Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun May 18 2025 21:52:19 AWUS01 KWNH 182150 FFGMPD TXZ000-OKZ000-190300- Mesoscale Precipitation Discussion 0284 NWS Weather Prediction Center College Park MD 549 PM EDT Sun May 18 2025 Areas affected...Northwest and North TX into far southern OK an Concerning...Heavy rainfall...Flash flooding possible Valid 182150Z - 190300Z Summary...Rapidly growing thunderstorms near a bulge in the dryline may result in rainfall rates as high as 2-3"/hr (and short-term totals of 3-5" with localized backbuilding). Isolated to scattered instances of flash flooding are possible. Discussion...Thunderstorms are rapidly initiating late this afternoon along a bulge in the dryline in the vicinity of Abilene, TX, near a maximum in surface-based instability (with 21z RAP analysis indicating 3000-5000 J/kg of SBCAPE across the greater North TX region). Convection should rapidly grow upscale in this mesoscale environment, which is also characterized by precipitable water values of 1.5-1.9 inches (between the 90th percentile and max moving average, per FWD sounding climatology), and (equally anomolous) deep layer shear of 50-60 kts. GOES-East water vapor imagery suggests a subtle shortwave trough near Midland, TX may be contributing to enhanced lift, and an associated ~100 kt jet streak (embedded within the broader phased jet structure) may also be ideally situated to the north (providing enhanced upper divergence via the right-entrance region). Storm mode may initially favor splitting supercells (relatively straight hodographs) with bunkers right vectors favoring much slower ENE motion (~25 kts) relative to the mean wind (~45 kts). With rainfall rates as high as 2-3"/hr anticipated, any backbuilding and training could result in significant short-term (3-6 hour) localized totals. This is expected to drive the greatest localized flash flood threat to the west of the DFW metro area (though upscale development into an MCS may allow for upwind propagation towards the ESE, and backbuilding along the western flank could bring training of heavier totals farther east into the DFW metro area). Hi-res CAMs are in relatively good agreement with regard to convective initiation along the (very well modeled) bulge in the dryline, though resulting QPF does vary quite dramatically. Some of the stronger solutions suggest the potential for 3-5" totals (mainly the FV3 and RRFS, the later of which has outlier solutions of 5"+ with some of the hourly runs). Taking a more probabilistic approach with the HREF and RRFSe ensemble systems (18z and 12z runs, respectively), a 40-km neighborhood method suggests a chance (15-30%) of 3" exceedance and a slight chance (10-20%) of 5" exceedance. These probability maxima are mostly concentrated to the north and west of the DFW metro areas, but an upwind propagating MCS could bring the threat of these totals into the DFW metro (and surroudning) area as well. Isolated to scattered instances of flash flooding are possible (and could be locally significant should backbuilding of convection manifest). Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8Xx0ler_E1yqiuvG2mxWyG8iBYDFiP8mCnHnL_bZRSp2KrYpMX8Nl4JGsNYNnXOUUIBU= HMescxKkMwd_B6P1O_on_j0$ for graphic product... ATTN...WFO...FWD...OUN...SHV...SJT...TSA... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 34319646 33889576 32839560 31459626 31109773=20 31270024 32290012 33869946 34309805=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) .