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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KCAE 190738
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
338 AM EDT Sat Oct 19 2019

.SYNOPSIS...
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Tropical Storm Nestor will move inland over the Florida Panhandle
this morning, move across Georgia this evening then cross
eastern South Carolina tonight as it becomes a post-tropical
cyclone. The system will bring potentially significant rainfall
to the area along with windy conditions. A brief break in the
weather is expected Monday followed by another cold front
crossing the area Tuesday.
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&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Mid level clouds will begin increasing across the area this
morning and lowering as the air mass moistens with the approach
of Tropical Storm Nestor. Rain showers will move into the CSRA
this morning, but onset of any rainfall may be delayed slightly
due to the drier air currently in place. The center of Nestor
is expected to track across Southern Georgia through the day
today and then across the Midlands this evening as it
transitions into a post-tropical low. This system will bring
significant rainfall along with windy conditions, with the
greatest impacts later this afternoon and evening. With peak
precipitable water values exceeding 2 inches and a deep warm
layer aloft fueling high rainfall rates, expect rainfall totals
around 2 inches across the northern Midlands to near 3 inches in
the south. The system will be progressive which should limit
the flood threat, but there is the possibility of higher
amounts with localized flooding due to runoff. Instability
should remain limited because of widespread rain and a lack of
time for the development of significant surface-based
destabilization because of the fast system movement, but wind
shear will be high so cannot rule out a few stronger cells with
a marginal threat of tornadoes, especially across the eastern
Midlands. A model blend supports most likely peak wind gusts 30
to 40 mph, mainly in the southern CSRA and east. There is some
concern of stronger wind because of the accelerating storm
movement and some possibility of greater instability, but based
on the forecast storm track with the greater instability
forecast to stay well east of the forecast area believe this
threat is low. However, a Lake Wind Advisory has been issued due
with the expectation of frequent gusts greater than 25 kts.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
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Post Tropical Storm Nestor is forecast to cross southeast GA and the
Coastal Plain of SC tonight then move off the NC coast Sunday. This
system will bring significant rainfall along with breezy conditions.
Categorical pops in order tonight as the system crosses eastern SC.
Precipitation should lift northeast of the Midlands during the early
morning hours Sunday.

The models depict strong lift associated with a 40-knot southeast
h85 jet and negative tilt h5 shortwave trough. A model blend
supports general rain totals of 1.5 to 2.0 inches in the Piedmont to
2 to 3 inches in the eastern Midlands and lower Central Savannah
River Area. The system will be progressive which should limit the
flood threat. Precipitable water forecast to exceed 2 inches so
there may be high rainfall rates with some possibility of localized
flooding. Instability should remain limited because of widespread
rain and a lack of time for the development of significant surface-
based destabilization because of the fast system movement. The
models keep surface-based LI values above zero except possibly in
the extreme east part where both the GFS and NAM show values near
-1 this evening. Shear will be high but we believe there is a
 diminished tornado threat because of little instability. A
 model blend supports most likely peak wind gusts around 30 mph,
 mainly across the eastern Midlands. There is some concern of
 stronger wind because of the accelerating storm movement and
 some possibility of greater instability, but based on the
 forecast storm track with the greater instability forecast to
 stay well east of the forecast area we believe this threat is
 low.

Dry ridging is forecast to be in the region Sunday and Sunday
night.

Low temperatures tonight will be in the mid 50s west to low 60s
east. High Sunday should be in the mid 70s to around 80 as skies
clear and winds diminish. Lows Sunday night are expected to be in
the 50s.
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&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
The models depict a progressive fall weather pattern during the
medium-range period. Ridging is forecast to move off the coast
early Monday ahead of an approaching cold front. The front is
expected to cross the area Tuesday. The models depict the
deepest moisture ahead of the front Monday night into early
Tuesday. The dry air mass behind the front should dominate
Wednesday and Thursday. Moisture may increase again ahead of
sharpening upper troughing and as associated cold front Friday.
The GFS and ECMWF MOS support near-normal temperatures during
the period.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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VFR conditions through tonight. Restrictions expected to
develop later this morning and continue through the end of the
TAF period in widespread rainfall. Windy conditions this
afternoon and evening.

Moisture and clouds will increase from the south as Tropical
Storm Nestor approaches the northern Gulf Coast tonight, moving
across Georgia and South Carolina today as it becomes a post-
tropical cyclone. Ceilings expected to lower overnight, but
should remain VFR through at least 11-13Z, with a lot of dry air
still in place at the surface. Expecting MVFR ceiling
restrictions by mid morning at all of the terminals and IFR
ceilings and visibility restrictions by 15-17Z at all of the
terminals. AGS/DNL terminals will drop first. Potential for
moderate to heavy rainfall will increase this afternoon and
through the end of the 24-hr TAF period as the deepest moisture
and forcing associated with Nestor sets up over the area.
Northeasterly winds will also be increasing through the day
with gusts up to 20 knots by midday. With 2000 AGL winds
forecast to be 35-45 kts and 5000 AGL winds 45-50 kts,
approaches and departures will be challenging with strong LLWS.

EXTENDED AVIATION OUTLOOK...Showers and associated restrictions
with windy conditions through Sunday morning, as a post
tropical system moves across southern GA and the eastern
Carolinas. A cold front will cross the region Tuesday bringing
showers/tstms and associated restrictions Monday night into
Tuesday.
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&&

.CAE WATCHES/WARNINGS/ADVISORIES...
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GA...Lake Wind Advisory from 2 PM this afternoon to 2 AM EDT Sunday
     for GAZ040-063>065-077.
SC...Lake Wind Advisory from 2 PM this afternoon to 2 AM EDT Sunday
     for SCZ016-018-020>022-025>031-035>038-041-115-116.
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&&

$$