934
FXUS62 KJAX 081228
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
828 AM EDT Sat Jun 8 2024

...New UPDATE...

...NEAR RECORD HEAT THIS WEEKEND...

.UPDATE...
Issued at 817 AM EDT Sat Jun 8 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

Continued hot and mostly dry today except for 20-35% chances of
afternoon showers and possibly a rouge thunderstorm roughly along
and south of a St. Augustine to Gainesville line. This is where
near climo PWATs of 1.5 inches will coincide over an unstable low
level airmass where sea, lake and river boundary collisions focus
roughly between 3 pm - 8 pm. Elsewhere, post-frontal dry air will
bring mostly dry and sunny skies as high temps soar into the mid
to upper 90s making for heat index values in the 100-106 deg range
across NE FL where higher moisture will linger with heat index
values 95-100 deg near and north of the I-10 corridor where drier
air will mix down this afternoon (dew pts mid 50s to near 60).

As a reminder, local heat advisory criteria is for the heat index
to reach 108-112 degrees F.


&&

.SYNOPSIS...
Issued at 401 AM EDT Sat Jun 8 2024

Overnight surface analysis depicts a weakening frontal boundary
along the FL/GA border, with weak pressure pattern in place on
either side of the boundary across the southeastern states.
Aloft...a weakening trough was progressing southeastward across
our area, with ridging building over eastern Texas and the lower
Mississippi Valley in the wake of this trough. Latest GOES- East
derived Total Precipitable Water imagery indicates that a much
drier air mass continues to advect southeastward into our region,
with PWATS falling below one inch for locations north of Waycross
in southeast GA, while values remain around 1.5 inches across
north central FL. Only a few patches of mid-level clouds were
migrating across our skies along and ahead of the weakening
frontal boundary, with fair skies otherwise prevailing throughout
our region. A light west- southwesterly breeze prevails to the
south of the frontal boundary across northeast and north central
FL, where temperatures at 08Z generally remain in the 75-80 degree
range, with dewpoints in the 70s. North of this boundary, a light
northwest to northerly breeze prevails, with cool air advection
dropping temperatures to the upper 60s and lower 70s for inland
locations from Waycross northward, while dewpoints were falling to
the 55-60 range for locations to the northwest of Waycross, while
values elsewhere remain in the 65-70 range.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 401 AM EDT Sat Jun 8 2024

Ridging aloft will build eastward along the northern Gulf coast in
the wake of the departing trough today, resulting in rising
heights and a drier northerly flow aloft. The departing trough
will allow the frontal boundary to dissolve along the Interstate
10 corridor this afternoon, with a weak pressure pattern allowing
both the Gulf and Atlantic sea breezes to develop late this
morning and move inland this afternoon. Just enough moisture will
be in place across north central and coastal northeast FL to allow
for isolated to widely scattered, low-topped convection to
develop late this afternoon as mesoscale boundaries such as the
St. Johns River breeze collide with the Atlantic and Gulf coast
sea breezes, with this activity being confined for locations south
of I-10.

The drier air mass will allow dewpoints to remain in the 50s
today for inland locations along and north of I-10, while
dewpoints elsewhere inland fall through the 60s this afternoon,
which will help keep heat index values below Advisory levels
across our area this afternoon. This unseasonably dry air mass and
plenty of sunshine will again boost high temperatures up to near
daily records (see Climate section below for details), with mid to
upper 90s expected again nearly area-wide. Breezy onshore winds
developing behind the inland moving Atlantic sea breeze boundary
will likely drop temperatures back to the 80s by late afternoon
for coastal locations, but rebounding humidity values behind this
boundary will push heat index values to the 100-105 degree range
during the early to mid afternoon hours along the coast. The
increasingly dry and subsident air mass should keep convection
that develops this afternoon transient and generally weak in
nature, with only briefly heavy downpours and lightning strikes
being the primary threats today within southern portions of the
St. Johns River Basin and north central FL.

Any convection that manages to develop for locations south of the
I-10 corridor late this afternoon will quickly diminish around or
shortly after sunset. Fair skies, decoupling winds, and a
subsident air mass could promote patchy fog development during the
predawn and early morning hours on Sunday, mainly for locations in
the Suwannee Valley and north central FL. Lows will fall to the
mid and upper 60s across inland southeast GA and northern portions
of the Suwannee Valley, ranging to the low and mid 70s at coastal
locations.

&&

.SHORT TERM...
(Sunday through Monday night)
Issued at 401 AM EDT Sat Jun 8 2024

Dry conditions continue into Sunday ending the week with highs
reaching well into the upper 90s area wide. Heat index values will
be near heat advisory levels along the St Johns river basin to the
NE FL coast generally to the south of Jacksonville ranging 102-106
degrees. Overnight temperatures will drop into the low 70s,
keeping warmer along the coast. Monday morning a cold front will
begin making its way into the region from the north but, with weak
short waves aloft and PWAT values of 1.3 to 1.7 inches, chances
will be around 30-40% for scattered storms and precipitation
focused in the afternoon and evening hours. Daytime temperatures
will be in the low to mid 90s for SE GA and mid to upper 90s with
some areas closer to the coast possibly seeing 100 degrees for NE
FL. Heat indices will be around 100 degrees along and east of US
17. Temperatures will cool overnight into the low to mid 70s
inland sticking in the upper 70s along the coast.

