Area Forecast Discussion
Issued by NWS Charleston, WV

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474
FXUS61 KRLX 171434
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
934 AM EST Fri Nov 17 2017

.SYNOPSIS...
A high pressure system will provide gradual clearing today. A
strong cold front crosses Saturday night. Many may see first
flakes of season Sunday. High pressure much of next week.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
As of 934 AM Friday...
Minor update to prolong cloud cover over our northern counties
longer into the afternoon based on visible satellite imagery.
Model soundings show low level winds veering around to the south
and picking up in speed late in the afternoon which should do
the trick and scour things out...but it will take a while.

As of 550 AM Friday...
Stratus finally starting to erode across the south, and updated
sky grids accordingly.

As of 325 AM Friday...

Widespread stratus will continue to linger across the area through
the first part of the morning, but gradually erode as high pressure
continues to nudge eastward into the area. With the high in control,
expecting a mostly sunny day, after stratus erodes, with light
surface winds, and temperatures generally topping out in the upper
40s to mid 50s.

Focus then shifts to a warm frontal boundary, which will lift north
across the area late tonight/early Saturday, with showers
developing, mainly across western zones towards Saturday morning.
Winds will be on the increase Friday night across the region as
surface pressure gradient tightens ahead of approaching system,
along with a non diurnal temperature trend. In addition, developing
LLJ across the area, particularly as the day progresses on Saturday,
will lead to the possibility of rather gusty conditions in
showers.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH MONDAY NIGHT/...
As of 325 AM Friday...

Strong cold front crosses the area right at the start of the
forecast period, Saturday night 02z-08Z. with strong surface low
pressure tracking just north of the forecast area. This places
the area in strong forcing associated with the upper level
short wave trough.

Model soundings depict peak potential of 40 kts beneath an
inversion mixing down Saturday afternoon, then up to 45 knots as
inversion breaks just ahead of the cold front Saturday night,
mainly in gusty showers and thunderstorms. Have coded up gusts
nearly this high across the higher ridges, and 10 to 15 kts
lower across the lowlands. Will highlight high terrain gusts
in the HWO and state briefing.

Rainfall may be briefly heavy, but manageable in total, with pw
values peaking between one and 1.25 in in this fast moving
system.

Colder air quickly moves in behind the system late Saturday
night and Sunday, with a transition directly from rain to snow,
as it gets sufficiently cold aloft before the surface.

Orographic effects and snow ratios suggest 1 to 2 inches across
the higher windward terrain late Saturday night through Sunday.
Many across lower terrain could see first flakes of the season.

Low clouds will again follow this system Sunday into Sunday
night, before high pressure brings clearing late Sunday night.
That high brings mainly clear weather Monday and Monday night,
save perhaps for morning cu Monday morning.

Central guidance temperatures generally accepted, save for lower
highs Sunday beneath the low cloud canopy.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 325 AM Friday...

High pressure exits Tuesday, only for another to build in
Wednesday, and then prevail through the balance of the work
week, beneath upper level northwest flow. A short wave trough
in that flow may push a weak cold front through between highs
Tuesday night.

Pulled central guidance temperatures down slightly, toward
previous forecast, in late November stable air and clear nights.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
As of 550 AM Friday...

12Z Friday thru 12Z Saturday...

Widespread MVFR stratus through at least 12-15Z Friday, with
VFR expected area wide after 15Z with light surface winds.
After 02Z Saturday, ceilings will increase and gradually lower,
along with increasing southerly winds, out ahead of an
approaching low pressure system and cold front. SHRA also
expected to develop across southeast Ohio and northeast KY after
02Z, spreading eastward into West Virginia towards the end of
the TAF period, with brief MVFR restrictions expected.

There is the possibility of wind shear late tonight, but for
now, will leave out of the TAF.


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

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Timing of improvement to VFR conditions on
Friday may vary from current 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       12   13   14   15   16   17   18   19   20   21   22   23
EST 1HRLY       07   08   09   10   11   12   13   14   15   16   17   18
CRW CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    M
HTS CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    M
BKW CONSISTENCY  M    M    M    H    H    H    H    H    H    H    H    M
EKN CONSISTENCY  H    M    H    H    H    H    H    H    H    H    H    M
PKB CONSISTENCY  H    M    L    L    L    H    H    H    H    H    H    M
CKB CONSISTENCY  H    H    H    H    H    L    H    H    H    H    H    M

AFTER 12Z SATURDAY...
IFR possible Saturday and Saturday night in precipitation.

&&

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

&&

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



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