Area Forecast Discussion
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FXUS62 KTAE 280730

Area Forecast Discussion
National Weather Service Tallahassee FL
230 AM EST Sat Nov 28 2020

.NEAR TERM [Through Saturday Night]...

Cold front has entered our southeast Alabama counties with showers
and isolated thunderstorms along and behind the front. Further east,
patchy fog is occurring through the Florida panhandle into southern
Georgia. Expect the rain to continue moving eastward as the front
moves southeast with some isolated pockets of heavy rainfall. Lift
begins to decrease towards mid morning as the front nears the
western Florida Big Bend so an overall decrease in rain chances will
occur towards the afternoon hours as the front makes it into the
northeast Gulf. Drier air on northerly flow will advect in behind
the front as the front stalls in the northern Gulf Saturday evening.
Attention then turns upstream to a closed low moves into the
southern Plains and a surface low develops on the stalled front in
the western Gulf. Rain chances re-enter our western counties
overnight Saturday night as overrunning showers develop north of the
stalled boundary.

.SHORT TERM [Sunday through Sunday Night]...

Some uncertainty remains in this portion of the forecast with
regards to severe weather potential. The upper low moving over the
Red River Valley Sunday will become absorbed in a southward moving
shortwave trough moving down from the northern Plains. It will take
on a negative tilt with plenty of diffluence overspreading the
surface low pressure system. The surface low will move northeast
into southern Louisiana/Mississippi Sunday afternoon and eastern
Tennessee Sunday night. The stalled boundary to our south will move
north as a warm front ahead of a strong cold front expected to move
through much of our CWA Sunday night.

Wind profiles ahead of the system will strengthen with bulk shear
values of 50-60 knots by late morning Sunday which is more than
conducive to support severe weather. Area hodographs become long and
curved depicting the increase in low level winds and good veering of
the winds in the low levels. SRH values increase as well on the
order of 300-600 m2s2 in the vicinity of the warm front. Forecasting
the instability and the northward progression of the warm front and
warm sector remains a challenge with spread between the
deterministic and hires models. The GFS and a few hires models keep
the instability more offshore whereas the NAM and ECMWF more the
warm front further northward and thus the instability further

Damaging winds and isolated tornadoes are the main threats with this
system. The tornado threat will be tied to the warm front and how
far north the front will get and the extent of the warm sector.
Damaging winds will mainly be tied to the cold front, although that
threat will also accompany any supercells that can develop in the
warm sector. With the uncertainty in mind, SPC continues the
marginal risk through the area Sunday and Sunday night. However, if
confidence grows in greater instability making it further inland,
SPC may raise the threat level in later outlooks.

.LONG TERM [Monday through Saturday]...

Monday and Monday Night:

The main story will be much colder temperatures in the wake of a
cold frontal passage Monday morning, along with breezy conditions.
A few residual showers are possible during the morning from the
FL Big Bend into the I-75 corridor of Southwest GA, otherwise a dry
day is on tap, with widespread stratocumulus below the low-level
frontal inversion. Model soundings indicate the boundary layer
extending to around 4k ft, under strong cold air advection, with
925 hPa temperatures falling 10-15 deg C throughout the day!
Expect a slow rise in temperatures, only rebounding several degrees
off morning lows, ranging from the mid-50s in Southeast AL to the
mid-60s in the FL Big Bend. Given the aforementioned height of
the boundary layer, momentum transfer should yield wind gusts in
the 20-30 mph range out of the northwest. The combination of
considerable cloudiness, below normal temperatures, and gusty
winds will make for a chilly day!

The coldest night of the fall season is in store come Tuesday
morning, with low temperatures forecast to range from the upper
20s in SE AL to the low-mid 30s in the FL Big Bend. Given the
continued cold air advection, the boundary layer will likely not
fully decouple, keeping the wind elevated Monday Night. This,
along with Relative Humidity values well below saturation, is
expected to preclude the development of a widespread frost.

Tuesday through Saturday:

This period will feature continued below average temperatures,
with a shot at frost Wednesday morning, followed by the next
chance of precipitation centered on Friday.

