447
FXUS62 KJAX 071258
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
858 AM EDT Tue Oct 7 2025

...New UPDATE...

.KEY MESSAGES...

For the latest NE FL and SE GA Daily Key Messages please visit:
https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

- Mostly Minor Tidal Flooding Continues within the St. Johns River
  Basin through Wednesday Night.

- Significant Coastal / Tidal Flood Event Develops on Thursday and
  Friday as Strong Onshore Winds Overspread Our Area. Coastal
  Flood Watches are Likely for Thursday and Friday all along the
  Atlantic Coast and within the St. Johns River Basin.

- Heavy Downpours and Embedded Thunderstorms Possible on Thursday
  and Friday Along the I-95 Corridor, with Localized Flooding
  Possible, Especially During Times of High Tide.

&&

.UPDATE...
Issued at 855 AM EDT Tue Oct 7 2025

Deep easterly flow continues with PWATs noted via satellite at
about 1.72 inches which is what the JAX sounding recorded. There
was not much change to the forecast today with isolated to scattered
showers expected with minimal chances for thunderstorms based on
the guidance, and the fact that ridge aloft may suppress updraft
strength. Even so, there is plenty of moisture and convergence to
generate at least scattered shower activity during the day but
rainfall amounts will be muted given the westerly flow at about
15 mph. Using some later guidance, just tweaked the POPs up a bit.
Current forecast temps are on track. Only other change was about
the fog and stratus to reflect that in the forecast, with some
patchy fog lingering over inland southeast GA. A similar forecast
for fog and stratus expected Wednesday morning.

&&

.NEAR TERM...
Issued at 405 AM EDT Tue Oct 7 2025

High pressure over the mid-Atlantic states will continue to push
towards the Atlantic as a cold front shifts towards the eastern
and the southeastern CONUS. Dry air begins to filter into the area
Today, which will keep precipitation chances lower than the past
couple of days across the area. With that said, the continued
easterly onshore flow will likely bring enough moisture onshore to
allow for isolated to scattered showers to push in from the local
waters towards coastal locations during the morning hours and
push towards inland locations by the afternoon hours, and begin to
clear by the late afternoon hours as dry air (PWATs ~1.45")
continues to advect into the area during the overnight hours into
Wednesday morning.

Daytime highs in the upper 80s for locations west of the US-301
corridor, while the continued onshore flow will keep coastal
locations relatively cooler in the lower to mid 80s. Overnight
lows in the upper 60s over inland SE GA and from the Suwannee
Valley Region towards the US-301 corridor of NE FL, lower 70s
along the coast and north central FL counties.

&&

.SHORT TERM...
(Wednesday through Thursday night)
Issued at 405 AM EDT Tue Oct 7 2025

Ridging aloft stretching along the northern Gulf coast on
Wednesday morning will flatten and retrograde westward as
troughing progresses eastward across New England and the Mid-
Atlantic states. This trough will drive a cold front across the
southeastern states on Wednesday afternoon, with this boundary
then crossing southeast GA on Wednesday night and the rest of our
area on Thursday. Coastal troughing that has persisted over our
near shore waters will weaken ahead of this approaching front,
with only a few light showers or sprinkles possibly moving onshore
for locations south of St. Augustine, mainly on Wednesday morning.
Otherwise, a drier and more subsident air mass will overspread
our region by Wednesday afternoon, with partly cloudy skies
boosting highs to the 85-90 degree range at inland locations,
while a northeasterly breeze keeps coastal highs generally in the
mid 80s. Wednesday may be the final seasonably warm and humid day
during the next week, and dewpoints remaining around 70 for inland
north central and northeast FL will drive maximum heat index
values into the mid 90s during the afternoon hours.

A few showers may accompany the frontal passage on Wednesday night
across southeast GA, with multi-layered cloudiness otherwise
increasing across our area from north to south as the night
progresses. Meanwhile, a sprawling surface ridge building
southeastward from the Great Lakes region in the wake of this
frontal passage will begin to wedge down the southeastern seaboard
towards sunrise, which will begin to tighten our local pressure
gradient from north to south towards sunrise. Breezy northeasterly
winds are expected to develop over coastal southeast GA during
the predawn hours. Lows on Wednesday night will fall to the upper
60s to around 70 at inland locations, while low to mid 70s prevail
at coastal locations.

A potent shortwave trough digging east-southeastward from the
Ozarks through the Tennessee Valley on Wednesday night and
Thursday will deepen and cutoff over the southeastern states by
Thursday night. Meanwhile, surface ridging will build over New
England, with this feature continuing to wedge down the
southeastern seaboard as coastal troughing redevelops and sharpens
by Thursday evening over our local Atlantic waters. Coastal
convergence will strengthen once the frontal boundary slips south
of our area by Thursday afternoon and evening, resulting in
increasing shower coverage along the I-95 corridor. Cooling
temperatures aloft may also support isolated, mainly elevated
convective development over the Atlantic waters on Thursday, with
this activity potentially moving onshore along the I-95 corridor
by Thursday evening.

The big weather story on Thursday and Thursday night will be
steadily increasing onshore winds, as our tightening local
pressure gradient creates wind speeds of 20-30 mph by the mid to
late afternoon hours at coastal locations, with breezy conditions
spreading inland as the day progresses. Wind gusts of 35-40 mph at
coastal locations will introduce potential Wind Advisories along
the I-95 corridor by Thursday afternoon and evening. Increasing
cloud cover, rain chances, and onshore winds will keep highs in
the upper 70s across southeast GA, lower 80s for northeast FL, and
mid 80s for north central FL, where the front will likely not move
through until later in the afternoon.

Coverage of showers and a few embedded, mainly elevated
thunderstorms is expected to increase along the I-95 corridor on
Thursday evening, with activity potentially persisting into the
overnight hours as a sharpening coastal trough and strong onshore
winds result in strong coastal convergence. Locally heavy rainfall
will be possible, with training bands potentially setting up over
portions of coastal northeast FL that may present a localized
flood threat, particularly if heavy downpours coincide with high
tide. Cool air advection in the wake of the front will drive lows
down to the lower 60s for inland portions of southeast GA, with
60s elsewhere, except around 70 for inland northeast FL and the
low to mid 70s for coastal northeast FL.

&&

.LONG TERM...
(Friday through Monday)
Issued at 405 AM EDT Tue Oct 7 2025

Troughing will continue to cutoff from the main flow over the
southeastern states on Friday and Saturday. This feature will
allow for cyclogenesis along the frontal boundary east of Cape
Canaveral on Friday, with this deepening low pressure center then
lifting slowly northward this weekend, likely paralleling the
southeastern seaboard. Meanwhile, strong high pressure centered
over New England on Friday morning will weaken and shift eastward
by Friday night as this low pressure center takes shape over the
Gulf Stream waters adjacent to our region. This weather pattern
will maintain a very tight local pressure gradient across our
area, and a drier air mass will likely advect into our region this
weekend as this storm system slowly migrates towards the coastal
Carolinas. Strong coastal convergence will keep a threat for heavy
rainfall in place along the I-95 corridor on Friday, followed by
scattered, occasional coastal showers moving onshore along the
Atlantic coastal counties in the brisk north-northeasterly flow on
Saturday. These strong onshore winds on Friday and Saturday will
combine with lingering high astronomical tides from this week`s
full "Harvest" Supermoon to produce significant, potentially
widespread moderate to major coastal flooding along the Atlantic
coast and within the St. Johns River basin (see "Hydrology"
section below for some preliminary details).

Northeasterly winds will remain breezy to windy, with cool air
advection keeping highs mostly in the 70s on Friday and Saturday,
with a few 80 degree values possible in north central FL. Lows on
Friday night will fall to the lower to mid 60s throughout
southeast GA and inland portions of northeast FL, ranging to the
mid to upper 60s for north central and coastal northeast FL. A
much drier air mass will then advect into our area from northwest
to southeast on Saturday night, with model blends indicating lows
falling into the upper 50s for inland portions of southeast GA and
the Suwannee Valley, with low and mid 60s prevailing elsewhere.
Gusty northerly winds along the I-95 corridor and a lighter breeze
at inland locations will make these temperatures feel even
cooler!

The non-tropical or hybrid gale center off the Carolina coast
will likely become stationary late this weekend and early next
week, keeping a funnel of seasonably cool and dry air over our
region, compliments of breezy northerly winds. Coastal troughing
may linger off the FL Atlantic coast on Sunday, keeping the threat
for a few showers along the I-95 corridor from St. Augustine
southward. The dry air mass and plenty of sunshine will allow
highs to climb to the lower 80s inland on Sunday and Monday, with
coastal highs likely remaining in the upper 70s to around 80.
Heights aloft should begin to rise by Tuesday, allowing for highs
to slowly climb to the mid 80s inland, while breezy onshore winds
keep coastal highs around 80. Nighttime lows will be the bigger
story, as inland temperatures fall to the 55-60 range, while an
onshore breeze keeps lows in the mid 60s at coastal locations.

