Area Forecast Discussion
Issued by NWS
Issued by NWS
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300 FXUS62 KTAE 242000 AFDTAE Area Forecast Discussion National Weather Service Tallahassee FL 400 PM EDT Tue Sep 24 2024 ...WEATHER TURNS ACTIVE TOMORROW WITH POTENTIAL FOR STRONG TO SEVERE STORMS AND HEAVY RAIN... ...New SYNOPSIS, NEAR TERM, SHORT TERM, LONG TERM, MARINE, FIRE WEATHER, HYDROLOGY... .SYNOPSIS... Issued at 354 PM EDT Tue Sep 24 2024 Weather turns active on Wednesday as showers/thunderstorms increase ahead of Tropical Storm Helene. Isolated severe weather and heavy rain is possible with this activity. Helene is forecast to approach Apalachee Bay as a likely major hurricane on Thursday with conditions deteriorating from south to north. Landfall is forecast somewhere along the NE Gulf Coast as a major hurricane and bring a myriad of potentially significant threats: life-threatening storm surge, tropical storm/hurricane- force winds, flash flooding, and isolated tornadoes. Conditions should improve heading into the weekend as Helene exits the region. && .NEAR TERM... (Through Wednesday) Issued at 354 PM EDT Tue Sep 24 2024 The benign weather we have been experiencing the past couple days gives way to increasing rain chances tomorrow. A frontal boundary attendant to a broad/energetic upper trough over the Central Plains interacts with tropical moisture off the Gulf to be the primary foci for showers/thunderstorms. The environment is forecast to be somewhat conducive for loosely organized convection capable of isolated gusty/damaging winds, locally heavy rain, and perhaps a brief tornado or two. For these reasons, the SPC introduced a Marginal Risk (level 1 of 5) of severe weather in the Day 2 Outlook for SE AL, the FL Panhandle, and parts of the FL Big Bend/SW GA. The 18Z HRRR initiates convection off the Emerald Coast as a N-S- oriented cluster in the morning before spreading inland with time. Storm mode appears to take on linear-like banding shapes, which could spell heavy rain/flooding trouble that`s not even directly associated with TC Helene, yet. In response to this evolution, the WPC maintains a Slight Risk (level 2 of 4) over parts of the Emerald/Forgotten Coasts and Marginal Risk (level 1 of 4) elsewhere for the Day 2 Outlook. The former may drop southward to the Wiregrass Region in subsequent outlooks. With weather aiming to be active on Wednesday, users are highly encouraged to finalize any outdoor preparedness plans ahead for Helene sooner than later. Given the increased cloud cover/rain chances, expect relatively cooler daytime temperatures with widespread highs in the 80s. Overnight lows drop to the low 70s. && .SHORT TERM... (Wednesday night through Friday) Issued at 354 PM EDT Tue Sep 24 2024 The focus will be the approaching Tropical Storm Helene, which is expected to become a hurricane or major hurricane prior to landfall somewhere along the Florida Panhandle or Big Bend. There will be a developing upper level trough over the middle Mississippi Valley that will pull in Tropical Storm Helene, bringing it up north through the Gulf of Mexico. Tropical Storm Helene is expected to strengthen to a hurricane bringing significant impacts to the Florida Panhandle and Big Bend, possibly extending further inland to SE Alabama and SW Georgia. Winds will be gradually increasing through the day on Thursday with scattered showers already occurring. The 11AM EDT Advisory still indicates that Tropical Storm Helene will make landfall along the Florida Big Bend as a Major Category 3 Hurricane sometime late Thursday evening. The 12z ensemble runs do not show much shift east or west from the 06z ensemble runs as to where the center may go. The object to focus on is that this will be a very large storm in size. Impacts will be felt well outside of the cone of uncertainty. Expect conditions to begin deteriorating by midday Thursday. All locations along the northern Gulf and along the eastern portions of the Florida Big Bend and west coast of Florida are at risk currently for a major hurricane bringing significant wind, storm surge inundation, and rainfall. Additionally, Tropical Storm Helene is likely to have a faster than usual storm motion as it accelerates north around landfall and moves inland. When combined with the storm`s large size and fast forward motion, significant winds and gusts could extend further inland than folks are typically accustomed to seeing during tropical systems. Reminder, every storm is unique in its own way with what it brings in regards to threats and hazards, and each system brings uncertainty that can leave you unprepared if you`re not ready for a *reasonable* worst case scenario. Don`t underestimate the danger you could experience with Helene just because you avoided impacts from previous storms. With watches issued and upcoming warnings are likely, if you are under a tropical/hurricane/surge watch or warning, be sure to check the forecast at weather.gov (type your zip code to see watches/warnings at your location) and read the tropical watch/warning text. These watches/warnings will list out conditions that you should be prepared for. These watches/warnings also list out reasonable worst case scenarios you should be ready for at your location. && .LONG TERM... (Friday Night through