Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 08 2023 19:59:52 ACUS01 KWNS 081959 SWODY1 SPC AC 081958 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Fri Sep 08 2023 Valid 082000Z - 091200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHEAST AND MID-ATLANTIC REGION...AND OVER PARTS OF THE EASTERN TEXAS/SOUTHERN LOUISIANA VICINITY... ....SUMMARY... Scattered damaging winds and isolated large hail remain possible across parts of the Mid-Atlantic States into New England into this evening, and across parts of the South-Central States in multiple rounds through tonight. ....Discussion... Convection, and associated severe-weather risk, continues to evolve largely as anticipated in earlier outlooks. As such, no substantive changes to outlook areas or reasoning appear necessary at this time. The most substantial adjustments were to remove portions of Florida from MRGL risk, in the wake of earlier storms which have moved offshore, and to trim parts of the MRGL and SLGT north of the convective line now moving southward across southern Louisiana. ...Goss.. 09/08/2023 ..PREV DISCUSSION... /ISSUED 1123 AM CDT Fri Sep 08 2023/ ....Mid-Atlantic States to New England... Thunderstorms this afternoon through early evening will again be capable of damaging winds and hail, in a scenario somewhat similar to yesterday. Late morning/midday observations continue to suggest that abundant insolation east of the Appalachians, combined with a pervasive plume of 60s to low 70s F surface dew points, will yield a pronounced west/east-oriented gradient in MLCAPE across the region, with peak values approaching 2500-3000 J/kg over the coastal plain. Scattered thunderstorms are expected to develop within the MLCAPE gradient from near the West Virginia/Virginia border northeast into parts of eastern New England. With forecast soundings suggesting nearly unidirectional southwest flow will weaken with height from the mid to upper-levels, multicell clustering will dominate. 700-mb winds in excess of 30 kt from eastern New York to Maine should support slightly more organized clustering. Steeper low-level lapse rates from Virginia to the Delaware Valley should compensate for the weaker flow and support relatively more prolific downburst potential. Scattered damaging winds along with isolated severe hail are expected regionally, mainly from mid-afternoon into evening. ....Texas/Oklahoma Red River vicinity and Sabine Valley... An elevated semi-organized linear cluster of storms persists southward at late morning across northern Louisiana. While boundary layer inhibition still currently exists, relatively cloud-free skies are noted to its south, with some potential that this cluster and/or new development on its western-peripheral outflow could root within a very moist/heating boundary layer. If so, damaging winds would be possible across southern Louisiana/southeast Texas. Farther to the northwest along the Red River Valley, record hot temperatures and a deep-mixed boundary layer should support sporadic downbursts from late afternoon to early evening with isolated thunderstorms that develop near the surface front. Some of this activity may try to congeal and grow upscale south-southeastward into east Texas during the evening/overnight within the persistent northwest flow regime atop the low-level moisture gradient. But low confidence exists in this scenario, with potential effects of the daytime round of storms modulating the downstream environment and ascent. ....Northern High Plains to Black Hills vicinity... Relatively isolated instances of severe wind and hail will be possible across the region. A low-amplitude shortwave impulse along the international border over the northern Rockies will move eastward today toward the northern High Plains. Forcing for ascent attendant to this wave will support isolated to scattered thunderstorms focused primarily across the southern half of Montana, but perhaps also far northeast Wyoming and the Black Hills vicinity as well. While there will be MLCIN concerns to the north and east, 35-45 kt effective bulk shear should support a few organized cells capable of isolated severe wind and hail. A more favorable supercell wind profile will conditionally exist near the Black Hills pending sustained storm development. ....Northern/central Florida... A mid-level low near the Florida/Georgia border should slowly weaken as it drifts south today. Relatively cold mid-level temperatures sampled by the 12Z JAX sounding of -13 C at 500 mb should support enhanced CAPE profiles between 700-300 mb yielding pronounced vertical growth. Effective bulk shear will tend to remain weak, especially near the cold core, suggesting the potential for organized storms is limited. Still, sporadic occurrences of marginally severe hail and wind are possible, mainly this afternoon. $$ = = = 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) .