Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 08 2023 17:01:26 AWUS01 KWNH 081701 FFGMPD TNZ000-ALZ000-MSZ000-ARZ000-TXZ000-OKZ000-082300- Mesoscale Precipitation Discussion 0663 NWS Weather Prediction Center College Park MD 100 PM EDT Sat Jul 08 2023 Areas affected...Southern AR...Southwest TN...Northern MS...Northern AL Concerning...Heavy rainfall...Flash flooding possible Valid 081700Z - 082300Z SUMMARY...Numerous thunderstorms within an increasingly unstable airmass load with rich moisture both at the surface and aloft will spell strong-to-severe storms in parts of the Mid-South. Flash flooding as a result of these storms is possible. DISCUSSION...A remnant MCV from overnight convection is tracking through AR this afternoon, coinciding out in front of the nose of a 250mb jet streak centered over the central Rockies/Plains. At 850mb, southwesterly 850mb inflow is helping to supply rich low level moisture to the region, while contrasting northwesterly flow to the north is causing a low level convergence area to form from the Red River Valley to the Tennessee Valley. The region contains no shortage of moisture as PWATs will eclipse 2" for the vast majority of the highlighted region. There is also plenty of instability as MLCAPE >2,000 J/kg will be common this afternoon. Dew points are in the mid-upper 70s and RAP guidance shows low-mid level RH values averaging between 80-90%. Warm cloud layers could also be as deep as 12,500ft in some areas. The key in flash flood potential not only lies with the available warm rain processes, but how and where thunderstorms track. The MCV will likely reinvigorate storms in eastern AR and western TN, but its southern flank could also trigger additional storms in northern MS where some storms have already initiated. The concern is the potential for training convection on the southern flank of the MCS where instability is greatest and 850mb inflow persists through the afternoon hours. This could mean areas in northern MS/AL, where storms have broken out ahead of the MCV, may not receive much in the way of a break in the action. Mean 850-300mb winds are generally out of the west at all levels, suggesting the steady low level inflow into the southern periphery of the approaching MCV could support not only training, but backbuilding thunderstorms. Latest 12Z HREF indicates not only that storms can produce >2"/hr rainfall rates, but could even make a run at 3"/hr in the most intense cells. With soils being more on the neutral side, it will be 2-3"/hr excessive rainfall rates and training storms that pose the biggest threat for flash flooding. Urbanized settings and poor drainage areas are most prone to flash flooding this afternoon. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-VaeXGAfWUWvwWjzH16xHDV3X0fKd8YsQzQKsViqRG9TQ9IxXEGaIWWvMauGbbYh8ETh= 0GpucQ4UHUUeN039LKtKMQ0$ for graphic product... ATTN...WFO...BMX...HUN...JAN...LZK...MEG...SHV... ATTN...RFC...ABRFC...LMRFC...SERFC...NWC... LAT...LON 35559053 35048817 33678635 32158675 32888825=20 33218968 33269087 33179229 33169356 33319462=20 33899473 34419329 35089257=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) .