Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Sep 14 2024 19:18:49 ACUS03 KWNS 141918 SWODY3 SPC AC 141917 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0217 PM CDT Sat Sep 14 2024 Valid 161200Z - 171200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE GREAT BASIN INTO THE FOUR CORNERS REGION... ....SUMMARY... Isolated severe gusts and small to marginally severe hail will be possible on Monday afternoon to early evening across parts of the eastern Great Basin to Four Corners. ....Synopsis... The upper-level trough currently in place across the northeastern Pacific is forecast to amplify over the next 24-72 hours as it migrates southward along the West Coast and eventually into the Great Basin. As this occurs, an attendant mid-level jet streak will pivot into the interior West. The combination of increasing ascent and strengthening mid/upper-level winds will support isolated to scattered strong to severe thunderstorms across parts of the Great Basin and Four Corners. To the east across the Plains, surface pressure falls will become increasingly concentrated across the central to northern High Plains, which will maintain a moisture return regime. Weak ascent over a broadening warm sector will support isolated to widely scattered thunderstorm chances. ....Great Basin/Four Corners... Forecast guidance continues to show reasonably good agreement in strengthening wind fields across NV into UT and AZ by peak heating Monday as the mid/upper jet noses into the region. Mid-level lapse rates will steepen through the day ahead of the approaching wave, which, despite very modest moisture content, should support adequate buoyancy for convection. Deep, well-mixed boundary layers will facilitate efficient downward mixing of strong mid-level flow, which will likely be augmented by evaporatively-cooled downdraft accelerations. Consequently, the probability for strong to severe wind gusts appears higher and somewhat more concentrated compared to preceding days. Portions of the Four Corners region may also see a large hail threat given elongated wind profiles and slightly better buoyancy due to an influx of low/mid-level moisture from the Gulf of California. ....Central to northern Plains... Northward moisture return is expected to persist through Monday evening as a lee cyclone becomes more consolidated across the central to northern High Plains. With the primary upper-level trough displaced well to the west, synoptic-scale ascent will remain weak across the Great Plains region. However, signals for thunderstorm development within a modest warm-advection regime across ND and along the lee trough over parts of central/western KS into far northwest OK are noted in recent solutions. Predictability in either scenario is too limited to warrant risk probabilities, but the convective parameter space across both ND and KS/OK appears conducive for a conditional severe threat. ....Coastal North Carolina... A low off the Carolina coast is forecast to gradually intensify/organize over the next 72 hours, though forecast uncertainty regarding its exact evolution remains very high (see the latest NHC forecast discussion for additional details). However, a few solutions, notably recent GFS and NAM runs, suggest the low will migrate inland across the Carolinas during the day Monday. As this occurs, a narrow swath of high theta-e air will span from the NC coast into eastern NC and perhaps southeast VA. Wind profiles within this swath may feature strong low-level helicity that could support some tornado threat given sufficient buoyancy for deep convection. Confidence in this scenario remains very limited, but forecast trends will be monitored. ...Moore.. 09/14/2024 $$ = = = 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) .