Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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401 FXUS62 KJAX 171808 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 208 PM EDT Tue Sep 17 2024 ...New NEAR TERM, SHORT TERM, LONG TERM, MARINE, HYDROLOGY... .NEAR TERM... (This afternoon and Tonight) Issued at 204 PM EDT Tue Sep 17 2024 For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf This afternoon...Drier airmass aloft will keep most of SE GA rain-free, while diurnal heating into the mid/upper 80s and inland moving sea breeze fronts across NE FL will be enough to trigger scattered showers and isolated storms, mainly south of the I-10 corridor, with best chances of any isolated storm activity across Marion/Putnam/Flagler counties. A few storms could have some gusty winds up to 40 mph/brief heavy downpours, but not expecting any significant issues. Tonight...Overall steering flow becomes Southwesterly and this will begin to lift the old frontal boundary currently across Central Florida northward into the NE FL/SE GA area during the overnight hours. A few isolated showers/storms will be possible across inland NE FL early this evening, otherwise expect a few isolated showers possible over land areas as this feature lifts northward through the night, although rainfall chances will remain less than 20%, while scattered showers and isolated storms will develop over the Atlantic Coastal waters as this feature lifts northward. Patchy fog is expected again over inland areas as winds become near calm, with locally dense fog possible. Low temps just slightly warmer than last night with lows in the upper 60s over inland areas and lower/middle 70s along Atlantic Coastal Counties. && .SHORT TERM... (Wednesday through Thursday night) Issued at 204 PM EDT Tue Sep 17 2024 Remnant stacked low pressure over far northern GA will lift north and eastward further away from the area throughout Wednesday, which in response will help pull the nearly stationary weak front south of the area into northeast FL/southeast GA. As a result, higher chances for afternoon/evening convection will return to the area on Wednesday, and especially for northeast FL. There may be some pockets of lingering drier aloft which could limit coverage to being more than of the scattered variety. However, on the flip side of this point, some drier air intrusion could help to produce some stronger downbursts up to 40-55mph in some isolated storms, especially with cell mergers/boundary collision situations. The front lifting northward will also help high temps bump up a little bit compared to today, with generally mid to upper 80s to some low 90s south. Some convection could linger into the first part of Wednesday Night with the boundary in the area, and also should keep some clouds around for most of the night as lows fall closer to normal in the upper 60s to low 70s. Thursday, the frontal boundary becomes more diffuse over the area as the upper trough overhead on WEdnesday starts to lift northeastward. This will keep most of the area under the influence of the more subsident upstream side of the same trough, and also rotate in some drier air as a more northwesterly flow develops both near the surface and aloft. Diurnal convection will therefore will revert back towards a more limited/isolated capacity on Thursday, with the best chances for isolated to widely scattered coverage being south of I-10 in northeast FL as well as near the pinned sea breeze. The lower convective coverage and drier northwesterly flow combo generally offset to result in similar temperatures Thursday as compared to Wednesday. && .LONG TERM... (Friday through next Tuesday) Issued at 204 PM EDT Tue Sep 17 2024 An overall drier than normal pattern looks to be in store for most of the long term, as guidance is coming into better agreement with the upper level pattern. The upper low/trough south of New England that lifts away from the area on Wednesday/Thursday looks persist a generally broad/weak trough overhead for Friday before the low dives southward this weekend, north and east of the region into the western Atlantic. This will result in an increasingly subsident flow aloft on the west side of the same low, as well as a coinciding surface ridge building southward along the eastern seaboard, dropping the above mentioned frontal boundary well south of the region. The extent of how far south the upper level energy digs will certainly play a big role in how far south the frontal boundary drops, and therefore the precip/temperature outlook. However, confidence is increasing with respect to below normal layer moisture, below normal chances for convection, and temperatures trending towards below normal for the weekend and possibly into the start of next week. && .AVIATION... (18Z TAFS) Issued at 122 PM EDT Tue Sep 17 2024 Abundant Cumulus cloud deck development across NE FL this afternoon with most CIGS in the 3500-4000 ft range, but a few brief MVFR CIGS of 2500-3000 ft still possible for a few hours at SGJ, but overall VFR with light winds. Rainfall chances remain fairly low at SGJ/GNV but will leave in VCSH until 00Z for consistency for now. After sunset mainly VFR conds with low rainfall chances although a few Hi-res models are suggesting a few sprinkles possible with old frontal boundary lifting northward but will continue to leave out of forecast for now and focus on potential fog formation at inland TAF sites with IFR VSBYS expected at GNV/VQQ in the 08-13Z time frame and MVFR VSBYS at JAX from 09-12Z. Mixed solutions for Wednesday morning but expect SCT clouds around 2500ft from 14-18Z, as well as potential for rainfall chances at SSI with the frontal boundary, so have added VCSH in this time frame with the new TAF package. && .MARINE... Issued at 204 PM EDT Tue Sep 17 2024 Weak flow pattern will remain in place through Wednesday with daily sea breeze for the near-shore waters and expect to remain headline free through the short term period. Frontal passage on Thursday will be followed by high pressure building to the north of the local waters Friday through the upcoming weekend. Northeast/Onshore flow will set in on Friday and increase through the weekend, with at least Small Craft Exercise Caution headlines expected and possible Small Craft Advisories by the Sunday time frame as winds/seas continue to build. Rip Currents: High risk of rip currents and rough surf/breakers of 3-5 ft today will become Moderate on Wednesday in the light wind flow pattern as surf/breakers subside to 2-3 ft. && .HYDROLOGY... Issued at 204 PM EDT Tue Sep 17 2024 No changes planned to current headlines as Coastal Flood Warning will remain in place for most of this week and into the upcoming weekend for the St. Johns River Basin as Moderate flooding is expected to continue due to the freshwater inflow along with high tides due to the full moon with peak water levels of 2 to 2.5 feet above MHHW. Will continue Coastal Flood Advisory for Minor Flooding along the NE FL beachfront locations, mainly due to the higher tides due to the full moon phase with peak water levels of 1.5 to 2 feet above MHHW. && .PRELIMINARY POINT TEMPS/POPS... AMG 67 86 68 87 / 10 40 10 10 SSI 73 85 72 85 / 20 40 20 10 JAX 71 89 71 88 / 20 50 30 20 SGJ 72 90 73 88 / 20 50 40 20 GNV 69 90 70 89 / 20 50 10 30 OCF 70 91 72 90 / 20 40 10 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Warning until 5 AM EDT Thursday for FLZ033-038-125- 132-137-225-325. Coastal Flood Advisory until 5 AM EDT Thursday for FLZ124-133- 138. High Rip Current Risk through late tonight for FLZ124-125-133- 138. GA...High Rip Current Risk through late tonight for GAZ154-166. AM...None. && $$