Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun May 21 2023 19:44:02 ACUS01 KWNS 211943 SWODY1 SPC AC 211942 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun May 21 2023 Valid 212000Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN OREGON AND NORTHEAST WASHINGTON INTO WESTERN AND NORTHERN IDAHO... ....SUMMARY... Scattered severe thunderstorms are possible across portions of the interior Northwest, centered on 2 to 9 PM PDT. Large hail and isolated damaging gusts will be the primary hazards. ....20z Update... Other than trimming the 10 percent general thunderstorm line across parts of GA and the Carolinas, severe probabilities remain unchanged from the previous outlook. A few strong storms remain possible across parts of southeast GA into northern FL. For details on short term severe thunderstorm potential across that area, reference MCD 831. Severe thunderstorms are also expected to develop across parts of eastern OR into northeast WA and western/northern ID from late afternoon through the evening. Large hail and gusty winds are expected with this activity. For info on short term severe potential across the area, reference MCDs 832 and 833. ...Leitman.. 05/21/2023 ..PREV DISCUSSION... /ISSUED 1118 AM CDT Sun May 21 2023/ ....Interior Northwest... Around the northwest periphery of a mid-level anticyclone over the Great Basin, a plume of 0.75 to 1 inch PW values will support rounds of convection persisting into early tonight. The threat for scattered afternoon/evening thunderstorms will shift eastward compared to prior days as a shortwave trough off the Pacific Northwest coast shifts inland into WA/OR. A weak 1013 mb surface low over eastern WA and attendant cold front arcing southwest into south-central OR will be the focus for more vigorous thunderstorm development later this afternoon. Low to mid 50s boundary-layer dew points will contribute to a corridor of MLCAPE from 1000-1500 J/kg in an arc ahead of the cold front. This moderate buoyancy along with strengthening speed shear above 700 mb will favor a few high-based supercells with mid-level rotation, especially over eastern OR to the southern ID Panhandle and in far northeast WA/northern ID Panhandle. Large hail should be the primary initial threat. Consolidating cells will yield more multicell clustering into the evening with an isolated mix of severe wind gusts and hail, before convection weakens over the northern Rockies after sunset. ....Southeast GA and the north FL Peninsula... A diffuse front along with colliding sea breezes will support scattered thunderstorms into early evening. 12Z JAX/TLH observed soundings sampled a belt of enhanced speed shear through the mid to upper-levels, which may be adequate to foster small hail production despite poor mid-level lapse rates. This may yield precip-loaded, locally strong downbursts in the more intense cells as MLCAPE peaks from 1500-2000 J/kg. ....Southern High Plains... Scattered, slow-moving thunderstorms are expected later this afternoon into the evening within a weakly buoyant air mass characterized by MLCAPE of 500-1000 J/kg. Modest mid-level lapse rates (especially compared to late May climo) away from the higher terrain and relatively weak vertical shear suggest that organized severe storms are unlikely. A very low probability of marginally severe hail and wind exists, but appears too minimal to warrant an areal delineation. $$ = = = 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) .