####018000909#### PENA01 KWNH 131200 @UHPISF000CN MPDSUM@V2.0@0101700060@12130524@@0NMCGPHMPD ]p@!' `' ` @ & B7)p&PNAM02@@=y}||||}{||||||}~}~~}{z|||}{@@y@@y@@<$~~~{{y|||{{{~}}}|}}}~}~~@@$@@$@@xO0265 @@0266 @@d&MESOSCALE DISCUSSION SUMMARY GRAPHIC @@d& OF ALL VALID MESOSCALE DISCUSSIONS AT @@d& TIME OF PRODUCT CREATION:@@d& ISSUED 05/13/2024 1945Z @@ dNOAA/NWS/NCEP@@d WEATHER PREDICTION CENTER @@d FOR COLOR VERSION SEE: @@d WWW.WPC.NCEP.NOAA.GOV @####018003654#### AWUS01 KWNH 131949 FFGMPD MSZ000-LAZ000-TXZ000-140130- Mesoscale Precipitation Discussion 0267 NWS Weather Prediction Center College Park MD 348 PM EDT Mon May 13 2024 Areas affected...Upper Coast of Texas into central Louisiana Concerning...Heavy rainfall...Flash flooding likely Valid 131947Z - 140130Z Summary...Thunderstorms developing along a stationary front will strengthen and train to the E/NE through the evening. Rainfall rates of 2-3"/hr will be common within these thunderstorms, producing locally 3-5" of rain. Flash flooding is likely. Discussion...GOES-E IR imagery this afternoon depicts rapidly cooling cloud tops embedded within a large canopy of convective clouds across eastern TX. These high level and cooling clouds are a result of rapidly blossoming thunderstorms from south-central TX into southern LA, developing primarily along a stationary front draped near the Upper Texas Coast. Forcing for ascent is being provided through convergence along this boundary, aided by modest shortwaves rotating beneath the base of a mid-level trough centered over KS, and within the favorable diffluent RRQ of a poleward arcing jet streak. This deep layer ascent is acting upon extremely favorable thermodynamics for heavy rain noted by SPC RAP SBCAPE of 4000-5000 J/kg, and PWs measured by GPS of over 2 inches. This has already resulted in rainfall rates estimated by KHGX WSR-88D of 2-2.5"/hr. As the afternoon progresses, it is likely that thunderstorms will continue to regenerate along this boundary within the strongest low-level convergence as synoptic ascent remains intense. The high-res CAMs, including the HRRR and ARWs suggest convection may grow upscale into an MCS, which is supported by the presence of 30-50 kts of bulk shear. While this organization could eventually result in a cold pool dominated MCS due to the extreme SBCAPE, which would likely push convection offshore TX, until that happens, the continued intensification and expansion of convection will result in a continued flash flood risk. Storms that form along the boundary will organize and train along the stationary due to boundary-parallel 0-6km mean winds and aligned Corfidi vectors, which with rainfall rates likely peaking at 2-3"/hr will produce more than 3" of rain in some areas. Locally, more than 5" of rain is possible in the next 6-hrs as reflected by HREF probabilities for 5"/6hrs as high as 40%. The models are generally under-initializing the current convection as well, so these probabilities may be a bit underdone. Additionally, this area has received excessive rain over the past 7 days as noted by AHPS rainfall departures 300-600% of normal, especially from the Heart of Texas through the Piney Woods and into central LA. Here, NASA SPoRT 40cm soil moisture is above the 98th percentile, indicating highly hydrophobic soils and resulting in FFG as low as 0.5"/3hrs which should easily be exceeded in some areas. The greatest risk for flash flooding will be in urban areas or atop these most sensitive soils, but anywhere these impressive rain rates train will likely lead to rapid runoff and instances of flash flooding. Weiss ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...HGX...JAN...LCH...LIX...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 31779158 31559103 31159090 30519110 30219135 30099226 29969337 29729402 29449464 28989534 28869562 28739587 28889617 29299628 30179568 31129391 31689238 ####018001099#### PENA01 KWNH 131200 @UHPISF000CN MPDSUM@V2.0@0101700060@12130524@@0NMCGPHMPD ]p@!' `' ` @ & B7)p&PNAM02@@AA~|zt{z|~~~~~~~~}}}}|}||||}}~@@A@@A@@=y}||||}{||||||}~}~~}{z|||}{@@y@@y@@<$~~~{{y|||{{{~}}}|}}}~}~~@@$@@$@@xO0265 @@0266 @@~0267 @@d&MESOSCALE DISCUSSION SUMMARY GRAPHIC @@d& OF ALL VALID MESOSCALE DISCUSSIONS AT @@d& TIME OF PRODUCT CREATION:@@d& ISSUED 05/13/2024 1948Z @@ dNOAA/NWS/NCEP@@d WEATHER PREDICTION CENTER @@d FOR COLOR VERSION SEE: @@d WWW.WPC.NCEP.NOAA.GOV @