Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jul 14 2023 04:27:07 AWUS01 KWNH 140427 FFGMPD MOZ000-ARZ000-TXZ000-OKZ000-KSZ000-140930- Mesoscale Precipitation Discussion 0720 NWS Weather Prediction Center College Park MD 1225 AM EDT Fri Jul 14 2023 Areas affected...Much of OK and surrounding portions of KS, AR, and MO Concerning...Heavy rainfall...Flash flooding likely Valid 140430Z - 140930Z Summary...Thunderstorms with 1-3"/hr rainfall rates will likely lead to isolated to widely scattered instances of flash flooding. Localized totals of 4-8" over 3-6 hours may occur, and an instance or two of significant flash flooding are possible. Discussion...Deep convective activity is beginning to proliferate across portions of central Oklahoma late this evening, taking advantage of an exceptionally moist and unstable air mass in place across the region. With surface dew points near 80deg F and temperatures still in the mid to upper 80s, SB CAPE is yielding a whooping 4000-6000 J/kg with precipitable water (PWAT) values of 1.8-2.3 inches (per EMC RAP analysis). The 00z sounding (just a few hours ago) from OUN was even more impressive, indicating a near all-time record PWAT of 2.47 inches and SB CAPE of 6770 J/kg. Now that deep convection seems to be persisting in this environment, effective bulk shear of 25-45 kts should have no problem organizing activity into larger clusters, and eventual organization into an MCS is certainly possible (as indicated by an MCS maintenance probability of 60-90%). Confidence is relatively low with regard to that eventual organization, given the weakly-forced enviornment, and it is also difficult to tell exactly what locations are most at risk of repeating of 1-3"/hr rates due to training/repeating (as the new 00z HREF remains widely dispersed with regard to the organization of convection and resultant QPF). The 850-300 mb mean wind is from the west at about 20 kts, which should keep individual cells from lingering over any one spot for too long, but low-level (925 mb) flow and moisture transport are increasing with the diurnal cycle of the low-level jet, and backbuilding of convection to the west may allow for some localized repeating of heavy rainfall. In addition, hodographs do favor right-moving supercells, which will yield slower storm motions (closer to 10 kts) towards the SSE. Given this highly favorable environment for heavy rainfall, it is no wonder that the HREF probability matched mean QPF suggests the potential for extreme 4-8" localized amounts through 09z across northeastern OK. Corresponding HREF 40-km neighborhood probabilities for 5" exceedance over 6-hr are as high as 10-20%, with 3" exceedance over 3-hr as high as 20-30%. While the HREF does not show as much potential farther south, this appears to be underdone given recent observational trends. Corresponding Flash Flood Guidance (FFG) average 2.5" and 3", respectively, thus isolated to widely scattered instances of flash flooding are considered likely (with the potential for a significant instance or two of flash flooding, especially if these extreme totals coincide with a more vulnerable metropolitan area).=20 Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6wIPrYCliklucOFJrrMy1Lf3BmR7UtCc7P7_7-g69XfzZjFzHloccKAU05E1vb32CrVV= ekXckKDqzl8ENTCM8LJS5z8$ for graphic product... ATTN...WFO...ICT...OUN...SGF...TSA... ATTN...RFC...ABRFC...LMRFC...NWC... LAT...LON 37729671 37589530 36909409 35819373 34529504=20 34029663 34079865 34439931 35939919 36999833=20 37479770=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) .