Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Dec 10 2022 23:36:51 AWUS01 KWNH 102336 FFGMPD TXZ000-110535- Mesoscale Precipitation Discussion 1150 NWS Weather Prediction Center College Park MD 636 PM EST Sat Dec 10 2022 Areas affected...portions of Southeast TX Concerning...Heavy rainfall...Flash flooding possible Valid 102335Z - 110535Z Summary...Showers and thunderstorms across Southeast TX are showing an increasing training signature in and around Conroe.=20 Hourly rain totals to 2" with local amounts of 3-5" are possible through 06z. Discussion...Showers and thunderstorms have been increasing in intensity and coverage as of late west and north of Houston, along an outflow boundary/convergence axis which is noted in the thermal pattern and wind observations across southeast TX and southern LA. Divergence aloft has been sponsored by an upper level shortwave moving across western TX. More organized activity is moving more eastward, occasionally colliding with less organized activity moving more northeast, which is amping up the hourly rain totals.=20 Precipitable water values are 1.3-1.75" in this region per GPS data. Inflow at 850 hPa is ~20 kts from the southwest based on the KPOE and KHGX VAD wind profiles. ML CAPE of 1500-2000 J/kg exists, per SPC mesoanalyses, with the heart of the instability pool showing 72-73F dew points. Effective bulk shear of 40 kts is leading to more organized convective structures normally seen in HP/high precipitation environments. As a polar front comes in from the north and the upper level shortwave approaches from the west, the areal extent of the heavy rainfall should increase overnight as low-level convergence increases further. The concern is that training and merging convection would be capable of hourly rain totals up to 2" or so with local amounts of 3-5" per the current mesoscale guidance.=20 While the region has been dry, this degree of rainfall would be problematic in any urban environments it would occur within.=20 Thus, flash flooding is expected to be isolated at first but could become widely scattered towards 06z, particularly if the high end guidance (HRRR and NAM CONEST) come to pass. Roth ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8tA6HWzSl83b9EcqPr0IqwujGkTNipuTXVTxEYxpmNvduO8tz6NE_38en6g-ZxHCGos0= LbVlOdo3meeW7LAH-VDyHX8$ for graphic product... ATTN...WFO...EWX...FWD...HGX...LCH...SHV... ATTN...RFC...WGRFC...NWC... LAT...LON 31279392 30439409 30159510 29769665 29809715=20 30629702 31149596=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) .