Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Nov 30 2025 03:57:29 AWUS01 KWNH 300357 FFGMPD LAZ000-TXZ000-301000- Mesoscale Precipitation Discussion 1255 NWS Weather Prediction Center College Park MD 1056 PM EST Sat Nov 29 2025 Areas affected...Central and Upper Texas Coastal Plain... Concerning...Heavy rainfall...Flash flooding possible Valid 300400Z - 301000Z SUMMARY...Slow moving, pre-frontal cells with rates of 2"/hr eventually merge with south-southeastward pressing cold front convection resulting in localized 2-4" totals in 1-3 hours.=20 Isolated flash flooding remains possible, especially near urban centers. DISCUSSION...GOES-E 3.9um SWIR highlights a few low level boundaries that will remain the focus of scattered thunderstorm activity through the overnight period. The main being the surging cold front being reinforced by favorable upper-level orientations to support steepening of theta-E gradient while increasing northerly surface wind flow to over 20-25kts nearly counter to the weaker but solid onshore flow. Currently active convection along the leading edge of the front is slow moving from Burleson to Polk county as the winds are not fully intersecting with the line, but will likely be propagating southward in the next hour or so. The other boundary is the return moisture plume off the western Gulf (which arches similar to the Lower TX Gulf coast before angling east- northeast just south of the aforementioned convection). Tds in the upper 60s to near 70 can be traced best in CIRA LPW sfc-850 and 850-700mb layers covering much of the MPD area of concern across the Central and Upper Texas Coastal Plain. Onshore flow is also increasing to 15-20kts resulting in frictional convergence near coast. Conditionally unstable airmass with MLCAPEs of 1000-1250 J/kg remain weakly capped but there are some signs in satellite imagery of some weak cu field near Victoria, TX as well as an isolated weakening supercells northeast of Galveston Bay. The merging of the boundaries is also allowing a westward expansion of new development upstream into Bastrop/Caldwell county vicinity.=20 Total deep moisture of 1.5" as noted in the CIRA LPW is loaded below 700mb, but there is solid deep saturation. These isolated cells driven by frictional convergence will be slow moving and eventually capable of 1-2"/hr rates. Spotty 2-3" totals will occur in 1-2hrs, but as they mature and expand the slower moving cells along the cold front will have started increased forward speed and with very high low level moisture flux convergence will have the capability of 1-1.25"/15min rainfall totals as they intersect/merge with the cells across the Plain. 00z HREF probabilities continue to suggest 3"/3hr totals in the 20-30% range (3"/6hr over 50%) which is fairly impressive given the strength of the updraft due to instability is fairly limited.=20 While the overall coverage will continue to be limited, spots of 3-4" totals are probable through 09z. This places sufficient overlap of FFG exceedance (as 1hr FFG is 2.5-3" and 3hr is 3-4") for possible localized incident or two of flash/rapid inundation flooding. This only further increases with intersection with urban centers, such as Victoria, Houston and Beaumont.=20=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6eBqZJFeXYwfdfjOanroH9GQeQtbydrQfNUR442JL4eOoRDBCnP5-W_eKdR2izXE3AJE= Wxq3reM5uV59a3QArZIE_ho$ for graphic product... ATTN...WFO...CRP...EWX...HGX...LCH... ATTN...RFC...FWR...NWC... LAT...LON 30999472 30719393 30099362 29749380 29519420=20 29359466 28499607 27779725 27969777 28499795=20 29529752 29879714 30199681 30729602=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .