Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 17 2024 20:03:22 AWUS01 KWNH 172003 FFGMPD LAZ000-ARZ000-TXZ000-OKZ000-180130- Mesoscale Precipitation Discussion 0642 NWS Weather Prediction Center College Park MD 402 PM EDT Wed Jul 17 2024 Areas affected...Southeast OK...Northwest TX...Western AR...Northwest LA Concerning...Heavy rainfall...Flash flooding possible Valid 172000Z - 180130Z SUMMARY...Vigorous line of storms over northeast TX is the precursor to an active afternoon and evening of vigorous thunderstorms. Anomalous moisture aloft and no shortage of instability will support rainfall rates up to 2.5"/hr. Flash flooding is possible within slower moving segments of storms. DISCUSSION...A remnant MCV approaching from central OK is also accompanying a strong cold front that has crossed the Red River this afternoon. Doppler Radar shows thunderstorms have erupted along a pre-frontal trough located over northeast TX. These storms have formed in an area with 2.0-2.1" PWs and MLCAPE as high as 3,000 J/kg. As the cloud cover over central AR lessens, additional surface based heating will lead to an increase in instability, while at the same time a cold front to the north gradually advances south. This is the case in southern AR where a cumulus field is gradually building along a surface trough to the south of Texarkana. With both a strong mid-level feature approaching, and a series of surface boundaries acting as triggers, storms should continue to develop throughout the ArkLaTex region over the next several hours. As storms fire, the environment features winds that are more convergent with weaker upper level winds aloft. As a result, 850-300mb winds are topping out not much higher than 10 knots or so. There is also little in the way of effective bulk wind shear, so while storms will be potent as they develop, they may pack a punch but quickly produce an outflow boundary and gradually weaken. This is an environment ripe for explosive and slow moving storms that, given the available instability and moisture aloft, would support as high as 2.5"/hr rainfall rates. The 12Z HREF showed low probabilities (10-30%) for 3-hr rainfall rates > 3-hr FFGs in western and southern AR. While the torrential rainfall rates with slow moving storms in are anticipated, the region sports relatively high FFGs (3hr FFGs > 4" in most cases). This should help keep the flash flood threat more localized rather than widespread. Still, the available instability and moisture parameters, as well as sufficient forcing both aloft and at the surface provide some support for potential localized flooding. Urbanized communities and low lying, poor drainage areas are most prone to potential flash flooding. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5vqNyKuTmJgrHBespsIftnP7RPZaKe9m2v5ErriWJaa8u-ndIemVR3j4fGT2VgAW_DQj= vW2JoJCUkEMmpSuhaHD8CwY$ for graphic product... ATTN...WFO...FWD...LZK...SHV...TSA... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 35039452 34859323 33909253 33199268 32399382=20 31819610 31799692 32169729 32499694 33089624=20 33769559=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) .