Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 030938
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
438 AM EST Sat Dec 3 2016

.SYNOPSIS...
Chilly high pressure this weekend. Weak upper trough late Sunday
into Sunday night. Low pressure Monday night Tuesday. Briefly
milder in its wake mid week, then much colder late week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 430 AM Saturday...

-DZ, along with isold -shsn, particularly across the higher terrain,
will taper off later this morning into early afternoon, as high
pressure builds into the region, and flow becomes less favorable for
upslope. Still looking at yet another cloudy cool day, with low
level moisture remaining trapped beneath inversion in light flow
pattern.

Overnight, kept temperatures several degrees warmer than guidance
with overcast sky expected. Some light precipitation will move into
southwest Virginia and southern WV zones towards the end of the
period as moisture from the gulf advects into the region, and an
upper shortwave trough pushes east into the Great Lakes Region
during the day Sunday. Still a bit of uncertainty in precipitation
type across aforementioned areas early Sunday morning, but at least
a brief wintry mix at the onset looks to be likely, with little to
no accumulations expected due to brief duration, and light qpf,
before changing over to all rain.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
As of 430 PM Saturday...

Precipitation overspreads the area from southwest to northeast on
Sunday, as a weak short wave trough crosses. This will be a split
system, with the best forcing associated with the short wave
passing north of the forecast area. However, channeled vorticity
and southern stream moisture will make for another precipitation
maxima to the south. With this maxima coming close to the
forecast area from the south, precipitation is most likely late
Sunday far southern portions of the forecast area, mainly the
southern mountains.

Precipitation may begin as a wintry mix far south first thing
Sunday morning, but low level warming will bring about a quick
change over to rain, without much accumulation or hazard. As the
system moves off to the east on Sunday night, there may be enough
cold air aloft for a wintry mix in the northern mountains.
However, since the moisture layer will be becoming shallow, lack
of ice crystals may lead to just drizzle / freezing drizzle but,
again, not much hazard.

Weak Pacific high pressure crosses Monday, as upper level ridging
crosses late Monday. This will be quickly followed by the next
system, an upper level closed low over northwest Mexico early
this morning, that ejects out into TX early Monday morning, and
then dampens out as it moves up the Ohio Valley Tuesday morning.
This, and its attendant surface low pressure system and associated
warm advection and dynamics, will result in rain overspreading the
forcast area quickly as dawn Tuesday approaches.

The rain will diminish from southwest to northeast Tuesday as the
system lifts on through. Little in the way of cold air initially
follows the system Tuesday night, so an overcast, damp night
appears in store, but any lingering precipitation will be light,
and primarily of the liquid variety.

Temperature close to a raw and MOS based blend.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 430 PM Saturday...

Much colder air arrives this period, but with lingering questions
as to when the colder air arrives. Models disagree on the degree
of cold air eventually coming in Wednesday and Wednesday night in
the wake of the Tuesday system, and on the timing of a cold front
on Thursday. The two factors combined result in a 15 F degree or
more spread between temperature outcomes Thursday. The forecast
represents a blend, but a little toward the colder solution, per
WPC preference and coordination with neighboring offices.

Rain showers in the wake of the cold front Thursday are thus most
likely to mix with and change to snow showers in the west, and
over the higher terrain.

Cold canadian air takes over by Thursday night, and dominates
through the balance of the forecast, with highs below freezing for
the first time this early winter season Friday, and maybe getting
back above freezing over the lowlands on Saturday, as upslope snow
showers diminish.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
As of 1230 AM Saturday...

Widespread MVFR cigs across the area, particularly across the
higher terrain, where Isold IFR exists in spots in -shsn/-fzdz.
Some lifting of the cloud deck to VFR expected generally after
18Z, however, mountainous locations may remain MVFR for the
period. Otherwise, light surface winds lowlands, with occasional
gusts in the teens across the higher terrain through much of the
period.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY...

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Timing of category changes in clouds 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.

DATE                    SAT 12/03/16
UTC 1HRLY       09   10   11   12   13   14   15   16   17   18   19   20
EST 1HRLY       04   05   06   07   08   09   10   11   12   13   14   15
CRW CONSISTENCY  H    M    M    M    H    M    H    M    H    H    H    M
HTS CONSISTENCY  H    H    M    M    H    H    H    H    H    H    H    M
BKW CONSISTENCY  M    M    M    M    M    M    M    M    M    M    H    M
EKN CONSISTENCY  L    L    L    M    M    H    H    H    H    M    M    L
PKB CONSISTENCY  M    M    M    M    H    H    H    M    M    H    H    L
CKB CONSISTENCY  H    H    H    H    H    M    H    H    M    M    M    L

AFTER 06Z SUNDAY...
IFR possible in rain and snow, particularly in the mountains
Sunday night into Monday. Additional IFR possible in rain and snow
towards mid week.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Winter Weather Advisory until 6 AM EST early this morning for
     WVZ521>523-525-526.
OH...None.
KY...None.
VA...None.

&&

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



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