Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 180316
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
1016 PM EST Wed Jan 17 2018

.SYNOPSIS...
High pressure passes south of the area through Thursday.
Southwest flow of milder air Friday through the weekend, with a
warm front passing Saturday. Cold front Monday.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 1015 PM Wednesday...

Seeing some readings close to zero in the outlying locations
where it has cleared and some decoupling has occurred. It
remains a challenging low temperature forecast overnight for the
reasoning laid in the earlier discussion. Case in point, LHQ
was -3 a few hours ago and has now jumped 13 degrees upon
receiving a puff of wind.

As of 700 PM Wednesday...

Clearing line is progressing eastward this evening, with
southeast Ohio, northeast Kentucky, and western West Virginia
under a starry sky. This clearing will continue to progress east
through the evening, though likely slowing up once east of the
I79 corridor. A challenging temperature forecast exists
overnight. A clearing sky and good snowpack would typically
scream tank overnight, scoring big points on MOS guidance.
However, surface high resides across the southern states and
winds in the H925 to H85 layer will be increasing late
tonight...in the 25 to 35 kt range. This would help to mitigate
the freefall especially on the hilltops, while the high ridges
actually rise late with WAA. I did not get too carried away with
lows as a result, but I did allow significant drops in the
valleys and hollers. The thinking there is that a significant
inversion will setup this evening that should be able to stiff
arm the increase in boundary layer winds overnight. In these
locations, -3 to -5 below was coded up, with lower single
digits elsewhere. This may be conservative, and I will likely
have to further adjust later this evening depending on the
trends.

As of 1110 AM Wednesday...

Guidance show a broad high pressure located over the south
central states, with a ridge extending northeast into KY and WV
through Thursday.

SFC obs indicate flurries still occurring at some sites. Models
suggest that there still enough sfc to low level moisture over
the area tonight. This moisture will continue squeezing against
the mountains to produce flurries or light snow tonight. No
additional snow accumulations expected.

Weather charts show a broad sfc high pressure centered over the
south central states, with a ridge extending northeast into KY
and WV. This feature will keep light to calm flow overnight.

With snow on the ground, and skies trying to clear from west to
east overnight, temperatures are expected to plummet into the
lower single digits lowlands, and below zero over the higher
elevations northeast mountains. With the wind factor, over the
elevated terrain will produce wind chill values from -3F to
-20F. These conditions prompt the issuance of a Winter Weather
 advisory for dangerous wind chills tonight through 14Z
 Thursday.

Went with the coldest guidance tweaking down some degrees over
the classic cold spots.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 230 PM Wednesday...

Overall, short term forecast is very quiet with a warming trend
as we head into the weekend. Ridging and high pressure is
basically overhead through the entire period. This will moderate
our temperatures nicely, with highs climbing into the low to mid
40s on Friday and mid to upper 40s on Saturday. Clouds will be
on the increase Saturday afternoon as a warm front approaches
from the southwest.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 240 PM Wednesday...

Fairly good agreement among the guidance now with a warm front
crossing on Saturday night into early Sunday morning. May see a
few light rain showers through the day on Sunday, but for the
most part we will be within the warm sector and relatively
stable conditions aloft. Strong low pressure will track into the
Great Lakes region by early Monday morning. This system will
drag a cold front across the forecast area on Monday, with
widespread rainfall looking more and more likely. PWATs are
showing to be slightly anomalous in the latest GEFS runs so with
the decent moisture, would not be surprised to see some spots
get an inch of rain out of this. Rivers remain quite high with
some ice jams in spots. There is some potential for some minor
flooding, but generally not thinking any major issues at this
time. Any lingering precipitation will change over to light rain
and possibly snow showers Monday night, with light
accumulations possible as colder air presses in behind the
front.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
As of 705 PM Wednesday...

Clearing has worked east of PKB/HTS as of 00Z. MVFR stratus and
flurries will gradually erode elsewhere this evening. This will
take longest across the mountain terminals, perhaps until after
06Z.

VFR conditions Thursday with southwesterly surface winds 10 to
15 kts in the afternoon.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z FRIDAY...

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Timing of clearing overnight may vary a few
hours at BKW/EKN.

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                                                  THU 01/18/18
UTC 1HRLY       03   04   05   06   07   08   09   10   11   12   13   14
EST 1HRLY       22   23   00   01   02   03   04   05   06   07   08   09
CRW CONSISTENCY  M    M    M    M    M    M    M    M    M    M    H    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
BKW CONSISTENCY  M    M    M    M    M    M    M    M    M    M    H    M
EKN CONSISTENCY  H    M    M    M    M    M    H    M    M    M    H    M
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
CKB CONSISTENCY  M    M    M    M    M    M    M    M    M    M    H    M

AFTER 00Z FRIDAY...
None.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Wind Chill Advisory until 9 AM EST Thursday for WVZ520-522>526.
OH...None.
KY...None.
VA...None.

&&

$$
SYNOPSIS...ARJ/SL
NEAR TERM...ARJ/30
SHORT TERM...MPK
LONG TERM...MPK
AVIATION...30



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