113
FXUS62 KJAX 121152
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
752 AM EDT Mon Aug 12 2024

...New AVIATION...

.SYNOPSIS...
Issued at 420 AM EDT Mon Aug 12 2024

Early morning surface analysis depicts a stationary trough that
stretches from the coastal Carolinas southwestward across the Deep
South and along the northern Gulf coast. Meanwhile, weakening
high pressure (1020 millibars) blankets the Ohio, Tennessee, and
lower Mississippi Valleys in the wake of this surface trough.
Aloft...weak flow persists locally between Atlantic ridging that
was building westward across the Bahamas and another ridge
centered over Texas that was nosing eastward along the Interstate
10 corridor. Otherwise, troughing was digging southward from
Quebec through New England and eastern portions of the Great
Lakes. Latest GOES-East derived Total Precipitable Water imagery
indicates that a moisture gradient persists along the surface
trough axis across inland southeast GA, where PWATs have fallen to
near 1.5 inches along the Altamaha and Ocmulgee Rivers.
Meanwhile, deeper moisture persists for locations south and east
of Waycross, where PWATs were around or above 2 inches.
Cirrostratus debris cloudiness from late evening convection over
coastal southeast GA has been slow to thin as it drifts southward
across northeast and north central FL, while fair skies now
prevail for ideal viewing of the peak of the Perseid meteor shower
across southeast GA during the predawn hours. Overnight
convection generated by low level west southwesterly flow has
remained confined to the FL Big Bend and Nature coasts thus far,
with only a few light showers occasionally approaching southern
portions of the Suwannee River basin. Temperatures and dewpoints
were in the 70s at inland locations as of 08Z, ranging to around
80 at coastal locations.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 420 AM EDT Mon Aug 12 2024

Debris cloud cover should continue to gradually thin out through
sunrise across northeast and north central FL, while patchy fog
may develop around sunrise for locations near the Altamaha and
Ocmulgee Rivers that are beneath the drier and more subsident air
mass. Any fog or lower stratus clouds that manage to develop will
quickly dissipate during the early morning hours, with a healthy
cumulus field expected to be generated during the mid to late
morning hours, especially for locations within the moist air mass
to the south and east of Waycross. Meanwhile, low-topped
convection developing within the low level west southwesterly flow
pattern along the FL Big Bend and Nature coasts may begin to move
across the Suwannee River and also into north central FL by the
mid to late morning hours. Heat index values will begin to
approach advisory criteria before noon for locations south and
east of Waycross, where dewpoints will remain in the mid to upper
70s for most of the day today. Temperatures will soar to the low
and mid 90s this afternoon, with a few upper 90s possible for
inland locations along and north of the Interstate 10 corridor.
Dewpoints for locations north and west of a line from Homerville
to Waycross to Jesup will fall to the upper 60s and lower 70s this
afternoon, keeping heat index values closer to 100. A Heat
Advisory is again in effect today elsewhere for maximum heat
index values of 108-112 degrees.

The moisture gradient in place across our area should keep
afternoon convection isolated to widely scattered at best for most
of inland southeast GA, with west-southwesterly low level flow
keeping afternoon and evening convection focused along the I-95
corridor in coastal southeast GA. Early afternoon convection is
expected to increase in coverage along the I-75 corridor in the
Suwannee Valley and north central FL as it progresses east-
northeastward along the Gulf coast sea breeze. This activity
should then collide with a pinned Atlantic sea breeze along the
I-95 corridor, resulting in a few storms pulsing and briefly
becoming strong during the late afternoon or early evening hours.
A few storms could be slow movers along the I-95 corridor around
sunset, but activity should quickly diminish as it moves offshore
during the early to mid evening hours. Debris cloud cover should
thin out towards midnight, with lows falling to the mid 70s inland
and the upper 70s at coastal locations.

&&

.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 420 AM EDT Mon Aug 12 2024

The region will be between high pressure to the east southeast,
and  an elongated frontal zone to the north and northwest
Tuesday. The frontal zone will sink south across forecast area
Tuesday night, then push to the south Wednesday, as high pressure
builds down the east coast. The boundary will begin to break down
Wednesday night, as a potential tropical system develops over the
western Atlantic. A little bit drier air will advect into region
with boundary will help to limit convection this period. Isolated
to scattered showers and storms will develop in the late
morning/early afternoon period each afternoon each day. This
activity will then largely diminish will loss of diurnal heating
in the evenings.

Temperatures will trend above normal this period.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 420 AM EDT Mon Aug 12 2024

A high pressure ridge will extend down the east coast of the US
Thursday, then slide off the coast Friday. Meanwhile, a
northward moving potential tropical system will pass by well to
the east. Once the tropical system passes further away to the
northeast, the high will continue to move further to the east
southeast over the weekend, as a trough digs along the US east
coast. Surface ridging, and drier air that will be in place
behind, will yield lower than normal precipitation chances this
period. With diurnal heating, isolated to scattered afternoon
convection is forecast.

Temperatures will trend near to a little below normal Thursday and
Friday, then trend a little above over the weekend.

