Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Dec 25 2024 00:34:05 AWUS01 KWNH 250033 FFGMPD LAZ000-TXZ000-250600- Mesoscale Precipitation Discussion 1187 NWS Weather Prediction Center College Park MD 733 PM EST Tue Dec 24 2024 Areas affected...east-central/southeastern TX Concerning...Heavy rainfall...Flash flooding possible Valid 250030Z - 250600Z SUMMARY...A few areas of flash flooding, especially across urban locations, will be possible through 06Z for portions of east-central/southeastern TX. Rainfall rates of 2 to 3 in/hr are expected but should remain localized. DISCUSSION...00Z surface observations showed a complex depiction of effective boundaries in place over central and eastern TX, but with two of the more significant features driving ongoing convection being a wavy stationary front and southward extending trough axis south of the DFW metroplex and the leading edge of higher theta-e air which extended from near RWV to GLS. Thunderstorms were scattered across the region but have recently been increasing along/ahead of a pre-frontal trough axis/wind shift located east of I-35 and extending to just south of SSF. SPC mesoanalysis showed uninhibited MLCAPE of 500-1500 J/kg within the warm sector of the wavy stationary front to the north, and 2000+ along the middle to lower TX coast. Anomalous moisture (PWATs 1.0 to 1.4 inches) combined with favorable instability/shear profiles have allowed for organized cells with slower cell motions than the deeper-layer mean wind of 15-25 kt. One of these slower cells resulted in observed 2-3 in/hr rainfall rates in a southeastern Houston suburb ending 2330Z with MRMS showing occasional/spotty rates in the 2-3 in/hr since 21Z over north-central TX. As the base of a mid to upper-level trough continues to amplify over central TX early tonight while translating eastward, forcing will be aided by diffluent flow downstream over eastern TX. Thunderstorms are likely to continue expanding near the southward extending trough axis over east-central TX within the reservoir of instability as well as near the quasi-stationary fronts over northeastern and southeastern TX. Mean/unidirectional southwest flow is likely to allow for some training and repeating cells with increasing 850 mb winds overnight (up to ~25 kt) possibly supporting slower cell movement and brief backbuilding. Localized 2-3 in/hr rainfall rates will be likely with isolated 2-3 hour rainfall totals of 3-5 inches possible. While soils have been fairly dry over this portion of TX over the past couple of weeks and FFG values are fairly high (3-5 inches in 3 hours), overlap of heavy rain with any urban areas will exacerbate flash flood potential due to poor drainage of these potential higher rates. A few areas of flash flooding will be possible, but the threat is expected to remain relatively localized. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-M72DAobPLmIhD3qOMgraYugFl6_6YsSHFXYQOW4cO0fOt8RNy_yOJE7iEgTmbQZ9GQb= 5OaACXjPjHbWotmP9jG6qb4$ for graphic product... ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 32609438 32559392 32129359 31049383 29779491=20 29189635 28709829 29119879 30659714 31539649=20 32149586 32479506=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) .