Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Apr 20 2025 23:09:56 AWUS01 KWNH 202308 FFGMPD TXZ000-210435- Mesoscale Precipitation Discussion 0151 NWS Weather Prediction Center College Park MD 708 PM EDT Sun Apr 20 2025 Areas affected...middle/upper TX Coastal Plain Concerning...Heavy rainfall...Flash flooding possible Valid 202306Z - 210435Z SUMMARY...Isolated flash flooding will be possible from training, slow movement and/or backbuilding thunderstorms along portions of the TX Coastal Plain through early tonight. Rainfall rates could exceed 2 to 3 in/hr resulting in storm total rainfall of 3 to 6 inches. DISCUSSION...Visible satellite and radar imagery showed a line of scattered thunderstorms extending from eastern TX to the middle TX coast, located along a trough axis positioned ahead of a cold front/dryline which extended SSW from northeast TX into the southern Coastal Plain. The environment was supportive of heavy rain with PWATs of 1.7-1.9 inches, MLCAPE of 2000-2500 J/kg and effective bulk shear of 25-40 kt (22Z SPC mesoanalysis). Over the past few hours, cell motions have been averaging 20-25 kt toward the NE (similar to the 0-6 km AGL mean wind), parallel to the initiating trough axis, although slower motions were observed south of 29 degrees N, where shear values were weaker. Cells to the south were less numerous but have had a history of backbuilding and rainfall rates of ~1 inch in 15 minutes across portions of eastern Victoria County. MLCAPE of at least 1000-2000 J/kg with little to no CIN is forecast by the RAP to persist across the TX Coastal Plain beyond sunset along with some degree of continued convection. While bulk shear values are forecast to lower from south to north with a departing mid-level shortwave over KS/MO, there may remain a narrow zone where sufficient shear exists for at least quasi-organized cells where low level inflow remains modest along the middle to upper TX coast after 00Z. The combination of slowing cell motions with a continued (though modest) influx of low level moisture may be enough to sustain a cell or two with slow net movement (backbuilding/training) which could result in localized heavy rain with 3 to 6 inches possible. However, this threat is considered to be very isolated in nature and given dry antecedent conditions from a lack of rainfall over the past two weeks, any impactful threat of heavy rainfall would likely remain isolated and urban in nature. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9Xwum2D-HNNvpNkuhJ1VMI4cungmctJ4h9_IkFKXekp1mIMO9FuWFgVAwGCaVVcEUoNj= BcuU_IhmnOccn2CnGoDtkhc$ for graphic product... ATTN...WFO...CRP...EWX...HGX...LCH...SHV... ATTN...RFC...WGRFC...NWC... LAT...LON 31499497 31249426 29809509 28639650 28679709=20 29419670 30369581=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) .