Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Apr 26 2025 14:47:47 AWUS01 KWNH 261447 FFGMPD TXZ000-OKZ000-262100- Mesoscale Precipitation Discussion 0184 NWS Weather Prediction Center College Park MD 1046 AM EDT Sat Apr 26 2025 Areas affected...portions of Northwest TX into North TX and south-central OK Concerning...Heavy rainfall...Flash flooding likely Valid 261500Z - 262100Z Summary...Scattered instances of flash flooding are likely to continue and expand in association with a mature MCS/MCV with additional localized totals of 3-6" expected (most likely from Norman/OKC southwestward into portions of North TX). Localized significant and life threatening flash flooding is possible. Discussion...A mature MCS (mesoscale convective system) has progressed southeastward out of the TX Panhandle and northwestern OK from overnight into the morning, resulting in 6-12 hour localized rainfall totals of 3-6 inches. The leading edge of the squall line has reached a quasi-stationary surface boundary draped from the southern Permian Basin eastward along and near the Red River of the South. Some of the heaviest totals have occurred in association with a well-defined MCV (mesoscale convective vortex) and accompanying RIJ (rear-inflow jet), producing localized 3-6" totals in the vicinity of Lawton, OK over just the past 3 hours (with hourly totals as high as 2-3"). Most recent observational trends support continued training and repeating of cells with 1-3"/hr rainfall rates along and near the path of the MCV/RIJ (which should progress towards the northeast at near 20 kts within the southwesterly mid-level flow). While instability is somewhat limited on this trajectory (though MU CAPE of 500-1000 J/kg extends northeast into the OKC/Norman metro area), the dynamics of the MCV (as well as the influence of the right-entrance region of a 90 kt polar jet streak over the Middle MS Valley) are providing ample diffluence aloft with effective bulk shear of 30-40 kts. Along the southern and southwestern flanks of the MCS, much more ample instability (gradient of 1000-2000 J/kg of SB CAPE) with appreciable low-level (850 mb) moisture transport via 20 kt LLJ (low-level jet) should continue to support localized rainfall rates of 1-2"/hr. Training and repeating of cells moving west to east along the combined gust front and quasi-stationary boundary may support excessive rainfall farther south into northwest TX as well. Primarily relied on hourly runs of the HRRR and experimental RRFS since 06z, which are in remarkably good agreement (hour-to-hour and between the two separate models). Additional 3-6 hour totals as high as 3-6" are expected, though generally occurring to the south and east of where prior rainfall has occurred (though some additional overlap is possible, resulting in combined totals of up to 8" in some localities from south of Norman, OK to the southwest along and near I-44 to the Red River of the South). Very wet antecedent conditions (with NASA SPoRT-LIS 0-1 m soil moisture anomalies at or above the 90th percentile) have resulted in 3-6 hour FFGs (flash flood guidance) of 2.0-3.0 inches, suggesting that additional scattered instances of flash flooding are likely (and could locally be significant and life threatening, particularly if these higher-end totals occur over metro areas). Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7dh7aFHyBpfxJKjPKhZ1sow3WOq8VPkGTc7P0t0bKdbP9t0JJcYcqqDf7CuNVDhy5yya= qQ4KARA0ETRWFEmOzWfnZhE$ for graphic product... ATTN...WFO...FWD...LUB...MAF...OUN...SJT...TSA... ATTN...RFC...ABRFC...WGRFC...NWC... LAT...LON 36039651 35389590 34409620 33529759 32869861=20 32500005 32770224 33670264 34060208 34250107=20 34410000 35019889 35439824 35849754=20 =3D =3D =3D 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) .