Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jan 04 2023 04:06:13 AWUS01 KWNH 040406 FFGMPD FLZ000-GAZ000-ALZ000-MSZ000-LAZ000-041000- Mesoscale Precipitation Discussion 0015 NWS Weather Prediction Center College Park MD 1105 PM EST Tue Jan 03 2023 Areas affected...parts of Mississippi, Alabama, and southeastern Louisiana Concerning...Heavy rainfall...Flash flooding possible Valid 040404Z - 041000Z Summary...Deep convection continues to expand in coverage especially across Mississippi and southeastern Louisiana. Heavy rainfall and localized training of cells should lead to an increased risk of flash flooding through 10Z. Discussion...Deep convection continues to mature and organize into a mix of cells and clusters especially across Mississippi. Most of the activity was located ahead of a cold front along the Mississippi River. The airmass ahead of the front was characterized by abundant moisture and instability (1.5+ inch PW and 1000-2500 J/kg MLCAPE, respectively). Meanwhile, the orientation of the storms (as cells/clusters aligned in bands loosely parallel to steering flow aloft) was favoring localized repeating/training, which was increasing rainfall rates to near 2 inches/hr in spots based on MRMS estimates. MRMS Flash responses were fairly impressive given the environment (moderate values observed where training was most apparent). The moderate values were also suggestive of localized areas of excessive runoff at times. The overall scenario should continue to support occasional excessive runoff and flash flooding through the night and early morning hours tomorrow. New rainfall amounts of 1-3 inches are likely especially where convective training occurs. The greatest concern will exist with any heavier rainfall that can materialize over sensitive grounds (resulting either from prior rainfall/moist soils or low-lying/urbanized areas that are flood prone). FFGs are generally in the 1-2 inch/hr range (locally lower) and these values could be exceeded occasionally given the aforementioned flash flood scenario. Convection should gradually shift eastward over time, with the bulk of the activity extending from north-central Alabama southwestward to Lake Pontchartrain by 07Z or so and from northwest Georgia through central Alabama around 09-10Z.=20 It is worth noting that while slower eastward progression and better instability will lead to heavier rain rates across southern Mississippi/southeast Louisiana, FFGs are also appreciably higher there, which would tie any potential flash flood risk more closely to those areas that are most susceptible. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-LJZAufzxEIMzuwr7rvLkU9x9ECqMT6di-SqbrLRhthKhSeFapkJzBzo2O2nZpHzaXbH= ycvTb5_ra8YEZGb__u-V6vQ$ for graphic product... ATTN...WFO...BMX...FFC...HUN...JAN...LCH...LIX...MEG...MOB... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 34998748 34848579 34668539 33718517 32428581=20 31198692 30378755 30018836 29128910 28968971=20 29189158 29749218 30799150 32059058 33788950=20 34628860=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) .