651
FXUS62 KJAX 040805
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
405 AM EDT Sat Oct 4 2025

...New SYNOPSIS, NEAR TERM, SHORT TERM, LONG TERM, MARINE, HYDROLOGY...

.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

- Moderate to Minor Tidal Flooding through Weekend. Coastal Flood
  Warning: Moderate Tidal Flood impacts within the St. Johns River
  Basin, Coastal Northeast FL & Intracoastal Waterway. Coastal
  Flood Advisory: Minor Tidal Flood impacts Coastal Southeast GA &
  Nassau County

- Dangerous Beach & Marine Conditions through Early Next Week.
  High Rip Current Risk, High Surf & Small Craft Advisory.

- Locally Heavy Rain & Flood Risk on Sunday and Monday. Waves of
  Heavy Downpours and Isolated Coastal Thunderstorms. Localized
  Flood Risk at Coastal & Normally Flood Prone, Low-lying
  Locations

&&

.SYNOPSIS...
Issued at 405 AM EDT Sat Oct 4 2025

Overnight surface analysis depicts gradually weakening high
pressure (1027 millibars) centered near the Delmarva peninsula in
the Mid-Atlantic region. This feature continues to wedge down the
southeastern seaboard, with a sharp coastal trough remaining
positioned over our near shore Atlantic waters to the south of
this surface ridge. Meanwhile, weak low pressure was moving slowly
northwestward across central and northwestern portions of the
Bahamas, with this feature located along a remnant frontal
boundary that was lifting slowly northward towards southern FL.
Aloft...a complex weather pattern prevails over the eastern half
of the nation, featuring ridging that extends from the Southern
Plains through the Upper Midwest, the Great Lakes, and Ohio
Valley, while troughing was cutting off to the south of this ridge
over the lower Mississippi Valley and the north central Gulf,
with this trough axis extending eastward across south FL and the
Bahamas.

Latest GOES-East derived Total Precipitable Water imagery
indicates that slightly below average PWATs for early October
prevailed across inland portions of southeast GA, where values
were around 1.25 inches, while values elsewhere were near
climatology, with values generally around 1.5 inches. Widely
scattered light to moderate showers continue to be generated by
coastal troughing over the near shore Atlantic waters, with this
activity being steered quickly westward across northeast FL and
southeast GA, while drier conditions prevailed across north
central FL. Multi-layered cloudiness has overspread our region
overnight, with temperatures at 08Z ranging from the mid and upper
60s across inland southeast GA to the low and mid 70s elsewhere.
Dewpoints ranged from the upper 50s to around 60 across inland
portions of southeast GA to the lower 70s at coastal locations.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 405 AM EDT Sat Oct 4 2025

High pressure centered over the Delmarva region will continue to
slowly weaken through tonight while gradually pushing offshore.
This feature will continue to wedge down the southeastern
seaboard, with sharp coastal troughing remaining positioned over
our near shore waters. This weather pattern will keep a tight
local pressure gradient in place today, with breezy onshore winds
at coastal locations this morning expanding inland by early
afternoon. The coastal trough will continue to generate scattered
to numerous showers over the Atlantic waters that will move
onshore, with the drier air mass tending to limit measurable
rainfall for locations west of the U.S. Highway 301 corridor.
Despite multi-layered cloudiness remaining overhead, highs should
climb to the mid 80s for inland locations west of U.S.-301, while
thicker low and mid level clouds and higher chances for occasional
showers will limit highs elsewhere mostly remaining in the lower
80s.

Cutoff troughing over the lower Mississippi and the northern
Gulf is creating south-southwesterly flow across our region, with
this flow gradually deepening tonight. Meanwhile, a frontal
boundary stretching across south FL will begin to slowly lift
northward, with isentropic lift beginning to strengthen to the
north of this feature across north central and northeast FL
tonight. Model soundings indicate that PWATs will climb to above
early October climatology from south to north late this afternoon
and tonight, with values reaching the 1.5 - 1.75 inch range late
this afternoon and then up to the 1.75 - 2 inch range towards
sunrise on Sunday. Deeper moisture will result in increasing
moderate to heavy shower activity over the Atlantic waters
overnight, with this activity accompanied by isolated embedded
thunderstorms moving onshore after midnight along the northeast
FL coast. Scattered showers should move across U.S.-301 after
midnight as moisture levels increase and isentropic lift
strengthens. Increasing cloud cover and warm air advection will
keep lows in the low to mid 70s at most locations, except upper
60s to around 70 for inland southeast GA.

&&

.SHORT TERM...
(Sunday through Monday night)
Issued at 405 AM EDT Sat Oct 4 2025

Sunday, slight downtrend in pops inland compared to this time
yesterday as the upper level wave and related surface low along
an east to west frontal boundary will move slowly north and west
into the southern the half of the FL peninsula. Coastal troughing
extending northward from this frontal boundary along the FL waters
will generate waves of numerous coastal showers pushing onshore,
but diminish to more scattered coverage over the western half of
the area. Afternoon low topped isolated T`storms will be possible
as well, but limited to areas of NE FL as locally heavy convergent
showers move onshore. High pressure axis will stretch from the VA
Piedmont ENE into the Atlantic waters off the NE coast and flow
between the high and the trough to the east will create surface
winds more easterly 15-25 mph with gusts to 30-35 at the coast to
10-15 mph inland gusting to 25-30 mph. Multiple layers of clouds
will filter sunshine and along with cool onshore flow will keep
highs along the coast in the low 80s, but warm to the mid 80s
inland.

Sunday night, coastal showers will reinvigorate over the coastal
waters and continue to push from the ESE to the WNW onto the coast
as the surface low shifts from the NW Bahamas towards the south FL
coast. Mostly cloudy skies and increasing deep moisture will keep
lows above normal in the low 70s inland and mid 70s at the coast.

Monday, the surface low will lift NW across the southern half of
the FL peninsula and lift a stationary front towards central FL as
coastal troughing persists over the waters. More energy and lift
from the boundary to the south and shortwave energy moving in aloft
will keep waves of numerous showers pushing well onshore from the
coastal waters with less coverage over NW portions of SE GA and
the Suwannee Valley of NE FL. Higher moisture will lead to heavier
downpours as nearly topical moisture (PWATS around 2.00 inches)
spread northward into the area and locally heavy downpours may
produce flooding in low lying and urban locations. This rainfall
will be on top of ongoing coastal flooding along the St Johns
river basin and the Atlantic coast during high tides (see hydrology
section). Breezy easterly winds 15-25 at the coast will lessen
inland more in the 10-15 mph range. Highs will be mostly below
normal in the low 80s at the coast and mid 80s well inland thanks
to clouds and shower coverage.

Monday night, showers will start fading in coverage as energy aloft
lifts north and west of the area and high pressure shifts further
to the ENE. Decreasing clouds will allow lows to fall to the upper
60s over inland SE GA, but onshore flow will keep coastal lows
in the mid 70s with low 70s over inland NE FL.

Rainfall totals through Monday night/early Tuesday will be 1-3
inches east of highway 301 with locally higher totals along the
St Johns river basin and the St Johns and Flagler county coast
up to 3-6 inches.

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 405 AM EDT Sat Oct 4 2025

This period will begin with ridging aloft exiting east into the
western Atlantic waters as a trough swings through the US
Midwest, Ontario, and Quebec Canada regions. In the low levels,
much drier air will move in from the western Atlantic waters and
limit shower chances into midweek. The trough will push through
the east coast Thursday and send a surface cold front into the
area which will stall near the area through Friday. The front will
bring a return of breezy NE winds as strong high pressure builds
in from the north across the eastern Great Lakes and NE states.

Temperatures will begin the period with near normal highs in the
mid/upper 80s inland and low/mid 80s at the coast, then cool to a
little below normal in the low 80s by Friday. Lows will be above
normal in the low 70s along the coast and slightly above normal
inland with lows in the mid/upper 60s through Thursday, then cool
to below normal Friday in the low 60s inland and near normal in
the upper 60s along the coast and north central FL.

&&

.AVIATION...
(06Z TAFS)
Issued at 154 AM EDT Sat Oct 4 2025

Moderate to heavy showers will continue progressing westward from
the Atlantic waters overnight, impacting SSI and the Duval County
terminals through around 09Z. Brief periods of IFR visibilities
will be possible during heavier downpours overnight. Periods of
MVFR ceilings are expected overnight at the regional terminals,
except at GNV, where VFR conditions are expected to prevail
through at least 18Z Saturday. Shower activity will likely
increase near the SGJ terminal towards sunrise, with another wave
of showers expected to cross the terminals during the late morning
and afternoon hours. Confidence in timing and intensity was too
low for TEMPO groups, and we thus opted for PROB30 groups for IFR
conditions during heavier downpours on Saturday. Another round of
showers is likely during the overnight hours on Saturday night,
but a period of VFR conditions appears to be likely around sunset
and during the early evening hours. Breezy east-northeasterly
surface winds will remain sustained around 15 knots overnight
through the early morning hours at SGJ, followed by speeds
increasing to 15-20 knots and gusty towards 15Z. North or
northeasterly surface winds will remain sustained at 5-10 knots
elsewhere through around 14Z, followed by winds shifting to east-
northeasterly and increasing to around 15 knots and gusty by 17Z.
Speeds will diminish to around 10 knots at the inland terminals
towards 00Z Sunday.

