769
FXUS62 KJAX 171558
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1158 AM EDT Mon Jun 17 2024

...ONSHORE WINDS CONTINUE TO STRENGTHEN THROUGH THURSDAY...
...MARINE AND COASTAL CONDITIONS DETERIORATE TOWARDS MIDWEEK...
...BENEFICIAL RAINFALL POSSIBLE LATER THIS WEEK...

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

.UPDATE...
Issued at 1159 AM EDT Mon Jun 17 2024

Early 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, low pressure (1003 millibars) was
emerging into the Bay of Campeche (southwestern Gulf of Mexico)
from Mexico`s Yucatan Peninsula. 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 1.2 inches across north central FL to around
1.5 inches for inland southeast GA. A surge of easterly winds has
triggered a few heavier showers that were moving quickly across
inland portions of southeast GA, while isolated showers extended
southwestward along this inland moving surge of onshore winds
along the I-95 corridor in southeast GA. Breezy easterly winds
have overspread northeast and north central FL as our local
pressure gradient tightens, with the easterly wind surge and
associated shower activity progressing across inland portions of
southeast GA. These breezy winds have developed a healthy cumulus
field across our area, with thin cirrus also overspreading our
skies from west to east late this morning. Temperatures were
generally in the mid to upper 80s area-wide as of 16Z, with
dewpoints mostly in the low to mid 70s.

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,
especially later tonight for the Atlantic coastal counties. The
overall subsident air mass will likely limit the potential for
sustained updrafts, and thunderstorm activity appears to be
unlikely or very isolated at best, with the low-topped activity
currently crossing inland southeast GA being the most likely
possibility for a sporadic lightning strike through the early
afternoon hours. Winds this afternoon will occasionally gust to
the 25-35 mph range as our local pressure gradient continues to
gradually tighten, and onshore winds will likely remain breezy at
coastal locations well into the evening hours before slowly
weakening overnight.

Highs this afternoon will soar to the low and mid 90s for
locations along and west of Interstate 75, where dewpoints will
crash through the 60s due to the dry and subsident air mass in
place, which will keep maximum heat index values to around 100 for
these locations. Highs elsewhere will generally top out in the
upper 80s to around 90. Lows tonight will fall to the lower 70s
inland, while onshore winds keep coastal lows in the upper 70s to
around 80.

&&

.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 102 AM EDT Mon Jun 17 2024

Tuesday...Not much change in the pattern as high pressure remains
locked in north of the region and breezy to almost windy easterly
flow will continue at 15-25G35-40mph range at the Atlantic Coast
with a high risk of rip current and 10-20G30-35mph range over
inland areas during the afternoon hours. This flow pattern will
continue to stream rounds of scattered showers and isolated storms
from the coastal waters and into land areas through the day with
gusty winds the main threat from storm activity over inland areas
during the afternoon hours. Temps at or slightly below normal
levels with highs in the mid/upper 80s along the Atlantic
Coast/I-95 corridor and into the lower 90s over far inland areas.

Tuesday Night...Breezy easterly flow continues along the Atlantic
Coast with continued scattered showers and isolated storms
pushing onshore, while partly cloudy and mainly dry conditions
will exist over inland areas. Lows in the 70-75 range inland and
75-80 along the Atlantic Coastal areas as the breezy winds keep
temps elevated.

Wednesday...Breezy onshore/easterly flow continue at 15-25G35-40mph
range at the Atlantic Coast with a high risk of rip current and
10-20G30-35mph range over inland areas during the afternoon hours.
This flow pattern will continue to stream rounds of scattered
showers and isolated storms from the coastal waters and into land
areas through the day with gusty winds the main threat from storm
activity over inland areas during the afternoon hours. Temps at or
slightly below normal levels with highs in the mid/upper 80s
along the Atlantic Coast/I-95 corridor and into the lower 90s over
far inland areas.

Wednesday Night...Breezy easterly flow continues along the Atlantic
Coast with continued scattered showers and isolated storms
pushing onshore, while partly cloudy and mainly dry conditions
will exist over inland areas. Lows in the 70-75 range inland and
75-80 along the Atlantic Coastal areas as the breezy winds keep
temps elevated.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 102 AM EDT Mon Jun 17 2024

Thursday...GFS/ECMWF model runs are still trying to spin up a low
pressure system underneath mid level trough/disturbance pushing
quickly westward from the Bahamas into the FL peninsula. Still way
too early if this system becomes actual tropical low pressure
system or more likely a disorganized area of widespread showers
and embedded thunderstorms with a locally heavy rainfall and
strong gusty wind potential during this period. Bottom line during
this period will be an increase in rainfall chances to 50-80%
with numerous to widespread showers and embedded heavy storms
pushing onshore at times with strong gusty winds as the main
threat. Max temps will remain at or slightly below normal levels
with the increased rainfall chances with highs in the mid/upper
80s along the Atlantic Coast/I-95 corridor and still reaching into
the lower 90s over inland areas. With most of the local NE FL/SE
GA area having below normal rainfall so far this month, this will
be welcome rainfall in many locations, but localized flood
potential will mainly exist in urban areas and along the Atlantic
Coast during high tide cycles and the stronger onshore flow may
produce minor tidal flooding along the Atlantic Coast beaches with
the approach of the full moon phase.

Friday/Saturday/Sunday...In the wake of departing low pressure
system, a weaker high pressure ridge will build in just north of
the region and still expect near breezy East-Southeast winds at
10-15G20-25 mph, but more normal East Coast sea breeze convection
expected as it moves inland both days and lingering deeper
tropical moisture will still lead to above normal rainfall chances
in the 40-70% range with daily scattered to numerous showers and
storms. Max temps bounce back to slightly above normal levels with
highs in the upper 80s/near 90 along the Atlantic Coast/I-95
corridor with lower to middle 90s over inland areas. By the
weekend the steering flow begins to become more southerly and
helps to push afternoon convection closer to the Atlantic Coast.
The increase in Max temps back to above normal levels will push
daily maximum heat indices closer to 105F at just heat advisory
levels.

&&

.AVIATION...
(12Z TAFS)
Issued at 614 AM EDT Mon Jun 17 2024

Restrictions in stratus coming off the Atlantic will be possible
early this period. Otherwise, prevailing VFR conditions forecast
Today. Gusty winds are expected at all area TAF sites, especially
near the coast. Isolated to scattered showers and storms are
expected from mid morning through the afternoon. Brief
restrictions in and near these storms are possible. This
convection will largely dissipate with loss of diurnal heating in
the evening, but will linger over the coastal waters into the
night.

&&

.MARINE...
Issued at 1159 AM 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
speeds today remaining just below Caution levels, with seas of 3-5
feet expected both near shore and offshore. Caution level wind
speeds of 15-20 knots will develop tonight, followed by Small
Craft Advisory level speeds around 20 knots setting in offshore
on Tuesday, with these Small Craft Advisory conditions expanding
to the near shore waters by Tuesday evening. Seas will build to
5-7 feet by Tuesday evening both near shore and offshore.

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 thunderstorms will
increase beginning around midweek, 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 6-8 foot range near shore from Wednesday
through Thursday night, while seas offshore peak in the 7-9 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  93  71  91  69 /  10  10  10  10
SSI  87  79  86  78 /  10  10  30  20
JAX  90  72  89  72 /  10  20  30  10
SGJ  89  79  87  78 /  20  30  30  20
GNV  93  72  92  71 /  10  10  20   0
OCF  93  73  92  73 /  10  10  20  10

&&

.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...None.
&&

$$