453
FXUS62 KJAX 151641
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1241 PM EDT Sun Sep 15 2024

...New AVIATION...

.UPDATE...
Issued at 841 AM EDT Sun Sep 15 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

Rest of Today...Spoke of energy expected to rotate around the west
side of developing low pressure center off the SE US coastline and
push southward through SE GA and into the I-10 corridor of NE FL
this afternoon and through the rest of NE FL south of the I-10
corridor this evening. This will bring an uptick in shower and
isolated thunderstorm activity this afternoon along with
increasing North to Northeast winds up to 15-20 mph along the
Atlantic Coastal areas with wind gusts in the 25-35 mph range with
lesser winds of 10-15 mph inland with gusts of 20-25 mph. A
mixture of low clouds near the surface along with high clouds
streaming in aloft will keep temps muted again today with highs in
the lower 80s across SE GA and in the middle 80s across NE FL and
these slightly below normal temps should keep any afternoon
thunderstorm activity isolated, but any of this activity could
still produce some heavy downpours, but movement should be
slightly higher today to prevent any significant flooding issues.

Tonight...The remainder of the spoke of energy should push through
NE FL during the evening hours which may continue scattered
showers and isolated thunderstorm activity a few hours past
sunset. Otherwise expect decreasing rainfall chances and
diminishing winds over inland areas, although breezy North to
Northeast winds will continue through the night at Atlantic
beachfront locations. Skies will continue at mostly cloudy levels
and will prevent any significant fog formation, except for the
usual patchy fog over inland NE FL along the I-75 corridor. Low
temps in the upper 60s for inland SE GA, lower 70s for inland NE
FL and middle 70s along the Atlantic Coastal areas.

&&

.SYNOPSIS...
Issued at 437 AM EDT Sun Sep 15 2024

Early morning surface analysis depicts developing low pressure
(1009 millibars) located over the Gulf Stream waters adjacent to
the Georgia and South Carolina coasts. Meanwhile, strong high
pressure (1030 millibars) was centered over Maine and was wedging
down the southeastern seaboard. Otherwise, a wavy and stationary
frontal boundary situated along the Interstate 4 corridor in
central FL extends westward across the FL panhandle and along the
northern Gulf coast. Aloft...a persistent "Rex Block" remains in
place over the eastern half of the nation, with stout ridging
centered over the eastern Great Lakes region and New England,
keeping Francine`s remnant trough trapped over the lower
Mississippi Valley and the Deep South. A drier air mass has
advected across our region, with latest GOES-East derived Total
Precipitable Water imagery indicating that PWAT values have fallen
back to near climatological values for mid-September, with values
of 1.6 to 1.8 inches prevailing area-wide. Multi-layered cloud
cover was increasing across our our area overnight, but only a few
light showers or sprinkles were located near the southeast GA
coast. Temperatures and dewpoints were in the 70s across
northeast and north central FL as of 08Z, while dewpoints have
fallen to the upper 60s across inland portions of southeast GA.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 437 AM EDT Sun Sep 15 2024

Low pressure will continue to gradually organize and will remain
nearly stationary through tonight over the Gulf Stream waters
adjacent to GA and SC. Meanwhile, strong high pressure will remain
situated over New England, with this feature continuing to wedge
down the southeastern seaboard today, tightening our local
pressure gradient. Breezy north-northeasterly winds will continue
at coastal locations this morning, with windy conditions
developing this afternoon as speeds increase to 15-25 mph with
occasional gusts up to 35 mph. Breezy conditions will develop at
inland locations this afternoon. Deeper tropical moisture will
remain offshore today, but low level onshore flow will become more
convergent, with showers and a few embedded thunderstorms expected
to increase in coverage along the GA coast by the mid to late
morning hours, with this low-topped activity then pushing
southwestward across the rest of our area as the afternoon
progresses. While briefly heavy downpours are possible, the lack
of deeper moisture should make activity transient in nature as it
shifts southwestward, and chances for widespread thunderstorms
appear to be unlikely this afternoon. Higher coverage of showers
and a few embedded thunderstorms are expected to remain along and
north of the Interstate 10 corridor, with another corridor of
higher coverage located west of I-75 in the Suwannee Valley later
this afternoon, possibly extending into the evening hours. Breezy
conditions and multi-layered cloudiness will keep highs generally
in the low to mid 80s, with upper 80s forecast across north
central FL.

Breezy onshore winds will shift to a more north-northwesterly
direction at coastal locations overnight. Widely scattered showers
developing to the south of the organizing low pressure center off
the Carolina coast may occasionally brush locations along and east
of I-95 overnight. Otherwise, low stratus clouds may develop
during the predawn hours across inland portions of southeast GA,
where winds will decouple, allowing lows to fall to the upper 60s.
Lows elsewhere will fall to around 70 inland, ranging to the mid
and upper 70s at coastal locations.

