322
FXUS62 KJAX 172321
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
721 PM EDT Mon Jun 17 2024

...New UPDATE, AVIATION...

.UPDATE...
Issued at 720 PM EDT Mon Jun 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

No major updates needed on the forecast this evening. Gusty
easterly winds will continue overnight with very mild low
temperatures along the coast in the upper 70s.

&&

.SYNOPSIS...
Issued at 242 PM EDT Mon Jun 17 2024

Afternoon surface analysis depicts high pressure (1027 millibars)
centered off coastal New England. Meanwhile, surface troughing
was situated over the southwestern Atlantic Ocean to the east of
the Bahamas. Otherwise, a slow moving, broad low pressure center
(1003 millibars) has emerged into the Bay of Campeche
(southwestern Gulf of Mexico). Aloft...stout ridging centered
over the Carolinas remains in control of our local weather
pattern, while a trough was located just north of the Greater
Antilles in the southwestern Atlantic Ocean. Latest GOES-East
derived Total Precipitable Water imagery indicates that a drier
than average air mass persists across our region, with values
ranging from around 1.1 inches across north central FL to around
1.6 inches for inland southeast GA. Spotty showers were moving
quickly westward across our region, and breezy east-northeasterly
winds have overspread northeast and north central FL as our local
pressure gradient tightens. These breezy winds have developed a
healthy cumulus field across our area, with thin cirrus also
overspreading our skies. Temperatures ranged from the mid 80s to
the lower 90s as of 18Z, with dewpoints ranging from the mid and
upper 60s to the lower 70s at coastal locations.

&&

.NEAR TERM...
(through Tonight)
Issued at 242 PM EDT Mon Jun 17 2024

Already stout ridging centered to our north will expand and
strengthen further through Tuesday, resulting in a deepening
east-northeasterly wind regime for our area. This flow pattern
will generally advect a drier than average air mass over our
region from the Atlantic waters, but strengthening and convergent
onshore flow should be able to squeeze out a few showers
overnight, especially for the Atlantic coastal counties. Breezy
onshore winds will continue at coastal locations overnight, which
will keep lows in the upper 70s to around 80. Winds at inland
locations will gradually decouple as the night progresses,
allowing lows to generally fall to the lower 70s.

&&

.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 242 PM EDT Mon Jun 17 2024

Low to mid level high pressure ridging remains the dominant
feature during this period, as high pressure southeast of New
England changes little in strength and orientation through
Wednesday. Troughing east of the Bahamas which is expected to
develop a tropical wave (more on that below) will help maintain a
rather tight pressure gradient, and therefore continuing breezy
onshore conditions which will start to strengthen a bit Wednesday
and into Wednesday Night. This will help to cool temps a bit area
wide and especially closer to the coast and St. Johns River, in
which temps in the mid to upper 80s will be expected, warmer into
the low 90s approaching I-75. Winds are expected to remain below
any wind advisory criteria, though still in the 15-20mph range
with gusts to 30-35 mph and perhaps a bit higher at times along
the coast. Chances for showers and isolated t`storms does slowly
increase Tuesday and into Wednesday with increase in tropical-like
moisture, with the highest chances generally for areas east and
southeast.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 242 PM EDT Mon Jun 17 2024

Eyes continue to be on a tropical wave forming east of the Bahamas
over the next few days, and starting to make its way northwestward
towards the southeastern US by the end of the week. Guidance
remains more split than one would like for the expected time frame
regarding potential development and track, though there has been
an overall slowing trend with respect to the progress and movement
of the disturbance and therefore timing. Expecting the trough/wave
to approach the southeast coastline around the Thursday to
possibly even Friday time frame, though confidence is low with
many other aspects regarding potential impacts. The main aspect
that we are confident in is with respect to enhanced onshore
conditions continuing, as high pressure over the Atlantic drifts a
bit southward and tightens the pressure gradient with the
troughing/disturbance approaching. Beneficial rainfall also
remains very possible as well, though confidence is not very high
at this time with regards to more widespread POPs.

