Area Forecast Discussion
Issued by NWS Charleston, WV
FXUS61 KRLX 242342
Area Forecast Discussion
National Weather Service Charleston WV
742 PM EDT SAT SEP 24 2016
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 730 PM Saturday...
Cold front looks to have made it through the CWA. Radar had shown
a pop-up shower or two a couple hours ago, but those have since
disappeared. Only minor changes made to previous forecast.
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
.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 /00Z SUNDAY THROUGH THURSDAY/...
As of 730 PM Saturday...
Cold front has moved south of CWA with generally northerly flow in
place. With clearing skies and winds decreasing, expect dense
river valley fog to form outside of the mountains. In the
mountains, flow will gradually transition through NE to E which
should create a low stratus deck. This is already showing up at
EKN. So have IFR in low stratus at BKW and EKN, and across the
rest of the mountainous counties. This does create some
uncertainty on fog formation at EKN. Guidance pretty much all says
fog will form. Either way -- clouds or fog-- IFR is expected at
After the fog dissipates Sunday morning, clear skies are expected
across the west, with some cumulus across the east.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY...
FORECAST CONFIDENCE: Medium.
ALTERNATE SCENARIOS: Timing, extent and intensity of fog tonight
is likely to vary. Timing and extent of low stratus 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 22 23 00 01 02 03 04 05 06 07 08 09
EDT 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
CRW CONSISTENCY H H H H H H H M M M M L
HTS CONSISTENCY H H H H H H H H H M M L
BKW CONSISTENCY H H H H H H M M M M M L
EKN CONSISTENCY H H H M M M M M M M M L
PKB CONSISTENCY H H H H H H H H M M M L
CKB CONSISTENCY H M H H H H H H H M M L
AFTER 00Z MONDAY...
Low stratus possible Monday night, then morning valley fog
possible next week.