Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jun 14 2023 23:38:10 AWUS01 KWNH 142338 FFGMPD FLZ000-GAZ000-ALZ000-150430- Mesoscale Precipitation Discussion 0484 NWS Weather Prediction Center College Park MD 737 PM EDT Wed Jun 14 2023 Areas affected...Southern AL, Southern GA, FL Panhandle Concerning...Heavy rainfall...Flash flooding possible Valid 142336Z - 150430Z Summary...A nearly unbroken line of thunderstorms along an outflow will continue to sink slowly southward this evening. Rainfall rates within this convection above 2"/hr will slowly wane, but will produce an additional 2-3" of rain with locally higher amounts. Flash flooding is possible. Discussion...An extremely active day of convection continues across the Southeast as noted by an unbroken line of thunderstorms draped from far eastern MS through the GA coast. These thunderstorms are moving along a slowly sinking outflow boundary south of a stationary front, and being supplied by extreme thermodynamics characterized by PWs of 1.75 inches in the pre-convective environment, and SBCAPE as high as 5000 J/kg according to the SPC RAP. An upper level jet streak moving into the lower MS VLY paired with convectively enhanced, but subtle, vort centers embedded in the flow are helping to back the low-level flow noted via regional VWPs. This is manifesting as 850mb winds that are from the SSW at 20-30 kts, re-supplying moisture and instability northward while coincidentally driving enhanced ascent through isentropic lift atop the outflow. The recent high-res guidance has become a bit more progressive and farther south with the recent simulated reflectivity, likely due to the strong instability allowing for more intense cold pools pushing south, while at the same time the 850mb inflow will begin to veer more to the WSW. Together these should allow the overall intensity of the convection to wane with time while also diving as far as the Gulf of Mexico this evening. This is reflected by a steady decline in hourly rainfall on the WoFS as well a maximum probability of rainfall exceeding 2 inches remaining north of the FL Panhandle. Despite that, the flash flood risk will continue as Corfidi vectors remain aligned to the mean wind which suggests training of echoes along the outflow as the entire complex shifts southeast. With the HREF neighborhood probabilities still indicating a moderate to high chance of 1"+/hr rain rates through the next several hours, this could result in 2-3" of additional rainfall with locally higher amounts. This could surpass the FFG as reflected by exceedance probabilities of 10-20% through the evening. As convection continues to surge southward, it will encounter soils that are more tolerant to heavy rainfall from drier antecedent conditions noted by AHPS 7-day rainfall generally 50-100% of normal, and normal to below normal USGS streamflow anomalies. While rainfall already today has exceeded 5" in parts of MS/AL according to MRMS and mesonet observations, those areas have exhausted their instability so the heaviest rainfall this evening should remain south of that footprint. However, any training of these heavy rates could still result in instances of flash flooding before this entire complex weakens and shifts eastward tonight. It is worth noting that the high-res guidance suggests another MCS could move across these same areas by Thursday morning. With soils primed from today's heavy rainfall, renewed flash flooding is possible with this later event should it materialize. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7NN4D-pYurHeSvQZ0EJGKD7bn3ZNr-TW75mkHHq-MuwIL6sski3redB8dGOqnyM29i3H= fn5A53COSs3l_orcIPi0X30$ for graphic product... ATTN...WFO...BMX...CHS...FFC...JAX...MOB...TAE... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 32148523 32018383 31928247 31788161 31608117=20 31218100 31088110 30658117 30028119 29818169=20 29708343 29798471 30118580 30578670 30848786=20 30998820 31428843 31788826 32108716=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) .