-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 210603
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
203 AM EDT Mon Aug 21 2017

.SYNOPSIS...
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High pressure into Tuesday. Strong cold front late
Tuesday/Tuesday night. Cooler and drier for the end of the week.
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&&

.NEAR TERM /THROUGH TODAY/...
As of 1000 PM Sunday...

Updated to include isolated shower mention from PKB north and
west. A few showers have popped up recently. They are already
falling apart as they drift northward so stayed in isolated
range. These appear to have formed along a low level boundary
that is likely the outflow from the thunderstorms that moved
across the far northern CWA Saturday evening.

As of 120 PM Sunday...

Weak high pressure keeps the CWA dry and warm today. A minor
impulse at 500 mb passes to our north overnight though trended
towards SREF and GFS ensembles keeping the forecast dry. There
should be fog again in the river valleys overnight though the
impulse and a full day of sun today may lessen the density and
extent overnight. Despite this, still kept a general mention of
fog in the river valleys.

Monday high pressure holds on albeit weakly, but should be
enough to keep us dry again with minimal cloud cover except in
the mountains where daytime heating may be enough to spark a few
isolated showers.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
As of 230 PM Sunday...

5h trough digs southeast into the Great Lakes with an
accompanying front at the surface. This feature will drive a
colder airmass of continental Canadian air into the eastern US
by Wednesday night. Have front pegged to be along the Ohio River
along the WV-OH border at around 06Z Wednesday and this feature
will drive shower and isolated thunderstorm activity across the
forecast area with decent wetting rains. Made some adjustments
to the model blend pops by just a few hours but generally
accepting guidance.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 230 PM Sunday...

Cool period in the long term as Canadian airmass in control of
our sensible weather. Surface high dominates the eastern
seaboard. Used guidance throughout the period.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
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06Z Monday thru 06Z Tuesday...
As of 135 AM Monday...

With an upper impulse and great cirrus coverage to combine with
more tropical like dewpoints, will cut back just a bit on
timing and intensity with river valley LIFR fog coverage early
this morning, but most sites will still see at least some IFR
fog between 09Z and 12Z.

Thru 00Z Tuesday...
Fog will dissipate quickly after sunrise. then VFR. Generally
thin cirrus clouds this morning followed by SCT-BKN clouds
4500-6000 feet AGL this afternoon. An isolated shower this
afternoon is possible across east facing slopes of the northern
mountains due to elevated heat source and pooling of low level
moisture there, and across parts of southeast OH with an upper
disturbance. Light and variable wind early becoming southwest 3
to 7 KTS this afternoon.

After 00Z...
VFR with mainly thin cirrus with any river valley fog holding
off til after 06Z and not as much as this early morning. Winds
light and variable.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z
TUESDAY...

FORECAST CONFIDENCE: High, except low to medium with fog.

ALTERNATE SCENARIOS: Timing and density of fog may vary based
mainly on clouds.

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                              MON 08/21/17
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
CRW CONSISTENCY  H    M    M    L    L    L    L    M    H    H    H    M
HTS CONSISTENCY  H    H    H    M    M    L    L    M    H    H    H    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
EKN CONSISTENCY  M    L    L    L    L    L    L    M    H    H    H    M
PKB CONSISTENCY  H    H    M    M    L    L    M    H    H    H    H    M
CKB CONSISTENCY  H    H    H    M    M    M    H    H    H    H    H    M

AFTER 06Z TUESDAY...
Dense river valley fog possible each morning.
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&&

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

&&

$$
SYNOPSIS...KMC/JMV/JW
NEAR TERM...JW/MZ
SHORT TERM...KMC
LONG TERM...KMC
AVIATION...JMV