&&

.AVIATION...
(12Z TAFS)
Issued at 750 AM EDT Mon Aug 12 2024

VFR conditions prevail at 12z this morning but a chance of MVFR
ceilings of around 1500-2500 ft as low levels are very moist and
will get cumulus developing pretty quickly this morning. VFR
clouds will then develop by early aftn and should already see
some convection forming from about 15z-17z (initially near GNV),
and we have TEMPO group for GNV and either PROB30 or TEMPO group
for other TAFs. Confidence is not too high to go full to TEMPO for
all the TAFs as the probabilities are not very high but we will
continue to monitor trends in the radar and guidance. Gusts of
25-35 kt will be possible in the convection and some brief vis/cig
restrictions. Most of the convection will end by 01z-02z with a
lingering shower or two along the coast from SGJ to SSI by that
time. Mainly southwest winds 5-10 kt will develop this morning
and expect the Atlantic sea breeze boundary will again be slow to
progress inland today at SGJ and SSI.

&&

.MARINE...
Issued at 420 AM EDT Mon Aug 12 2024

A surface trough will remain situated to the west of our local
waters through Tuesday night, resulting in prevailing
southwesterly winds across our local waters. Scattered showers and
thunderstorms will progress east-northeastward across mainly the
near shore waters during the late afternoon and early evening
hours today and again on Tuesday. Outside of thunderstorm
activity, winds will become southeasterly over the near shore
waters during the afternoon hours as the sea breeze pushes slowly
inland. Seas of 2 to 4 feet will prevail both near shore and
offshore through Wednesday night.

A cold front will then approach our area from the north on
Tuesday night, pushing through the Georgia waters on Wednesday
morning and the northeast Florida waters by Wednesday evening.
High pressure building over New England and the Mid- Atlantic
states in the wake of this frontal boundary will then wedge down
the southeastern seaboard in the wake of this frontal passage,
creating strengthening onshore winds by Wednesday night and
Thursday. Meanwhile, distant Potential Tropical Cyclone 5 will
remain east of the Bahamas as it turns northward late this week,
resulting in building seas and increasingly rough surf throughout
our local waters by late Friday and the upcoming weekend. Caution
level seas of 4 to 6 feet are expected offshore by Friday, with
near shore seas building to the 3 to 5 foot range.

Rip Currents: A lingering easterly ocean swell will combine with
developing onshore winds this afternoon to keep a lower-end
moderate rip current risk in place at the northeast FL beaches
today. Low wave heights should keep the risk low at the southeast
GA beaches today, and a low risk appears likely at all area
beaches on Tuesday. Long period swells from distant Potential
Tropical Cyclone #5 will begin to enter our local waters on
Friday, bringing an elevated rip current risk to all area beaches
from Friday afternoon through the upcoming weekend.

&&

.HYDROLOGY...
Issued at 420 AM EDT Mon Aug 12 2024

Water levels have crested in a moderate flood along lower
portions of the Santa Fe River near the gauge at Fort White.
Moderate flooding will continue around this gauge through at least
early Friday. Rises will continue downstream towards the Three
Rivers Estates gauge, where a crest near major flood levels is
forecast later this week. Water levels along middle and lower
portions of the Santa Fe near the gauges at High Springs, O`Leno
State Park and Worthington Springs have fallen back to minor flood
levels. Otherwise, minor flooding is forecast at the gauge near
Hildreth, where a crest is forecast late this week or during the
upcoming weekend.

Water levels have crested in a minor flood along upper portions
of the Suwannee River near the gauges at Suwannee Springs and
White Springs. Water levels have crested in a moderate flood near
the gauge at Benton. Rises will continue downstream along lower
portions of the Suwannee River during the next week, with minor
flooding forecast at several gauges from around the gauge at
Luraville and points downstream.

Water levels have crested in a moderate flood along lower
portions of the Satilla River near the gauge at Atkinson, where water
levels have since fallen back to minor flood levels. Water levels
are forecast to fall below flood stage late this afternoon at the
gauge further upstream near Waycross.

Water levels are cresting in a moderate flood along lower portions
of the Altamaha River near the Everett City gauge. Water levels
are forecast to fall below flood stage at this gauge by late
Tuesday afternoon. River levels have fallen below flood stage for
gauges upstream on the middle and upper portions of the Altamaha
River.

Moderate flooding will continue through late this week along the
St. Marys River near the gauge at Macclenny, with water levels
downstream recently crest at the major flood threshold near the
gauge at Traders Hill.

Crests have occurred along the Alapaha River, where water levels
will fall below flood stage later today near the gauge at
Jennings.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  96  74  96  75 /  20  10  20  10
SSI  92  80  92  77 /  40  20  30  10
JAX  96  76  96  77 /  50  50  30  10
SGJ  93  78  94  77 /  50  10  30  10
GNV  93  75  94  75 /  60  10  40   0
OCF  93  75  94  76 /  60  10  40   0

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory from 11 AM this morning to 7 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 from 11 AM this morning to 7 PM EDT this evening
     for GAZ136-151>154-162-163-165-166-250-264-350-364.

AM...None.
&&

$$