286 FXUS62 KJAX 061154 AFDJAXArea Forecast Discussion National Weather Service Jacksonville FL 754 AM EDT Sat Sep 6 2025
...New UPDATE...
.UPDATE... Issued at 753 AM EDT Sat Sep 6 2025
For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf
Forecast remains on track as weak trough/old frontal boundary across Central Florida continues to slowly shift back northward into NE FL today with increasing shower and thunderstorm chances by the afternoon hours with locally heavy rainfall and some gusty winds possible over inland areas of NE FL, mainly south of the I-10 corridor. Areas across SE GA the drier airmass will slowly moisten, but remains mostly dry today into tonight. Max temps still expected to reach into the lower to middle 90s inland and upper 80s along the Atlantic Coast in the continued onshore flow. Peak Heat indices will reach into the 100-105 range across NE FL and around 100F across SE GA.
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.NEAR TERM...Today and Tonight...
Calming conditions, mostly clear skies, and shrinking dewpoint depressions may result in areas of patchy shallow fog across inland areas this morning, which may become locally dense in areas near marsh/estuaries around sunrise.
Onshore flow will continue locally as a stalled trough to the south begins to lift northward into central FL today. Meanwhile, rising heights aloft will trend temperatures warmer by another degree or two this afternoon, putting highs in the low 90s inland and upper 80s along the coast. WIth the seasonable dewpoints and low 90s temperature readings, peak heat index values will rise to the lower 100s across NE FL this afternoon.
As the aforementioned trough or pseudo warm front approaches, moisture aloft will accompany it and aid the development of numerous showers and scattered thunderstorms generally south of I-10 this afternoon. Interactions with the St Johns River and Lake George breezes may initiate convection as early noon today. Isolated thunderstorms are generally expected along and south of a moisture/instability gradient that will extend from Jacksonville to Gainesville. Main concerns will be locally gust winds, lightning, and localized minor flooding/ponding due to sluggish storm motion.
The aforementioned warm front will continue to lift north tonight and rest across NE FL by dawn Sunday. Patchy to areas of fog are expected with some of those areas becoming dense in areas between the Interstate 10 and 95 corridors. Tonight`s lows will be right around normal with inland lows in the lower 70s and mid/upper 70s along the coast.
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.SHORT TERM... (Sunday through Monday night) Issued at 1254 AM EDT Sat Sep 6 2025
Sunday, A broad mid/upper trough will shift from the upper Midwest into the eastern Great Lakes and OH/TN valley. This will push a surface cold front into the Gulf coast and SE GA. As the surface trough to the south dissipates and the new front moves in, deep moisture levels will rise with PWATs increasing to 1.8-2.10 inches across NE FL while near normal over SE GA 1.5-1.8 inches. The additional moisture, lift along the front and inland progressing Atlantic seabreeze and slightly steeper lapse rates aloft (~6.0 c/km) will support increased chances for showers and T`storms with numerous showers and T`storms over NE FL south of a line from Gainesville to St Augustine and scattered coverage of showers and T`storms northward into SE GA as the front moves in. Locations west of US 441 may see diminished chances as the front pushes through and entrain drier air in it`s wake. Slightly stronger 0-6km shear in the environment ahead of the front may support a higher threat for wind gusts 40-55 mph and small hail in stronger T`storms. East northeasterly winds will continue, highest along the coast 10-15 mph and diminishing to 5-10 mph west of I-95. Highs will rise into the low 90s inland to the upper 80s along the coast. Max heat index values will rise to around 100-105 from Jacksonville south and west into central FL.
Sunday night, the front will press into NE FL with isolated showers lingering past midnight over inland NE FL, but revamping along the coast towards sunrise as coastal convergence increases over the waters. Light easterly winds 5-10 mph will back north northeasterly and increase to 10-15 mph at the coast in the predawn morning hours. Lows will be in the mid 70s at the coast, low 70s over inland NE FL and around 70 over inland SE GA.
Monday, the broad trough to the north will lift northeastward into New England/eastern Quebec on Monday as a ridge axis moves east from the plains into the mid and upper MS river valley. Under the ridging, surface high pressure will sprawl across the Midwest states and move into the upper OH valley near the end of the day. As the high moves east, NNE winds will become more northeasterly and increase as an inverted coastal trough forms near the Gulf stream as the front stalls from central FL into the offshore FL waters. This feature will create strong coastal convergence sending waves of showers and embedded T`storms onshore pushing inland south and westward into the St Johns river basin and north central FL. Only far NW portions of SE GA will see diminished chances for showers due to drier continental air flow from the northeast well inland. Heavier convergent bands may produce locally heavy rainfall amounts from the coast into the St Johns river basin. Abundant clouds and showers will keep our high temperatures below average in the mid 80s along the coast and into I-95 with upper 80s west of I-95 and near 90 degrees along and west of I-75 where more partly cloudy skies reside.
