Saint Simons Island, Georgia Weather Forecast Discussion

080
FXUS62 KJAX 141805
AFDJAX
Area Forecast Discussion
National Weather Service Jacksonville FL
205 PM EDT Sun Sep 14 2025
...New NEAR TERM, SHORT TERM, LONG TERM, AVIATION, MARINE, HYDROLOGY, CLIMATE...
.NEAR TERM...
(Through Tonight)
Issued at 200 PM EDT Sun Sep 14 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
A mid to upper level trough continues across the forecast region
this afternoon with a cut off low at 500 mb right around the JAX
Metro area. Cool temp aloft on the JAX sounding this morning
about -11C at 500mb. Mean, deep layer trough axis will shift only
slightly southeastward through tonight, and PWAT moisture levels
will likely drop further Monday morning. It was noted that
dewpoint have mixed out stronger than guidance was showing, with
values as low as the upper 40s to lower 50s over parts of
southeast GA near the coast.
Some weak convection is still possible mainly across Marion county
dewpoints are in the upper 60s and where MLCAPE is about 2000-2500
J/kg this afternoon, though strong convergence is lacking and
there is significant dry air above 8-10 kft. Otherwise mostly dry
for the area with mostly clear to partly cloudy skies through
tonight with only scattered mid and high clouds possible around
the mid/upper level low for tonight. Only a brief, very isolated
shower possible tonight over Flagler county off the Atlantic.
Breezy northeasterly winds along the coastal areas and lower winds
inland will be reduced tonight as low temps cool about 5-10 deg
below normal. Lows in the lower 60s inland, probably a few upper
50s over inland southeast GA. Low temps along the coast drop to
the upper 60s late tonight as the flow starts to become
northwesterly (i.e., drainage flow) pushing the cool temps to the
coastal areas before sunrise. In fact, lows may near the record
Monday morning with best chance of the record at JAX. See climate
section below.
&&
.SHORT TERM...
(Monday through Tuesday night)
Issued at 200 PM EDT Sun Sep 14 2025
Mostly dry weather prevails with seasonably warm highs in the 80s
to near 90 well inland with below normal lows in the upper 50s to
low 60s inland due to drier air. Only isolated coastal showers
were advertised for St. Johns & Flagler counties Monday before the
coastal trough offshore of the Florida east coast is shunted
farther south of northeast Florida as a high builds southward
across the region. The surface high will extend across the local
area through Wednesday bringing dry weather, seasonably warm highs
and cool nighttime lows given good radiational cooling conditions.
There will be some potential for patchy shallow ground fog across
inland areas before sunrise each morning.
&&
.LONG TERM...
(Wednesday through next Sunday)
Issued at 200 PM EDT Sun Sep 14 2025
Rain chances increase from south of north across northeast Florida
as a front lifts northward up the peninsula with an increase in
deep layer moisture. Southeast Georgia and the northern Suwannee
River Valley remain fairly dry under the influence of a low level
ridge axis. Models starting to indicate another potential local
nor`easter event late Friday into next week with a coastal trough
or even surface low forming just offshore of the FL Atlantic coast
as high pressure strengthens northeast of the region and wedges
down across north GA. A return to locally heavy coastal showers,
deteriorating surf zone conditions and gusty onshore winds is
possible Saturday into Sunday with the potential for high rip
current risk, small craft advisory conditions and the continuation
and expansion of tidal flooding to coastal areas.
Temperatures warm above climo values Thursday and Friday, then
begin to trend back down toward climo with increasing cloud over
and rain chances next weekend.
&&
.AVIATION...
(18Z TAFS)
Issued at 200 PM EDT Sun Sep 14 2025
Breezy NNE winds continue to around 00Z with sustained winds
10-13 kts and gusts around 20 kts. Winds decrease after sunset to
5 knots or less inland, remaining closer to 10 knots along the
Atlantic Coast. MVFR ceilings at SGJ have lifted this afternoon.
VFR conditions are expected through the period.
&&
.MARINE...
Issued at 200 PM EDT Sun Sep 14 2025
Low pressure system off the Outer Banks near or east of the Gulf
Stream expected to drift northward slowly through mid week while
weakening. As this happens, surface high pressure ridging over
the Appalachians weakens. This will result in a weakening pressure
gradient and weakening trend in the wind field. Winds are currently
forecast around 20 kt and may be just shy of advisory. An ASCAT
pass recently showed winds of 18 kt over a large part of the
waters and seas are about 6 ft about 20 nm out. In addition, a ship
observation well offshore showed 8 ft near just beyond 60 nm show
7 ft seas are very possible in our offshore waters. Thus, will
maintain this small craft advisory leaving it to expire at 5 pm
nearshore waters and til 11 pm offshore waters.
Still a breezy north-northeast winds on Monday, but not as high
today and yesterday. Lighter and variable flow on Tuesday with
even a southeasterly flow by Tue aftn and evening as high pressure
cell moves offshore of the southeast U.S. coast, with a similar
setup on Wednesday. By Thu and Fri, we see some changes occur as
high pressure strengthens slowly to the north of the area while
low pressure troughing develops over the FL straits and Cuba.
This should result in an increased pres gradient. Winds still
currently forecast to be 10-15 kt both Thu and Fri but could be
slightly higher by Friday. Seas rise further mainly on Sat and may
peak just below 7 ft.
Otherwise, for synopsis...
A wave of low pressure will track slowly northward along a
stalled frontal boundary well offshore through early next week as
high pressure persists northwest of the region. Gusty northeast
winds between these two features will continue Small Craft
Advisory conditions across the local waters today before the
onshore flow slowly weakens early next week and seas slowly
subside during the upcoming week. Occasional scattered showers and
isolated storms are expected, mainly across the northeast Florida
waters into Monday. Shower and storm activity will slowly
decrease during the upcoming week.
Rip currents: Life-threatening rip Currents and rough surf
continue at area beaches through Monday, with surf up to 3-5 ft.
&&
.HYDROLOGY...
Issued at 200 PM EDT Sun Sep 14 2025
Minor coastal flooding is likely to continue in the St Johns River
Basin and Intracoastal Waterway through Monday, and may also continue
along the immediate beachfront, though the beachfront may be less
prone to minor flood criteria based on extra-tropical surge values
dropping further as the winds continue to lighten. Surge values
up to 1.1 to 1.6 ft today will be about 1 ft or so on Monday, but
may be a little higher in the Intracoastal Waterway and in the St
Johns River Basin. So, overall no changes in the advisory at this
time, but there is a good chance of extension in time of the advisory
for the St Johns River Basin, especially from around Downtown JAX
southward to Palatka from Monday night through Tuesday.
&&
.CLIMATE...
Issued at 200 PM EDT Sun Sep 14 2025
Current Record Low Temperatures:
Monday, September 15th:
KJAX: 62/1996
KGNV: 60/1976
KCRG: 64/2010
KAMG: 55/1968
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG  59  87  61  87 /   0   0   0   0
SSI  68  82  68  84 /  10  10  10  10
JAX  64  86  66  87 /  10  20   0  10
SGJ  69  85  70  84 /  20  30  10  10
GNV  62  90  65  90 /  10  10   0  10
OCF  64  89  67  89 /  10  10   0  10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Monday evening for FLZ124-125-138-
     233-333.
Coastal Flood Advisory until 8 PM EDT Monday for FLZ125-132-137-
     138-225-233-325-333-633.
GA...High Rip Current Risk through Monday evening for GAZ154-166.
AM...Small Craft Advisory until 5 PM EDT this afternoon for AMZ450-
     452-454.
Small Craft Advisory until 11 PM EDT this evening for AMZ470-472-
     474.
&&
$$

NWS jax Office Area Forecast Discussion