Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 17 2023 19:59:47 ACUS01 KWNS 171959 SWODY1 SPC AC 171958 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Thu Aug 17 2023 Valid 172000Z - 181200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/SOUTHERN GREAT LAKES REGION AND ALSO PARTS OF THE NORTHEAST... ....SUMMARY... Isolated strong to severe thunderstorms remain possible late this afternoon across parts of the central/southern Great Lakes region, and later tonight over parts of the Northeast. ....IL/IN/OH/MI... The Marginal Risk has been trimmed slightly from the west across northeast IL, to account for the progression of the cold front. Otherwise, the previous outlook reasoning remains valid. A few strong storms may develop as the cold front moves eastward, with a threat of isolated hail and damaging winds. See the previous discussion below for more information. ....PA/NJ/NY... The 5% wind and 2% tornado probabilities have been expanded slightly eastward, to account for the potential progression of overnight convection through the end of the period. Wind profiles will be favorable for organized convection in the vicinity of a warm front, as storms develop late tonight across eastern PA. The magnitude of the severe threat remains uncertain due to limited instability, but locally damaging winds and perhaps a tornado will be possible as storms move eastward toward southern New England by Friday morning. ...Dean.. 08/17/2023 ..PREV DISCUSSION... /ISSUED 1109 AM CDT Thu Aug 17 2023/ ....IN/OH/Lower MI... A large and progressive upper trough is moving across the central Great Lakes region today, with an associated surface cold front digging southeastward across northern IL. A pre-frontal band of thunderstorms extends from central IL into lower MI, and is situated along the axis of the low-level jet. This precipitation will significantly limit daytime heating for much of the day ahead of the front and preclude a more organized severe threat. Nevertheless, a consensus of 12z CAM solutions suggest a narrow corridor of heating in the wake of this pre-frontal activity later this afternoon over parts of IN/OH. Sufficient instability and favorable deep-layer shear will support a few organized storms, with a risk of strong winds and hail in the most intense cells. This threat should end around sunset. ....PA/NJ/NY... Later tonight, large scale forcing associated with the approaching upper trough will spread into eastern PA and vicinity. Greater low-level moisture will be in place across this region as dewpoints in the upper 60s advect northward. Diurnal cooling/de-coupling will likely limit the severe threat. But there is some chance of an occasional rotating storm during the late evening or overnight, capable of gusty winds or perhaps a brief tornado. $$ = = = 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) .