Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 16 2024 05:47:57 ACUS01 KWNS 160547 SWODY1 SPC AC 160546 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Fri Aug 16 2024 Valid 161200Z - 171200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL/SOUTHERN PLAINS INTO THE OZARKS OF NORTHWEST ARKANSAS... ....SUMMARY... Isolated-scattered severe thunderstorms are expected across portions of the central and southern Plains, extending into northwest Arkansas. Less concentrated severe is possible across the Midwest into the Tennessee Valley. ....Central/Southern Plains Region... MS Valley trough is forecast to shift into the upper Great Lakes/Midwest region by late afternoon while a dominant upper anticyclone will hold across the southern Rockies. This lead trough will result in a pronounced surface front arcing across the Ozarks-southern KS-northeast CO/NE Panhandle at peak heating. Additionally, there is some indication that a weak short-wave trough may top the southern Rockies ridge and turn southeast along this frontal zone during the latter half of the period. Latest model guidance suggests very strong surface heating will lead to steep 0-3km lapse rates across the central High Plains into northern OK. Forecast soundings depict convective temperatures being breached by 22-23z as surface readings rise through the upper 90s/100F. This boundary should serve as the focus for robust convection shortly after peak heating. Additionally, any storms that develop should grow upscale during the evening as the LLJ is expected to increase across the TX Panhandle into southeast KS in response to the ridge-topping short wave. Initial storm mode may be high based, but potentially supercellular in nature. However, convection should gradually expand in areal coverage and storm mergers are expected along a favorable corridor of low-level warm advection. As a result, one or more MCSs should evolve which will propagate southeast along the front toward the Ozarks during the overnight hours. Severe gusts and very large hail could be noted across the Plains before MCS maturation. ....Midwest/TN Valley... Scattered robust convection is currently ongoing ahead of the MS Valley trough, notably across IL into southern MO. This activity will propagate downstream ahead of the progressive trough and likely be ongoing at the start of the day1 period, especially across the lower OH Valley along the nose of a veered LLJ. Remnants of this convection should propagate southeast across middle TN as the LLJ weakens. With 500mb flow forecast to strengthen there is some concern this activity could advance further into the northern Gulf States than currently anticipated. Some organization is also possible which may necessitate higher severe probabilities. However, nature/extent of the early-day MCS remains a bit too uncertain to warrant more than MRGL at this time. A narrow corridor of stronger boundary-layer heating is expected across eastern IA/northwest IL into extreme southern WI by mid day. This should aid buoyancy and isolated strong/severe thunderstorms are expected to develop immediately ahead of the upper low. Hail/wind are possible with storms that evolve along this corridor of stronger instability. ...Darrow/Halbert.. 08/16/2024 $$ = = = 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) .