Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Mar 03 2025 20:03:27 ACUS01 KWNS 032002 SWODY1 SPC AC 032001 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0201 PM CST Mon Mar 03 2025 Valid 032000Z - 041200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH-CENTRAL TEXAS AND WESTERN/CENTRAL OKLAHOMA... ....SUMMARY... Thunderstorms should increase late this evening and merge into a squall line overnight across parts of the southern and central Plains. Several tornadoes, scattered to numerous severe wind gusts, and large hail are all possible. ....20Z Update... The forecast remains on track, and only minor adjustments were made with this update. In particular, the Marginal Risk was expanded northward into southwest IA, where steepening midlevel lapse rates and sufficient deep-layer shear orthogonal to the low-level front could promote an isolated severe hail risk late in the forecast period. Elsewhere, the Marginal and Slight Risk areas were expanded slightly westward over the southern/central Plains, to account for the latest high-resolution guidance depicting slightly earlier convective initiation in an environment favorable for large hail and severe wind gusts. For additional details, see the previous discussion below. ...Weinman.. 03/03/2025 ..PREV DISCUSSION... /ISSUED 1032 AM CST Mon Mar 03 2025/ ....Southern/Central Plains... A pronounced upper trough with attendant 80-100 kt mid-level jet will eject eastward from the Great Basin and Southwest across the southern/central High Plains through tonight. As large-scale ascent associated with this system overspreads the High Plains, lee cyclogenesis will occur over eastern CO. This surface low should deepen further late tonight into early Tuesday morning as it develops into western KS, and as a Pacific cold front sweeps east-southeastward over the southern High Plains through the end of the period. Low-level moisture (surface dewpoints generally in the upper 50s to low/mid 60s) over south/central TX this morning will continue to stream northward over the southern/central Plains ahead of the cold front and an eastward-mixing dryline. Current expectations are for a cap to inhibit robust, surface-based thunderstorm development until late this evening, likely after 03Z. Once the large-scale ascent preceding the upper trough and the Pacific cold front begin to intersect with the warm sector, intense thunderstorms should quickly develop over parts of western OK into south-central KS. Steep mid-level lapse rates, cold temperatures aloft, increasing low-level moisture, and strong deep-layer shear will all contribute to an environment conducive for supercells, with an associated threat for large hail initially. A fairly quick transition to a more linear/QLCS mode is expected as the cold front moves quickly east-southeastward overnight across KS/OK and north TX. Ample low-level shear will be present owing to a 45-60 kt south-southwesterly low-level jet, and embedded circulations within the line will likely be capable of producing tornadoes, assuming sufficient boundary-layer instability to support surface-based convection. Even with various NAM/RAP forecast soundings showing near-neutral lapse rates in the boundary layer overnight, the strength of the low-level flow should still be more than enough to support at least scattered severe/damaging winds with the line as it sweeps eastward across the southern/central Plains through the end of the period (early Tuesday morning). Recent surface observations show at least low 60s surface dewpoints into parts of western north TX and the Red River vicinity of southwest OK. This appears to be a little ahead of schedule for some guidance, and with about 12 more hours of low-level moisture return likely ahead of the cold front, concern is increasing that around 63-64F surface dewpoints should be in place across parts of western/central OK into north-central TX by the time convective initiation occurs tonight. An Enhanced Risk for tornadoes and severe/damaging winds has been introduced across parts of this region where confidence in surface-based thunderstorms and the best combination of instability and low-level shear is forecast. $$ = = = 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) .