Excessive Heat in Florida, August 26, 2023

Area Forecast Discussion
National Weather Service Tallahassee FL
1022 AM EDT Sat Aug 26 2023

...New UPDATE, MARINE...

...DANGEROUS HEAT EXPECTED TODAY...

.UPDATE...
Issued at 1008 AM EDT Sat Aug 26 2023

No major changes to the forecast was required. Rain chances for
the rest of this morning were trimmed back across our waters as
most of the overnight convection has cleared with remnant cloud
debris thinning out inland. The 12Z KTAE sounding shows a
moist/unstable profile under deep-layer NE flow and a pocket of
dry air aloft. These parameters support isolated to scattered
afternoon showers and thunderstorms this afternoon that aim to
develop along the seabreeze, but likely remain confined to the
I-10 corridor down to the coast. Storms will be capable of strong,
gusty winds given DCAPE values around 1000 J/kg. A severe
downburst or two cannot be ruled out, either.

The heat products currently in effect are on still on track. Observed
850-mb temperature is 20C, which is a daily record max for TLH,
per SPC sounding climo. Many locations stand a good chance of
reaching or exceeding 100 degrees (i.e., Tallahassee, Dothan,
Albany), especially if convection does not interfere. Some
locations may even go over/under a degree or two than the
official forecast. Regardless, widespread heat indices in excess
of 108 degrees are expected with much of the FL Panhandle poised
to reach 113+.

&&

.NEAR TERM...
(Today and tonight)
Issued at 314 AM EDT Sat Aug 26 2023

The center of the upper-level ridge begins to retreat westward
toward the SW US, though the eastward extension noses into the
southeast US. This will lead to a continuation of what seems to be a
never-ending heat wave for our neck of the woods. TLH reached 102
yesterday, which tied the record high. This was also above most
guidance yesterday. Thus, have opted to nudge a bit above guidance
for highs today. This yields highs of 100-103 for pretty much
everyone from Tallahassee to Albany westward with upper 90s
elsewhere We should see dew points mixing out a bit this afternoon
(and even went a bit below guidance), but it doesn't appear to be
enough to stave off dangerous heat indices. With heat index values
of 110-115 forecast, have issued an Excessive Heat Warning for much
of the Panhandle and western Big Bend. Have maintained the Heat
Advisory elsewhere for heat index values of 108-112. Please use
extreme caution if you have outdoor plans today. Drink plenty of
water, stay in the shade, and find air conditioning. Also, know the
signs of heat exhaustion and heat stroke.

The only form of heat relief will be in scattered thunderstorms that
will develop during the peak heating of the day along the sea
breeze. This will mostly be confined to the Florida counties. Given
a bit of dry air aloft, storms may produce gusty winds. DCAPE values
of 1000-1200 will lead to the potential of strong to maybe even
severe downburst winds with the stronger storms. Storms will fade in
the evening, and lows will only cool to the upper 70s to lower 80s.

&&

.SHORT TERM...
(Sunday through Monday night)
Issued at 314 AM EDT Sat Aug 26 2023

The upper ridge across the southeast US will weaken and retrograde
west as troughing over the northeast US digs further south and TC
Franklin moves northward in the western Atlantic. Also, a weak
frontal boundary will dip south into central and southern Alabama
into Monday night and hold to our west. Flow will be southerly
which will aid in more scattered coverage of diurnal convection
this period. Highs will be in the upper 90s to lower 100s this
period with portions of the area having heat indices in the
108-112 range.

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 314 AM EDT Sat Aug 26 2023

Attention turns to the south with the eventual track and evolution
of the tropical system in the western Caribbean. The break in the
ridge, along with a retrograding upper low in the northern Gulf,
should allow the system to move north rather quickly towards the
northern and northeast Gulf coast Tuesday night and Wednesday. As
of this morning, NHC gives this system a 60% chance of development
in the next 48 hours and a 90% chance of development in the next
7 days.

Since the system hasn't 'developed' yet, model solutions for the
track and intensity are fairly wide and uncertainty is high.
Once and if the system develops, this will greatly determine the
magnitude of impacts to the region. Its too early to pinpoint
specific impacts at this stage.

