Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Mar 20 2024 05:40:23 ACUS01 KWNS 200540 SWODY1 SPC AC 200538 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1238 AM CDT Wed Mar 20 2024 Valid 201200Z - 211200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS AND WESTERN OKLAHOMA... ....SUMMARY... A few clusters of thunderstorms should develop across parts of Texas and western Oklahoma this afternoon through tonight. Some of this activity may pose a marginal hail or gusty wind risk. ....Synopsis... A southern-stream mid/upper-level jet will persist today over Mexico and the Gulf, along with the southern Plains into the Southeast. A weak mid-level shortwave trough will move eastward across NM and into west TX by this evening, while a separate perturbation develops across northern Mexico and south TX through late tonight. Surface high pressure centered over the Gulf and Southeast will hamper the northward advance of rich low-level moisture over much of TX through this afternoon, although limited moisture should be able to reach parts of the TX Panhandle and western OK along/east of a weak surface trough. Somewhat greater low-level moisture should eventually spread inland over portions of south/coastal TX late tonight into early Thursday morning. ....Texas Panhandle into Western Oklahoma... Even with weak surface cyclogenesis occurring over the southern High Plains today, low-level moisture will likely remain quite modest with surface dewpoints generally in the mid 40s to low 50s. Still, cold temperatures aloft (around -16 to -20C at 500 mb) and steep low/mid-level lapse rates should aid in the development of weak MLCAPE this afternoon as modest daytime heating occurs. Sufficient deep-layer shear owing to modestly enhanced mid-level winds should be in place to support some updraft organization with any convection that can form along/east of the surface trough. With lengthy mid/upper-level hodographs, some of these thunderstorms could produce small to marginally severe hail. A very well-mixed boundary layer should also foster an isolated threat for strong to severe downdraft winds. Limited moisture/instability are expected to keep the overall severe threat fairly marginal/isolated across this area. ....South/Coastal Texas... Low-level moisture will gradually increase this evening and overnight across parts of south/coastal TX. While a stout cap will likely suppress convection through much of the day, large-scale ascent preceding a southern-stream shortwave trough may eventually encourage isolated thunderstorms to develop late tonight. If this occurs, convection should tend to remain elevated. But with moderate MUCAPE and strong deep-layer shear, any thunderstorms that form and persist could produce severe hail. This threat appears rather conditional, with most high-resolution guidance suggesting that robust convective development will be delayed until around 09-12Z Thursday morning. ....Northeast... A strong mid/upper-level cyclone, with associated 70-90 kt mid-level jet, will be in place over much of the Great Lakes and Northeast today. A related surface low will develop eastward across southern Quebec through the day, while a secondary surface low deepens and quickly advances eastward in tandem with a cold front across coastal parts of the Northeast and Mid-Atlantic. Most guidance shows minimal instability ahead of the front, but cold mid-level temperatures and modest diurnal heating may be enough to support the development of very weak boundary-layer instability. It remains questionable if any low-topped convection that develops will reach sufficient depths to produce lightning. Regardless, occasional strong/gusty winds may occur with this activity given the forecast strength of the low/mid-level flow. ...Gleason/Flournoy.. 03/20/2024 $$ = = = 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) .