Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 09 2023 08:20:36 AWUS01 KWNH 090820 FFGMPD ARZ000-TXZ000-OKZ000-091400- Mesoscale Precipitation Discussion 0671 NWS Weather Prediction Center College Park MD 419 AM EDT Sun Jul 09 2023 Areas affected...Oklahoma and northern Texas Concerning...Heavy rainfall...Flash flooding likely Valid 090819Z - 091400Z Summary...An MCS and increasing downstream convection will merge across Oklahoma this morning. Rainfall rates of 2-3+"/hr are likely, which through training could produce 3-5" of rain. Flash flooding is likely Discussion...The regional radar mosaic across the Southern Plains this morning depicts a potent MCS diving across the TX Panhandle and northern OK, while additional thunderstorm development is occurring along a NW to SE axis in central and southern OK. This MCS has remained progressive to the southeast, but has produced mesonet observed rainfall of 2-3" across northern OK. This MCS will continue to thrive as it dives southward and encounters even more favorable thermodynamics on an increasing LLJ. Regional VWPs indicate the 850mb inflow is increasing to 25-30 kts while backing to the S/SE, advecting PWs above 2" and MUCAPE of more than 2000 J/kg northward. Along the nose of this LLJ, additional convection has developed within this robust environment, with radar-estimated rainfall rates already reaching 1.5"/hr on KTLX. This downstream convection is moving little as regeneration along the convergent nose of the LLJ occurs, and signals continue to increase for flash flooding where the MCS and this leading convection interact. Although the MCS will remain progressive noted by Corfidi vectors of 30+ kts, rainfall rates could reach as high as 4"/hr as noted by 15-min rainfall on the HRRR of more than 1 inch. These rates by themselves could overwhelm soils to produce rapid runoff. However, the more significant concern through the morning is where this MCS tracks across areas that will also receive downstream convection along the LLJ. The most likely region for this is from central to southeast OK where the LLJ will drive additional ascent through convergence along its nose, but also through increasing isentropic upglide as it locally backs to rise atop a stationary front near the Red River Valley. Rainfall rates within this other convection could exceed 2"/hr as noted by HREF neighborhood probabilities, and these storms will likely have weak net motion as regeneration occurs repeatedly along the convergence axis. Where the MCS tracks across these same areas, the HREF has an axis of impressive probabilities for more than 3"/6hrs, and even some modest probabilities for 5"/6hrs. Additionally, recent rainfall across this area has been significant noted by AHPS 7-day rainfall that is 300-600% of normal leading to high streamflows and 1-hr FFG as low as 1-1.5", suggesting extremely hydrophobic soils. The HREF exceedance probabilities for the 1-hr FFG peak at 50-60%, providing additional support for an axis of flash flooding impacts. While any place within the MCS could receive short term rates sufficient for instances of flash flooding, the most likely region is in areas that receive both leading convection and the MCS to lengthen the duration of heavy rainfall. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4V5ceOFV0qrJiKVrypeihj5FPGrRbRg-KqKfjDw9bYBI41QGCf762-MozNXIXDqqN-me= 1pfgkGJtJ1mIRCcn4q8F47I$ for graphic product... ATTN...WFO...AMA...FWD...LUB...LZK...OUN...SHV...TSA... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 36469682 36229595 35799475 35399403 34909423=20 34129500 33579556 33189643 33299732 33579819=20 33889879 33919890 34169972 34490065 34790104=20 35260102 35780033 36169925 36459766=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) .