656
FXUS62 KJAX 130657
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
257 AM EDT Tue Aug 13 2024

...HEAT ADVISORY TODAY FOR THE I-95 AND I-10 CORRIDORS...
...COLD FRONT MOVES SOUTHWARD ACROSS OUR REGION ON WEDNESDAY...
...DANGEROUS SURF CONDITIONS AT AREA BEACHES FROM FRIDAY THROUGH
THE WEEKEND...

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

.NEAR TERM...
(Today and Tonight)
Issued at 258 AM EDT Tue Aug 13 2024

A frontal zone to the northwest will begin to slide southeast into
area through the day, with high pressure to the southeast. This
frontal zone will sink southeast across forecast area Tonight. Some
drier air will be associated with this front, so precipitation
chances will be lower than normal. The best chances this afternoon
will be across NE FL where better heating and moisture will persist.
Any activity which does develop will largely diminish this evening.
With convergence along the front, could see a few showers or storms
linger a little longer Tonight.

Temperatures will trend above normal through Tonight. With the front
bringing in some drier air from the northwest, the best chance to
reach heat advisory criteria this afternoon will be across
eastern counties.

&&

.SHORT TERM...
(Wednesday through Thursday night)
Issued at 258 AM EDT Tue Aug 13 2024

Deep troughing over New England will begin to cutoff from the main
flow pattern on Wednesday, while ridging aloft centered over the
Southern Plains states begins to build southeastward towards the
lower Mississippi Valley and the northern Gulf coast. This change
in the weather pattern will create deepening northwesterly flow
aloft, which will allow a "backdoor" cold front to move through
our area from north to south from late Wednesday morning through
late Wednesday night. Meanwhile, high pressure building over the
Great Lakes in the wake of this front will begin to wedge down the
southeastern seaboard, resulting in a surge of onshore winds along
the southeast GA coast towards noon on Wednesday, with this wind
surge then spreading down the northeast FL coast during the
afternoon hours.

Convergence will increase along the leading edge of this wind
surge, resulting in scattered to numerous afternoon showers and
thunderstorms, especially for inland locations between the I-95
and I-75 corridors. Activity will shift southwestward ahead of the
approaching frontal boundary and could linger into the evening
hours for locations along and west of the I-75 corridor.
Temperatures ahead of the front will soar to the mid and upper 90s
for locations west of the I-95 corridor, except lower 90s for
locations north of Waycross, where the front will pass through
earlier in the day, as well as at coastal locations, where
developing onshore winds will put a halt to rising temperatures.
Wednesday should be the last day of Heat Index values reaching
Heat Advisory criteria, mainly for locations south of Waycross.
Convection should dissipate along the I-75 corridor before
midnight, and lows on Wednesday night will fall to the low and mid
70s inland, while an onshore breeze keeps coastal lows in the
upper 70s to around 80.

High pressure will continue to wedge down the southeastern
seaboard on Thursday, ushering in a slightly cooler and drier air
mass into our area. Breezy northeasterly winds will prevail along
the I-95 corridor, keeping highs in the mid to upper 80s, while
highs further inland climb to the lower 90s. There may be enough
moisture and convergence in the deepening onshore flow pattern to
produce scattered showers and thunderstorms for locations along
and south of the I-10 corridor, with only widely isolated coverage
possible for locations south and east of Waycross in southeast GA.
A much drier air mass will then overspread our region on Thursday
night, with breezy onshore winds keeping coastal lows in the upper
70s to around 80. Meanwhile, decoupling winds and fair skies may
allow lows to fall to the upper 60s for much of inland southeast
GA by sunrise on Friday, with lower 70s expected elsewhere inland.

&&

.LONG TERM...
(Friday through Monday)
Issued at 258 AM EDT Tue Aug 13 2024

Stacked ridging will be in place across our region on Friday,
allowing for our local pressure gradient to gradually relax by
Friday evening. Meanwhile, distant Tropical Cyclone Ernesto will
reinforce an unseasonably dry air mass across our region, with
only isolated late afternoon or early evening showers and
thunderstorms possible for north central FL. Breezy onshore winds
on Friday will keep coastal highs in the mid to upper 80s, while
highs further inland generally climb to the lower 90s. Radiational
cooling on Friday night will allow lows to fall to the upper 60s
to around 70 at most inland locations, while a light onshore
breeze keeps coastal lows in the mid to upper 70s.

A potent shortwave trough digging southeastward from the Great
Lakes region through the Ohio Valley on Saturday will shift
ridging over our area offshore by the afternoon and evening hours.
Mid-level flow will shift to northwesterly as a longwave trough
begins to dig into the southeastern states, and moisture levels
may recover enough to develop isolated convection during the late
afternoon and evening hours, especially along the inland moving
Gulf coast sea breeze. Highs will rebound slightly to the low and
mid 90s for inland locations, with the afternoon sea breeze
keeping coastal highs in the upper 80s to around 90. Any
convection that manages to develop on Saturday afternoon at inland
locations should dissipate by the mid-evening hours. Lows will
fall to the 70s area-wide on Saturday night.

