Subj : MESO: Heavy rain - floodi To : All From : Mike Powell Date : Fri Jul 14 2023 15:14:00 AWUS01 KWNH 141759 FFGMPD FLZ000-ALZ000-MSZ000-142330- Mesoscale Precipitation Discussion 0726 NWS Weather Prediction Center College Park MD 159 PM EDT Fri Jul 14 2023 Areas affected...Mississippi, Alabama, and Florida Panhandle Concerning...Heavy rainfall...Flash flooding likely Valid 141751Z - 142330Z Summary...An axis of slow moving and heavy thunderstorms will continue to develop between a line of thunderstorms moving east along the MS/TN line and persistent activity over the western FL Panhandle. Under the axis between these features is the footprint of the extreme (5-10") rainfall from yesterday over east-central Mississippi into western Alabama. Given the sensitive nature of these areas, there is likely to be further flash flooding this afternoon there and localized elsewhere in the area of concern. Discussion...Radar imagery depicts an MCS tracking east over northern MS into western TN that is approaching northern AL at 1745Z. The south end of this line is rapidly developing with rainfall rates likely 1" to 2"/hr. An axis of scattered thunderstorms then extends south-southeast to the western FL Panhandle which is where remnant MCS activity persists after the extreme rainfall this morning that occurred along the Emerald Coast of FL (and west of the associated MCV south of Panama City). Along this axis is very moist air with PW of 2.0 to 2.2" (over +2 sigma), strong instability with MLCAPE 2000 to 3000 J/kg, and light steering flow of 10kt or less from the north. A continued expectation for a slow net westward propagation of the activity over FL into higher instability and eastward progression of the MCS along the TN border may further cause slow motion a pivoting of the axis near the central MS/AL border where the extreme rainfall fell yesterday. All 12Z CAMs feature an axis of slow thunderstorms this afternoon near the MS/AL border, though this is earlier than forecast. Recent HRRRs also feature this activity, though only for a few hours before dying off. The length of this event is uncertain given how slow the flow is which may cause activity to rain out. However, given the ample instability and robust moisture, there should be plenty of outflow boundaries to reignite activity. Therefore, there is a likely risk for further and possibly considerable flash flooding over these sensitive areas along the central MS/AL border and more localized flash flooding over far western FL into southern AL and northeast MS into northwest AL where 3hr FFG is generally 2.5 to 3". Jackson ATTN...WFO...BMX...HUN...JAN...MEG...MOB... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 34908843 34598790 33038688 31698642 30828648 30308660 30358737 30738811 32388897 33258935 33708952 33978951 34828907 = = = --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .