016
FXUS62 KJAX 191042
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
642 AM EDT Thu Sep 19 2024

...New AVIATION...

.NEAR TERM...
Issued at 349 AM EDT Thu Sep 19 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

A weak cold front over SE GA this morning will continue to shift
southward and into central FL this afternoon. A drier (PWATs
1.3-1.5 in.) and more stable north-northwesterly flow builds over
the region squashing convective coverage to be mainly isolated.
Convection today will be limited to along the inland moving sea
breezes, the only source of lift, this afternoon into evening.
Highs today will range from the upper 80s to around 90. Any
convection that manages to develop will wane this evening with the
loss of daytime heating. A drier and more subsident air mass may
allow another round of patchy inland fog to develop early Friday
morning. Overnight lows will fall to the upper 60s in inland SE GA
to the lows 70s elsewhere.

&&

.SHORT TERM...
(Friday through Saturday night)
Issued at 349 AM EDT Thu Sep 19 2024

Troughing will persist along the U.S. eastern seaboard on
Friday and Saturday, while stout ridging aloft resides over
Texas. This weather pattern will result in deep northerly
flow across our area, and our local pressure gradient will
begin to tighten during the afternoon hours on Friday as
low pressure strengthens off coastal New England and high
pressure builds down the spine of the Appalachians,
resulting in breezy onshore winds developing along the I-95
corridor during the afternoon hours. This breezy and
convergent low level flow could develop a few showers and
thunderstorms along an inland moving Atlantic sea breeze
boundary during the afternoon hours, with activity then
potentially becoming widely scattered over north central
FL and southern portions of the Suwannee Valley during the
late afternoon hours as the Atlantic sea breeze boundary
collides with a pinned Gulf coast sea breeze along and
west of the I-75 corridor. A drier air mass and plenty
of morning and early afternoon sunshine will boost highs
to the upper 80s to around 90 for locations along and
west of I-95. Breezy onshore winds will keep coastal highs
in the mid 80s.

An onshore breeze will continue at coastal locations on
Friday night, keeping lows in the low to mid 70s. Winds
at inland locations will decouple by late in the evening,
with a seasonably dry air mass and fair skies allowing
lows to fall to the mid and upper 60s by sunrise on
Saturday.

Breezy northeasterly winds will prevail on Saturday along
the I-95 corridor, with these breezy conditions spreading
inland during the afternoon hours. There may be just enough
moisture and low level convergence for a few showers to
advect onshore along the northeast FL coast, with activity
potentially shifting inland towards north central FL during
the late afternoon hours, where an isolated thunderstorm
cannot be ruled out. A seasonably dry and subsident air mass
will prevail for southeast GA and the Suwannee Valley. Highs
on Saturday will again climb to the upper 80s to around 90
for inland locations along and west of I-95, with breezy
onshore winds keeping coastal highs in the mid 80s.

Any showers or thunderstorms that manage to develop on
Saturday afternoon for locations south of I-10 will
dissipate around sunset, with fair skies expected overnight
area-wide. Decoupling winds at inland locations will allow
lows to fall to the mid to upper 60s at most inland
locations, with breezy onshore winds keeping coastal lows
in the low to mid 70s.

&&

.LONG TERM...
(Sunday through Wednesday)
Issued at 349 AM EDT Thu Sep 19 2024

Ridging aloft will continue to flatten but will expand
eastward along the northern Gulf Coast on Sunday as a
potent shortwave trough progresses across the eastern
Rockies and enters the High Plains states. This ridge
will then become centered along the northern Gulf coast
states on Monday and then directly overhead by Tuesday.
Long-term models then diverge on the evolution of the
trough that will progress from the High Plains towards
the Upper Midwest on Tuesday and then the Great Lakes
region by midweek, as the base of this trough may become
cutoff over west Texas. This will have important
implications for a potentially developing tropical
cyclone over the northwestern Caribbean Sea during the
early to middle portions of next week. Confidence in the
evolution of this weather pattern remains low in the
extended portion of the forecast, with global models
trending slower with the potential for a tropical cyclone
to emerge into the Gulf of Mexico at some point next week.

A dry and subsident air mass will prevail locally beneath
the ridge, with only isolated afternoon showers possible
along the inland moving Atlantic sea breeze boundary for
locations in north central FL and southern portions of the
St. Johns River basin on Sunday and Tuesday, with dry
weather expected area-wide on Monday. Highs will continue
to climb to the upper 80s to around 90 at inland locations,
while persistent breezy onshore winds keep coastal highs
mostly in the mid 80s. Lows will continue to fall to the
mid and upper 60s inland, while onshore winds keep coastal
lows in the low to mid 70s. Breezy easterly winds are
currently forecast on Wednesday, and a moistening trend
may commence from south to north, which may result in
isolated to widely scattered showers and thunderstorms,
especially for locations south of I-10. Highs should again
reach the mid to upper 80s, with lows falling to around 70
inland and the mid to upper 70s at coastal locations.

&&

.AVIATION...
(12Z TAFS)
Issued at 642 AM EDT Thu Sep 19 2024

A few showers have developed along the frontal boundary over NE FL
and may pass in the vicinity of SGJ between 11-12Z. Patchy fog and
low stratus over inland TAF sites will lift and dissipate after
12Z. Calm winds this morning become north- northwesterly as the
front shifts into central FL by this afternoon. Easterly winds
develop at the coastal and Duval TAF sites between 17-20Z as the
weak Atlantic sea breeze shifts inland. Low chances for rain this
afternoon with maybe a shower passing by a TAF site but chances
are too low to include at this time.

&&

.MARINE...
Issued at 349 AM EDT Thu Sep 19 2024

A weak cold front over the coastal waters will shift south of the
waters later this morning. Light northwesterly winds shift to
east-northeasterly as the sea breeze shifts inland this afternoon.
Stronger high pressure will build down the east coast Friday into
early next week. This will lead to an increase in Northeast winds
and seas for this weekend reaching Small Craft Exercise Caution
levels. Caution levels will likely continue into early next week
for the offshore waters.

Rip Currents: Moderate rip current risk for NE FL and SE GA
beaches continues through Friday. Risk will likely increase this
weekend with higher tides combined with the return of onshore
winds.

&&

.HYDROLOGY...
Issued at 349 AM EDT Thu Sep 19 2024

High tides have now been peaking in minor flood stage within the
St. Johns river basin which prompted the downgrade of the Coastal
Flood Warning to an advisory. Minor coastal flooding will
continue at times of high tide for the St. Johns river through at
least Friday. Peak tidal levels for this full moon cycle will
continue through Sept. 21st. Minor coastal flooding likely returns
on Friday for the NE FL Atlantic coast and ICWW with the peak
tides and developing northeasterly winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  87  68  87  66 /  10   0  20   0
SSI  84  71  84  72 /  20  10  10   0
JAX  87  71  87  69 /  20  10  20   0
SGJ  87  73  85  73 /  10  10  20  10
GNV  89  70  88  68 /  20  10  30   0
OCF  90  71  89  69 /  20  10  20   0

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 5 AM EDT Saturday for FLZ033-038-
     125-132-137-225-325.

     Coastal Flood Advisory from 5 AM Friday to 5 AM EDT Saturday for
     FLZ124-133-138.

GA...None.
AM...None.
&&

$$