Area Forecast Discussion
Issued by NWS Charleston, WV-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRLX 041954
Area Forecast Discussion
National Weather Service Charleston WV
254 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, then much colder late week.
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --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.
-- End Changed Discussion --
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
As of 420 AM Sunday...
System pulls out first thing Monday morning. Low level westerly
flow quickly takes out the CAD and, with a lack of cold air
arriving in the wake of this system, temperatures climb quickly
above freezing, and any lingering light precipitation Monday
morning should be of the liquid variety.
The next system, a closed upper level low over northwest Mexico
this morning that loiters around there today before lifting out
into TX tonight and Monday, opens up and dampens out as it lifts
through the Ohio Valley Tuesday. This causes rain to rapidly
overspread the area overnight Monday night, and then move through
the area on Tuesday.
With a stronger surface low pressure system compared with its
predecessor, a stronger CAD wedge develops as the system
approaches Monday night, and freezing rain is again possible on
the higher eastern slopes and ridge lines of Pocahontas and
Randolph counties. Warm advection should erode the CAD wedge on
A bit of snow is possible over the higher terrain of the northern
WV mountains on west to northwest upslope flow in the wake of the
system Wednesday morning, but only slightly colder air moves in, as
weak high pressure of Pacific origin approaches on Wednesday.
Models continue to differ on weather the next cold front, a much
stronger one, arrives Wednesday night.
Temperatures close to guidance blends, which reflect a compromise
that leans toward the lower side when models diverge Wednesday
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 420 AM Sunday...
A strong cold front crosses the area sometime Thursday. Models
continue to differ on this, one factor being whether a wave forms
along the front and slows it down. Per WPC and coordination with
neighboring offices, the forecast continues to represent a
compromise that leans toward the faster and colder side. This
would have rain showers that mix with and change to snow showers
in the west and over the higher terrain Thursday, followed by a
transition to all snow showers as Thursday evening approaches.
The cold air takes charge Thursday night, and remains in firm
control into Saturday. This sets up the potential for frozen
precipitation as the next weather system approaches Saturday
night, which would then likely change to rain at least across
much of the lowlands on Sunday given a track west of the area, at
Temperatures close to a guidance blend, except leaning toward the
lower side on Thursday.
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
As of 1245 PM Sunday....
Mid to upper level clouds will lower this afternoon and evening
as a weak system approaches from the west. Generally, VFR
conditions should hold through about 00Z. Then more widespread
rainfall arrives as well as MVFR conditions, with IFR conditions
mostly in the mountains with southeasterly upslope flow.
High pressure will start to build into the area Monday morning,
but low level moisture could linger until Monday afternoon,
especially in the mountains.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...
FORECAST CONFIDENCE: Medium to High.
ALTERNATE SCENARIOS: Timing of precipitation and MVFR/IFR
conditions tonight may vary. Ceilings may lift faster tomorrow
morning 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 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY H H H H L L L L M M M L
HTS CONSISTENCY H H H H H M L H H H H L
BKW CONSISTENCY H H M M M M H H L M M L
EKN CONSISTENCY H H H H H H H H M L L L
PKB CONSISTENCY H H H H H H L H H H H L
CKB CONSISTENCY H H H H H H H H H M M L
AFTER 18Z MONDAY...
IFR possible in rain on Tuesday.
WV...Winter Weather Advisory until 6 AM EST Monday for WVZ523-524-