Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Dec 13 2024 12:45:06 ACUS01 KWNS 131244 SWODY1 SPC AC 131243 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Fri Dec 13 2024 Valid 131300Z - 141200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Severe thunderstorms are not expected through tonight. ....Synopsis/Discussion... As heights rise in the East following the departure of a substantial synoptic-scale trough, two strong shortwave troughs will progress through the midlatitude westerlies upstream, and influence thunder potential across the western/central CONUS: 1. A leading perturbation -- now apparent over the eastern Great Basin and southern ID -- should extend from southeastern WY across east-central CO to eastern NM by 00Z. By the end of the period, the trough should reach central portions of SD/NE/KS and northwestern OK, while deepening. A closed 500-mb low may develop on the trough, either then or within a few hours into day 2, over south-central/ southeastern NE. Strong, foregoing low-level warm advection and moisture transport will persist through the period, atop a relatively stable near-surface layer. Increasing thunderstorm coverage is expected after about 06Z from the middle/upper TX Coast to the lower Missouri Valley, as increasingly moist parcels above that stable layer reach LFC. This will occur in concordance with steepening low/middle-level lapse rates and decreasing MUCINH, mainly related to the warm advection (but also late DCVA over northwestern parts of the outlook area). Small hail may fall from the strongest cells; however, forecast soundings indicate effective shear, buoyancy and inflow-layer moisture content should be too small for a severe threat. 2. The trailing shortwave trough -- initially evident in moisture- channel imagery over the North Pacific around 40N150W -- will move rapidly eastward and amplify, with preceding large-scale ascent reaching the CA/OR coastline after 06Z on either side of a low-level cold front. While lapse rates in the frontal band should be modest, and buoyancy meager, areas of MUCAPE around 50-200 J/kg, rooted near 700 mb -- may extend deeply enough into suitable icing layers to support isolated lightning. ...Edwards/Goss.. 12/13/2024 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .