Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 181604
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
1104 AM EST Mon Dec 18 2017

.SYNOPSIS...
Weak disturbance with light precipitation through tonight.
A dry cold fronts crosses late Tuesday. A stronger, wetter cold
front crosses Saturday. Low pressure Christmas Eve and Day.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1120 PM Monday...

Forecast is generally on track. Low clouds continue to cover the
forecast area. Not many locations actually reporting drizzle or
light rain at the moment. However, radar data and model
information suggest that drizzle and light rain are still a
possibility.  So not many changes made.

As of 155 AM Monday...

Overall, a rather dreary day on tap, although it will be
warmer. Near term period looks to remain socked in with clouds,
and areas of drizzle, with saturated lower levels of the
atmosphere trapped beneath inversion. Still the possibility of
very light rain, particularly across northern zones later today,
as a weak shortwave crosses the region in zonal flow. Have
maintained slight chance to chance pops, mainly across the north
and central zones, with patchy drizzle included area wide. Hard
to exactly tell when -dz will end, but expect it to continue
through at least dawn Tuesday, along with low ceilings.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 345 AM Monday...

Low level moisture beneath a shallow inversion erodes from the
southeast Tuesday, as high pressure noses in from the south, and
low level flow backs to the southwest, parallel to the
mountains.

A subtle northern stream upper level short wave trough drives an
equally subtle cold front through Tuesday night. With very
little moisture, this will be followed by a null upslope event
overnight Tuesday night.

High pressure builds north of the area Wednesday and Wednesday
night, as a southern stream short wave trough and surface low
pass just south of the area. There is the chance for rain on
the northern edge of this system, across southern portions of
the forecast area. Air cold enough to support snow is not likely
to intersect with this southern stream system.

The high to the north, and low to the south, exit first thing
Thursday morning, and then southerly low level flow develops in
their wake Thursday, ahead of a new cold front approaching from
the west Thursday night.

Central guidance temperatures looked reasonable. The cold air
behind the Tuesday night cold front only results in near normal
highs Wednesday, and near normal lows Wednesday night.
Temperatures moderate ahead of the cold front Thursday and
Thursday night.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 345 AM Monday...

The forecast leading up to the Christmas holiday is mild, and
wet.

A cold front crossing Friday night into Saturday could bring a
copious rainfall, given good inflow out of the gulf on 3
isobars at 4 mb increments. The cold front pushes east of the
area Saturday night, for a possible dry interlude pushing in
from the west.

The upper level northern stream short wave trough driving the
weekend cold front through lifts out, in favor of another
digging into the western states, all rotating about a large
central Canadian upper low. This western short wave will either
push east, or remains held back by an upper level high over the
western Atlantic building back into Florida , with a flatter
wave being ejected instead. Either way, a surface wave will form
in response, but its track will be farther west if only a flat
wave is ejected, keeping the upper level flow over the area
backed. This has precipitation timing and type implications for
Christmas Eve and Day. Run to run changes have lead to high
uncertainty, but latest guidance is leaning milder and wet, with
the colder air behind the weekend front either retreating, or
not even making good inroads into the area in the first place.

Central guidance temperatures reflect very mild weather ahead of
the cold front Friday and Saturday, with readings struggling to
even get down to normal behind the front on Christmas Eve. The
chance for snow with the Christmas Eve/Day system is limited to
interior southeast Ohio and the higher WV mountains this
package, and is low even in those places.

&&

.AVIATION /16Z MONDAY THROUGH FRIDAY/...
As of 555 AM Monday...

Widespread MVFR and IFR conditions in low stratus and fog. Areas
of drizzle expected for much of the TAF period. Expecting
widespread MVFR and Local IFR conditions to continue through
20Z, when some improvement to mainly MVFR conditions expected,
but IFR will continue in spots, particularly across mountainous
locations. Light southwesterly surface winds.

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

FORECAST CONFIDENCE: Low.

ALTERNATE SCENARIOS: May have more widespread and longer
duration IFR ceilings today and tonight 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.

UTC 1HRLY       15   16   17   18   19   20   21   22   23   00   01   02
EST 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
CRW CONSISTENCY  L    H    H    M    H    M    M    M    M    M    M    M
HTS CONSISTENCY  M    M    M    M    H    M    H    H    H    H    H    M
BKW CONSISTENCY  L    M    M    L    L    L    M    M    M    M    M    L
EKN CONSISTENCY  L    M    M    M    M    M    L    L    L    L    L    L
PKB CONSISTENCY  L    H    H    M    H    H    M    H    H    H    H    M
CKB CONSISTENCY  H    H    H    H    H    H    M    M    M    H    M    L

AFTER 18Z TUESDAY...
IFR in stratus possibly lingering into Tuesday.

&&

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

&&

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



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