Area Forecast Discussion
Issued by NWS
Issued by NWS
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125 FXUS62 KTAE 171959 AFDTAE Area Forecast Discussion National Weather Service Tallahassee FL 359 PM EDT Fri May 17 2024 ...New NEAR TERM, SHORT TERM, LONG TERM, AVIATION, MARINE, FIRE WEATHER, HYDROLOGY... .NEAR TERM... (Through Saturday) Issued at 355 PM EDT Fri May 17 2024 The main concern through Saturday will be severe thunderstorms and heavy rain. In the big picture, a positively tilted southern stream upper trough has moved east to Texas, ramping up west-southwesterly jet stream winds along the northern Gulf Coast. A turn to southerly low-level flow has brought a return of low-level moisture as a warm front tries to creep northward and inland. Already, a band of moderate rain and thunderstorms currently stretches from southwest Alabama to west-central Georgia, mainly along the north of the warm front. It should take on a more positive tilt through this evening and start to slowly move southeast, affecting most of the service area except perhaps the Forgotten Coast and southeast Big Bend. Given the slow movement of this line, a quick couple inches of rain should occur in spots. So a few severe wind gusts and flash flooding will be the main threats through this evening. We just issued a Flood Watch for areas along and west of the Flint River, and for the inland FL Panhandle. Looking upstream, a shortwave trough west of Del Rio TX will race east through this evening, sparking development of a new MCS late this evening off the Texas and Louisiana coasts. It will continue to race east overnight near the northern Gulf Coast, pushing across the tri- state region from west to east from early Saturday morning into the mid-afternoon hours. Assuming this takes on a classic MCS structure and tracks more onshore than over the Gulf waters, then fairly widespread severe wind gusts would be possible, with isolated convective gusts in excess of 70 mph. As MCS exits east later Saturday afternoon, we will likely see a significant lull in activity develop in the rain-stabilized air that follows. && .SHORT TERM... (Saturday night through Sunday night) Issued at 355 PM EDT Fri May 17 2024 Widespread showers, in addition to scattered severe storms, continue into Saturday evening but a general downtrend in severe weather should begin to develop as the forcing moves east and instability wanes. However, with one last shortwave passage left, isolated severe storms remain possible overnight Saturday into early Sunday. The trough pushes through Sunday with cooler temperatures aloft moving in. While the severe threat will be noticeably lower and east compared to Saturday`s event, our GA counties along the I-75 corridor and down into the southeast Big Bend could see strong, possibly severe, storms given the favorable temperatures aloft and remnant instability. We`ve also added some patchy fog to the forecast Sunday morning. && .LONG TERM... (Monday through Thursday) Issued at 355 PM EDT Fri May 17 2024 Upper level ridge settles in as the trough from the weekend moves out. Cannot rule out a slight chance of showers across far eastern areas on Monday as another shortwave swings through. A quieter and drier pattern is forecast through much of next week. This pattern should lead to a warm up in temperatures with highs back in the low 90s by Tuesday and Wednesday. && .AVIATION... (18Z TAFS) Issued at 355 PM EDT Fri May 17 2024 The main challenge will be timing two rounds of showers and thunderstorms over the next 24 hours, with the possibility of a thunderstorm squall line on Saturday morning that could bring a healthy coverage of severe thunderstorm wind gusts. Radar currently shows an east-west band of moderate rain and embedded thunderstorms from southwest Alabama to west-central Georgia. This will start to make more progress to the southeast through early evening, likely affecting all terminals except possibly ECP. A lull is likely overnight, then the squall line will move in from the west on Saturday morning. && .MARINE... Issued at 355 PM EDT Fri May 17 2024 Moderate southerly breezes will prevail across the northeast Gulf through tonight. A line of thunderstorms is likely to move across the waters on Saturday morning and evening, bringing strong to severe wind gusts. A weak front will move across the waters on Saturday and Saturday night, and stall on Sunday, bringing renewed chances of showers and thunderstorms. High pressure will pass across the northeast Gulf on Sunday night, and then elongate along the U.S. Eastern Seaboard on Monday and Tuesday. && .FIRE WEATHER... Issued at 355 PM EDT Fri May 17 2024 Two rounds of thunderstorms will affect districts, the first through this evening, then the second from Saturday morning through mid- afternoon. Widespread wetting rains are expected. Severe thunderstorm wind gusts are possible as well. A weak cold front will pass the districts on Saturday night, followed by a turn to westerly winds on Sunday. Given moderate westerly transport winds and a deeply mixed layer on Sunday, pockets of high dispersion values are expected during the afternoon. The high dispersion values on Monday are mainly due to deep mixing albeit less wind. This would support well-developed vertical smoke columns. && .HYDROLOGY... Issued at 355 PM EDT Fri May 17 2024 The potential for flash flooding is increasing over portions of the FL Panhandle north of I-10, Southwest GA mainly west of the Flint River, and Southeast AL, where a Flash Flood Watch is in effect into Saturday. Parts of this same region are also in a WPC Moderate Risk (Level 3 of 4) for excessive rainfall, which means there is the potential for numerous flash flooding. The remainder of the area outside of the FL Big Bend is in a Slight Risk of Excessive Rainfall, while the Big Bend is under a Marginal Risk. While average rainfall amounts of 2-3 inches are expected across the Flash Flood Watch area, the potential for localized higher amounts of 6 inches from thunderstorms moving repeatedly over the same areas (i.e., training), would result in flash flooding. Wet antecedent conditions with moist soils will accentuate this. The Withlacoochee River at Valdosta (Skipper Bridge Road) and Quitman as well, as the Ochlockonee River at Concord, continue in minor flood stage. && .SPOTTER INFORMATION STATEMENT... Spotter activation is requested. Spotters should safely report significant weather conditions and/or damage by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 86 73 85 69 / 50 50 80 60 Panama City 82 72 82 70 / 80 50 80 40 Dothan 84 70 80 67 / 70 70 90 30 Albany 85 70 81 67 / 80 80 90 40 Valdosta 88 73 87 69 / 30 50 80 60 Cross City 87 73 88 69 / 40 10 50 70 Apalachicola 81 74 82 72 / 80 30 70 60 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...Flood Watch through Saturday afternoon for FLZ007-009-011. High Rip Current Risk through late Sunday night for FLZ108-112- 114-115. GA...Flood Watch through Saturday afternoon for GAZ120>126-142>145- 155. AL...Flood Watch through Saturday afternoon for ALZ065>069. GM...None. && $$ NEAR TERM...Haner SHORT TERM...Dobbs/LF LONG TERM....Haner/LF AVIATION...Haner MARINE...Haner/LF FIRE WEATHER...Haner HYDROLOGY...LF