Area Forecast Discussion
Issued by NWS Charleston, WV-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRLX 050001
Area Forecast Discussion
National Weather Service Charleston WV
701 PM EST Sun Dec 4 2016
Weak upper trough crosses this afternoon and tonight. A low
pressure system crosses Monday night and Tuesday. Briefly milder
in its wake mid week. Colder after a cold front passes Thursday.
.NEAR TERM /THROUGH MONDAY/...
As of 230 PM Sunday...
Warm air advection aloft and weak isentropic lift is bringing light
rain to Southwest Virginia this afternoon. The rain has been
confined mostly to our south with just mid and upper level clouds
currently across the forecast region. Fairly dry air in the low
levels has mostly kept precip at bay and seeing just mid level
clouds across much of the region for now. Low level southeast
flow this afternoon and into the evening will likely produce
upslope clouds and an isolated shower in the Eastern Mountains but
not expecting widespread PoPs to enter the region until later this
evening with approaching short wave.
The weak shortwave moves through late tonight into tomorrow
morning. Dewpoints are mostly in the mid to upper 20s and as
precip moves in this drier air at the surface will likely allow
for some evaporational cooling. Although confidence is still
fairly low at this time, there is certainly still some potential
for a wintry mix, including periods freezing rain overnight,
mostly across the parts of Randolph and Pocahontas counties. Not
expecting significant impacts, but a trace to a couple of
hundredths of ice accumulation could make for slick travel. Have
decided to leave current winter weather advisory as is for now.
High pressure builds back in for a brief period tomorrow and
conditions should improve late morning into the early afternoon.
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 315 PM Sunday...
No major changes to the short term forecast with decent model run
to run consistency. Trickiest part of the forecast will be the
cold air trapped in the far northern mountain valleys at the onset
of precipitation, as this would likely translate to another
marginal freezing rain issue in isolated areas. Will transition to
rain eventually, and this will be more of a liquid precipitation
event as opposed to the onset freezing rain potential.
For the timing, isentropic lift on the 295K surface arrives after
06Z Tuesday over the Tug Fork Valley and will overspread the rest
of the CWA fairly quickly. Frontogenetic forcing will also pass
through quickly, while the center of low pressure passes and drags
a cold front through into Tuesday night. Still looking at around
an inch of liquid precipitation for the system.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 325 AM Sunday...
Cold front for Thursday is looking a bit weaker in latest model
runs with the closed 500mb low not as deep as previous runs.
Southward penetration of the 850mb thermal trough will be less as
a result of the weaker system overall, but will still get near
-16C down into the middle Ohio Valley for the end of the week.
Post frontal/cold advection snow possible behind the front.
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --As of 1245 PM Sunday....
Weather system moving through bringing light rain and a good
chance for IFR conditions at all sites. For this package, trended
lower due to upstream obs and the NAM suggesting lower ceilings.
Kept IFR in through early monday when conditions should improve as
high pressure builds again.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY...
FORECAST CONFIDENCE: Medium.
ALTERNATE SCENARIOS: Timing of precipitation and MVFR/IFR
conditions tonight 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.
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 M H H L
HTS CONSISTENCY H H H H H H H H H H H L
BKW CONSISTENCY H H H H L H L L M M L L
EKN CONSISTENCY H H M H H H M H M M M L
PKB CONSISTENCY M H H H M M M M M M H M
CKB CONSISTENCY H H M M M H H M M M M M
AFTER 00Z TUESDAY...
IFR possible in rain on Tuesday.
-- End Changed Discussion --
WV...Winter Weather Advisory until 6 AM EST Monday for WVZ523-524-