Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jan 03 2023 21:47:06 AWUS01 KWNH 032147 FFGMPD GAZ000-ALZ000-040345- Mesoscale Precipitation Discussion 0013 NWS Weather Prediction Center College Park MD 446 PM EST Tue Jan 03 2023 Areas affected...Central/Southern AL through much of Central GA Concerning...Heavy rainfall...Flash flooding likely Valid 032145Z - 040345Z SUMMARY...The threat for areas of flash flooding will continue going into the evening hours from organized clusters of heavy showers and thunderstorms that will locally repeat/train over the same area. DISCUSSION...Radar and satellite imagery shows well organized areas of heavy showers and thunderstorms involving a mixture of supercell and multicell convection impacting large areas of central/southern AL with the activity gradually advancing into areas of western GA. The activity continues to be driven by an anomalously moist and unstable airmass pooled across the Gulf Coast states out ahead of a deep layer trough/closed low over the Midwest and an attendant cold front gradually advancing east through the lower/middle MS Valley. A convergent southwest low-level jet of 40 to 50 kts continues to focus a high PW axis across the region with values of 1.5 to 1.75 inches in place. The 850/700 mb layer remains quite moist upstream across the northern Gulf of Mexico per the latest CIRA-ALPW data analysis and the moisture flux anomalies are on the order of 2 to 3 standard deviations above the mean. This coupled with MLCAPE values of 1000 to 2000 J/kg will definitely support convection with enhanced rainfall rate potential that may reach 2 inches/hour. The latest HRRR guidance and earlier 12Z HREF suite suggest that convection will remain well organized going into the evening hours across areas of central and southern AL, with an increasing focus on areas of western and central GA. Aside from the favorable thermodynamic environment, the convection is being strongly aided by enhanced shear profiles with effective bulk shear values of 50 to 60 kts. The strong kinematic environment coupled with the aforementioned instability will favor robust organized updrafts persisting over the next several hours with supercells continuing to be a threat. The repeating nature of this activity along with a gradual west-southwest to east-northeast orientation of some of the convective line-segments will continue to yield concerns for excessive rainfall. Given the high rainfall rate potential, threat of cell-mergers, and repeating/training convective cell considerations, additional rainfall totals heading through at least mid-evening may reach 2 to 4 inches with isolated areas possibly exceeding 5 inches. The strongest HREF signal points to areas of east-central AL (generally near and east of Montgomery) and west-central GA (including the Columbus area) seeing the heaviest rainfall potential over the next several hours. The HRRR guidance recently has been suggesting a multiple linear swath of enhanced rainfall as well with some footprint for seeing 5+ inch amounts. These rainfall amounts overall are likely to result in some areas of flash flooding, and this will especially be the case should these heavier rainfall totals materialize over the more urbanized areas this evening. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6ZhiZSc_A0Iamfwi14kYvP7BZK1JyS2z5KjmtAHk558Ik5h4E34QHrolx1toN8KJITrc= WptjNhTjfwmzkfyxIKscCkE$ for graphic product... ATTN...WFO...BMX...CAE...FFC...MOB...TAE... ATTN...RFC...SERFC...NWC... LAT...LON 34188349 33458255 32268292 31578496 31278729=20 31588826 32418823 33168643 34168489=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) .