&&

.AVIATION...
(12Z TAFS)
Issued at 710 AM EDT Tue Oct 7 2025

Mostly VFR conditions except for some periods of MVFR cigs through
the morning hours and possibly early afternoon, with the low level
flow continuing to be easterly. Brief vsby also down to MVFR
about 4-5SM this morning should dissipate. Some low chances of
showers for the coastal areas through about 17z, and then translating
further inland this aftn. We have VCSH to cover this for the
morning and then have GNV at VCSH staring about 18z. The thunder
probabilities look low enough to exclude from mention at this
time. Sfc winds...light northeast winds will become easterly quickly,
or about 14z-15z, to about 8-14 kt with gusts up to about 20 kt.
Winds should diminish by 00z tonight. For now, low cigs at MVFR
and IFR, look to stay northwest of the TAF sites late tonight/early
Wed.

&&

.MARINE...
Issued at 405 AM EDT Tue Oct 7 2025

Small Craft conditions will steadily begin to drop off over the
local waters Today. The elevated seas will begin to diminish
heading into midweek as High pressure over the Mid-Atlantic coast
shifts away towards the Atlantic in addition to the weakening of
local coastal troughing over the local waters. Seas and winds are
expected to become elevated once again to Small Craft conditions
by the later half of the week as an approaching cold front shifts
towards the local waters in addition to an area of low pressure
shifting north along the southeastern Atlantic coast. Gusts may
reach near gale force which will may lead to the issuance of a
Gale Watch for the end of this week.

&&

.FIRE WEATHER...
Issued at 405 AM EDT Tue Oct 7 2025

Breezy easterly surface and transport winds today will create fair
to good daytime dispersion values. Surface and transport winds
will shift to northeasterly on Wednesday, with breezy conditions
continuing for coastal locations in northeast FL. Northeasterly
surface and transport winds will steadily strengthen from north to
south on Thursday, with strong surface winds gusts increasing to
30- 35 mph at coastal locations by Thursday afternoon. Fair to
good daytime dispersion values with continue throughout our region
on Wednesday and Thursday.

&&

.HYDROLOGY...
Issued at 405 AM EDT Tue Oct 7 2025

Water levels have continued to gradually subside along the
Atlantic coast and within the St. Johns River basin, with moderate
flooding now being confined to southern portions of the St. Johns
River basin, mostly in Putnam County, where a Coastal Flood
Warning remains posted. Water levels were reaching minor flooding
during times of high tide elsewhere within the St. Johns River
basin, where a Coastal Flood Advisory is in effect. Water levels
are now remaining mostly below minor flood levels along the
Atlantic coast and within the Intracoastal Waterway (ICCW), and
the Coastal Flood Advisory has been cancelled for these locations.

The lull in tidal flooding will be short-lived, as astronomical
influences from today`s "Supermoon" set up a significant coastal
and tidal flood event later this week and into the upcoming
weekend as a surge of strong northeasterly winds overspreads our
area. This event has the potential to bring the highest tidal
levels that we have seen along the Atlantic coast and within the
St. Johns River basin thus far this Fall, and a Coastal Flood
Watch will likely be issued on Wednesday in anticipation of
widespread moderate tidal flooding that should begin during high
tide cycles from Thursday afternoon through the upcoming weekend.

Strong onshore winds will likely bring another round of high surf
advisories and the potential for even more significant beach
erosion all along the Atlantic coast by Friday and the upcoming
weekend, along with a high risk of deadly rip currents.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  87  66  88  67 /  30  10   0  20
SSI  83  71  83  70 /  30  10   0  10
JAX  87  68  87  70 /  30  10  10  10
SGJ  85  72  85  73 /  30  10  10  20
GNV  89  67  90  70 /  20  10  10  10
OCF  88  68  89  71 /  20  10  10  10

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 5 AM EDT Wednesday for FLZ038-125-
     132-225-325-633.

     High Rip Current Risk through Wednesday evening for FLZ124-125-
     138-233-333.

     Coastal Flood Warning until 5 AM EDT Wednesday for FLZ137.

GA...High Rip Current Risk until 8 PM EDT this evening for GAZ154-166.

AM...Small Craft Advisory until 10 AM EDT this morning for AMZ450.

     Small Craft Advisory until 5 AM EDT Wednesday for AMZ452-454-472-
     474.

     Small Craft Advisory until 5 PM EDT this afternoon for AMZ470.

&&

$$