Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 241939
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
339 PM EDT SAT SEP 24 2016

.SYNOPSIS...
A weak cold front slides southward across the area through this
evening. A much stronger cold front will cross late Monday,
setting us up with more autumn-like temperatures next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 3 PM Saturday...

Quiet weather continues as a weak cold front slides south of the
area this evening, with little fanfare. High pressure over the
Great Lakes ridges south and east down the eastern slopes of the
Appalachians tonight and Sunday. This will set up an inverted
surface trough just west of the mountains later tonight and
Sunday. The main effect of this will be to allow some low level
moisture and clouds east of the mountains to advect westward into
the mountains later tonight, as low level flow turns more
easterly. Models tries to spit out some very low and spotty QPF
in the mountains tonight, but not buying into this with shallow
moisture and building heights. While noting there is a question as
to whether these clouds may reach the I79 corridor later tonight
if the winds remain more northeasterly...we look for mostly clear
skies west of the mountains tonight. This will to better river
valley fog formation in the drier and cooler air behind the front.
Sunday will be continued warm adn dry with abundant sunshine under
high pressure, with mountains clouds mixing out during the
morning.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 340 PM Saturday...

Pre frontal upper trough could begin the convective activity over
the mountains prior to the main band of frontogenetic forcing
Monday, and POPs reflect this accordingly. Front/surface low will
be on the stronger side given the deepening of the upper level low
over the northern Great Lakes, and it should be a clean sweep
through the CWA as a result without hanging up in the mountains.
Significant change of airmass expected behind the front, finally
alleviating us from the unseasonably warm weather. Resulting
thicknesses will be around the 560dkm mark, and 850mb temperatures
eventually down into the single digits by Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 340 PM Friday...

While the operational models are at least consistent with a stout
upper low bringing a cold front through in the short term portion
of the forecast, the evolution of the upper low beyond that in the
extended is where forecast spread comes into play. The ECMWF
continues to bring the upper low south into the central
Appalachians, with it oscillating around that general area
through the end of the week. The GFS brings a similar track to an
extent...but eventually has it become an open wave and exiting
our area by Friday. This makes the grids challenging because of a
GFS specific trough axis dropping in and creating more defined
areas of potential precipitation while the ECMWF will be more
involved with less specific forcing details. Crossing fingers for
increased model run consistency in the coming days to sharpen up
this part of the forecast. Will keep the cooler trend going
through the period regardless with low end POPs.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
18Z Saturday thru 12Z Sunday...

As of 145 PM Saturday...

Thru 00Z,
A weak east to west cold front, across the central portion of WV
and extreme southeast OH at 17z, will continue southward through
this afternoon. Front will exit the far south early this evening.
Band of associated clouds has largely dissipated...and we look
VFR SCT-BKN clouds between 3500-5000 feet AGL remainder of this
afternoon. Light and variable winds ahead of the front becomes
northerly 5 to 10 KTS behind the front.

After 00Z,
Most clouds will have dissipated by around 00Z, then generally
FEW-SCT 5000-8000 feet AGL, but with one important exception. As
the winds turn more light northeasterly and then southeasterly
tonight, MVFR/IFR ceilings will tend to form in the WV mountain
chain. This will bring MVFR ceilings by 06z to EKN and BKW, then
IFR after 08z, with some LIFR in the higher elevations. River
valley fog looks be more of an issue after 06Z tonight behind the
front, especially where skies are clear. This will bring
MVFR/IFR fog to major TAF sites, except BKW, after 07Z.

After 13z, Outside of the mountains, improving to VFR mostly
clear by 14z. In the mountains, fog lifting to MVFR ceilings by
14z.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY...

FORECAST CONFIDENCE: Medium to High.

ALTERNATE SCENARIOS: Timing, extent and intensity of fog tonight
is likely to vary. Timing and extent of MVFR stratocu in the
mountains tonight may vary.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH:   TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW:    TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.

UTC 1HRLY       18   19   20   21   22   23   00   01   02   03   04   05
EDT 1HRLY       14   15   16   17   18   19   20   21   22   23   00   01
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    L
EKN CONSISTENCY  H    H    H    H    H    H    H    M    H    H    M    L
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
CKB CONSISTENCY  L    L    H    H    H    M    H    H    H    H    H    L

AFTER 18Z SUNDAY...
Low stratus possible Monday night, then morning valley fog
possible next week.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.

&&

$$
SYNOPSIS...TRM/JMV/SL
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...26
AVIATION...JMV



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