It is highly recommended to stay tuned to future forecasts and
latest updates. You can also check for updates at the NHC webpage at
www.hurricanes.gov along with hurricane preparedness tips at
www.noaa.gov/hurricane-prep

&&

.AVIATION...
(12Z TAFS)
Issued at 637 AM EDT Sat Aug 26 2023

Patchy fog has developed near VLD and DHN this morning and could
still develop near TLH in the next hour or two. MVFR to IFR vsbys
are possible at VLD and TLH. VFR conditions then resume for all
sites through the remainder of the TAF period. Scattered
thunderstorms will develop this afternoon near TLH and ECP, some
with gusty winds. Have maintained mention of VCTS for these sites.
Could be some fog near the end of the TAF period, but confidence
is too low for inclusion in this TAF cycle.

&&

.MARINE...
Issued at 1008 AM EDT Sat Aug 26 2023

Buoy 42039 is reporting slightly more elevated north winds and
seas compared to Buoy 42036 this morning, likely from the
influence of maritime convection moving across the southwestern
waters. Generally light winds and low seas will continue through
the weekend. Isolated showers and thunderstorms will gradually
become more numerous through the weekend into early next week. An
area of low pressure over the northwestern Caribbean Sea is being
monitored for potential development late in the weekend into early
next week as it slowly lifts north into the eastern Gulf of
Mexico. Marine interests should monitor the progress of this
system.

&&

.FIRE WEATHER...
Issued at 314 AM EDT Sat Aug 26 2023

High dispersions are expected across the much of the area this
afternoon due to high mixing heights of 6,500 to 8,500 feet.
Transport winds will be out of the northeast around 10-15 mph
today, though they will become more southeasterly late in the
afternoon across the Florida zones as the sea breeze advances
inland. Min RH values will range from the low 30s in the
southeast Alabama zones to the low 50s in the southeast Big Bend.
Scattered thunderstorms are expected this afternoon, mostly in the
FL zones, some of which will be capable of producing strong,
erratic winds. Temperatures will be near or above 100 for most
zones today with heat index values of 108 to 115. For Sunday and
Monday, transport winds will be lighter out of the south with
lower mixing heights. Thus, dispersions are expected to be good
both days. Chances for thunderstorms also increase each day.

&&

.HYDROLOGY...
Issued at 314 AM EDT Sat Aug 26 2023

The eventual evolution and track of the tropical system in the
western Caribbean will be the main driver of any hydro impacts
by midweek. Before this feature potentially impacts the area, we
will transition more into the diurnally driven shower and
thunderstorm regime this weekend. A weak frontal boundary does
make its way towards southern Alabama later this weekend which
will also aid to focus convection ahead of the tropical system.

Concerning the tropical system, appears that it will move through
on the quicker side which should limit riverine flooding though
some localized flash flooding could occur, especially in areas
that may receive heavy rainfall before its impacts arrive.

&&

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.

&&

.PRELIMINARY POINT TEMPS/POPS...
Tallahassee  100  77  98  76 /  40  20  40  20
Panama City   99  81  95  79 /  50  20  40  30
Dothan       100  77  99  74 /  20  10  50  30
Albany       100  77  99  74 /  20  10  50  40
Valdosta      98  76  98  74 /  10  10  30  20
Cross City    95  75  96  75 /  40  10  30  20
Apalachicola  95  81  92  79 /  50  20  30  40

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     FLZ007>009-016>019-028-029-034-118-128-134.

     Excessive Heat Warning until 8 PM EDT /7 PM CDT/ this evening
     for FLZ010>015-026-027-108-112-114-115-127.

GA...Heat Advisory until 8 PM EDT this evening for GAZ120>131-142>148-
     155>161.

AL...Heat Advisory until 7 PM CDT this evening for ALZ065>069.

GM...None.
&&

UPDATE...IG3
NEAR TERM...Young
SHORT TERM...Scholl
LONG TERM....Scholl
AVIATION...Young
MARINE...Scholl/IG3
FIRE WEATHER...Young
HYDROLOGY...Scholl