Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 13 2023 07:04:20 AWUS01 KWNH 130704 FFGMPD MSZ000-131200- Mesoscale Precipitation Discussion 0712 NWS Weather Prediction Center College Park MD 303 AM EDT Thu Jul 13 2023 Areas affected...North-Central Mississippi Concerning...Heavy rainfall...Flash flooding possible Valid 130700Z - 131200Z Summary...Convective coverage is expected to increase over the next several hours with the potential for hourly rainfall rates of 1-3"/hr. Widely scattered instances of flash flooding are possible. Discussion...A convective lull is beginning to come to an end across portions of central MS with showers starting to percolate on radar and satellite imagery. These showers are coming about due to low-level (925-850 mb) overrunning being facilitated by a lingering MCV aloft (most prominently at 700 mb). Deep layer moisture flux is expected to increase as a result of this overrunning (in addition to some DPVA and divergence aloft) with convective coverage and intensity likely increasing over the next 3-6 hours. Deep layer (850-300 mb) mean wind currently ranges from 5-10 kts across the area (from the NE-E), suggesting relatively slow storm motions are likely within an anomalously moist (PWATs 1.7-2.2 inches) tropospheric column. Along with sufficient instability (ML CAPE 500-1500 J/kg), mature updrafts should easily be capable of 1-3"/hr rates (with the HRRR also indicating peak 15-min accumulations of at least 1"). Soils should initially be able to handle these rates without too much excessive runoff (as 3-hr FFGs average close to 3"), but the potential for backbuilding increases after dawn (per many of the CAM solutions) with training/repeating of these high rates being capable of significant accumulations. Should deeper, more organized convection start to take shape, the chances for this backbuilding will increase with storm propagation beginning to favor a more southerly to southwesterly trajectory (per the upwind propagation vector). A subsequent MPD may become necessary for an increase in convective coverage/organization after dawn, when flash flooding may become more likely... but in the meantime, widely scattered instances of flash flooding are considered possible (with localized accumulations of 3-5" possible through 12z). Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!522RkQ62b9t-uTEiww92dHaWlQKQmTxRQIwoppfjKsei-AAb-c6_vtMG52TvjFWGcyi9= f6x9yaNqnRqffQCni1N3g0M$ for graphic product... ATTN...WFO...JAN...MEG... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 34219001 34068876 33698835 32878839 32068856=20 31758922 31839005 32329068 33019106 33919094=20 =20=20=20=20=20=20=20=20=20=20=20=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) .