Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 051123
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
623 AM EST Mon Dec 5 2016

.SYNOPSIS...
High pressure crosses today. Low pressure crosses Tuesday. Weak
high pressure crosses Wednesday. A cold front crosses early
Thursday, followed by much colder weather into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 620 Am Monday...

Forecast is on track.

As of 330 AM Monday...

Cancelled winter weather advisory for early this morning in
conjunction with neighboring offices, as precipitation has
tapered off to spotty drizzle, and temperatures were slowly
climbing above freezing in the advisory area.

As of 245 AM Monday...

Deep layer moisture moved east of the forecast area overnight, as
the causative upper level short wave trough and surface cold
front push east of the area. Precipitation had diminished to very
light rain and drizzle, which will taper off from west to east
early this morning.

Westerly flow behind the cold front, actually a bit gusty
overnight, was eroding the CAD wedge, and any freezing rain or
freezing drizzle over the very high terrain will be gone by
daybreak, so the advisory could likely be allowed to expire at its
6 AM expiration time.

Otherwise any lingering drizzle in the mountians after daybreak
should be gone by late morning, and high pressure crossing this
afternoon should break the clouds up as the inversion lowers.

Higher clouds will lower and thicken tonight, as the next low
pressure system approaches from the southwest. This system
originates from a closed upper level low over northern Mexico
early this morning. It ejects into TX today and then dampens into
an open wave as it lifts through the lower MS and then TN valleys
tonight. This will cause rain to quickly overspread the forecast
area toward dawn Tuesday. Timing of the onset is slower compared
with previous runs, so the forecast area remains dry into this
evening and all but the far south probably dry through midnight.

As the surface low pressure system approaches, a CAD wedge will
develop toward dawn Tuesday. That raises the possibility of
freezing rain over the higher terrain, just beneath the inversion,
where temperatures drop to just below freezing by dawn Tuesday.

Updated temperatures and dew points through tonight via a blend of
near term guidance, with not much change from previous aside
higher values early on.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 245 AM Monday...

The active weather pattern continues in the short term period.
Precipitation returns to the CWA on Tuesday, as a shortwave trough
and attendant surface low lifts northeast out of the Gulf of Mexico
region towards the area. Good lift/ascent on Tuesday, along with
above normal PW values, will result in a good soaking rain for much
of the CWA. There still exists the potential for freezing rain
through early Tuesday afternoon across Randolph and Pocahontas
counties as the potential for near or below freezing temperatures at
the surface exists, along with increasing southeasterly flow.
Depending on timing of system, may need to address the situation
with a freezing rain advisory. Will highlight this in the HWO. In
addition, could be a bit breezy at times on Tuesday particularly
across higher terrain, but overall, no headlines expected.

The low and associated cold front will push east of the CWA Tuesday
evening, with decreasing precipitation as it does so. Will likely
transition to -dz across much of the area Tuesday evening as deeper
moisture is lost.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 245 AM Monday...

Wednesday looks to be dry and cool, with high pressure nudging in
from the west. However, the weather will become colder by Thursday
and Friday, as an upper level trough deepens across the eastern
U.S.and Canada. Temperatures will steadily fall throughout the day
on Thursday, with light rain and snow showers developing on Thursday
as favorable northwesterly flow develops off the Great Lakes. At
least light accumulations will be possible in favored upslope areas
in the mountains. -shsn expected to continue across the higher
terrain through at least Friday night in nwly flow.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 620 AM Monday....

Conditions were improving somewhat early this morning, as the last
of the light rain and drizzle associated with the passage of a
cold front overnight was tapering off.

Ceilings were generally following the mixing height beneath the
post frontal inversion, which was deepening to near 4 kft early
this morning. This deepening will be brief, as what becomes a
subsidence inversion as high pressure builds in, lowers to 2-3
kft today. So, after brief VFR ceilings east of the Ohio River
first thing this morning, MVFR ceilings should dominate much of
today. This is because, even with high pressure, light flow and
the low December sun angle spell difficulty in eradicating the
low level moisture trapped beneath the inversion.

Enough dry air may eventually push in below the inversion to
break up the clouds late today or this evening, only to find
higher clouds already in place. These clouds will lower and
thicken tonight, as low pressure approaches from the southwest.
Ceilings will lower back to MVFR 08Z to 11Z as rain overspreads
the area from south to north. Visibility may drop to MVFR by 12Z
south, in rain.

West surface winds will diminish today, and then increase from
the east to southeast tonight, as low pressure approaches.
Southeast winds will become gusty on the ridges toward 12Z
Tuesday. Light to moderate west to northwest flow aloft will
diminish today, and then become light southeast tonight, and then
light to moderate south overnight.

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

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Timing and heights of mostly MVFR ceilings
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               MON 12/05/16
UTC 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
EST 1HRLY       05   06   07   08   09   10   11   12   13   14   15   16
CRW CONSISTENCY  M    M    M    M    H    H    H    H    H    H    M    L
HTS CONSISTENCY  M    M    H    H    H    H    H    H    H    H    L    L
BKW CONSISTENCY  L    L    M    M    M    M    H    H    H    H    M    M
EKN CONSISTENCY  M    M    L    L    H    H    H    M    M    H    M    M
PKB CONSISTENCY  M    M    H    H    H    H    H    H    H    H    M    M
CKB CONSISTENCY  H    M    M    M    M    H    H    H    H    H    L    M

AFTER 12Z TUESDAY...
IFR possible in rain on Tuesday, and in possible snow showers,
mainly in the mountains, Thursday through Thursday night.

&&

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

&&

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



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