Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 18 2023 05:02:45 AWUS01 KWNH 180502 FFGMPD ARZ000-TXZ000-OKZ000-181100- Mesoscale Precipitation Discussion 0517 NWS Weather Prediction Center College Park MD 100 AM EDT Sun Jun 18 2023 Areas affected...Red River Valley of the South Concerning...Heavy rainfall...Flash flooding possible Valid 180500Z - 181100Z SUMMARY...Strong to severe clusters of thunderstorms will pose an isolated threat of flash flooding going through the overnight hours across the Red River Valley of the South. DISCUSSION...The latest GOES-E IR satellite imagery shows a pair of well-organized convective complexes advancing off to the east as a robust mid-level shortwave trough and associated closed low ejects east across the Southern Plains. One long-lived MCS is seen oriented from southern KS down through central to southwest OK, with a separate strong MCS seen closer to the Red River involving southeast OK. All of this MCS activity is embedded within an extremely unstable and very moist airmass characterized by MLCAPE values of 3000 to 5000 J/kg and PWs that are as high as 1.75 to 2 inches. Meanwhile, the vertical column is strongly sheared out ahead of the approaching upstream height falls/shortwave dynamics with effective bulk shear values as high as 50 to 70 kts. This coupled with the extreme thermodynamic parameters will yield sustainable and persistently strong to severe MCS activity well into the overnight time frame. The expectation of a gradually increasing nocturnally enhanced south to southwest low-level jet overrunning a quasi-stationary front near the Red River will be a key player in facilitating the overnight convective threat as well. Already the area VWP data shows as much as 30 to 40 kts of southerly flow in the 850/925 mb nosing up toward the Red River Valley, and this jet energy will gradually veer overnight to the southwest and increase to as much as 50 kts in the 06Z to 09Z time frame which will maintain strong moisture and instability transport. The latest radar and satellite trends suggest areas of central to southeast OK could see enough repeating cell activity from a combination of both complexes to favor some locally excessive rainfall totals. Areas downstream across west-central to southwest AR may also gradually have concerns later in the night and toward dawn from repeating areas of convection for enhanced rainfall totals. GC-MRMS data already shows the stronger convective cells with both convective complexes reaching 1.5 to 2 inches/hour, and some storm totals by dawn may reach as high as 3 to 4 inches with isolated heavier amounts. These totals will foster a threat for mainly isolated instances of flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6NSXjXFoq46SVXjpX86e_HEwBWcuoAvWem0k7F8ZcLAqpgUd-oK5KbBabrkMG7zrwu6O= PQnIyMqnOAxBmjRpkSQgR6c$ for graphic product... ATTN...WFO...FWD...JAN...LZK...OUN...SHV...TSA... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 35649682 35589503 35169314 34629214 34029175=20 33169208 33179476 33249600 33459776 33779879=20 34139954 34729973 35029938 35349810=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) .