Area Forecast Discussion
Issued by NWS Charleston, WV

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840
FXUS61 KRLX 231435
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
935 AM EST Tue Jan 23 2018

.SYNOPSIS...
Low pressure system exits northeast, but remains unsettled
through Wednesday. Warmer to end the week. Cold front next
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 935 AM Tuesday...
Updated pops across parts of southeast Ohio, as area of light
rain and snow showers approaches that area this morning. In
addition, lowered temperatures slightly this morning,
particularly across southeast Ohio. Otherwise, previous forecast
remains on track.

As of 555 AM Tuesday...

Last of the showers to move through the northeast mountains over
the next couple of hours. Dried out the forecast for the bulk of
the morning and afternoon hours today before the low level
moisture returns.

As of 250 AM Tuesday...

Line of showers weakening as it passes the I79 corridor this
morning. Still have lingering showers behind this line, and the
low level cold air advection lagging behind the cold front a
bit, but will see slowly falling temperatures through the day.
The broad upper level cyclone has pulled in dry air that will
provide breaks in the clouds for the first part of the day, but
the low level moisture returns and timed this with the higher RH
values in the 925mb layer and the continuing cold air advection.
This will last through tonight, and ramp the sky cover grids to
overcast after 00Z Wednesday.

That low level moisture should end up deep enough to warrant
light isolated to scattered snow showers, most persistent in the
mountains. Amounts in the near term will be light, with the only
amounts over an inch in the highest ridges.

Winds will be on the increase over the next several hours in
descending air in the cold advection process. Will be
transferring momentum down to the surface from around 800mb, but
should stay well below advisory criteria. Highest elevations
will receive the highest gusts.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
As of 325 AM Tuesday...

A 500mb shortwave trough will swing through on Wednesday.
Moisture is fairly limited, but with 850mb temps in the -10C
range, should still be able to get some light snow
showers...especially across the northern mountainous counties.
The snow showers should taper off from west to east overnight.
Still have some cold air advection lingering Thursday morning,
so cannot rule out some lingering flurries, but opted to not
include them at this point since moisture will be limited and
the air is not super cold.

Surface flow turns SW Thursday into Friday with a surface high
drifting toward the NC/VA coast. This will bring a warming trend
to end the work week.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
As of 320 AM Tuesday...

Models remain fairly unhelpful for weekend system. The GFS is
much faster with the system, bringing a cold front through late
Saturday and Saturday night. The GFS is fairly progressive and
is dry by midday Sunday. The ECMWF is much slower with this
system, as it tries to cutoff the 500mb flow and pulls a
southern stream surface low up the Appalachian spine Sunday into
Monday. With the stronger system on the ECMWF -- enough cold
air would arrive for a changeover to snow Sunday night into
Monday. The GFS is much warmer... and mainly dry at this time.
For now did not stray far from a consensus blend, having high
chance POPs Saturday night into Sunday.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
As of 555 AM Tuesday...

Ceilings to scatter out west to east through the daytime hours
with strong surface wind gusts out of the west southwest in the
25-35kt range. These gusts will peak in the 16Z-22Z time frame
depending on terminal. Expecting MVFR ceilings to return to the
region as the low pressure system lifts out to the northeast.
Isolated to scattered rain showers develop in this scenario,
gradually changing to a rain/snow mix and then all snow tonight
as temperatures continue to fall. Only the mountain terminals
carry chances high enough for prevailing conditions at this
point.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...


FORECAST CONFIDENCE: Medium to high.

ALTERNATE SCENARIOS: May need more prevailing rain/snow after
00Z Wednesday.


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  H    H    H    H    H    H    H    H    M    M    M    L
HTS CONSISTENCY  H    H    M    H    H    H    M    M    M    M    M    L
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    M    M    L
EKN CONSISTENCY  H    H    H    H    M    H    H    M    M    M    H    M
PKB CONSISTENCY  H    H    H    H    H    H    H    H    M    M    M    M
CKB CONSISTENCY  H    H    H    H    H    H    L    M    M    M    M    L

AFTER 12Z WEDNESDAY...
IFR snow possible in mountain terminals Wednesday/Wednesday
night.

&&

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

&&

$$
SYNOPSIS...MZ/26
NEAR TERM...SL/26
SHORT TERM...MZ
LONG TERM...MZ
AVIATION...26



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