213
FXUS62 KJAX 241119
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
719 AM EDT Mon Jun 24 2024

...New AVIATION...

.SYNOPSIS...
Issued at 437 AM EDT Mon Jun 24 2024

Early morning surface analysis depicts a frontal boundary pushing
southeastward from the Mid-Atlantic states and the Ohio and
Tennessee Valleys, with the axis of Atlantic high pressure
stretching westward across the FL peninsula. Aloft...the large
"Heat Wave" ridge in place over the southern tier of the nation
continues to retrograde westward towards the Rio Grande Valley and
the Desert Southwest as troughing digs southeastward from the
Great Lakes region and the Ohio Valley towards New England the
Mid-Atlantic states. Latest GOES-East derived Total Precipitable
Water imagery indicates that an unseasonably dry air mass remains
in place across most of inland southeast GA, where PWAT values
were below 1.5 inches for locations north and west of Waycross.
Values elsewhere across northeast and north central FL were close
to late June climatology, as PWATs were generally in the 1.8 - 2
inch range.

Weak shortwave energy and remnant outflow boundaries from
convection on Sunday afternoon have developed isolated showers
during the predawn hours along the I-10 corridor in Baker County
as well as portions of coastal Duval County, while southwesterly
flow has driven a few showers into Gilchrist County from the
northeastern Gulf of Mexico. Otherwise, a band of mid- level
cloudiness was progressing southward across the FL/GA border, with
fair skies in place elsewhere across inland southeast GA as well
as across most of north central FL. Temperatures at 08Z were
mostly in the 75-80 degree range, with dewpoints in the 70s area-
wide.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 437 AM EDT Mon Jun 24 2024

Troughing aloft will continue to dig southeastward towards New
England and the Mid-Atlantic coast by this afternoon, with this
feature driving a weakening frontal boundary into the southeastern
states. Low and mid-level west-southwesterly flow ahead of this
weakening boundary will shift to northwesterly by this evening,
and a ribbon of deeper moisture values preceding this boundary
will traverse southeast GA late this afternoon and northeast FL
this evening. West-southwesterly flow will delay the development
of the Atlantic sea breeze to the early afternoon hours, with
near record heat expected today for locations along and north of
the I-10 corridor, where highs will climb to the mid and upper 90s
all the way to the Atlantic coast. Dewpoints will mix down to the
60s this afternoon within the drier air mass across southeast GA,
keeping maximum heat index values generally in the 100-105 degree
range. Dewpoints will remain in the 70s elsewhere today, with
these values combining with the near record heat (see Climate
section below for details) along the I-10 and I-95 corridors to
create heat indices in the 108-111 degree range through the late
afternoon hours. A Heat Advisory has been issued for the coastal
counties along the I-95 corridor as well as the inland counties
all along the I-10 corridor throughout the afternoon and early
evening hours before sunset.

Convection should remain scattered and focused along mesoscale
boundaries such as the Atlantic and Gulf coast sea breezes, as
well as the St. Johns River breeze later this afternoon through
around midnight tonight. Some of the higher resolution guidance is
suggesting that convection will focus along the I-95 corridor in
northeast FL towards sunset. Model soundings indicate that
downdraft CAPE values will rise to the 1,000-1,500 j/kg range
across northeast and north central FL, so a few storms may pulse
and become strong later this afternoon and this evening, with
downburst wind gusts of 40-50 mph, frequent lightning strikes, and
heavy downpours possible. Activity could linger through around
midnight as the ribbon of deeper moisture migrates southward
towards the I-10 corridor, while a drier air mass again advects
into southeast GA overnight as low and mid level flow shifts to
northwesterly. Debris cloudiness will gradually thin out during
the predawn hours on Tuesday, with lows only falling to the mid
and upper 70s at most locations.

&&

.SHORT TERM...
(Tuesday and Wednesday)
Issued at 437 AM EDT Mon Jun 24 2024

Drier air (PWATs around 1.5") lingering over parts of SE GA will
keep rain chances and cloud cover a bit lower than across NE FL on
Tuesday, with higher coverage in diurnal thunderstorms over north
central FL as the sea breezes push inland and interact. High
precip chances will continue Wednesday as light southerly flow
allows for a repeat of sea breeze formation and interactions.

Southerly winds and mostly sunny skies will help temperatures soar
into the mid to upper 90s both days, with heat indices reaching
above 100 degrees for most of the area. The majority of the area
is expected to remain just below heat advisory criteria, though
some spots could see heat indices flirting with that threshold at
times, especially around the St. Johns River to the coast and
Suwannee Valley.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 437 AM EDT Mon Jun 24 2024

Hot temperatures will continue through the end of the week, with
highs generally in the 90s, with lows in the 70s. Weak southerly
winds through the period will promote diurnal showers and embedded
thunderstorms as both the Gulf and Atlantic sea breezes develop
and interact inland.

&&

.AVIATION...
(12Z TAFS)
Issued at 713 AM EDT Mon Jun 24 2024

Typical humid airmass in place with a few isolated showers (VCSH)
around this morning with mainly VFR mid cloud decks around 7000 ft
and these conditions should slowly disperse in the W-SW flow
through the rest of the morning hours, then as heat builds expect
sea breeze to develop late in the day and provide focus for
scattered storms during the late afternoon/evening hours and will
keep current PROB30 groups in place at the JAX metro TAF sites for
the 22-02Z time frame as the sea breeze pushes inland and these
may need to be upgraded to TEMPO groups by the afternoon TAF
package as convection becomes more apparent. Convection will
linger later into the evening/overnight hours than usual and have
kept VCSH at all TAF sites until the 06-08Z time frame, then light
SW winds and VFR mid clouds expected along with low chances of
MVFR fog at the inland TAF sites of GNV/VQQ towards sunrise
Tuesday morning.


&&

.MARINE...
Issued at 437 AM EDT Mon Jun 24 2024

A surface trough progressing across the southeastern states will
stall to the northwest of our area tonight and Tuesday.
Southwesterly winds will prevail across our local waters, with a
southerly evening wind surge bringing speeds up to Caution levels
tonight for the offshore waters. Seas of 2 to 4 feet both near
shore and offshore today will build to 3-5 feet tonight offshore.

Daily rounds of showers and thunderstorms over land areas will
progress eastward across our local waters each day this week, with
another trough expected to enter the southeastern states later
this week that will also stall to the northwest of our local
waters. Prevailing winds will then shift to southeasterly by
Friday and Saturday as high pressure builds off coastal New
England in the wake of the stalled surface trough. Seas of 2 to 4
feet are expected to prevail throughout our local waters from
Tuesday through the upcoming weekend.

Rip Currents: Breezy onshore winds this afternoon will combine
with a lingering east-southeasterly ocean swell to create a
lower-end moderate rip current risk at all area beaches today. The
risk is expected to become low on Tuesday at the southeast GA
beaches as surf heights diminish below 2 feet, while a lower-end
moderate risk may persist during the afternoon hours on Tuesday at
the northeast FL beaches.

&&

.CLIMATE...
Issued at 437 AM EDT Mon Jun 24 2024

Record high temperatures through Wednesday at our designated
climate sites:

               June 24    June 25     June 26
              --------------------------------
Jacksonville   101/1914   99/2016    101/1952
Gainesville    101/1950   102/1950   103/1950
Alma, GA       100/1998   100/1998   100/1954
Craig Airport  98/2019    101/1998   95/2014

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  98  74  98  74 /  20  20  50  20
SSI  97  79  92  78 /  20  30  50  20
JAX  99  76  96  75 /  40  30  70  20
SGJ  96  77  93  76 /  30  30  70  40
GNV  96  75  94  73 /  40  40  70  30
OCF  95  75  94  75 /  40  30  70  40

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory from 1 PM this afternoon to 7 PM EDT this evening
     for FLZ021-023-024-030-031-033-035-038-120-124-125-132-133-
     137-138-220-225-232-322-325-422-425-522.

GA...Heat Advisory from 1 PM this afternoon to 7 PM EDT this evening
     for GAZ153-154-165-166.

AM...None.
&&

$$