Troughing aloft will become established over the southeastern
states by Sunday and Monday, driving a frontal boundary into the
Deep South. West-southwesterly flow will deepen over our region,
activating convection along the inland moving Gulf Coast sea
breeze boundary. At least scattered afternoon and evening
thunderstorms are expected to traverse our region, with a few
strong storms possible along the I-95 corridor during the late
afternoon or early evening hours as activity interacts with a
pinned Atlantic sea breeze boundary. Highs will soar to the low
and mid 90s throughout our region, with Heat Index values likely
climbing back towards Heat Advisory criteria (108 degrees) by
early next week. Lows will remain in the 70s area-wide.

&&

.AVIATION...
(06Z TAFS)
Issued at 123 AM EDT Tue Aug 13 2024

A little bit of patchy fog will be possible around sunrise at KVQQ,
otherwise prevailing VFR conditions are forecast for this period.
Thunderstorm chances are forecast to be below normal this afternoon,
with only isolated to scattered storms forecast. At this time, have
forecast a VCTS during time when best chance for storms will
occur. Later forecast updates, can then refine this timing as
activity develops, and add restrictions where appropriate.

&&

.MARINE...
Issued at 258 AM EDT Tue Aug 13 2024

A frontal boundary will slowly move southeast across the area
through Wednesday. This boundary will move off to the southeast
Wednesday night, as high pressure builds down the east coast of the
US. This ridge of high pressure will remain across the coast through
Friday, then will begin to push out over the western Atlantic
waters.

Tropical Storm Ernesto is well to the southeast of area waters
Today, and will track northwest through Thursday, before turning
to the north and passing well to the east through the weekend.
While Ernesto`s track will be well to the east, it will push
elevated seas toward region. Small craft advisory level seas will
be possible as a result over outer waters Friday and Saturday.

Monitor the National Hurricane Center for the latest forecast track
information on Ernesto.

Rip Currents: Moderate through Wednesday. Rip current risk
will trend toward high for this weekend due to distant Ernesto.

&&

.FIRE WEATHER...
Issued at 258 AM EDT Tue Aug 13 2024

Westerly transport winds will prevail today, with surface winds
becoming onshore this afternoon along the Interstate 95 corridor
as the Atlantic sea breeze boundary pushes inland. Good daytime
dispersion values are forecast at most inland locations, while
fair values prevail at coastal locations as well as across north
central Florida. Transport winds will shift to northwesterly on
Wednesday morning and then northeasterly by late Wednesday
afternoon, with breezy northeasterly surface winds developing at
coastal locations during the afternoon hours. Marginally high
daytime dispersion values will be possible for inland locations
along the I-10 corridor as well as portions of inland southeast
Georgia on Wednesday. Breezy northeasterly surface and transport
winds will then overspread our region on Thursday, creating good
daytime dispersion values area-wide, with marginally high values
possible at inland locations.

&&

.HYDROLOGY...
Issued at 258 AM EDT Tue Aug 13 2024

Water levels continue to slowly rise along lower portions of the
Santa Fe River near the Three Rivers Estates gauge, where a crest
near a major flood is forecast later this week and into the
upcoming weekend. Meanwhile, minor flooding is forecast at the
gauge near Hildreth, where a crest is forecast late this week or
during the upcoming weekend. Further upstream, water levels have
crested in a moderate flood near the gauge at Fort White. Moderate
flooding will continue around this gauge through at least Friday.
Water levels along middle and lower portions of the Santa Fe
remain in a minor flood, with levels forecast to fall below flood
stage near the gauge at High Springs late this week.

Moderate flooding will continue through late this week along the
St. Marys River near the gauge at Macclenny. Moderate flooding
also continues at the downstream gauge near Traders Hill.

Minor flooding continues along upper portions of the Suwannee
River, where water levels are forecast to fall below flood stage
later this week near the gauge at White Springs. Water levels are
cresting in a moderate flood near the gauge at Benton. Rises will
continue 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 fallen back to minor flood levels along lower
portions of the Satilla River near the gauge at Atkinson. Minor
flooding will continue along lower portions of the Satilla River
during the next several days. Water levels have fallen below
flood stage further upstream near the gauge at Waycross.

Water levels have fallen to minor flood levels 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 this evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  96  74  92  72 /  20  10  40  30
SSI  93  78  92  80 /  20  20  40  30
JAX  96  77  94  75 /  20  20  50  20
SGJ  94  77  92  79 /  20  30  40  20
GNV  94  75  95  75 /  30  10  60  40
OCF  94  76  95  75 /  30  10  50  30

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory from 11 AM this morning to 6 PM EDT this evening
     for FLZ023-024-030-031-033-038-120-124-125-132-133-138-220-
     225-232-322-325-422-425.

GA...Heat Advisory from 11 AM this morning to 6 PM EDT this evening
     for GAZ153-154-162-163-165-166-264-350-364.

AM...None.
&&

$$