Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Apr 14 2025 16:31:54 ACUS01 KWNS 141631 SWODY1 SPC AC 141630 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Apr 14 2025 Valid 141630Z - 151200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS WEST VIRGINIA AND NORTHWEST VIRGINIA... ....SUMMARY... Scattered strong to severe storms are expected this afternoon through early tonight from the Upper Ohio Valley eastward to the Mid-Atlantic. Large hail, severe wind gusts, and a couple of tornadoes will be possible. ....Upper OH Valley this afternoon into VA early tonight... Recent satellite imagery depicts a maturing mid-latitude cyclone moving eastward across Lake Superior towards northeastern Ontario with an upstream shortwave trough moving through the northern Plains. Expectation is for the cyclone to continue deepening/maturing as it moves into and through northeastern Ontario today, while the upstream shortwave progresses quickly southeastward through the Mid MO Valley and into the Mid MS Valley. As this occurs, strong mid-level flow will spread eastward across the OH Valley and over the Northeast and Mid-Atlantic States. At the same time, a cold front will spread eastward across the OH Valley this afternoon and evening, and across the central Appalachians tonight. Current surface analysis reveals upper 40s to low 50s dewpoints ahead of the front in the Middle OH Valley, with the upper 50s/low 60s dewpoints farther southwest over western KY. This greater low-level moisture is expected to surge northeastward amid the moderate southwesterly low-level flow, combining with evapotranspiration to bring upper 50s dewpoints into upper OH Valley ahead of the front. This increase in low-level moisture combined with daytime heating should be enough to destabilize the airmass ahead of the front across the Upper OH Valley. Forcing for ascent (from a combination of increasing large-scale ascent and forcing along the front) will increase across this destabilized area, supporting thunderstorm development during the afternoon. An initially cellular mode is anticipated, with steep mid-level lapse rates and long hodographs potentially resulting in a few supercells. Primary severe risk with these supercells is large hail of 1-2 inches in diameter. Some damaging gusts and a tornado or two are possible, although the lack of higher low-level moisture will mitigate the overall tornado potential. Strong outflow and increasing mid-level flow suggest a transition to a more linear mode is likely, with several bowing segments possible. There is also some potential for the development of a singular, more coherent convective line. In either case, a transition from hail to damaging gusts as the primary severe risk is anticipated as this activity spreads eastward. Clusters/line segments will likely persist east of the Appalachians into VA through early tonight, though the severe threat will diminish with eastward extent and after 03z. ....SD to IA this afternoon/evening... Low-level moisture will be limited, but surface heating beneath cooling midlevel temperatures will support weak surface-based buoyancy and the potential for low-topped showers and a few thunderstorms from SD into IA (in advance of a digging shortwave trough now over western ND/eastern MT). Relatively cold temperature profiles will favor some threat for small hail, while steep low-level lapse rates and 30+ kt flow through the mixed layer favor gusty outflow winds of 40-50 mph. ...Mosier/Weinman.. 04/14/2025 $$ = = = 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) .