043
FXUS62 KJAX 091425
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1025 AM EDT Fri Aug 9 2024

...New UPDATE...

.UPDATE...
Issued at 1019 AM EDT Fri Aug 9 2024

Temperatures are quickly rising through the 80s and will push
into the 90s before noon. Very humid conditions amid dewpoints in
the upper 70s to 80 degrees areawide have already pushed heat
index into the low 100s as of 10 AM. A Heat Advisory is now in
effect for the entire area with peak heat indices expected to
reach the 108-111 degree range this afternoon. Consider the heat
with any outdoor plans today. For those working outside, hydrate
frequently and seek relief in cool/shaded areas.

Moist southwesterly flow has been initiating isolated and widely
scattered showers this morning, mainly west of I-75. Showers will
shift eastward with further heating and destabilization through the
rest of the morning and into the afternoon. Quick storm motion
should lower the risk of flooding today unless training storms
develop. Given the warm temps aloft, it`s unlikely that severe
storms will develop; however, strong outflows (30-50 mph) could
still down trees weakened by Debby, especially those in moistened
soils. Convection should wane this evening as it fades and shifts
east into the Atlantic.

For the latest NE FL and SE GA Daily Key Messages please visit:
https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

&&

.SYNOPSIS...
Issued at 440 AM EDT Fri Aug 9 2024

Early morning surface analysis depicts the remnants of Debby
accelerating north-northeastward across the southern Appalachians,
with a trough extending south of Debby through the Deep South and
the FL panhandle. Aloft...weak flow prevails across our region,
with ridges centered over Texas and east of Bermuda and troughing
over western portions of the Great Lakes and the Upper Midwest.
Latest GOES-East derived Total Precipitable Water Imagery
indicates that a drier air mass was filtering into the FL
Panhandle in the wake of the surface trough passage, where PWATs
were below 1.25 inches, while deeper moisture prevails to the east
of this trough, with PWATs of 1.7 - 1.9 inches across the
Suwannee Valley as well as northeast and north central FL, ranging
to around 2.1 inches for coastal southeast GA. A few pockets of
lower stratus cloudiness were developing within a very humid air
mass across our area during the predawn hours, and a few showers
were developing ahead of the approaching trough / moisture
gradient over Apalachee Bay and the FL Big Bend. Temperatures and
dewpoints at 08Z were in the upper 70s and lower 80s nearly area-
wide.

&&

.NEAR TERM (Today and Tonight)...
Issued at 440 AM EDT Fri Aug 9 2024

The approaching surface trough / moisture gradient currently
crossing the FL Panhandle will continue to develop low-topped
convection over Apalachee Bay and the FL Big Bend early this
morning, with activity likely pushing across western portions of
the Suwannee Valley after sunrise and then crossing the Interstate
75 corridor during the mid to late morning hours. Meanwhile,
brisk low level southwesterly flow will likely delay the
development of the Atlantic sea breeze boundary until the early or
mid-afternoon hours along the Atlantic coast. Outflow boundaries
from morning convection should approach the I-95 corridor by the
early to mid-afternoon hours as well, with mesoscale boundary
collisions likely resulting in an increase in convective coverage
and intensity along the I-95 corridor during the mid to late
afternoon hours. Another round of convection will also develop by
the mid to late afternoon hours across southeast GA along and
ahead of the surface trough, with this activity potentially
lingering into the early evening hours, especially over the
Okefenokee Swamp and along the I-95 corridor. Storms may pulse
this afternoon as mesoscale boundaries collide, with stronger
storms being capable of producing downburst winds of 40-50 mph,
frequent lightning strikes, and briefly heavy downpours. East-
northeast storm motion of 15-25 mph should limit localized flood
potential, although any downpours that train over the same
locations will be capable of producing flooding due to saturated
ground conditions that prevail throughout our region.

Brisk low level west-southwesterly flow and near record dewpoints
this morning are foreshadowing another dangerously hot and humid
day, with Heat Advisories posted throughout our region. A
relatively early start to convection may be the only variable
that keeps most locations from reaching Excessive Heat criteria
(Heat Index of 113 or higher) today. Temperatures will soar to the
mid 90s at most locations, with peak heat index values of 108-112
degrees during the early to mid afternoon hours before convective
coverage increases later this afternoon. The record warmth and
humidity in place early this morning (see record warm minimum
temperature information in the "Climate" section below) has
resulted in the Heat Advisory beginning an hour earlier (10 AM)
than yesterday.

Convection should move offshore of the southeast GA and northeast
FL coasts before sunset this evening, while outflow boundaries
potentially allow for convection to linger over inland portions of
southeast GA. Otherwise, the surface trough will stall just west
of the Suwannee and Alapaha Rivers tonight, with moist
southwesterly low level flow likely developing convection once
again across Apalachee Bay and the FL Big Bend region after
midnight. This convection may move inland across the Suwannee
Valley during the predawn hours on Saturday, with low-topped
convection potentially crossing the I-75 corridor in north central
FL before sunrise. Lows tonight will only fall to the 75-80
degree range at most locations.

