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049
FXUS61 KRLX 011243
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
843 AM EDT Wed May 1 2024

.SYNOPSIS...
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Dense fog this morning. High pressure brings dry weather with a
warming trend today into Friday. A cold front brings showers
and storms this weekend.
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&&

.NEAR TERM /UNTIL 10 AM THIS MORNING/...
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As of 840 AM Wednesday...

Dropped dense fog advisory for Perry County based on satellite.


As of 640 AM Wednesday...

Dense fog advisory is still ongoing until 10 AM. Getting reports
out of SE Ohio of only a quarter to a tenth of a mile
visibilities. Webcam footage shows the most dense fog along the
Ohio River, affecting the Huntington and Parkersburg areas the
most. Areas across the mountains are not seeing it quite as bad,
but webcam footage and GOES-R microphysics shows very dense
visibilities area wide, especially in the valleys.

As of 420 AM Wednesday...

GOES-R microphysics imagery, surface observations and area
cameras evince enough dense fog to warrant a Dense Fog Advisory
throughout the area. Coded one up until 10 AM.

As of 200 AM Wednesday...

A cold front has moved off to our northeast and a surface trough
sits east of the Appalachian Mountains. Skies will continue to
clear and winds will calm as a result. These factors, paired
with lingering low-level moisture from recent rainfall, will
allow the perfect setup for widespread dense fog with low
visibilities this morning.

Sheltered river valleys and mountain valleys with poor drainage
winds will see the lowest visibilities, which could be below a
quarter of a mile at times. A statement has been issued across
the entire forecast area for visibilities of a quarter of a mile
or less that will likely be observed within thicker fog columns.
Caution should be used traveling this morning.

Fog will lift and clear after sunrise this morning and a dome
of high pressure over the Deep South will move up over the area.
This feature will reinforce dry weather and invoke the start of
another warming trend under southwesterly flow. Temperatures
today look to be fairly warm with highs in the low to mid 80s
across the lowlands; 60s to high 70s in the mountains.

Another round of fog looks possible again tonight into Thursday
morning, though will not be as widespread and intense with low-
level moisture drying out this afternoon. Overnight lows will be
in the 50s again as we decouple under the high pressure.
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&&

.SHORT TERM /10 AM THIS MORNING THROUGH FRIDAY/...
335 AM Wednesday...

Thursday morning is likely to find a nearly stationary front
draped west to east just north of the area. This front will lift
north as a warm front, Thursday through Friday, ahead of a cold
front approaching from the west. There may be showers and
thunderstorms along and north of the front back in central Ohio
Thursday morning, where the front is already beginning its
northward move. This activity should move northeast, remaining
north of the forecast area, as the northward movement of the
front progresses east.

This leaves the area in very warm, dry air, with plenty of
sunshine on Thursday once any morning fog burns off.

As the cold front and its associated southern stream short wave
trough move into the area Friday, clouds will start to increase
ahead of it Thursday night in the form of cirrus and
stratocumulus, and then any sunshine Friday morning will give
way to lowering and thickening cloudiness, with showers and
thunderstorms becoming a possibility by the end of the day.

The forerunner increase in cloud, and modest dew points in the
lower 60s, likely contribute to modest instability Friday
afternoon, with CAPE less than a KJ/kg. Given modest low to mid
level flow.shear, thunderstorms are not expected to be
especially strong, but they can produce heavy downpours and gusty
winds in the middle Ohio Valley by late in the day.

Deterministic central guidance highs are now in line with the
50th percentile guidance is rather high for daytime highs both
days, and are comfortably below record highs. Thursday night
will be mild, although decoupling could allow lows lower than
central guidance.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 420 AM Tuesday...

A southern stream short wave trough that moves into the area
Friday exits Friday night, but the cold front washes out. With
the air mass actually a bit more moist by Saturday, and an
additional southern stream short wave trough crossing the area,
showers and thunderstorms are likely Friday night through
Saturday, and even into Sunday. The nearly saturated atmosphere
will not be that unstable, but PW values could climb to 1.5
inches or higher, so heavy downpours are a good possibility. The
vegetation and recent dry weather should minimize the potential
for high water.

By later in the day Sunday, the short wave trough exits, giving
way to ridging, lessening shower and thunderstorm coverage
Sunday afternoon, compared with Saturday afternoon, at least
across the middle Ohio Valley. This should also lead to a lull
in the active weather Sunday night into Monday.

The chance for showers and thunderstorms then ramps back up
during the day on Monday, and continues Tuesday, as a warm
front and mid-upper level flat waves cross, out ahead of a
large mid- upper level low over the plains. This could all
culminate in a better chance for strong, heavy thunderstorms on
Wednesday, as the plains mid-upper level low pushes into the
Great Lakes, pushing a strong cold front into the area. Gradient
winds will also increase and become gusty ahead of this front
Tuesday and especially Wednesday.

After a rain-cooled Saturday, perhaps not too unlike Tuesday,
central guidances reflects a slow moderation in temperatures
next week, ahead of the upcoming, potential strong midweek
system. Nights will also cool off a bit, and then warm back up a
bit. Above normal temperatures prevail throughout the period,
but we should remain well shy of record territory.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
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As of 645 AM Wednesday...

Widespread dense fog causing IFR/LIFR restrictions or lower
across the forecast area this morning with CRW, HTS and PKB
seeing the lowest VIS. stratocu and some patchy dense fog formed
along the mountains, with BKW and EKN reporting IFR/LIFR CIGs.
VIS has not been impacted, but GOES-R microphysics satellite
imagery shows dense fog all around the terminals. Therefore,
put BCFG and some TEMPO groups in the TAF to cover the
possibility of it making impacting the sites.

Fog will start to lift and dissipate shortly after sunrise
between ~13-14Z, subsequently giving way to VFR under mostly
clear skies. This reprieve will last through the day, until
river valley fog arrives overnight into Thursday morning. This
round will not be quite as widespread, but IFR restrictions or
lower are possible.

Winds calm to light and variable this morning, becoming light
and SW`rly during the day.

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

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Timing of dense fog dissipating this
morning could vary. Low stratus could form across the higher
portions of the mountains instead of dense fog.



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
EDT 1HRLY       08   09   10   11   12   13   14   15   16   17   18   19
CRW CONSISTENCY  H    M    L    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  H    L    L    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  M    M    L    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  L    M    M    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    M    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  M    L    M    H    H    H    H    H    H    H    H    H

AFTER 12Z THURSDAY...
IFR conditions possible due to fog Thursday morning.
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&&

.RLX WATCHES/WARNINGS/ADVISORIES...
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WV...Dense Fog Advisory until 10 AM EDT this morning for WVZ005>011-
     013>020-024>034-039-040-515>526.
OH...Dense Fog Advisory until 10 AM EDT this morning for OHZ067-
075-076-083>087. KY...Dense Fog Advisory until 10 AM EDT this
morning for KYZ101>103- 105. VA...Dense Fog Advisory until 10 AM
EDT this morning for VAZ003-004.
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&&

$$

SYNOPSIS...TRM/LTC
NEAR TERM...RPY/LTC
SHORT TERM...TRM
LONG TERM...TRM
AVIATION...LTC