789
FXUS62 KJAX 181713
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
113 PM EDT Wed Sep 18 2024

...New AVIATION...

.UPDATE...
Issued at 913 AM EDT Wed Sep 18 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

No major updates needed on the forecast this morning. The 12Z
balloon launch shows PWATs near average at 1.85", with slightly
drier air aloft promoting isolated stronger thunderstorm
development. The highest shower and storm coverage as well as
strong storm development (wind gusts around 40 mph) will be along
the northeast Florida coast where boundary collisions are expected
later this afternoon. High temperatures today will be near normal
across NE FL, in the mid to upper 80s, with temperatures a few
degrees cooler across SE GA.

&&

.SHORT TERM...
(Thursday through Friday night)
Issued at 355 AM EDT Wed Sep 18 2024

Troughing will lift slowly northeastward across the
Mid-Atlantic region on Thursday, nudging a stubborn
frontal boundary southeastward across inland portions
of southeast GA by late afternoon as deep-layer flow
veers to northwesterly. Enough moisture may be in place
for isolated to widely scattered afternoon and early
evening convection to develop along the frontal boundary
as it crosses coastal southeast GA and the rest of
northeast and north central FL. Highs on Thursday will
climb to the upper 80s and lower 90s, with maximum heat
indices peaking in the 95-100 degree range during the
afternoon hours.

Convection that manages to develop during the afternoon
hours should push offshore of the northeast FL coast
towards sunset, with fair skies expected area-wide
overnight. A drier and more subsident air mass may allow
for areas of locally dense fog to develop by early Friday
morning, especially across inland portions of southeast
GA and the Suwannee Valley. Lows will fall to the upper
60s inland, ranging to the low to mid 70s at coastal
locations.

Troughing will persist along the U.S. eastern seaboard on
Friday, 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 as strong high pressure
over eastern Canada begins to wedge down the spine of the
Appalachians, resulting in breezy onshore winds developing
along the I-95 corridor during the afternoon hours. This
breezy and increasingly convergent low level flow could
develop a few showers and thunderstorms along the I-95
corridor in northeast FL early in the afternoon, with
activity then spreading south-southwestward towards north
central FL during the mid to late afternoon hours. Dry
weather is expected elsewhere, with inland highs again
climbing to the upper 80s to around 90. Breezy onshore
winds will keep coastal highs in the mid to upper 80s.

Breezy onshore winds 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.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 355 AM EDT Wed Sep 18 2024

Troughing aloft will be slow to depart the Mid-Atlantic
and New England coasts this weekend, while stout ridging
centered over the southern Plains begins to flatten as
it expands eastward along the northern Gulf coast.
Surface low pressure may strengthen well off the
Mid-Atlantic coast as it meanders this weekend, while
strong high pressure over Atlantic Canada continues to
wedge down the U.S. eastern seaboard. This weather
pattern will keep a tight local pressure gradient in
place through early next week. This flow may advect
isolated to widely scattered showers and possibly a few
embedded thunderstorms onshore along the northeast FL
coast, with activity potentially shifting inland towards
north central FL during the afternoon hours each day.
A seasonably dry and subsident air mass will prevail for
southeast GA and the Suwannee Valley, where a dry stretch
of weather is expected through at least Monday.

Breezy onshore winds during this period should keep
coastal highs in the low to mid 80s, with mid to upper
80s forecast for most inland locations. Highs may
trend down a few degrees by Monday across inland
southeast GA as high pressure wedges into the Deep
South. The drier and more subsident air mass will allow
lows to fall to the mid to upper 60s at most inland
locations through the period, while onshore winds keep
coastal lows in the low to mid 70s.

Long term guidance remains in overall disagreement on
the potential for tropical low pressure consolidating
over the northwestern Caribbean Sea this weekend and
early next week as the Central American Gyre (CAG) spins
up. This is a climatologically favored area for tropical
cyclone formation as we move into late September, so
the National Hurricane Center will continue to closely
monitor the potential for tropical development later this
weekend and early next week over the northwestern Caribbean
Sea.

&&

.AVIATION...
(18Z TAFS)
Issued at 113 PM EDT Wed Sep 18 2024

Isolated thunderstorms are moving eastward across NE FL and SE GA,
and will later impact most of the TAF sites. TEMPOs are in place
indicating best guess timing for thunderstorms over the
airfields, which may lower ceilings and visibilities. Tonight,
patchy fog is expected to impact GNV, VQQ, ans JAX, with guidance
suggesting MVFR visibilities at this time until sunrise.

&&

.MARINE...
Issued at 355 AM EDT Wed Sep 18 2024

A weak frontal boundary and pressure pattern will linger over the
region through the middle of the week. The sea breeze returns
with afternoon wind shifts to onshore for the nearshore waters
through Thursday. A frontal passage is expected late this week
with high pressure building down the eastern seaboard by this
weekend. This will lead to an increase in Northeast winds by
Friday and into the weekend with Small Craft Advisory headlines
possible.

Rip Currents: Moderate risk of rip currents continues for area
beaches through Thursday.

&&

.HYDROLOGY...
Issued at 355 AM EDT Wed Sep 18 2024

Have expired the Coastal Flood advisories along most of the NE FL
Atlantic coast and downgraded Duval county to an advisory with
lighter onshore winds anticipated for this afternoon. Lingering
trapped tides and higher astronomical tides will continue minor
to moderate coastal flooding within the St. Johns through at least
mid-week. The moderate flooding will be mainly confined to areas
south of Jacksonville. The higher tides with this full moon cycle
will continue into September 26th with the peak levels between
Sept. 19th and 21st. Will likely need to reissue a Coastal Flood
Advisory along the Atlantic coast for Friday into the weekend with
the high tides and a surge of northeasterly winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  68  88  67  86 /  10  10  10  10
SSI  71  87  73  85 /  10  20  10  10
JAX  71  90  70  87 /  20  20  10  20
SGJ  73  89  74  87 /  30  20  20  20
GNV  70  90  69  89 /  20  20  10  20
OCF  71  90  70  90 /  10  20  20  20

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Warning until 5 AM EDT Friday for FLZ033-038-132-
     137.

     Coastal Flood Advisory until 5 AM EDT Friday for FLZ125-225-325.

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

$$