After the passage of the disturbance, high pressure ridging
returns at the low levels, though weaker overall. Guidance has
been suggesting the remnant upper low/trough may partially linger
near the area, which would certainly impact rain chances in either
direction. However, given the uncertainty and likely weak and/or
onshore flow, leaning towards climo with respect to POPs for this
upcoming weekend.

Temperatures start near to slightly below average for the end of
the work week (especially towards the coast), trending near to
slightly above average by next weekend.

&&

.AVIATION...
(00Z TAFS)
Issued at 720 PM EDT Mon Jun 17 2024

VFR conditions expected at the TAF sites with gusty easterly winds
continuing through the TAF period. Potential for MVFR ceilings at
SSI tomorrow afternoon, however winds will be too elevated for any
fog formation. Isolated to scattered showers will move onshore
beginning tomorrow morning throughout the day, thunderstorm
chances remain low.

&&

.MARINE...
Issued at 242 PM EDT Mon Jun 17 2024

Strong high pressure will remain anchored off coastal New England
through Thursday. This feature will create gradually increasing
onshore winds and building seas across our local waters, with
seas increasing to Caution levels of 15-20 knots and seas building
to 4-6 feet. Winds offshore will then increase to Small Craft
Advisory level speeds of around 20 knots offshore by late
Tuesday afternoon, with these Small Craft Advisory conditions
likely expanding to the near shore waters on Wednesday. Seas will
build to 5-7 feet by Tuesday evening offshore, with near shore
seas building to 4-6 feet.

Meanwhile, a trough situated to the northeast of the Bahamas will
be steered westward towards the southeastern seaboard late this
week, with weak low pressure possibly developing as this system
traverses the Gulf Stream waters. Showers and thunderstorm
activity will then increase late this week, with activity likely
continuing into the upcoming weekend. Winds may occasionally gust
to Gale Force across the offshore waters on Wednesday and
Wednesday night. Seas will peak in the 5-7 foot range near shore
from Wednesday through Thursday night, while seas offshore peak in
the 7-8 foot range on Wednesday and Wednesday night. High
pressure will then weaken as it sinks slowly southward towards
Bermuda, with the axis of this surface ridge extending across our
area during the upcoming weekend. Winds and seas will gradually
diminish as prevailing winds shift to southeasterly on Saturday
and then southerly by Sunday.

Rip Currents / Coastal Flooding / Beach Erosion / High Surf:
Breezy onshore winds will result in a high risk of rip currents
during the next several days. Breakers of 2-3 feet at the
northeast FL beaches today will build to 3-5 feet on Tuesday and
then 5-6 feet on Wednesday and Thursday. Values on Wednesday and
Thursday are just below High Surf Advisory criteria, and some
minor beach erosion during times of high tide will be possible
later this week. Although we will be entering the Full Moon cycle
later this week, astronomical tides are not particularly high at
this time of the year, so water levels will likely remain around
or just below minor flooding during the evening high tides from
Wednesday through Friday.

&&

.FIRE WEATHER...
Issued at 1159 AM EDT Mon Jun 17 2024

Gusty easterly surface and transport winds will continue through
midweek, creating high daytime dispersion values at inland
locations and good to marginally high dispersion values at
coastal locations. A drier air mass will prevail through midweek
across inland southeast GA and the Suwannee Valley, where
afternoon relative humidity values will fall to around 35 percent
each afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  71  91  69  89 /  10  10  10  20
SSI  79  86  78  86 /  20  30  20  50
JAX  72  89  72  87 /  20  30  10  50
SGJ  79  87  78  87 /  20  30  20  50
GNV  72  92  71  90 /  10  20   0  50
OCF  73  92  73  92 /  10  20  10  50

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through late Thursday night for FLZ124-125-
     133-138.

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

AM...Small Craft Advisory from 5 PM Tuesday to 5 AM EDT Friday for
     AMZ470-472-474.

&&

$$