052
FXUS62 KJAX 250834
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
434 AM EDT Tue Jun 25 2024

...HEAT ADVISORY IN EFFECT FOR LOCATIONS FROM WAYCROSS AND JESUP
SOUTHWARD THIS AFTERNOON...
...LATE AFTERNOON AND EVENING THUNDERSTORMS FOCUS ALONG U.S.
HIGHWAY 301 TODAY...
...SOUTHWESTERLY FLOW CONTINUES THROUGH FRIDAY WITH INCREASING
CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS...

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

.SYNOPSIS...
Issued at 435 AM EDT Tue Jun 25 2024

Early morning surface analysis depicts a frontal boundary located
just north of the Altamaha and Ocmulgee Rivers in southeast GA,
with the axis of Atlantic high pressure suppressed across south
FL. Aloft..."Heat Wave" ridging remains centered across the
Desert Southwest and the southern Plains states, while troughing
was progressing eastward along the New England and Mid-Atlantic
coasts, producing northwesterly flow across our region. Latest
GOES-East derived Total Precipitable Water imagery indicates that
an unseasonably dry air mass prevails across inland southeast GA,
especially for locations northwest of Waycross, where PWATS near
the Ocmulgee and upper portions of the Altamaha Rivers have fallen
to the 1.2 - 1.4 inch range, while values closer to late June
climatology of 1.8 - 2 inches prevail for locations along and
south of Interstate 10. A lingering area of mid-level cloudiness
and sprinkles continues along upper portions of the Santa Fe River
basin in north central FL early this morning, with fair skies in
place elsewhere across our area. Temperatures were generally in
the mid to upper 70s as of 08Z, with dewpoints in the low to mid
70s.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 435 AM EDT Tue Jun 25 2024

Troughing will push off the Mid-Atlantic and New England coasts by
this afternoon, leaving little in the way of support aloft for the
frontal boundary that has progressed into the Deep South. This
boundary will stall across southeast GA this afternoon and will
begin to dissipate tonight. Northwesterly flow aloft will
continue to advect an unseasonably dry air mass across inland
portions of southeast GA today, where dewpoints will crash through
the 60s this afternoon and only isolated to widely scattered late
afternoon or early evening convection is expected to develop.
High temperatures will soar to near record levels across inland
southeast GA and northern portions of the Suwannee Valley, where
maximums will reach or exceed 100 degrees. The dry air mass should
keep maximum heat index values around 105 degrees for locations
to the northwest of Waycross, while values from Waycross and Jesup
and points south and eastward climb to the 108-112 degree range,
which has prompted a Heat Advisory from Noon through 7 PM.

Northwesterly flow aloft will push weak shortwave energy across
northeast and north central FL late this afternoon and this
evening. A slightly looser local pressure gradient today should
allow both the Atlantic and Gulf coast sea breezes to develop and
move inland early this afternoon, with convective temperatures in
the mid 90s per model soundings being realized early this
afternoon, likely resulting in widely scattered convection
developing along the inland moving Gulf and Atlantic sea breeze
boundaries, in addition to the St. Johns River breeze. Mesoscale
boundary collisions should focus around the U.S. Highway 301
corridor in northeast and north central FL late this afternoon
and this evening, where likely to numerous POPs were placed in the
forecast grids. Downdraft CAPE values in these areas will peak
around 1,000 j/kg this afternoon, allowing a few storms to pulse
and potentially become briefly strong, with downburst winds of
40-50 mph possible. Continued mild mid-level temperatures and
potential slow storm motion will also result in locally heavy
downpours across inland portions of northeast and north central
FL, and localized flooding could again become a concern,
especially at urban and more normally flood prone locations. Highs
inland northeast and north central FL will soar to the mid and
upper 90s, with low to mid 90s forecast for coastal northeast FL
and southeast GA. Heat Index values will peak in the 108-112
degree range, with Heat Advisories covering all counties in these
areas from Noon through 7 PM.

Convection will again be slow to wind down this evening for
locations between U.S. Highway 301 and I-75 in north central and
northeast FL, with convective outflows potentially igniting
scattered convection across inland southeast GA during the evening
hours, especially over the Okefenokee Swamp. Convection should
conclude by midnight, with debris cloudiness thinning out by the
predawn hours on Wednesday. Lows tonight will generally fall to
the low and mid 70s, except mid to upper 70s at coastal locations.

&&

.SHORT TERM...
(Wednesday and Thursday)
Issued at 435 AM EDT Tue Jun 25 2024

Drier air will linger over SE GA, with PWATs around 1.5-1.75"
limiting precipitation coverage to scattered, whereas NE FL will
have ample moisture (PWATs 2.0"+) moving in with the help of
southwest flow. Numerous showers and embedded thunderstorms will
develop Wednesday afternoon/evening as the Gulf sea breeze pushes
far inland. The east coast sea breeze will not make it far inland,
however it will provide slight relief to the heat along the coast.
Highs Wednesday will again be above normal, reaching near 10
degrees for portions of inland SE GA, with highs in the lower to
upper 90s elsewhere.

Temperatures will trend downward a tad on Thursday, but still
remain above normal as southwest flow and an approaching front
from the north helps numerous showers and thunderstorms develop
area-wide.

&&

.LONG TERM...
(Friday through Monday)
Issued at 435 AM EDT Tue Jun 25 2024

Temperatures will remain above normal during this period, with
daily highs in the lower to upper 90s. Similar setup expected each
day Saturday onward as winds shift from SW to S/SE, allowing both
sea breezes push inland and interact, higher precipitation chances
will remain over NE FL, with more scattered coverage daily in SE
GA.

&&

.AVIATION...
(06Z TAFS)
Issued at 225 AM EDT Tue Jun 25 2024

MVFR visibilities are expected to develop during the predawn
hours at VQQ. A brief period of MVFR visibilities will also be
possible around or just after sunrise at GNV, but confidence was
too low to include in the overnight TAFs. Otherwise, VFR
conditions are expected to prevail at the regional terminals
through at least 18Z. Showers and thunderstorms will develop near
the regional terminals along sea breeze boundaries during the
afternoon hours, with activity possibly lingering past 00Z at the
inland terminals. PROB30 groups were maintained at all of the
regional terminals for brief wind gusts up to 30 knots and MVFR
visibilities, mainly after 19Z. VFR conditions are then expected
to prevail again by 03Z Wednesday. Southwesterly surface winds
sustained at 5 knots or less overnight will become west-
southwesterly after sunrise, with speeds increasing to 5-10 knots
after 14Z. The Atlantic sea breeze boundary will begin moving
inland a little earlier on Tuesday afternoon, resulting in surface
winds shifting to east- southeasterly and increasing to 10-15
knots before 18Z at the SGJ and SSI coastal terminals. The Gulf
coast sea breeze should cross the GNV terminal before 21Z, with
winds shifting to southwest and increasing to around 10 knots
outside of any developing convection. Surface winds will shift to
southeasterly before 21Z at the Duval County terminals. Light
southwesterly winds sustained at 5 knots or less are then expected
after 02Z Wednesday.

&&

.MARINE...
Issued at 435 AM EDT Tue Jun 25 2024

A frontal boundary will stall over the southeastern states today,
with prevailing offshore winds this morning becoming onshore
towards noon over the near shore waters as the Atlantic sea breeze
pushes inland. Scattered showers and thunderstorms will possibly
develop over our local waters late this afternoon and early this
evening. Outside of thunderstorm activity, southerly winds will
briefly surge this evening before shifting to southwesterly while
diminishing overnight. Speeds should remain below Caution levels
during afternoon and evening wind surges, and seas of 2-4 feet
will prevail throughout our local waters during the next several
days.

Southwesterly winds will prevail on Wednesday and Thursday ahead
of another weakening frontal boundary that will stall and dissipate
to the northwest of our local waters by Friday, with increasing
chances for showers and thunderstorms, mainly during the afternoon
and evening hours. Prevailing winds will become southeasterly by
the weekend as the axis of Atlantic high pressure briefly lifts
northward, with another frontal boundary then expected to enter
the southeastern states early next week, which will shift
prevailing winds back to southwesterly.

Rip Currents: Breezy onshore winds developing early this afternoon
will combine with a lingering east-southeasterly ocean swell to
create a lower end moderate risk at the northeast FL beaches. Low
wave heights at the southeast GA beaches should keep the risk low
through Thursday, with a low risk also anticipated at the
northeast FL beaches on Wednesday and Thursday.

&&

.CLIMATE...
Issued at 435 AM EDT Tue Jun 25 2024

Record high temperatures through Wednesday at our designated
climate sites:

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

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG 101  74  99  74 /  20  10  40  20
SSI  95  78  90  77 /  20  10  30  20
JAX  98  73  95  75 /  50  40  60  20
SGJ  93  76  92  76 /  60  40  60  20
GNV  96  74  94  74 /  70  70  70  20
OCF  95  75  93  75 /  60  50  60  30

&&

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

AM...None.
&&

$$