High pressure on the order of 1023 hPa will be centered in the
Tri-State area Wed morning. This should promote light winds
within a dry air mass. Relative Humidity values may fall short
for a widespread frost, but certainly more sheltered locations
will be susceptible, with low temperatures bottoming out in the
upper 20s to lower 30s away from the gulf coast. It`s worth
noting that the average date of the first frost occurs in the
first to second week of November away from the gulf coast. So
far this year, we came close on Nov 3rd with low temperatures
down to 35-36 F at ABY, DHN, and VLD, but the air mass was
too dry to promote widespread frost (look for RH values close
to 100 pct).

Looking ahead to the next system centered on Friday, there is
considerable uncertainty, with little run to run consistency
amongst the operational models and ensembles. Any impacts from
this system will be largely determined on where the northern/
southern streams phase. The latest EC phases the streams over
the lower plains, while the GFS is much farther east in the
mid-Atlantic states. For now, it`s too early to get into any
specifics on heavy rain/severe weather potential. Rainfall is
centered on late Thu into early Sat, with Pops increasing to
50 pct during this time frame, all of which will be refined
much more as we draw nearer.


[Through 06Z Sunday]

An area of showers will move from southern Alabama eastward through
southern Georgia and north Florida overnight. Ahead of this rain,
flight restrictions are noted in fog and low cigs. There could be
tempo improvement as the rainfall moves over but then restrictions
to redevelop behind the rain. A mixture of MVFR to LIFR is expected
through the overnight into tomorrow morning with a slow improvement
to MVFR towards the afternoon as rain continues to push south into
the Gulf waters. Tomorrow night a redevelopment of IFR conds appear



Southerly winds are expected to increase to advisory levels
on Sunday, and continue to be elevated in the wake of a cold
frontal passage Sunday Night into Tuesday. Seas will respond
accordingly, peaking between 8 and 10 feet late Monday into
early Tuesday over the offshore waters. Northwest winds may
briefly gust to gale force during this time frame as well.
A Small Craft Advisory is in effect starting Sunday afternoon.
Winds and seas decrease late Tuesday into Wednesday, only to
increase again late in the week in advance of the next cold
front. Some sea smoke is also possible Tuesday or Wednesday
morning as a much colder air mass moves over the relatively
warmer gulf waters.



No hazardous fire weather conditions are expected. A cold front and
associated showers will move through the area today with the front
stalling to our south in the Gulf waters. Sunday has a chance for
severe weather as a more potent cold front arrives Sunday night and
the stalled front returns northward through the day. Heavy rainfall
is also possible Sunday.



Rainfall amounts through day 7 will average 2-4 inches. Flooding
is not expected.



Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur (while following all local, state, and CDC guidelines) by
calling the office or tweeting us @NWSTallahassee.



Tallahassee   73  61  72  54  62 /  70  20  60  80  20
Panama City   75  64  74  52  60 /  50  30  80  80  10
Dothan        71  58  68  48  54 /  40  30  90  80  10
Albany        70  58  68  52  58 /  70  20  80  90  10
Valdosta      70  58  72  56  63 /  70  20  40  70  20
Cross City    76  61  77  61  68 /  50  20  20  70  40
Apalachicola  75  64  75  55  63 /  50  20  50  80  10


GM...Small Craft Advisory from 7 PM Sunday to 1 PM EST Tuesday for
     Apalachee Bay or Coastal Waters From Keaton Beach to
     Ochlockonee River FL out to 20 Nm-Coastal waters from
     Suwannee River to Keaton Beach FL out 20 NM.

     Small Craft Advisory from 1 PM EST /noon CST/ Sunday to 1 PM EST
     /noon CST/ Tuesday for Coastal Waters From Ochlockonee
     River to Apalachicola Fl out to 20 Nm-Coastal waters from
     Mexico Beach to Apalachicola FL out 20 NM-Coastal waters
     from Mexico Beach to Okaloosa Walton County Line FL out 20
     NM-Waters from Suwannee River to Apalachicola FL from 20 to
     60 NM-Waters from Apalachicola to Mexico Beach FL from 20
     to 60 NM-Waters from Mexico Beach to Okaloosa Walton County
     Line FL from 20 to 60 NM.



NEAR TERM...Scholl
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