&&

.LONG TERM...
(Tuesday through Saturday)
Issued at 401 AM EDT Sat Jun 8 2024

The cold front stalls along the FL/GA border Tuesday morning and
rebounds into SE GA Tuesday night becoming a stationary front for
the rest of the week. Moisture begins to pile in Wednesday evening
increasing PWAT values above 2 inches into next weekend. Expect
showers and thunderstorms each day with the highest percentages in
the afternoon due to diurnal heating and sea-breeze convergence.
Temperatures will cool into the mid to upper 80s by Thursday.

&&

.AVIATION...
(12Z TAFS)
Issued at 705 AM EDT Sat Jun 8 2024

Westerly winds prevail this morning 4-8 kts with a frontal passage,
then winds will transition at coastal terminals early this
afternoon as the east coast sea breeze shifts inland, with gusts
near 15 kts into the early evening. The best chance of afternoon
showers or maybe a lone storm will occur near GNV to SGJ 19z-23z
as drier air will limit rain chances today. After sunset, winds
will weaken and transition back to WSW with a land breeze at
coastal terminals to near calm inland. Included TEMPO IFR after
07z for VQQ for shallow ground fog and based on persistence.

&&

.MARINE...
Issued at 401 AM EDT Sat Jun 8 2024

A weakening frontal boundary pushing across the GA waters early
this morning will stall and dissipate this evening across the
northeast FL waters. A weak pressure pattern will prevail across
our local waters this weekend, with prevailing offshore winds
during the morning hours, followed by afternoon sea breezes near
shore and evening wind surges offshore. Winds will remain below
Caution levels through the period, with seas of 2-4 feet
prevailing both near shore and offshore.

A cold front will then approach our local waters from the
northwest on Monday, resulting in scattered showers and
thunderstorms during the late afternoon and evening hours. This
front will stall across our region, with a surge of tropical
moisture pushing northward from the Caribbean Sea and the Gulf of
Mexico over our area, resulting in waves of widespread showers and
thunderstorms throughout our local waters beginning on Tuesday
afternoon and continuing for the rest of the week.

Rip Currents: Developing onshore winds this afternoon will combine
with a lingering east southeasterly ocean swell to keep a lower
end moderate risk in place at area beaches. Breezy offshore winds
on Sunday will delay the development of the afternoon sea breeze,
with low wave heights likely resulting in a low risk at all area
beaches. This low risk should continue into early portions of the
upcoming week.

&&

.FIRE WEATHER...
Issued at 401 AM EDT Sat Jun 8 2024

A drier air mass filtering into our region will result in
minimum relative humidity values falling to critical thresholds
this afternoon for inland locations along and north of Interstate
10, while values fall to around 30 percent for inland locations
south of I-10. West-southwesterly transport winds will remain
sustained around 10 mph today and will combine with elevated
mixing heights to create good daytime dispersion values at most
locations today. Breezy onshore surface winds will develop by the
mid to late afternoon hours along the I-95 corridor in the wake of
the Atlantic sea breeze boundary, with breezy westerly surface
winds expected late this afternoon across north central FL in the
wake of the Gulf coast sea breeze. The dry air mass will linger
across our region on Sunday, and westerly transport winds will
strengthen after sunrise, becoming breezy during the afternoon
hours, creating marginally high to high daytime dispersion values
at most locations. These breezy westerly transport winds will
continue on Monday and will combine with elevated mixing heights
to create high to very high daytime dispersion values, especially
for locations along and east of I-75 during the afternoon hours.

Also of note, NWCG Predictive Services has NE FL and coastal SE
GA highlight under a Moderate to High wildfire risk today and
Moderate to High for SE GA and NE FL on Sunday due to the hot
weather and dry conditions.

&&

.CLIMATE...
Issued at 401 AM EDT Sat Jun 8 2024

Record high temperatures at our designated climate sites through
Monday:

   June 8      June 9       June 10
              -----------------------------------
Jacksonville   99/1993     101/1872     100/1954
Gainesville    98/1907     99/1907      99/1899
Alma, GA       100/1993    99/1993      103/1954
Craig Airport  97/1985     97/2006      99/2006

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  96  67  97  73 /   0   0   0  10
SSI  93  74  96  77 /  10   0   0  10
JAX  98  73  99  73 /  10   0   0   0
SGJ  95  76  98  75 /  10  10  10   0
GNV  98  72  97  70 /  20   0  10   0
OCF  97  73  96  73 /  30  10  20   0

&&

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

$$