Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 112344
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
644 PM EST Mon Dec 11 2017

.SYNOPSIS...
Cold front moves across the area tonight. Strong upper trough brings
cold air and snow showers Tuesday. Another system arrives by late
week with another chance for snow showers.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 640 PM Monday...

Made a few tweaks to the forecast this evening, mainly to hourly
temperature grids and winds. Upped wind forecast slightly for
tomorrow, based on strong winds aloft/caa taking hold throughout
the day. In addition, added blowing snow to the forecast across
the higher terrain counties.

As of 110 PM Monday...

The nice start to the workweek will quickly give way to the
reality of winter as snow showers return. A warm front lifted
north across the Mid Atlantic this afternoon. A trailing cold
front will begin to slide east overnight tonight. This front
will bring a reinforcing shot of cold air to the entire region.
Along with this front, enough moisture will be in place that
some snow showers will be likely. Expect to see some light snow
flying by tomorrow morning across the entire area. As this front
moves east, blustery condition will set in. Lake enhanced snow
showers will reduce visibilities with any heavier squalls during
the day. Areas where these streamers set up could pick up a
small amount of accumulating snows across the lowlands. Upslope
snow in the higher elevations will add to any snowfall
accumulations. Have issued a Winter Weather Advisory for these
higher elevations where a combination of dangerous wind chill,
snow and blowing snow will be more likely.

Overnight lows will in the lower to mid 30s. Highs on Tuesday will
occur in the morning and fall throughout the day. This is due to the
arctic air filtering in behind the cold front. By Tuesday afternoon,
temperatures will be in the 20s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
As of 315 PM Monday...

As the upper trough moves away, northwest flow again returns
with models starting to agree on narrow corridors of higher RH
stemming from Lake Michigan and reaching into the region. Should
these corridors of high RH come to fruition, there would be a
corresponding corridor of higher snowfall - especially in the
mountains. Given the fickle nature of these narrow corridors,
though, have opted to spread accumulation throughout the
mountains and in areas immediately adjacent to the west with
somewhat lower amounts. Gusty northwest winds will again
increase with these snow showers, and cold air advection will
drop temperatures further. Wednesday morning temperatures are
looking to be in the teens in the lowlands, and in the single
digits in the mountains. The aforementioned winter weather and
wind chill advisories extend through Wednesday morning to cover
these hazards.

Went with model blends for temperatures through the period.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
As of 335 PM Monday...

Another system swings through during this period. However.
models are somewhat different with the timing and the track of
the feature. Because of this uncertainty, have gone with the
model blend for the forecast. At this time, models are
converging a surface low tracking squarely through this area,
attached to yet another clipper-type trough aloft. Heavier
snowfall would therefore be across the northern counties with
upslope enhancement.

Cold air remains in place for Thursday and Friday with warmer
weather anticipated for Saturday and Sunday.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
00Z Tuesday through 00Z Wednesday...

As of 640 PM Monday...

VFR with generally light surface winds area wide through at
least 09Z, when conditions will rapidly deteriorate as a system
moves into the region. Expect snow showers to develop area wide,
with widespread MVFR and local IFR conditions developing,
particularly after 12Z. Mountains especially will be prone to
IFR or worse conditions.

In addition to the snow showers, gusty westerly/northwesterly
winds will develop Tuesday, particularly after 12Z, with
sustained winds in the teens, with gusts in the 20 to 30 kt
range, with higher gusts around 40 kts possible across the
higher terrain, with blowing snow and reduced visibility.

Snow will decrease in intensity and coverage across much of the
area after 20Z, however, will continue to see lake effect
bands/squalls for the remainder of the TAF period.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY...

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: Timing of snow showers and deteriorating
conditions on Tuesday may vary from forecast. Conditions may be
worse than currently forecast.

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.

DATE                                                                 TUE
UTC 1HRLY       00   01   02   03   04   05   06   07   08   09   10   11
EST 1HRLY       19   20   21   22   23   00   01   02   03   04   05   06
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    M    H    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    M    M    H    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    M    H    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M

AFTER 00Z WEDNESDAY...
Scattered snow showers and gusty winds will result in continued
areas of IFR through Wednesday morning particularly across the
mountains. Another round of snow is expected Wednesday night and
Thursday, particularly across the north, with IFR conditions
possible.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Winter Weather Advisory from 7 AM Tuesday to 7 AM EST
     Wednesday for WVZ518-520-522>526.
     Wind Chill Advisory from 4 PM Tuesday to 1 PM EST Wednesday
     for WVZ518-520-522>526.
OH...None.
KY...None.
VA...None.

&&

$$
SYNOPSIS...JB/MC
NEAR TERM...JB/SL
SHORT TERM...MC
LONG TERM...MC
AVIATION...SL


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