where confidence is highest that a few tornadoes may occur. This tornado threat will likely persist into Day 3/Wednesday as TC Idalia continues to move northeastward. The Marginal Risk has also been expanded to include more of the FL Peninsula, the Keys, and far southeastern GA, where strong/gusty winds may occur Tuesday afternoon with convection well removed from TC Idalia. ....Northwest... An upper trough will move eastward across the Northwest on Tuesday. South-southwesterly mid-level flow should gradually strengthen through the day across interior portions of the Pacific Northwest into the northern Rockies. Around 25-40 kt of effective bulk shear associated with this enhanced flow should provide for some updraft organization with any thunderstorms that can be sustained. Latest guidance continues to suggest that convection will form initially over eastern WA/OR into western ID, and quickly advance north-northeastward into western MT Tuesday afternoon and evening. A deeply mixed boundary layer and steepened low/mid-level lapse rates should support an isolated threat for severe wind gusts with any clusters that can form. Isolated hail may also occur with any more discrete thunderstorms, but instability and low-level moisture both look to remain fairly limited. ....Appalachians... Scattered thunderstorms should develop across parts of the southern/central Appalachians as modest ascent associated with an upper trough over eastern Canada and the Northeast/Mid-Atlantic moves slowly eastward. Enough mid-level flow and modest deep-layer shear may exist to support some updraft organization, but poor lapse rates should tend to limit instability and updraft strength. At this point, the potential for strong/gusty winds appears too limited to include low severe probabilities. ....Midwest/Great Lakes... A cold front should move southeastward across the Great Lakes and parts of the Midwest/OH Valley in tandem with an slowly eastward-moving upper trough. At least weak instability may develop along/ahead of the front through Tuesday afternoon, even though low-level moisture should remain fairly limited/shallow. While some threat for gusty winds may exist with any convection that can develop, the overall severe threat should remain generally low. ...Gleason.. 08/28/2023 $$ = = = 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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .