632 
FXUS62 KJAX 261334
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
934 AM EDT Wed Jul 26 2023

...New UPDATE...

.UPDATE...
Issued at 919 AM EDT Wed Jul 26 2023

A weak pressure pattern was across the local area this morning
with satellite imagery showing a weak low offshore of the local
Atlantic coast with a few spotty showers and isolated storms.
Aloft, a weak COL region extended across the FL panhandle with a
mid level ridge axis extending across the FL peninsula pivoting
northward to extend across the Carolinas tonight. The morning 12z
JAX RAOB still showed a saturated airmass across NE FL and the SE
GA coast with PWAT over 1.8 inches, with recent satellite showing
PWAT below 1.7 inches from a Jesup to Live Oak line. 

Very weak ESE steering flow < 5 kts and mostly clear skies will 
enable more dominant, but slow moving, east coast, river and lake
breezes to set-up and drift inland by early afternoon, triggering
spotty showers and isolated storms as airmass convective temps 
near 88 degF are achieved. Through the afternoon, convection will
shift inland (westward) with the bulk of late afternoon and 
evening storms focused west of the Highway 301 corridor and south 
of the I-10 corridor where deeper moisture will coincide with low 
level boundary mergers. The low offshore is expected to further 
weaken with a slight WNW drift into tonight, with some more 
nocturnal showers/storms developing near the SE GA Thursday 
morning. 

The main convective hazard today will be localized heavy rainfall
given slow storm motion, with a chance of a few isolated strong
storms late afternoon and early evening across inland along boundary
mergers. Stronger storms will be capable of wet downburst winds 
40-50 mph. 

Max temps will top out in the low/mid 90s well inland to near 90
along the coast before the east coast sea breeze shifts inland.
Heat index values will near 105. 

&&

.NEAR TERM...
Issued at 342 AM EDT Wed Jul 26 2023

With southerly steering flow, both the Atlantic and Gulf sea
breezes will form and push inland today. Scattered showers and
thunderstorms will develop over northeast Florida along the sea
breeze boundaries, while drier, more subsident air inhibits 
thunderstorm development over most of southeast Georgia. The sea 
breezes will likely collide near US-301 in north central Florida, 
increasing coverage and intensity chances as storms continue to 
move westward through the evening. Surface based CAPE over north 
central Florida is forecast to approach 1,500-2,000 J/kg this 
afternoon as inland temperatures rise into the lower to mid 90s, 
with most of the beaches staying just below 90 degrees. Despite 
decent CAPE today, shear and lapse rates are unimpressive, however
a couple strong thunderstorms will be possible mainly near I-75 
in the late afternoon. Any strong thunderstorm developments will 
be capable of producing gusty winds and locally heavy downpours. A
few models are indicating isolated convection lingering for a 
couple hours after sunset near the Suwannee valley, but overall
activity will die down quickly with the loss of diurnal heating. 

&&

.SHORT TERM...
(Thursday through Friday night)
Issued at 342 AM EDT Wed Jul 26 2023

Deep-layered Atlantic ridging centered near Bermuda will 
extend its axis across the southeastern states on Friday. 
This ridge will direct an inverted trough and Tropical 
Upper Tropospheric Trough (TUTT) currently positioned to the 
north of the southeastern Bahamas westward towards the FL 
Atlantic coast by Thursday night and Friday morning. In 
advance of this approaching TUTT feature, a subsident air mass 
will limit afternoon and evening convective coverage to 
isolated or widely scattered at best across inland locations, 
with most activity occurring where the inland moving Atlantic 
and Gulf coast sea breezes collide during the late afternoon 
and early evening hours. This collision will take place along 
and west of the U.S. Highway 301 corridor on Thursday 
afternoon, with activity moving west of the Interstate 75 
corridor by the early evening hours. Less convective coverage 
will allow inland highs to climb to low and mid 90s, with 
coastal highs remaining closer to 90 as onshore winds become 
breezy during the early afternoon hours following the passage 
of the sea breeze. Maximum heat index values are expected to 
reach the 100-105 range, as the more subsident air mass allows 
dew points to mix down to the upper 60s across inland southeast 
GA and the lower 70s for inland locations in northeast and north 
central FL. 

The forecast becomes more uncertain as the weak inverted trough/ 
TUTT feature approaches the FL Peninsula during the overnight 
hours, moving south of our area and into the eastern Gulf of 
Mexico by Friday evening. Although this system is not expected to 
organize into a coherent tropical cyclone, it will bring a surge 
of deeper tropical moisture across our area, with PWAT values 
rising above 2 inches at most locations by early Friday afternoon. 
Scattered low-topped convection should approach the northeast FL 
coast during the overnight and predawn hours, with numerous showers 
and a few embedded thunderstorms expected to cross the I-95 corridor 
during the morning and early afternoon hours, with activity then
crossing the I-75 corridor during the rest of the afternoon. 
Convective coverage should remain scattered across southeast GA, 
which will be closer to the deep-layered Atlantic ridge axis and 
associated subsidence. Highs on Friday should be held to the upper 
80s at coastal locations due to breezy onshore winds and an early
start to shower activity, with lower 90s forecast for most inland 
locations. 

Deep-layered flow will then shift to southerly on Friday night as
the inverted trough / TUTT move further westward across the Gulf 
of Mexico. Convection may re-ignite in the unstable air mass over
the Atlantic waters overnight, with some low-topped convection 
possibly moving onshore along the northeast FL coast overnight.
Lows on Thursday and Friday nights will range from the mid 70s 
inland to around 80 at coastal locations.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 342 AM EDT Wed Jul 26 2023

Deep-layered ridging in place across the southeastern states will 
shift slowly southward late this weekend as troughing digs over 
New England. Deep-layered southerly flow on Saturday will veer to 
westerly on Sunday. Scattered to numerous afternoon and evening 
showers and thunderstorms will develop along inland moving sea 
breezes this weekend. Highs will begin to gradually climb as 
convective coverage becomes diurnal in nature, mid/upper 90s 
forecast at inland locations and low/mid 90s at coastal locations. 
Heat index values will climb to around 105 degrees on Saturday and 
may approach Heat Advisory criteria (108-112 degrees) by Sunday 
afternoon. Lows this weekend will continue to only fall to the 
mid 70s inland and around 80 at coastal locations. 

Ridging aloft will then shift south of our area by Monday afternoon 
as a frontal boundary attempts to push southward through the 
Carolinas. Meanwhile, the "Heat Wave" ridge that will be in place 
over the Rockies this weekend will gradually shift eastward towards 
the Plains states by early next week. This weather pattern will 
create an unstable northwesterly flow pattern across our region, with 
scattered to numerous afternoon and evening thunderstorms forecast
on Monday and Tuesday, especially for inland northeast and north
central FL. Highs will generally climb to the mid/upper 90s inland
and the low/mid 90s at coastal locations, with Heat index values 
likely rising to the 108-112 degree range nearly area-wide early 
next week.

&&

.AVIATION...
(12Z TAFS)
Issued at 734 AM EDT Wed Jul 26 2023

Prevailing VFR conditions through 18z with light and variable
winds < 5 kts increasing to light easterly into the afternoon as
the more dominant east coast sea breeze develops and presses
inland. Continued to include VCTS at NE FL terminals between 
18-22z with TEMPO TSRA included at GNV between 20-24z. Lower
potential for rain near SSI today, so continued to refrain 
from VCSH/TS in the prevailing TAF for now. ESE winds develop 
into the afternoon and evening as the east coast sea breeze
presses inland with gusts 10-15 mph possible at coastal 
terminals into the early evening before winds further 
weaken after sunset. Light SE winds develop overnight tonight
with increasing low level clouds at coastal terminals 
through daybreak Thu morning. 

&&

.MARINE...
Issued at 342 AM EDT Wed Jul 26 2023

The stalled front to the northwest of the Georgia waters will
dissipate tonight. Atlantic high pressure ridging over the 
Florida peninsula will lift northward into the coastal waters on 
Wednesday and remain over the waters through the weekend. East- 
southeasterly flow with isolated to widely scattered showers and 
storms prevail mid-week into the weekend.

Rip Currents: A moderate risk of rip currents will exist at the 
NE FL and SE GA beaches today through the end of the week as 
southeasterly flow builds. 

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  93  73  95  73 /  10   0  20  20 
SSI  89  79  90  81 /  10   0  10  40 
JAX  91  76  92  74 /  30  10  30  50 
SGJ  88  76  90  78 /  30  10  20  50 
GNV  91  74  93  73 /  50  20  50  50 
OCF  91  74  93  73 /  60  30  40  50 

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&

$$