396
FXUS62 KJAX 181045
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
645 AM EDT Wed Sep 18 2024

...New AVIATION...

.NEAR TERM...
(This afternoon and Tonight)
Issued at 355 PM EDT Tue Sep 17 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

Stacked low pressure over northern GA and the Carolinas will lift
northeastward into the mid-Atlantic region tonight. This will
shift the diffused frontal boundary south down the FL peninsula as
another front moves into GA. A few passing shortwaves aloft
rounding the low early this morning has continued to bring a few
showers and storms across the FL/GA border. Later, isolated to
scattered convection develops along the sea breezes as they shift
inland later this morning into afternoon. In the west-southwesterly
flow, the Atlantic sea breeze will be pinned to the I-95 corridor
and be the focus of the mesoscale boundary collisions in the late
afternoon into evening. Possible dry air intrusion from lingering
drier air aloft and boundary collisions could result in a few
storms becoming strong and capable of producing downburst winds of
40-50 mph. The bulk of convection shifts offshore and the rest
wanes in the evening with the loss of daytime heating. Calming
winds overnight will lead to another round of patchy inland fog
developing in the pre-dawn hours. Highs will range from the mid
80s in SE GA to the low 90s in north-central FL. Overnight lows
will be in the upper 60s to low 70s.

&&

.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...
(12Z TAFS)
Issued at 645 AM EDT Wed Sep 18 2024

Fog at KVQQ should will lift and dissipate within the hour. West-
southwesterly winds around 5 kts develop today. The Atlantic sea
breeze shifts inland to the I-95 corridor shifting winds to
southeasterly for coastal sites around 18-20Z. Scattered showers
and storms will be possible in the afternoon across the TAF sites.
A couple of storms may be strong producing gusty winds and heavy
downpours at the KJAX, KCRG and KSGJ where the sea breezes
collide.

&&

.AVIATION...
(06Z TAFS)
Issued at 128 AM EDT Wed Sep 18 2024

A lone storm over KJAX moves away within the next hour. Potential
for early morning fog developments by around 08-12z for inland
sites, reducing visibility to MVFR and IFR levels and then lifting
by around sunrise. West-southwesterly winds around 5 kts develop
today. The Atlantic sea breeze shifts inland to the I-95 corridor
shifting winds to southeasterly. Scattered showers and storms will
be possible in the afternoon across the TAF sites. A couple of
storms may be strong at the KJAX, KCRG and KSGJ when the sea
breezes collide.

&&

.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  86  69  88  67 /  40  10  10  10
SSI  84  72  87  73 /  50  20  20  10
JAX  88  72  90  70 /  60  40  20  10
SGJ  88  73  89  74 /  70  30  20  20
GNV  89  71  90  69 /  40  10  20  10
OCF  91  72  90  70 /  30  10  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.
&&

$$