&&

.SHORT TERM...
(Monday through Tuesday)
Issued at 437 AM EDT Sun Sep 15 2024

Frontal boundary remains draped across FL as its associated low
pressure system shifts north-northwestward and potentially moves
onshore to the Carolinas and into the Mid-Atlantic region Monday
into Tuesday. NHC has a 50% chance that this low may become a
subtropical or tropical storm early this week if the associated
front dissipates and showers and thunderstorms become sufficiently
organized. Regardless of tropical or subtropical development,
local impacts for Monday will be breezy north-northeasterly winds
along the coast, coastal flooding, high risk of rip currents and
dangerous marine conditions. A lingering moist airmass over NE
FL, convergence along the frontal boundary, and upper energy from
the remnants of Francine will support daily scattered to numerous
showers with embedded thunderstorms. Highs will be in the low 80s
in SE GA to around 90 in north-central FL. Overnight lows will be
in the upper 60s and low 70s.

&&

.LONG TERM...
(Wednesday through Saturday)
Issued at 437 AM EDT Sun Sep 15 2024

Frontal boundary over northern FL on Wednesday will dissipate and
shift southward as its associated low weakens over the mid-
Atlantic region. Upper trough over the eastern US will place the
region under north-northwesterly flow aloft advecting in some
drier air for the latter half of the week. Rain chances decrease
through the week bringing an end to the wet pattern. High pressure
wedges down the eastern seaboard for the end of the week bringing
as return of northeasterly flow. Temperatures will be around
seasonal with highs in the 80s and lows in the upper 60s and low
70s.

&&

.AVIATION...
(18Z TAFS)
Issued at 1228 PM EDT Sun Sep 15 2024

Widespread MVFR CIGS will continue this afternoon with off and on
light rainfall chances that could bring MVFR VSBYS at times
through sunset, but again thunder chances still remain too low
(around 10% or less) to include in TAF sites. Meanwhile North to
Northeast winds have increased less than expected today, so will
back off some of the wind gusts at TAF sites through the rest of
the afternoon hours. Rainfall ends at the inland TAF sites of
GNV/VQQ after sunset, but low chances for showers (VCSH) linger at
coastal TAF sites through the overnight hours. With light North
winds developing overnight inland and some boundary layer cooling,
still on track for LIFR CIGS to develop by 09Z at GNV, and IFR
CIGS at VQQ, while MVFR CIGS will persist at all of the other TAF
sites. Slow lifting of CIGS at inland locations Monday morning to
MVFR CIGS, but overall widespread MVFR CIGS will persist at TAF
sites with a slow increase in Northeast winds along with rainfall
chances, but not much more than (VCSH) at best.

&&

.MARINE...
Issued at 437 AM EDT Sun Sep 15 2024

Low pressure will continue to organize over the Gulf Stream waters
adjacent to the Carolina coastline, with this feature potentially
acquiring tropical characteristics as it pushes northward towards
the Carolina coast on Monday night or early Tuesday morning. Small
Craft Advisory conditions over the Georgia waters and the
offshore waters north of St. Augustine this morning will
overspread the rest of the northeast Florida waters by this
afternoon as north-northeasterly winds strengthen to 20-25 knots
and seas build. Winds may occasionally gust to around Gale Force
over the Georgia waters this afternoon and evening. Seas will peak
in the 5-8 foot range for the near shore waters tonight and 7-10
feet offshore. Small Craft Advisory level seas will continue on
Monday night for the offshore waters, with Caution level seas of
4-6 feet forecast near shore.

Waves of showers and a few embedded thunderstorms will develop
across our local waters through Monday night. Winds will shift to
northwesterly on Monday night while diminishing, with seas then
gradually diminishing through midweek. Otherwise, a frontal
boundary positioned across the Florida peninsula will lift
northward over the northeast Florida waters on Wednesday, keeping
chances for mainly afternoon and evening thunderstorms in place.
This front will then shift south of our local waters late this
week.

Rip Currents/Elevated Surf: Strengthening north-northeasterly
winds and increasingly rough surf conditions will keep a high rip
current risk in place at all area beaches through Monday. Breaker
heights will build to 3-5 feet this afternoon and will peak in the
4-6 foot range on Monday, which is just below High Surf Advisory
criteria. Winds will become northwesterly on Monday night and
Tuesday, with decreasing breaker heights potentially allowing for
a high end moderate risk at area beaches by Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  82  68  81  66 /  60  20  20  10
SSI  81  72  81  71 /  50  30  20  10
JAX  84  71  83  70 /  50  30  40  10
SGJ  85  73  84  73 /  30  30  40  10
GNV  86  71  85  69 /  40  20  40  20
OCF  88  71  88  71 /  40  20  60  20

&&

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

     High Rip Current Risk through late Monday night for FLZ124-125-
     133-138.

     Coastal Flood Advisory from 6 PM this evening to 5 AM EDT
     Tuesday for FLZ124-125-133-138.

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

     Coastal Flood Advisory from 6 PM this evening to 5 AM EDT
     Tuesday for GAZ154-166.

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

     Small Craft Advisory until 5 AM EDT Tuesday for AMZ452-454-474.

&&

$$