Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 09 2024 09:26:40 AWUS01 KWNH 090926 FFGMPD MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-091525- Mesoscale Precipitation Discussion 0138 NWS Weather Prediction Center College Park MD 525 AM EDT Tue Apr 09 2024 Areas affected...eastern TX into southern AR/northern LA Concerning...Heavy rainfall...Flash flooding likely Valid 090925Z - 091525Z SUMMARY...A relatively narrow axis of heavy rain is expected to become better organized near or a little after 12Z with areas of training from SW to NE focusing from portions of central TX into the Arklatex and portions of southern AR/northern LA. 2 to 4 inch totals are expected by 15Z, although locally higher cannot be ruled out. DISCUSSION...Regional reflectivity across northeastern TX showed a weakening cluster of thunderstorms advancing past the DFW Metroplex at 0900Z with outflow preceding it from near LNC to MKN. To the east and southeast of the Metroplex, regional reflectivity showed overrunning showers and thunderstorms, with a recent uptick in intensity since 08Z. This newer activity was located to the north of an effective stationary front which extended WNW from southern LA into east-central TX. The recent uptick in intensity to the north of the effective stationary front appears to be related to an increase in elevated instability as seen in SPC mesoanalysis of MUCAPE, due to increasing low level moisture (sfc-700 mb) as seen on Layered Precipitable Water (LPW) imagery from CIRA. LPW and water vapor imagery also showed the presence of a shortwave located southeast of Big Bend, TX, advancing toward the northeast along with higher levels of moisture in the 700-500 mb layer. Expectations are for an increase in thunderstorms along the leading edge of low level moisture return, focused in the 925-850 mb layer, with roughly 20-30 kt of southerly flow. The low level convergence axis is forecast by recent runs of the RAP to extend from near GTU to JDD to TXK at 12Z as low level wind fields gradually strengthen ahead of an eastward advancing closed low over AZ/NM. The 08/09Z SPC mesoanalysis showed 500 to 2000+ J/kg ML and MU CAPE over east-central TX, with some relatively weak areas of CIN south of the Metroplex. The advection of low to mid-level moisture from the south into central/eastern TX through the morning is expected to help reduce CIN and moisten initially dry mid-levels. Simulated reflectivity from the HRRR has been consistent with the development of an axis of thunderstorms near the low level convergence axis, focusing the potential for training and repeating storms from central into northeastern TX and near the AR/LA border, perhaps developing near or just after 12Z. Some of that development appears to be ongoing over far northeastern TX. Portions of this region have received an estimated 1 to 4+ inches since 21Z (multi-sensor MRMS estimates) and the addition of an additional 2-4 inches would result in renewed flash flood concerns. There is some uncertainty with coverage of 2-4 inch totals with recent HRRR cycles trending downward with QPF through the mid/late morning, however, the setup looks favorable for heavy rain developing later this morning with rainfall rates of 1-2 in/hr. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!57BqDa0ELxLRqCuw03UhrQyng-eJ2Ya9M_rm1LL7I0lShpu1-IcKz-iDVjuDOUZGxF7i= TNtGWx-9jqHOcab6iw9vFeo$ for graphic product... ATTN...WFO...EWX...FWD...JAN...LZK...MEG...SHV... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 34399209 34279117 33949073 33269098 32899165=20 32379342 31999465 31389616 30629763 31119805=20 32409683 33649463 34319279=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) .