Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Dec 19 2022 13:35:14 AWUS01 KWNH 191335 FFGMPD LAZ000-TXZ000-191815- Mesoscale Precipitation Discussion 1165 NWS Weather Prediction Center College Park MD 834 AM EST Mon Dec 19 2022 Areas affected...Central to Southeast Texas... Concerning...Heavy rainfall...Flash flooding possible Valid 191335Z - 191815Z SUMMARY...Training elevated thunderstorms are a bit more efficient than forecast. Rates of 1-1.5"/hrs may allow for streaks of 1-2" totals and localized maxima of 2.5" in about 1-2hrs pose widely isolated incidents of possible flash flooding. DISCUSSION...GOES-E WV suite denotes a jet speed max crossing the Red River Valley opening up more favorable right entrance ascent pattern across central and southeast TX. Low level VWP have responded with strengthening southerly 850mb winds increasing to 30-35kts out of the western Gulf of Mexico surging higher moisture and more unstable air isentropically over the shallow cooler air at the surface as noted by the well defined frontal zone at the TX coastline. RAP analysis depicts the nose of 500 J/kg along tightening MUCAPE gradient consistent with the speed convergence at 850mb, while the winds are starting to veer for increased convergence due to directional component as well. As such, stronger convective development has blossomed from just east of Austin, TX toward Brazos and Grimes counties. Given some limited instability, the overall updrafts are fairly narrow and inconsistent, yet continue to show positive signs for additional development/cooling in 10.3um EIR with upstream signals of redevelopment (per transverse banding low level cloud structures at the nose of the LLJ). These cells have already been fairly prolific (seasonally speaking) with RADAR estimated 1-1.5"/hr rates, resulting in localized 1" totals observed in 1-2hrs along this axis.=20 Steering flow is fairly unidirectional and supporting of training profiles given the parallel nature of the flow to the convergence axis and nose of the MUCAPE gradient.=20=20 While the dynamic and thermodynamic environment appear to be ideally aligning to support 1.5-2" with may an isolated 2.5" total along this axis, the uncertainty remains in the hydrological response to such rains as FFG values are sizably higher than 1.5"/hr or up to 2.5" in 3hrs. Still, soils are dormant and this area (particularly east of College Station) has seen recent heavy rainfall with AHPS 2-week anomalies of 200-300% and NASA SPoRT 0-40cm relative soil moisture values above 50%. As such, while flash flooding is not very likely, a widely scattered incident or two of flooding is considered possible over the next few hours across the highlighted area, especially near urban/hydrophobic ground surfaces. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_ktlo7x-INHlrNU9PnjozTlFWT91Yb3jOLd5rjFtDAa1H9pCKGw8mxlo40NFL4LE0gmw= e1t-R3v6bfzubP9KRjxPGSs$ for graphic product... ATTN...WFO...EWX...FWD...HGX...LCH...SHV... ATTN...RFC...WGRFC...NWC... LAT...LON 31779427 31619379 30909368 30419446 30099538=20 29819624 29559718 29579776 30149844 31019682=20 31489531=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .