Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Feb 09 2023 03:15:13 AWUS01 KWNH 090315 FFGMPD TNZ000-ALZ000-MSZ000-LAZ000-ARZ000-090900- Mesoscale Precipitation Discussion 0060 NWS Weather Prediction Center College Park MD 1014 PM EST Wed Feb 08 2023 Areas affected...central Gulf Coast into MS, western AL and southwestern TN Concerning...Heavy rainfall...Flash flooding possible Valid 090313Z - 090900Z SUMMARY...Periods of training will continue a flash flood risk for portions of LA/MS/AL/TN through 09Z. Rainfall rates of 1-3 in/hr will be possible but the potential for higher rates will exist across southern locations where instability will be greater. DISCUSSION...Regional radar imagery at 0245Z showed widespread showers and thunderstorms stretching from the central coast of LA into MS and southwestern TN, located out ahead of an approaching cold front from the west. MRMS-derived rainfall rates have generally been peaking in the 1-2 in/hr range over the past few hours, with 1+ in/hr located as far north as northern MS. MLCAPE within the ongoing precipitation axis was 500 to just over 1000 J/kg with precipitable water values of 1.5 to 1.8 inches (02Z SPC mesoanalysis). Unidirectional flow from the SSW combined with strengthening 850 mb winds (35-50 kt at 02Z) was promoting training segments within the pre-frontal axes of convection. Supporting enhanced lift was divergent flow aloft within the entrance region of a 100-120 kt jet streak aloft, located ahead of a negatively titled upper trough axis swinging through eastern OK into AR. Wind vectors were also fairly diffluent aloft, as noted on water vapor imagery, with the greatest fanning out of the upper flow located near the Gulf Coast. Expectations are for a continued threat for training as the cold front steadily moves eastward over the next 3-6 hours. Some strengthening of the 850 mb flow is anticipated from northern MS/AL into TN, tied to the greatest CVA out ahead of the mid-upper level vorticity max. Flash flood guidance is lower for the northern half of MS/AL into southwestern TN at 2-3 inches in 3 hours but forecasts of lowering instability for these northern locations should preclude a greater threat for higher rainfall rates. Across southern locations, south of the I-20 corridor, instability of 500-1000 J/kg is expected to remain through the night with the greatest threat for rainfall rates in excess of 2 in/hr focusing within 50 miles of the I-10 corridor. Additional rainfall totals through 09Z could peak in the 3-5 inch range for southern locations and 1-3 inches for northern locations. Flash flooding will be possible for the entire MPD threat area through 09Z. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4HGF7bIH0g7u3AasWslsxd8XfjJN1VDa3hSK3CvxnJxrHTPOSLAQpRZb0a1iobg-8aVU= vtdSQuDApdL1aLOWBbNprfk$ for graphic product... ATTN...WFO...BMX...HUN...JAN...LCH...LIX...MEG...MOB...OHX... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 35948879 35748755 35008748 34348767 33628770=20 33218751 32778720 32208710 31588732 30048837=20 29088906 28698991 28899120 29479179 31429132=20 33689079 35348998=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) .