Area Forecast Discussion
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048
FXUS62 KTAE 260149
AFDTAE

Area Forecast Discussion
National Weather Service Tallahassee FL
949 PM EDT Tue Sep 25 2018

.UPDATE...

No mentionable updates were made to the overnight forecast.

&&

.PREV DISCUSSION [743 PM EDT]...

.NEAR TERM [Through Tonight]...

Deep ridging will continue through tonight with high pressure
centered over the Atlantic and southerly flow across the CWA.
Similar to yesterday, convection for the remainder of the afternoon
should generally be from TLH into far southwest GA and westward.
While a weak east coast seabreeze has formed, with drier air across
our eastern counties, any convection that makes it into the Suwanee
Valley should be more limited. Showers and thunderstorms are
expected to diminish quickly after sunset with the primary focus
overnight across the marine area and along the western Big
Bend/Florida Panhandle coast. As with the pattern we have been in,
lows will remain above average in the low to mid 70s.


.SHORT TERM [Wednesday Through Thursday Night]...

On Wednesday, a frontal boundary that moves into the Tennessee
Valley while the mid-level ridge axis approaches the area from the
south, locking in a mean southwesterly flow. This will lead to
greater coverage of precip across the region, with PoPs 50-70 pct.
The only exception is the Big Bend north into portions of south-
central GA, where greater subsidence will subdue activity, with
PoPs 30-50 pct. There is model disagreement with regard to the
degree of buoyancy, but with Mixed Layer CAPE in excess of 1.5k
J/kg and 500 hPa winds approaching 25 kts, localized strong
thunderstorm wind gusts are possible mainly northwest of the Big
Bend.

With a southwesterly flow maintaining a moist low-level air mass,
low clouds and fog may develop Wednesday night, especially north of
I-10.

With the approach of a long wave trough and the aforementioned
frontal boundary in the Tennessee Valley on Thursday, mean southwest
flow continues, but there will be a tendency for confluence in the
flow as the mid-level ridge remains just south of the area. This
will limit precip chances south of the greater synoptic scale
forcing tied to the frontal boundary. Therefore, PoPs remain 30
to 60 pct, lowest in the Suwanee Valley and highest in southwest
AL. Compared to Wednesday, increased cloud cover may limit
instability, so while localized strong thunderstorm wind gusts
remain possible mainly northwest of the Big Bend, coverage may be
more limited.

High temperatures on Wednesday and Thursday will be in the upper 80s
to lower 90s. Low temperatures Wednesday night and Thursday night in
the low to mid-70s. Heat indices on Wednesday will be around 100
degrees.


.LONG TERM [Friday Through Tuesday]...

With the mid-level flow increasingly paralleling the front, it will
stall and undergo frontolysis in the vicinity of the region in the
Friday through Monday time frame, as the subtropical ridge gradually
builds across the area. Despite a ridge of high pressure leading to
ageostrophic northeast flow down the east coast, southeasterly flow
across our area will present little if any opportunity for an air
mass change, with continued above average temperatures and humidity
expected through the period. PoPs 20-40 pct on Friday decrease 20-30
pct Saturday through Tuesday, due to increasing subsidence and the
lack of forcing, most of which will be attributed to the seabreeze
circulation. High temperatures in the upper 80s to lower 90s and low
temperatures in the upper 60s to lower 70s through the period, which
will favor daily means of several degrees above normal. Heat
indices Friday and Saturday will be around 100 degrees.

As we near the end of September 2018, we can now project Tallahassee
is on track to have the second warmest September, with the period of
record (POR) dating back to 1896. The warmest September was 1925 with
a mean of temperature of 84.0 and the third warmest was 2016 with a
mean of 81.9 degrees.


.AVIATION [Through 00Z Thursday]...

IFR ceilings and visibilities are expected at DHN overnight,
otherwise VFR should prevail at all terminals through the TAF
(outside of storms). Afternoon storms will be most likely at ECP,
DHN, and ABY on Wednesday.


.MARINE...

Southeast winds tonight will shift to the south for Wednesday and
Thursday, shifting to the east by Friday night and continuing
through Sunday, generally 15 knots or less. Seas 1 to 2 feet
tonight through Thursday night, increasing 2 to 3 feet Friday
through Sunday. Winds and seas will be higher in the vicinity of
thunderstorms.


.FIRE WEATHER...

Outside of the possibility of low dispersions across portions
of the Florida panhandle on Wednesday, hazardous fire weather
conditions are not expected.


.HYDROLOGY...

Areas approximately west of Tallahassee are forecast to receive 1-
1.5" of rain through the next few days with the approach of the cold
front. Elsewhere, less than an inch is expected. Coastal sea breeze
convection is possible each afternoon and it looks like Franklin
County, FL may have received about 3-4 inches of rain from that on
Monday. Although widespread flooding is not expected, isolated areas
of flooding of low lying and flood prone areas would be possible if
storms move over the same areas multiple days in a row. With regard
to rivers and streams, they`rE expected to remain below action
stage through the period.


.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   72  90  72  90  72 /  20  60  40  50  20
Panama City   74  88  74  87  73 /  20  50  40  40  30
Dothan        71  90  71  87  70 /  10  70  50  60  20
Albany        74  92  73  90  73 /  20  60  50  50  20
Valdosta      72  92  72  90  71 /  10  40  20  40  20
Cross City    74  92  73  92  73 /  10  40  20  30  20
Apalachicola  75  88  75  87  75 /  20  50  30  40  20

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&

$$

UPDATE...Harrigan
NEAR TERM...Fieux
SHORT TERM...LF
LONG TERM...LF
AVIATION...Harrigan
MARINE...LF
FIRE WEATHER...LF
HYDROLOGY...LF



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