Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 22 2024 22:22:01 AWUS01 KWNH 222221 FFGMPD MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-230400- Mesoscale Precipitation Discussion 0698 NWS Weather Prediction Center College Park MD 621 PM EDT Mon Jul 22 2024 Areas affected...Northeast TX...Northern LA...Southern AR...Northern MS...Shear Concerning...Heavy rainfall...Flash flooding possible Valid 222220Z - 230400Z SUMMARY...Slow moving, colliding outflow boundaries within very unstable, moisture rich environment to support numerous but scattered thunderstorms capable of 2-2.5"/hr rates. Isolated spots of 2-4" due to collisions pose possible incidents of flash flooding through early overnight period. DISCUSSION...GOES-E WV suite depicts a fairly flat intersection between return sub-tropical jet streak across N MX into southern TX and the base of the digging but broad positive tilt northern stream trough across the Southern Plains. As a result, high theta-E air from the Gulf has lifted north and aligned with low to mid-level subtropical moisture feed from the Pacific/Northwest Mexico monsoonal flow. The polar jet continues to enhance into the confluent flow across the lower TN valley with a 70kt jet streak over AR, as seen by pock-marked, transverse-banded cirro-cu from OK to W TN. This is providing broad scale ascent ahead of a weak shortwave in NE TX and backing low level flow across SE TX into central LA becoming convergent on the lingering stationary front that extends from central TN across N MS into S AR/NE TX.=20 VWP and RAP analysis suggest an 850mb wave is co-located with the surface wave over NE TX near Corsicana. As such, strengthening downstream moisture convergence has been breaking out thunderstorms in the modestly narrow, skinny profiles supporting 2000-2500 J/kg of MLCAPE along and south of the frontal zone across N LA into MS.=20=20 Moisture over 2-2.25" and speed/directional convergence of 5-15kts, will support strong moisture flux into thunderstorms developing along older outflows or the stationary front. Strong updrafts will support 2-2.5"/hr rates, perhaps a tad stronger as outflow boundaries collide and broaden widths of updrafts and subsequent downdrafts. Cell motions are slow at 15-20kts generally parallel to the boundary resulting in possible short-term training, but some dry air appears to be supporting stronger outflow boundaries, which have been the drivers of effective cell motions and propagation over the last few hours.=20 As such, the intense rates and spots of 2-4" totals may spur scattered incidents of flash flooding through the evening, currently north near the low in northeast TX across to N LA/S AR before expanding downstream into MS later this evening.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6Ttj7JEcFMVZmuz2oHTv8bqaqx79vFf9AUpa9iX3gfL8FKcLebk9tImDN_p1Hda1YGF1= mxdvgeXmOyMfD6GtUtYSQns$ for graphic product... ATTN...WFO...FWD...JAN...LZK...MEG...SHV... ATTN...RFC...ABRFC...LMRFC...SERFC...WGRFC...NWC... LAT...LON 34899035 34288930 33648875 32558872 32098993=20 31769248 32299455 31749715 31719783 32459784=20 33759478 34749171=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) .