Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 180226
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
1026 PM EDT Tue Oct 17 2017

.SYNOPSIS...
Dry high pressure with cool mornings and warm afternoons, with
temperatures moderating through the weekend. A cold front
crosses on Monday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 1025 PM Tuesday...

Changes made to ongoing forecast.

As of 235 PM Tuesday...

A clear sky dominates much of the Ohio Valley and central
Appalachians this afternoon. Dewpoints are running a bit below
guidance at some locations which this leads to the frost
conundrum overnight. With high pressure overhead amid a dry
airmass, expect a quick fall in temps this evening. Using this
afternoon`s dewpoints as a base and knocking a few degrees off
guidance in our colder spots, we have elected to hoist a frost
advisory for much of the area. The exception being the northern
and central mountains where we ended the growing season today.
Within the advisory area, expect dense main stem river valley
fog to form once again, which will likely keep frost from
forming in our more populated urban centers. I tried to hit this
thinking in the headline reiterating areas away from main stem
rivers and urban centers more likely to receive frost.

Surface high shifts to the east on Wednesday with a s/w trof
approaching from the west in the afternoon. Given the dry
airmass in place at all levels, expect no impacts from this,
with barely a cloud in the sky again. Highs were derived from
met/mav/nbm blend which sends afternoon temps back above normal
amid lowering RH values.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 230 PM Tuesday...

A sfc high pressure will extend from the adjacent coastal
waters of the Mid Atlantic, east and south into WV Wednesday
night. The high center shifts overhead as it strengthened
controlling the weather conditions. Very dry conditions
expected through Friday night.

Minimum RH values will dip into the 20s in parts
of the area Wednesday afternoon, with 30s again widespread
Thursday afternoon, becoming more confined to the mountains for
Friday afternoon.

By Saturday night, the high drifts east as an approaching cold
front tightens the pressure gradient to pump moist and warmer
air into the area under southwest flow.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 230 PM Tuesday...

High pressure continues in control on Saturday through Sunday
night. Will have to monitor each afternoon after mixing could
bring low RH into the mid 30s. An increase in southwest flow is
expected as the front approaches. An upper level trough and
surface cold front to cross from the west Sunday night into
Monday. Models are in agreement with the timing of FROPA as an
upper level through passes through.

After drying out behind the front Monday night, the slowing,
deepening upper level trough over the area spells lots of
clouds, and the chance for showers into Tuesday.

Guidance suggests a warming trend through Sunday, followed by
temperatures falling back to normal early next week.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
As of 720 PM Tuesday...

High pressure leading to cloud free sky with little to no wind.
Nearly all guidance says fog will not occur tonight, however it
said the same thing last night which was wrong. Opted to
disregard guidance and instead follow a trace of last nights
obs for tonights forecast with fog developing at valley sites.
Delayed onset at CKB and EKN a bit from last night since there
was no rain this evening.

Fog will dissipate 12Z-14Z, with clear skies and light winds
Wednesday.

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

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Less fog may develop tonight 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.

DATE                                                            WED 10/18/17
UTC 1HRLY       00   01   02   03   04   05   06   07   08   09   10   11
EDT 1HRLY       20   21   22   23   00   01   02   03   04   05   06   07
CRW CONSISTENCY  H    H    H    H    H    H    H    M    L    L    L    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    L
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
EKN CONSISTENCY  H    H    H    H    H    L    L    L    L    L    L    M
PKB CONSISTENCY  H    H    H    H    H    H    H    M    L    L    L    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    L    M

AFTER 00Z THURSDAY...
Dense valley fog possible each morning this week.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Frost Advisory from 2 AM to 9 AM EDT Wednesday for WVZ005>011-
     013>020-024>034-039-040-515-517-519-521.
OH...Frost Advisory from 2 AM to 9 AM EDT Wednesday for OHZ066-067-
     075-076-083>087.
KY...Frost Advisory from 2 AM to 9 AM EDT Wednesday for KYZ101>103-
     105.
VA...Frost Advisory from 2 AM to 9 AM EDT Wednesday for VAZ003-004.

&&

$$
SYNOPSIS...ARJ/30
NEAR TERM...MZ/30
SHORT TERM...ARJ
LONG TERM...ARJ
AVIATION...MZ


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