Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Oct 19 2024 12:46:46 ACUS01 KWNS 191246 SWODY1 SPC AC 191245 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Sat Oct 19 2024 Valid 191300Z - 201200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF EASTERN NEW MEXICO AND FAR WEST TEXAS... ....SUMMARY... Large hail, severe gusts and some tornado threat are possible across eastern New Mexico and portions of far West Texas this afternoon and evening. ....Synopsis... A highly amplified mid/upper-level pattern will become less so in the northern stream through the period, as nearly zonal flow takes shape across the northern international border region, and synoptic ridging deamplifies over the eastern CONUS. A compact cyclone -- initially centered over central AZ -- will remain near its present position through the period, having become cut off temporarily from the prevailing westerlies. At the surface, 11Z analysis showed a decelerating cold to quasistationary front from a weak low over northeastern MN to another near LXN, then southwestward over northeastern KS, southeastern CO and northeastern NM near LVS, merging with a slow- moving Pacific front related more directly to the AZ cyclone. That front extended south southwestward over the Tularosa Valley to between LRU-ELP, and should move little today (with just mesobeta- scale baroclinic shifts from precip/outflow). ....Eastern NM, west TX... Along and east of the front, scattered thunderstorms are expected to develop this afternoon into evening, and congeal with time into at least a loosely contiguous band. This activity should be oriented strongly parallel to the southerly to south-southwest flow characterizing the cyclone's peripheral eastern semicircle. A few supercells are possible in the transitional time between development and quasi-linear evolution of that activity, as well as in the warm sector farther east. Some of the convective lift -- then underway from diurnal heating of a weakly capped, EML-deprived air mass -- will be aided by the upslope component of southeasterly boundary-layer flow into higher terrain across this region. The same flow also will contribute to substantial veering with height, yielding favorable deep shear (effective-shear magnitudes 35-40 kt, locally larger) for supercells in any relatively sustained/discrete convection. Hodographs should reach their largest sizes for areas with surface- based effective-inflow parcels in the 23-03Z time frame, suggesting a window of relatively maximized local tornado opportunity for any supercells that can access what should be a much higher-theta-e inflow airmass than the previous day. Surface dewpoints in the 50s F should remain common in the warm sector through the diurnal heating cycle, and low 60s already are seen in mesonet data not far upstream, over the Pecos Valley of west TX. At elevations mainly above 4000 ft, the resulting boundary-layer thermodynamic profile (including lower LCL), and slightly cooler air aloft, should steepen previously meager lapse rates enough to permit a corridor of 1000- 1500 J/kg preconvective MLCAPE. A conditional significant-hail threat may develop as well, but given the lack of greater lapse rates typically found with such hail in this area, will refrain from an unconditional sig/hatched line at this time. ...Edwards/Goss.. 10/19/2024 $$ = = = 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) .