Monday) Issued at 354 PM EDT Tue Sep 24 2024 Helene will be out of the region by the start of this long term period. We can expect to return to typical conditions for late September with highs in the mid-80s with overnight lows in the upper 60s/low 70s. PoPs chances will be low during the weekend but the upper level trough from before the hurricane will be moving east/northeast across the eastern one-third of the U.S. pushing a frontal boundary across the TAE CWA that may increase rain chances to about 30% by the end of the long term. && .AVIATION... (18Z TAFS) Issued at 134 PM EDT Tue Sep 24 2024 The main aviation concern is convective for which the highest confidence is at ECP/DHN tmrw morning and aftn. A PROB30 group for -TSRA was intro`d at those sites from 12-18Z to acct. Storms may encroach on TLH where VCTS is in place while ABY has VCSH starting at 14Z. The most likely terminal to stay dry thru this TAF is VLD. Otherwise, VFR conds should prevail with SE winds about 10 kts or less. && .MARINE... Issued at 354 PM EDT Tue Sep 24 2024 At 11 am EDT, the center of Tropical Storm Helene was still over the northwest Caribbean. It will rapidly intensify while moving northward through the eastern Gulf on Wednesday and Wednesday night, making landfall likely as a major hurricane on the northeast Gulf coast on Thursday. Conditions should begin to deteriorate some time on Wednesday. Winds and seas will gradually start decreasing by Friday as Helene moves further inland and weakens. Broad low pressure over the Lower Mississippi Valley on Saturday will support gentle to moderate southwest breezes. && .FIRE WEATHER... Issued at 354 PM EDT Tue Sep 24 2024 Fire weather concerns are minimal over the next 3 days as rain chances markedly increase from a frontal system moving into the MS Valley, followed by the arrival of TC Helene late this week. For Wednesday, showers and thunderstorms mainly focus west of the Apalachicola River basin. Some may be strong to severe capable of gusty/damaging winds, and locally heavy rain. On Thursday, tropical moisture surging off the Gulf from the approaching Helene is expected to bring squally weather with conditions deteriorating ahead of landfall somewhere along the NE Gulf coast as a likely major hurricane. Hurricane conditions are possible across the FL Big Bend while tropical storm conditions are possible for eastern portions of the FL Panhandle. Widespread wetting rains are expected with potential for flash flooding (locally considerable). Very high dispersions are forecast on Friday thanks to breezy gradient winds from Helene`s large circulation despite pulling away from the region. && .HYDROLOGY... Issued at 354 PM EDT Tue Sep 24 2024 Primary focus continues to on the approach of Tropical Storm Helene to the region. The system has the potential to bring significant rain to the region, even accounting for its fast forward motion as it nears the Florida Big Bend. Model guidance has been in good agreement that a precursor event of heavy rainfall will overspread the Florida Big Bend and Panhandle Wednesday evening with the bulk of the rainfall arriving later on Thursday. This will lead to some heavy rainfall totals across North Florida and South Georgia totaling 5 to 10 inches of rain with isolated maximum totals approaching 10 to 15 inches. The entire forecast area is included in a Moderate risk for flash flooding (level 3 out of 4) for Thursday. It is possible that this risk level is increased in future outlooks. Nonetheless, these amounts will lead to considerable urban flash flooding along with the potential for moderate flooding, especially on the Ochlockonee River Basin. Depending on where the heaviest rains are distributed inland, it is entirely possible that other river basins could experience moderate riverine flooding in the days ahead. For storm surge information, please refer to the latest information from the National Hurricane Center. This is an extremely dangerous storm surge threat in the Apalachee Bay. Storm Surge around Apalachee Bay will not just merely be a coastal event in this system, but will spread many miles inland. If ordered to evacuate, heed the advice of local emergency managers - it could save your life! && .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 73 86 72 79 / 10 50 90 90 Panama City 75 85 72 79 / 30 80 90 90 Dothan 71 85 70 76 / 30 70 90 90 Albany 73 87 72 78 / 10 50 80 90 Valdosta 71 88 72 81 / 0 30 80 90 Cross City 73 90 73 85 / 0 60 90 90 Apalachicola 77 84 73 81 / 40 70 100 100 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...Flood Watch from Wednesday evening through Friday morning for FLZ007>019-026>029-034-108-112-114-115-118-127-128-134. Tropical Storm Watch for FLZ012>014-112-114. Hurricane Watch for FLZ015>019-026>029-034-115-118-127-128-134. High Rip Current Risk through late Friday night for FLZ114-115. Storm Surge Watch for FLZ115-118-127-128-134. GA...Flood Watch from Wednesday evening through Friday morning for GAZ120>131-142>148-155>161. AL...Flood Watch from Wednesday evening through Friday morning for ALZ065>069. GM...Tropical Storm Watch for GMZ750-770. Hurricane Watch for GMZ730-752-755-765-772-775. && $$ NEAR TERM...IG3 SHORT TERM...Montgomery LONG TERM....Montgomery AVIATION...IG3 MARINE...IG3 FIRE WEATHER...IG3 HYDROLOGY...Godsey