&&

.SHORT TERM...
(Saturday through Sunday night)
Issued at 440 AM EDT Fri Aug 9 2024

A trough will extend across southeastern US from distant remains of
Debby this period. And, high pressure will be centered to the east
of the region this period, with a ridge extending west from it
across the south half of Florida. This pattern will result in a
general flow from the southwest. This flow will make the Gulf sea
breeze dominant, with the east coast sea breeze struggling to move
much past I95 in the afternoons. Convection is expected to initiate
during the late morning/early afternoons with diurnal heating, with
the proximity of the trough helping to provide convergence over
northwestern counties. This activity will then spread east northeast
through the afternoon. A maximum in convection will be possible
later in the afternoons as activity reaches the east coast sea
breeze. Convection is expected to diminish each evening with loss of
heating.

Temperatures will trend near to a little above normal this period.

&&

.LONG TERM...
(Monday through Thursday)
Issued at 440 AM EDT Fri Aug 9 2024

A broad area of low pressure is expected to develop in the trough
across central GA and the Carolinas Monday into Tuesday, with the
associated frontal system remaining just to the northwest. The
frontal system may waiver north or south later in this period, but
in general the boundaries will remain north northwest of forecast
area. Each late morning/early afternoon convection will initiate due
to diurnal heating. The proximity of the boundary will provide
convergence over northwestern counties, with sea breeze interactions
producing added convergence elsewhere. The result will be scattered
to numerous coverage of showers and storms each afternoon. Day time
convection will diminish during the evening hours with loss of
diurnal heating.

Temperatures will trend near normal this period.

&&

.AVIATION...(12Z TAFS)
Issued at 738 AM EDT Fri Aug 9 2024

It`s a muggy morning featuring patchy light fog which will lift
into areas of low stratus, mainly MVFR, over the next couple of
hours before dispersing after 14z. Scattered showers will initiate
before noon amid a moist and breezy southwesterly flow. Vicinity
showers will develop as early as 13z at KGNV and 14z-15z along the
I-95 corridor. Convection will begin to deepen around noon and
coverage will expand along the I-95/east coast along the pinned
sea breeze this afternoon. Temporary degradation to flight
conditions is possible at all terminals due to that scattered
convection. The main concern will be gusty outflow and downpours
which may restrict visibility to IFR or LIFR. Convection will
fade early this evening while moving eastward off the coast.
Outside of thunderstorm influence, winds will be primarily
southwesterly today with gusts up to 20 knots this afternoon

&&

.MARINE...
Issued at 440 AM EDT Fri Aug 9 2024

A frontal boundary will remain stalled just west of the Georgia
waters through this weekend and early next week. Scattered to
numerous mainly afternoon and evening showers and thunderstorms
are expected to impact our local waters each day. This frontal
boundary will keep the axis of Atlantic high pressure displaced to
the south of our area, creating a prevailing south-southwesterly
wind flow into next week. Southerly winds are expected to surge to
Caution levels of 15 to 20 knots for the offshore waters during
the evening hours tonight. Seas of 3-5 feet will prevail through
tonight both near shore and offshore, followed by seas of 2-4
feet throughout our local waters this weekend and early next week.

Rip Currents: A lingering easterly ocean swell will combine with
developing onshore winds during the afternoon hours to create a
moderate rip current risk at all area beaches today. This swell
will begin to fade over the weekend, likely resulting in a low
risk at the southeast GA beaches, with a low-end moderate risk
possible at the northeast FL beaches.

&&

.HYDROLOGY...
Issued at 440 AM EDT Fri Aug 9 2024

Major flooding is forecast this weekend along lower portions of
the Santa Fe River near the gauge at Fort White, with rises
continuing downstream to the Three Rivers Estates gauge next week,
where major flooding is forecast to materialize by Tuesday. Crests
are occurring along middle portions of the Santa Fe near the
gauges at O`Leno State Park and High Springs, where moderate
flooding is occurring.

Moderate flooding is also forecast along upper portions of the
Suwannee River near Suwannee Springs, with rises to minor flooding
expected further downstream next week.

The Satilla River has crested in a moderate flood near the gauge
at Waycross, and moderate flooding is about to begin downstream at
the gauge near Atkinson.

Minor flooding is occurring along upper and middle portions of the
Altamaha River, and moderate flooding is forecast to begin later
tonight along lower portions of the Altamaha near the Everett City
gauge.

Crests have occurred along upper portions of the St. Marys River
near the gauge at Macclenny, where moderate flooding will continue
through the weekend.

The Alapaha River is cresting just below a moderate flood near the
gauge at Statenville, and water levels downstream near Jennings
have recently fallen below a moderate flood.

&&

.CLIMATE...
Issued at 440 AM EDT Fri Aug 9 2024

Record warm minimum temperatures at our designated climate sites
for today, August 9th:

Jacksonville   81/1882
Gainesville    79/1944
Alma, GA       79/2007
Craig Airport  79/2007

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  95  76  94  75 /  50  20  50  10
SSI  94  79  89  77 /  50  20  50  20
JAX  96  77  93  76 /  60  20  70  10
SGJ  94  78  92  76 /  60  20  70  20
GNV  91  76  91  74 /  60  40  80  10
OCF  91  76  89  76 /  50  40  80  20

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory until 6 PM EDT this evening for FLZ021-023-024-030-
     031-033-035-038-120-124-125-132-133-136>138-140-220-225-232-
     236-237-240-322-325-340-422-425-522.

GA...Heat Advisory until 6 PM EDT this evening for GAZ132>136-149-
     151>154-162-163-165-166-250-264-350-364.

AM...None.
&&

$$