Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 03 2023 18:26:14 AWUS01 KWNH 031826 FFGMPD GAZ000-TNZ000-ALZ000-MSZ000-ARZ000-040000- Mesoscale Precipitation Discussion 0628 NWS Weather Prediction Center College Park MD 225 PM EDT Mon Jul 03 2023 Areas affected...Northern MS...Northern AL...Northwest GA... Southern TN... Concerning...Heavy rainfall...Flash flooding possible Valid 031830Z - 040000Z SUMMARY...Slow moving, intense thunderstorms with possible repeating support a few spots of 2-4" and low-end but a flash flooding incident or two through evening. DISCUSSION...Surface analysis and GOES-E Visible imagery delineate a ill-defined older frontal boundary from near Memphis across Middle TN into the Appalachians. South of the boundary very unstable environment exists under unidirectional flow aloft.=20 While the entire south has very high Tds and ample moisture in the lowest layers of the environment (below 850mb) with most areas at or above 75F; aloft CIRA LPW denotes a shearing out, but enhanced ribbon of subtropical moisture from the eastern Pacific within the 700-300mb layer across E TX, N MS, N AL into SE TN, with nearly ..5" between 700-500mb which is quite anomalous in the 95+th percentile. This has allowed for Total Pwats to be at or slightly above 2" along the area of concern. While moisture flux is fairly small (5-10kts), there has been enough deep layer convergence for convective development across the area north of the sub-tropical jet streak (noted in with more dense cirrus across central MS/AL.=20 Full heating nearing lower to mid-90s, MLCAPEs to 3000+ J/kg support strong updrafts for localized isallobaric increase in flux into the updrafts (at least initially). As such, thunderstorms will be capable of 2.5"/hr with some downdrafts supporting subhourly totals over 1.5 per recent HRRR (15 minute totals), which seem reasonable.=20 Cell motions are fairly slow and further development will be forced along outflow boundaries across the area. Deeper layer unidirectional flow also suggests some cells may have the potential for repeating tracks. As such, numerous spots of 2-3" are probable, but spotty 3-4" totals are not out of the question over the late afternoon into the evening hours. Much of the has been dry and FFG values reflect that,especially in N MS into NW AL, though there is some lower values of 1.5-2" & 2-2.5" in the 1 and 3hr ranges, respectively across N AL and NW GA. However, the shear intensity is not likely to absorb in drier soil conditions resulting in increased runoff potential. As such, while likely widespread, a few incidents of flash flooding are consider possible through the evening hours as convection coverage increases a clusters merge.=20=20=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8aZyBMcdUcV-ECgdJgUIejukl1e_x61c8AupkldkiaWrN4HA4pkO3OYR1eJZrcFpLc8Y= m1LYhOHR4U4KQ2gMiLzuVFo$ for graphic product... ATTN...WFO...BMX...FFC...HUN...JAN...MEG...MRX...OHX... ATTN...RFC...LMRFC...OHRFC...SERFC...NWC... LAT...LON 35468740 35368533 35038447 34378449 33928505=20 33398669 33218881 33449058 34239079 34889014=20 35278894=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) .