Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Dec 28 2024 17:05:21 AWUS01 KWNH 281705 FFGMPD MSZ000-LAZ000-ARZ000-TXZ000-282230- Mesoscale Precipitation Discussion 1201 NWS Weather Prediction Center College Park MD 1204 PM EST Sat Dec 28 2024 Areas affected...eastern TX, northern LA, southern AR, northwestern MS Concerning...Heavy rainfall...Flash flooding likely Valid 281700Z - 282230Z SUMMARY...Areas of training heavy rain, with rates of 1-3 in/hr, will affect portions of eastern TX into northern LA, southern AR and perhaps far northwestern MS through 22Z. Rainfall totals of 3-5 inches in 2-3 hours will be possible across a SW to NE oriented axis, overlapping TX/LA/AR. DISCUSSION...Regional radar imagery at 17Z showed scattered to widespread thunderstorms from the AR/LA border into northeastern TX. Convection extended roughly near/north of a stationary front which was analyzed WSW from the MS/AR border into eastern TX at 17Z. Convection transitioned into a QLCS with southeastward bowing observed across I-20 in eastern TX. Meanwhile, an upstream NNE to SSW axis of thunderstorms was pressing east along I-35 between ACT and SAT, located just ahead of a pre-frontal trough/dryline. 30-40 kt of SW 925-850 mb flow was advecting moisture northward through southeastern TX into the stationary front which marked a gradient in MLCAPE with roughly 500-1500 J/kg along the boundary via 16Z SPC mesoanalysis data. As a potent mid-level shortwave continues to advance east from central TX today, downstream forcing will increase as an upper level jet max becomes better defined over eastern OK, placing right-entrance ascent over the Arklatex to Lower MS Valley. Low level winds may also increase a little more into the afternoon ahead of the upper trough axis. Thunderstorms are expected to continue to expand in coverage ahead of the advancing convective line near I-35 with low level convergence near the stationary front aligning with mean SW steering flow to support training/repeating cores of heavy rain. PWAT coverage of 1.5 inches and greater is forecast to expand across the region, coupled with more than sufficient instability and favorable shear to promote organized cells. Thunderstorms will be capable of producing 1 to 3 in/hr rainfall rates due to training and repeating rounds could amount to 3-5 inches of rain in a 2 to 3 hour period. The greatest concern for training and the heaviest rainfall totals through 22Z will be in the vicinity of the stationary front from northeastern TX into northern LA/southern AR and perhaps far northwestern MS. Farther south, while the convective line near I-35 is likely to remain progressive from west to east, additional development ahead of the line and periods of short term training within the convective axis may still promote a threat for flash flooding across portions of southeastern TX into western LA. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4i5B_CGCd0spZ74-7xxxyMPvLmBC7c-caEj4poEVxog-A1lcfgRu45FBPALHA4_OinGV= Q7HFihBaK-K5Mr1ZVIIl3wA$ for graphic product... ATTN...WFO...FWD...HGX...JAN...LCH...LZK...MEG...SHV... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 34599115 34399049 33749063 32799145 31879208=20 30719287 30099476 30589647 31169716 31819719=20 32369670 32679535 33579389 34119247=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) .