&&

.MARINE...
Issued at 405 AM EDT Sat Oct 4 2025

High pressure stretching along the Mid-Atlantic and Carolina coasts
will continue to wedge down the southeastern seaboard, with this
feature expected to gradually weaken today. Gusty east-northeasterly
winds and Small Craft Advisory conditions will continue this weekend
across our local waters, with occasional wind gusts to Gale Force
possible tonight offshore and rough, elevated seas continuing
into early next week. Seas of 6 to 9 feet will prevail through
tonight, with seas then building to 7 to 11 feet on Sunday and
Monday. Meanwhile, coastal troughing positioned over our local
waters will continue to generate waves of moderate to heavy
showers, with a few embedded thunderstorms possible. Otherwise,
weak low pressure developing along a frontal boundary over
southern Florida will lift slowly northward this weekend,
resulting in increasing coverage of showers and thunderstorms by
Sunday and Monday. Prevailing winds will shift to easterly on
Sunday as high pressure shifts off the Mid-Atlantic coast, with
Small Craft Advisory conditions and rough, elevated seas extending
into next week. Winds and seas should fall back to Caution levels
of 15-20 knots, with 4-6 foot seas expected both near shore and
offshore by Tuesday night.

Rip Currents / Beach Erosion: High risk of rip currents and high
surf advisory conditions, along with moderate to severe beach
erosion will continue along the northeast FL beachfront locations
through the weekend and into early next week. Surf/breakers into
the 5-7 ft range will continue through Monday. Moderate to major
beach erosion is expected at Atlantic beachfront locations during
times of high tide through next week, as astronomically high tides
continue after onshore winds begin to gradually subside. Surf
heights will generally run in the 4-6 foot range at the southeast
GA beaches, which is just below high surf advisory criteria.
However, a high risk of rip currents will also continue for the
southeast GA beaches through early next week.

&&

.HYDROLOGY...
Issued at 405 AM EDT Sat Oct 4 2025

With persistent, strong onshore winds continuing to "trap" tides
within the St. Johns River basin combining with the approach of
Tuesday`s "Harvest" Full Moon, a more widespread moderate tidal
flooding event will continue near high tides this weekend and
early next week.


Coastal Flood Warning: This warning includes the St. Johns River
Basin, Intracoastal Waterway (ICWW) and along the northeast FL
coast from Mayport to Flagler Beach. Tidal levels will continue to
crest generally between 2 to 2.5 ft above Mean Higher High Water
(MHHW) within the St. Johns River basin, the ICWW, and along the
Atlantic coast south of Mayport. Moderate tidal flooding impacts
include flooding of low-lying roads and water surrounding some
vulnerable structures.

Coastal Flood Advisory: This advisory now includes the Nassau
County coast as well as coastal southeast GA. Tidal levels will
build to 1.5 - 2 feet above MHHW, which will mainly cause minor
tidal flooding impacts including flooding of some boat ramps,
docks, over-topping of bulkheads and some tidal-prone roads in
low- lying areas.

The tidal flooding will be an extended duration, as astronomical
tides will not peak until the mid to late part of next week. With
brisk onshore flow continuing through Monday and then potentially
re-strengthening late next week, we can expect Coastal Flood
Advisories / Watches / Warnings to continue through much of the
upcoming week, possibly longer for some locations.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  83  69  84  69 /  30  20  40  20
SSI  81  73  83  74 /  50  60  50  30
JAX  82  73  85  73 /  40  60  70  40
SGJ  82  75  84  74 /  60  60  70  50
GNV  84  72  87  72 /  40  40  60  30
OCF  84  72  85  73 /  30  30  50  20

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 5 AM EDT Tuesday for .

     High Rip Current Risk through late Monday night for FLZ124-125-
     138-233-333.

     High Surf Advisory until 5 AM EDT Tuesday for FLZ124-125-138-233-
     333.

     Coastal Flood Warning until 5 AM EDT Tuesday for FLZ125-132-137-
     138-225-233-325-333-633.

GA...Coastal Flood Advisory until 5 AM EDT Tuesday for GAZ154-166.

     High Rip Current Risk through late Monday night for GAZ154-166.

AM...Small Craft Advisory until 5 AM EDT Tuesday for AMZ450-452-454-
     470-472-474.

&&

$$