Monday night, the surge of northeasterly winds will continue a fetch of coastal showers moving onto the immediate coast with coverage diminishing with inland extent. Locally heavy rainfall threat will continue east of the St Johns river to the coast with a few T`storms as well. Lows will be in the upper 60s over inland SE GA but moderate to the mid 70s along the coast. NE winds will continue elevated at the coast 10-20 mph and 5-10 mph inland.
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.LONG TERM... (Tuesday through Friday) Issued at 1254 AM EDT Sat Sep 6 2025
High pressure to the north building eastward will wedge a cooler and drier air down the lee of the Appalachians while inverted troughing persists near the Gulf stream waters along the previously stalled frontal boundary. This will continue an unsettled pattern for much of the area as mid/upper troughing forming over the spine of the appalachian mountains sends a parade of shortwaves moving across the area that will add lift and spin to the atmosphere over the top of breezy surface NNE onshore flow. This will support persistent coastal convergence over the first coast with numerous to widespread showers and embedded T`storms along the NE FL coast inland to I-75 which will allow for locally heavy rainfall amounts where the bands move onshore, continuing inland to I-75. Per the long range Grand Ensemble (includes the European, Canadian, and GFS Ensemble models) in DESI, The probability of locations receiving 2 inches of rain or more next week is up to 30% from the JAX beaches into the St Johns river and Ocala with up to 50% over coastal Flagler county.
Breezy conditions will prevail through much of the week as the high to the north shifts more to the northeast with a pinched gradient leading to northeasterly winds at the beaches 15-20 mph with higher gusts to 30 mph and 10-15 mph inland. The expectation during this long duration onshore flow event is for a stretch of dangerous rip currents at the beaches, elevated surf (4-6 ft breakers), and beach erosion impacting the beaches until the gradient relaxes late in the week as the high weakens to the northeast as another cold front arrives from the northwest next Friday.
Temperatures during the period will be feature below normal highs in the low to mid 80s at the coast and mid to upper 80s inland with near to below normal lows in the mid to upper 60s over inland SE GA/Suwannee valley and the low 70s along the coast.
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.AVIATION... (12Z TAFS) Issued at 725 AM EDT Sat Sep 6 2025
Some patchy fog/stratus development this morning over inland areas, but has remained just NW of inland TAF sites at sunrise, but have kept in some TEMPO IFR CIGS at VQQ/JAX until 13Z to cover any shift in this stratus deck. Otherwise VFR conds at other TAF sites except for some isolated showers (VCSH) and MVFR CIGS at SGJ which will linger through the morning hours. Moisture has shifted northward across NE FL and expect to continue VCSH addition at VQQ this afternoon and have kept VCTS at GNV this afternoon and included PROB30 group for TSRA activity from 20-24Z for potential MVFR conds as well. Convection chances fade after sunset then focus shifts to a more widespread stratus and fog event over inland areas, but probs too low for any LIFR/IFR CIGS/VSBYS, so have just placed MVFR VSBYS at VQQ/JAX/GNV in the 08-12Z time frame for now with further refinement in later packages.
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.MARINE...
Onshore flow pattern continues as a weak warm front lifts north and stalls across the northeast Florida and coastal waters through tonight. A cold front will approach from the north as the stalled warm front morphs into a coastal trough on Sunday, increasing rain and thunderstorm chances over the waters. By Monday, the cold front reach the Georgia waters and send a surge of northeasterly winds southward down the coast. A period of small craft advisory conditions are possible Monday and Tuesday with gradually weakening northeasterly winds Wednesday onward. The front will continue toward south Florida through the week with a reinforcing front pushing towards the local waters by next weekend.
Rip Currents: Moderate risk of rip currents is expected with breakers around 2-3 ft. A cold front and northeasterly wind surge will elevate surf and increase rip current risk along the SE GA by Monday.
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.HYDROLOGY...
Elevated tides due to higher astronomical tides will combine with a prolonged period of northeasterly flow next week and potentially bring another Minor coastal flood event, particularly south of Jacksonville within the St Johns River as well along the Atlantic coast, at times of high tide.
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.PRELIMINARY POINT TEMPS/POPS... AMG 94 71 91 68 / 10 10 30 20 SSI 86 75 87 74 / 10 20 30 40 JAX 91 73 91 73 / 20 30 50 30 SGJ 89 75 88 75 / 40 40 70 50 GNV 93 73 92 71 / 60 40 60 20 OCF 92 73 90 73 / 80 60 70 30
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.JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&
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NWS JAX Office Area Forecast Discussion