Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 09 2023 05:47:21 ACUS01 KWNS 090547 SWODY1 SPC AC 090545 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CDT Sun Jul 09 2023 Valid 091200Z - 101200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY ACROSS PARTS OF SOUTHEASTERN OKLAHOMA...NORTHEASTERN TEXAS...SOUTHERN ARKANSAS...NORTHEASTERN LOUISIANA...MISSISSIPPI...WESTERN AND SOUTHERN ALABAMA...THE WESTERN FLORIDA PANHANDLE...NORTHEASTERN SOUTH CAROLINA...EASTERN NORTH CAROLINA AND VIRGINIA...CENTRAL AND EASTERN MARYLAND...THE DISTRICT OF COLUMBIA...DELAWARE...AND SOUTHEASTERN PENNSYLVANIA... ....SUMMARY... Strong storms may pose a risk for damaging wind gusts from the southern Great Plains Red River Valley through the lower Mississippi Valley today, with a risk for damaging wind gusts also accompanying scattered strong storms across the Mid Atlantic. ....Synopsis... As a downstream blocking mid-level high is maintained to the south of Greenland, models indicate that an anomalously deep mid-level low may elongate to the southwest of Hudson Bay, in response to at least a couple of perturbations pivoting around its center. As this occurs, a belt of seasonably strong cyclonic mid/upper flow appears likely to dig from the eastern Canadian Prairies through the Lake Superior vicinity. An associated surface cyclone may continue to deepen over northern Ontario, with a significant trailing cold front advancing across the central Canadian/U.S. border vicinity this evening through the overnight hours. This front is preceded by a weaker/more diffuse cold front, which may reach the lower Great Lakes, Ohio Valley and southern Great Plains Red River Valley by 12Z this morning. The lead front is forecast to advance into the middle/southern Atlantic and Gulf Coast states by daybreak Monday, while associated larger-scale mid-level troughing within modest to weak westerlies slowly progresses across areas east of the Mississippi Valley. One notable embedded short wave may accelerate through the lower Ohio Valley into the northern Mid Atlantic vicinity by early Monday, while a significant convectively generated perturbation contributes to another digging short wave across and to the east of the lower Mississippi Valley. Farther west, modestly amplified large-scale mid-level ridging is forecast to overspread the Rockies into the Great Plains, to the north of a prominent subtropical high centered over southwest Texas/southern New Mexico. While elevated mixed-layer air has generally been suppressed to the south/southwest of the Red River, seasonably moist air precedes the lead surface front across the South and East. ....Red River through lower Mississippi Valley.... Convective evolution remains uncertain today through tonight. However, it appears that a significant convectively generated perturbation may be preceded by the development of moderate CAPE within the pre-cold frontal boundary layer across the Ark-La-Tex through Mississippi Delta region by early this afternoon. This may support at least scattered renewed strong thunderstorm development with potential to produce strong wind gusts while advancing across the Mississippi River through portions of Mississippi/Alabama through the remainder of the afternoon. Conglomerate outflow trailing back to the west-northwest across the lower Mississippi Valley may then provide a focus for additional strong thunderstorm development into this evening. Forcing for ascent, associated with low-level warm advection, and stronger shear along this boundary might provide support for a better organized convective system also capable of producing potentially damaging wind gusts, before weakening closer to the Gulf Coast overnight. ....Mid Atlantic... It appears that the primary short wave impulse might be preceded by a convectively generated or augmented perturbation, across and east of the Blue Ridge by midday. As this lead forcing encounters a destabilizing boundary-layer with weakening inhibition due to daytime heating, models suggest that numerous thunderstorms may initiate along the higher terrain, with convection becoming increasingly widespread while propagating eastward toward coastal areas. While low through mid-level wind fields are forecast to be rather weak, shear associated with modest southwesterly to westerly flow in mid/upper levels may contribute to organizing convection with cold pools capable of producing potentially damaging wind gusts. ....Upper Midwest... A corridor of more substantive boundary-layer moistening and associated convective development appears possible, but mainly in the post-frontal environment gradually advancing southward toward the international border area late this afternoon through mid to late evening. Within the more strong heated and deeply mixed pre-frontal boundary layer, thunderstorm initiation is more unclear. However, based on convection allowing ensemble output, at least isolated thunderstorm development appears possible, particularly near/east of the Bemidji vicinity after 00Z this evening. If this occurs, downward mixing of strengthening lower/mid-tropospheric wind fields may be accompanied by a few strong to severe surface gusts. ...Kerr/Thornton.. 07/09/2023 $$ = = = 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) .