Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 21 2024 06:07:26 AWUS01 KWNH 210607 FFGMPD MOZ000-ARZ000-TXZ000-OKZ000-KSZ000-211200- Mesoscale Precipitation Discussion 0677 NWS Weather Prediction Center College Park MD 206 AM EDT Sun Jul 21 2024 Areas affected...Central and Eastern Oklahoma Concerning...Heavy rainfall...Flash flooding likely Valid 210606Z - 211200Z Summary...Slow moving thunderstorms with 2-3"/hr rates will increase across Oklahoma overnight. This will produce 2-4" of rain with locally higher amounts above 5" possible. Instances of flash flooding are likely. Discussion...The GOES-E WV imagery tonight shows a complex structure evolving across the middle of the country. A prominent closed low is rotating over Iowa, while a weak vorticity impulse embedded within the flow pivots into Oklahoma. The accompanying longwave trough is amplifying across the Plains, bringing subtle height falls into Oklahoma, which is combining with modest PVA and a weakly diffluent upper level jet pattern to produce large scale synoptic ascent. In the lower levels, regional VWPs indicate the 850mb SW LLJ is beginning to ramp up, angling atop a weak surface trough to provide additional convergent ascent. This deep layer lift is occurring into robust thermodynamics noted by a ribbon of PWs measured by GPS of 1.6 to 1.8 inches, around the 90th percentile for the date, and MUCAPE of 1000-2000 J/kg. Recent reflectivity from the regional radar mosaic has blossomed quickly, indicating that the best ascent is beginning to impinge into the more impressive environment. The recent CAMs are in pretty good agreement both temporally and spatially with the evolution through the morning. This produces some higher confidence in the flash flood potential. As the LLJ begins to intensify in tandem with better height falls/PVA drifting southward, convective development should expand and intensify, especially for portions of eastern and central OK. Here, both the HREF and REFS 2"/1hr rain rate probabilities reach around 30%, and the HRRR 15-min rainfall accumulations peak around 0.75", suggesting at least short-duration 3"/hr rates can be expected. This will be fueled by the LLJ surging PWs to over 2" while MUCAPE remains above 1000 J/kg. As the LLJ increases, Corfidi vectors will veer to become increasingly angled to the right of the mean wind, indicating that as cells redevelop along the low-level convergent boundary they will train to the E/SE to lengthen the duration of heavy rain rates. This could result in corridors of 2-4" of rainfall, with locally higher amounts above 5" possible as reflected by 5"/6hr HREF probabilities of 20-30% and the REFS PMM peaking at 5.5", highest in the vicinity of Tulsa in the northeast part of the state. Soils across Oklahoma are generally below normal as reflected by 0-40cm soil moisture that is only around the 30th percentile according to NASA SPoRT. This will somewhat inhibit the flash flood risk initially due to water infiltration into these drier soils. However, intense rates of 2-3"/hr will likely still cause instances of rapid runoff, especially in urban areas, almost immediately, and where these rates can train/linger even the drier soils could be overwhelmed. The setup appears favorable, and the agreement of the guidance combined with the strong forcing suggests flash flooding is likely through the overnight. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8A5j4bmMs3U6jL_DC6IBrEtBvbRtN_DSh2__IeYPEGvmpj41pw_cfVsxwdmCG76ZqHFN= lWjPzLJkpGnxRPRQA_cg-eU$ for graphic product... ATTN...WFO...FWD...ICT...OUN...SGF...TSA... ATTN...RFC...ABRFC...NWC... LAT...LON 37419571 37269478 36849448 36319439 35619456=20 35089485 34829531 34609585 34179630 33919691=20 33979750 34219830 34339854 34639867 35109864=20 35729841 36399790 37309682=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) .