Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 20 2023 17:17:24 ACUS02 KWNS 201717 SWODY2 SPC AC 201715 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1215 PM CDT Sat May 20 2023 Valid 211200Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF EASTERN OREGON AND WASHINGTON INTO NORTHERN IDAHO AND FAR NORTHWEST MONTANA... ....SUMMARY... Severe thunderstorms are are possible from eastern Oregon into far eastern Washington, northern Idaho, and far western Montana Sunday afternoon and evening. Large hail and isolated damaging gusts will be possible with these storms. ....Northern Rockies... An upper ridge will be oriented over the Great Basin and northern Rockies vicinity Sunday morning. However, a shortwave trough off the Pacific Northwest/British Columbia coast will dig southeast into the northern Rockies vicinity by the end of the period. Increasing southwesterly mid/upper-level flow will overspread eastern WA/OR into ID and western MT by afternoon. Cold temperatures aloft will support steep lapse rates over the region, with southwesterly flow increasing midlevel moisture. This will support destabilization, with MLCAPE values around 1000-2000 J/kg forecast. Low-level winds will remain somewhat light, but speed shear will create elongated hodographs and effective shear favorable for marginal supercells (around 30 kt). Large hail (to around 1.75 inch diameter) will be the main hazard, with environmental parameters supporting an upgrade to Slight risk (level 2 of 5). Some risk for strong outflow winds also will exist, especially over parts of eastern Oregon into adjacent portions of Idaho where stronger heating will support steeper low-level lapse rates. ....Southern High Plains... Thunderstorms are expected to develop over the higher terrain of central NM during the afternoon. As these storms shift east into the high Plains and interact with a weak surface trough, some strengthening of updrafts may occur. However, instability is expected to remain modest and vertical shear weak. This should limit storm organization and longevity of any stronger updrafts, and severe potential appears too limited for probabilities. ....Southeast... A weakening cold front will shift east/southeast across the region in a generally weak flow regime. Seasonal moisture ahead of the front and pockets of heating will allow for weak destabilization. A few storms could be strong enough to produce gusty winds. However, limited forcing, poor lapse rates and weak shear should limit severe potential. ...Leitman.. 05/20/2023 $$ = = = 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) .