-- Discussion containing changed information from previous version are highlighted. --
521
FXUS61 KRLX 221639
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
1239 PM EDT Sun Sep 22 2024

.SYNOPSIS...
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Dry/hot today. Chances of showers/thunderstorms increase late
tonight through Wednesday, bringing possible beneficial
rainfall.
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&&

.NEAR TERM /THROUGH MONDAY/...
As of 955 AM Sunday...

The dense fog advisory for portions of West Virginia and
Southeast Ohio has been allowed to expire. Fog will continue to
dissipate over the next several hours.

As of 846 AM Sunday...

A Dense Fog Advisory continues for parts of the area until 10 AM
this morning. Once the fog dissipates, temperatures should
quickly rebound into the upper 80s and lower 90s this afternoon.
No changes are needed to the forecast at this time.

As of 625 AM Sunday...

Little to no changes were needed to the forecast this morning.
Dense river valley fog continues to flourish across the forecast
area this morning, with visibilities of half a mile or less
quite common along our most traveled roadways. In coordination
with surrounding offices, a Dense Fog Advisory will remain in
effect until 9 AM this morning to highlight the concern for
hazardous travel conditions across parts of southeast Ohio and
north-central West Virginia, where rain was observed yesterday
afternoon and evening.

As of 215 AM Sunday...

Satellite imagery early this morning reveals river valley fog
growing in coverage and intensity across northeast West Virginia
and along the southern Ohio River Valley. These two areas were
noted to have received measurable rainfall on Saturday from a
cold front and will likely festering through the predawn hours
into daybreak this morning. A Dense Fog Advisory could be
warranted later on this morning if half mile to quarter mile
visibilities continue down into our more populated areas.

The frontal boundary planted directly over the forecast area
early this morning is progged to shift slightly northward today
as a warm front. This will place the Central Appalachians in the
warm sector of an encroaching disturbance slated to arrive late
tonight into early Monday morning. In the meantime, afternoon
temperatures in the Tri-State area and into the central lowlands
will once again topple over the 90 degree mark.

Minimum relative humidity values will bottom out into the 20 to
30 percent range during peak heating hours this afternoon in
the lower elevations and down into the 30 to 40 percent range
along the mountains and southern coalfields. This will be the
last day through the foreseeable future for these low RH values
as low level moisture becomes present over the next several
days. We should lack the wind component today when it comes to
fire weather concerns.

A low pressure system tracking through the Ohio Valley today
will invade the forecast area by dusk this evening. Clouds will
first arrive this evening, followed by a line of broken showers
and thunderstorms late tonight into the overnight hours. This
marks the revival of unsettled weather for the start of the new
work week and brings beneficial rainfall to the area. Within
this portion of the forecast, QPF totals range from a few
hundredths to a tenth of an inch across southeast Ohio and
eastern Kentucky, where POPs will first arrive overnight.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 305 AM Sunday...

A moist airmass is forecast to be in place Monday through Tuesday as
the region sits in the open warm sector of a slow moving surface low
transiting the Mid-West. Diffluent flow aloft should allow for both
nocturnal elevated convection as well as diurnally enhanced surface
based storms Monday. Initially, deep layer shear will be on the
weaker so not expecting too much in the way of storm organization
Monday. The main threat with any activity will be locally heavy
downpours. While any rain would be largely beneficial, could see
some localized drainage issues over built up areas should one of
these downpours dwell too long.

Deep layer flow increases on Tuesday in response to the parent upper
trough approaching the region. Contingent on diurnal destabilization
could see a severe threat emerge for Tuesday afternoon with locally
damaging winds, and perhaps a low end tornado threat as the primary
hazards, most likely focused from the Metro Valley down the Tug
Fork, although confidence is low this far out.

Cold frontal passage is then expected Wednesday. At present this
looks to occur relatively early in the day and not yield as much of
a chance to destabilize diurnally.

Ensemble guidance is reasonably confident in the combination of this
activity to produce widespread beneficial rain, which should help
take the edge off very dry unsheltered fine fuels, even if it won`t
put much of a dent in our rainfall deficit. Interquartile 72hr
amounts ending Thursday morning range from around half an inch to
near 2 inches, highest in the northeast with our current
deterministic forecast generally falling in this range.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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As of 1220 PM Sunday...

Models are starting to come into slightly better agreement for
the extended period. A frontal boundary will stall near the area
for Wednesday and Wednesday night as an upper level low cuts
off over the central United States. This low will then interact
with a tropical system in the Gulf of Mexico, causing a
fujiwhara effect. This will sling the tropical system northward
and then northwestward, keeping the bulk of the system west of
our region. Models do show some outer bands moving into our
area and possibly evening stalling in our vicinity. Still way to
early to put stock in the timing and location of the outer band
moisture, but if this were to stall over the area, some heavy
rains would be possible.
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&&

.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
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As of 625 AM Sunday...

Dense river valley fog is quite apparent on nighttime satellite
imagery this morning, having now made it into all but two of our
TAF sites. The last site to see fog attempt to trickle in this
morning will be CRW. Should see conditions improve shortly after
13Z/14Z this morning as the erosion of low vsbys/ceilings
branches out into a mostly quiet day. A disturbance stretching
in from the west will begin to yield lowered ceilings late
tonight into Monday morning, with rain spreading in from west to
east. Out ahead of the precipitation shield, fog will once again
attempt to form in our river valleys. Western terminals may have
a more difficult time with fog production with the mid to upper
level cloud deck moving in from the Ohio Valley. Will hint at
most sites seeing fog tonight, but modifications are certainly
not out of the question with future TAF issuances.

Winds will be light and variable through the this evening,
becoming more southerly overnight into the end of the valid TAF
period.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...

FORECAST CONFIDENCE: Low to Medium this morning, then becoming
High after the erosion of fog.

ALTERNATE SCENARIOS: Improving conditions may vary from the
forecast after daybreak as fog scatters and lifts.

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       15   16   17   18   19   20   21   22   23   00   01   02
EDT 1HRLY       11   12   13   14   15   16   17   18   19   20   21   22
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 18Z MONDAY...
Brief IFR possible in thunderstorms Monday through Wednesday.
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&&

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

&&

$$

SYNOPSIS...MEK/RPY/JP
NEAR TERM...MEK/JMC
SHORT TERM...JP
LONG TERM...RPY
AVIATION...MEK