Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Sep 13 2023 12:40:51 ACUS01 KWNS 131240 SWODY1 SPC AC 131239 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 AM CDT Wed Sep 13 2023 Valid 131300Z - 141200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE SOUTHWEST...SOUTHERN NEW ENGLAND...AND SOUTH ATLANTIC COAST... ....SUMMARY... Isolated severe thunderstorms are possible across parts of the Southwest, southern New England, and the South Atlantic coast today. ....Southwest... A low-amplitude mid-level impulse near the AZ/NM border remains embedded within a confluent flow regime and should progress east into the southern High Plains this afternoon. Conditionally, the most favorable area for a few supercells should be over the Permian Basin and Trans-Pecos. Despite near moist-adiabatic mid-level lapse rates, as sampled by the 12Z MAF sounding, favorable speed shear will exist above 700 mb to support an elongated mid to upper hodograph. Nevertheless, timing of large-scale ascent attendant to the impulse appears to be early relative to peak heating, and boundary-layer warming will be the key driver to the degree of instability today. As such, will maintain low severe probabilities at this time. Otherwise, isolated, marginal severe hail/wind will be possible from late afternoon to mid-evening over the southeast quadrant of AZ across southwest into east-central NM. ....Southern New England... A long-lived cluster along the leading edge of stronger low-level warm advection is ongoing across western CT. See MCD 2143 for short-term discussion. Meager surface-based instability is largely relegated to the wake of this convection centered on the Lower Hudson Valley. With modest surface heating, a corridor of MLCAPE from 500-1000 J/kg may develop towards midday. This may be adequate to support redevelopment of slow-moving convection along an eastward-moving cold front. Weak mid-level lapse rates and modest low-level shear may ultimately preclude severe storms. But scant enlargement to hodograph curvature may be sufficient for a couple weakly rotating storms with a low-probability threat of a brief tornado and damaging winds into this afternoon. ....South Atlantic coast... Isolated to scattered thunderstorms should develop along the coastal sea breeze and across the Savannah Valley in association with a remnant MCV. While 0-3 km winds will be light, 20-25 kt 500-mb west-southwesterlies could support loose multicell clustering with locally strong gusts from 45-60 mph peaking in the late afternoon. ...Grams/Mosier.. 09/13/2023 $$ = = = 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) .