096 FXUS62 KTAE 192304 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 704 PM EDT Sun May 19 2013 ...SEVERE THUNDERSTORM WATCH HAS ENDED FOR SRN GA AND MADISON COUNTY... .NEAR TERM [Tonight]... The larger scale pattern is dominated by troughing over Wrn states and ridging over Ern states. However, at a more regional level, weak mid/upper shortwave moved over mid-Atlc states helping to deepen a trough down SE coast. This generated vorticity and a Swd moving impulse/cold pool and aided in lift and steepening mid- level lapse rates. At the surface, weak ridge stretched W-E over Nrn Gulf of Mex providing onshore moist and unstable flow along with a weak pressure gradient. Looking north a several outflow boundaries moved south across GA counties while the Gulf seabreeze moved newd and the east coast sea breeze moved wwd. During, the afternoon, the combination of impulse/upper cold pool moving into a moderately unstable airmass and interacting with outflow boundaries generated some strong storms propagating SSE parallel to outflow boundary across mainly NE tier of our GA counties. However, weak low/mid tropospheric flow was weak, preventing significant storm organization and/or updraft rotation and inhibiting storm clusters from organizing more. One report at 440 pm EDT noted several trees down in Fitzgerald, Ben Hill GA. By 7 PM EDT, most of the convection was located east of a line from Brooks thru Berrien Counties in GA enhanced by SE moving outflow boundary with strong winds and possibly small hail. However the widespread severe weather threat and the severe thunderstorm watch has ended. Although some strong storms remain possible into the evening across mainly Thomas Ewd to Lowndes counties, most of the strongest activity later this evening should be just east of our forecast area and I-75 where seabreeze and outflow mergers can generate strong to possibly severe storms. Father west, thunderstorms will gradually diminish, followed by generally fair weather later tonight. Once again there may be areas of low clouds and fog, especially west of the Apalachicola River and in areas that get rain. Expect lows generally 65 to 70. && .SHORT TERM [Monday through Tuesday Night]... The consensus of numerical model guidance portrays an average mid- upper level shortwave ridge over much of our area in the Monday and Tuesday time frame, with a west-to-east gradient in PWAT. The lowest values will be situated over the western part of our area, with the highest values in the east - closer to the influence of the Atlantic Ocean. The overall flow pattern through the depth of the troposphere should be fairly weak, so there shouldn't be a larger-scale forcing mechanism for widespread convection. PoPs were concentrated in our Georgia and Florida Big Bend zones where deeper moisture will reside, with a diurnal trend to be maximized in the late afternoon. Highs away from the coast will be around 90 degrees in general. && .LONG TERM [Wednesday through Sunday]... Chances for showers and thunderstorms are expected to be a little more widespread in our area on Wednesday and Thursday as a low amplitude mid-upper level trough ejects east from the Plains. On Wednesday, our area will be situated right underneath highly divergent flow aloft, and by Thursday a weak surface front should be developing into our area; both situations favor at least a bit of a focus for larger scale vertical motion. Therefore, PoPs on Wednesday and Thursday were increased into the 30-40% range. After that, a strong surface high builds south into the eastern US, and the weak surface front shifts south into the Florida Peninsula. This should allow for some drier air to arrive and slightly lower PoPs closer to climatological normals. The temperature forecast is one of persistence, with highs maintaining close to 90. && .AVIATION [through 00 UTC Tuesday]... Thunderstorms continue to diminish but will hold together across mainly Ern GA counties and adjacent Nrn Big Bend. Tstms possible until around 02z at KVLD. Wind gusts of 35 KT and IFR Vis are possible with any storms as they translate southeastward. It's unlikely that these storms will affect the other terminals. Fog and low CIGS are possible early Monday morning, especially at KECP and KDHN. && .MARINE... Winds and seas should remain relatively calm through the work week. Winds will be generally 10 knots or less, and seas 2 feet or less. There will be a chance for a few showers or storms, and winds could be briefly higher near storms. Storms would be most likely near the coast and in the late afternoon or evening hours. && .FIRE WEATHER... Relative humidity values will remain above critical levels through Tuesday with relatively light transport winds and deep mixing heights especially over Florida. The airmass should remain sufficiently moist to preclude red flag conditions into the upcoming weekend. && .HYDROLOGY... Any rain through Friday would likely arrive in the form of scattered showers and thunderstorms, and average rainfall totals should be low enough to prevent any widespread flooding concerns or issues on mainstem rivers across the area. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 66 90 66 90 69 / 20 20 10 20 20 Panama City 70 85 69 85 71 / 10 10 10 10 10 Dothan 68 91 67 91 71 / 10 10 10 10 10 Albany 68 90 67 91 69 / 30 20 20 20 20 Valdosta 67 89 65 90 68 / 30 40 20 30 20 Cross City 66 88 64 89 67 / 20 30 20 30 20 Apalachicola 69 83 68 82 71 / 0 10 10 20 10 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Block SHORT TERM...Lamers LONG TERM...Lamers AVIATION...Block MARINE...Block/Lamers FIRE WEATHER...Block HYDROLOGY...Lamers