Flash Flood Watch 11, NWS Charleston, WV

Area Forecast Discussion
National Weather Service Charleston WV
Issued by National Weather Service Pittsburgh PA
944 AM EDT Sat Sep 1 2018

.SYNOPSIS...
Showers/thunderstorms will be possible across the region on
Labor Day Weekend with the higher elevations having the greatest
chance of receiving storms each day. Temperatures will be well
above normal for September and heat index values may reach near
100 by next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 940 AM Saturday...

Fog that developed overnight has disspated leaving the region
with mostly sunny skies. However, satellite imagery shows a
large area of clouds was pushing east into the area.

Radar mosaic continues to show showers and thunderstorms were
moving east across portions of Ohio and Kentucky.

Have made tweaks to sky, temps and POPS to reflect the latest
trends and guidance.

Previous Discussion...
The previous forecast remains on track. Fog has been limited to
the far northern and eastern portions of West Virginia as cloud
cover elsewhere has inhibited widespread development. Any fog
will quickly mix out after sunrise.

Warm, humid conditions are expected over labor day weekend.
Showers/Tstorms will develop in the afternoon hours as diurnal
heating destabilizes the atmosphere. A weak shortwave rotating
around the NW periphery of the Atlantic High may help initiate
some convection today. Otherwise, most activity will be confined
to the higher elevations where insolation combined with this
warm, moist boundary layer will more than suffice for tstorm
development.

Forecast soundings are rather unimpressive for organized
or severe convection. Winds will be mostly light and uniform
through the profile. Lapse rates are modest at best. Still,
lapse rates will climb to near or in excess of 1500 J/kg during
peak heating. Not much in terms of capping... so will likely see
a decent CU field with some showers or weak thunderstorms.

&&

.SHORT TERM /SUNDAY/...
Convection will diminish after sunset Saturday with the loss of
heating. Broken or perhaps overcast skies will likely prevent
widespread fog formation... but like this morning, valley fog
will still be possible in the most susceptible areas.

Sunday will be similar but with a few less storms as high
pressure builds into the region. Temperatures will remain well
above seasonal both days.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The hot, humid conditions will continue through the long term
period. Models are in good agreement that a H5 595+ dm high
pressure becomes nearly centered over the region through late
next week or just east, allowing for persistent southerly flow
in the low levels. This will keep the stream of very warm,
moist air in place. Without much in the way of upper level
forcing, convection will be mostly confined to the Allegheny
Front / other high elevations during peak heating.

Temperatures will be much above normal over the next 7 days.
Heat index values may very well reach near or above 100 outside
of the high elevations.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Showers have dissipated, but mid and high cloudiness is likely
to continue inhibiting IFR fog formation at HTS and CRW through
the predawn hours. After daybreak, recovery to VFR will be
interrupted by sct convection a weak disturbance moves through
the western periphery of an wwd expanding Mid Atlantic ridge.

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

FORECAST CONFIDENCE: MODERATE

ALTERNATE SCENARIOS: MID/HIGH LEVEL CLOUDS MAY CLEAR IN THE
IMMEDIATE PREDAWN AND IFR FOG COULD BRIEFLY DEVELOP.

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.

AFTER 12Z SUNDAY...
May have brief IFR in thunderstorms Saturday.

&&

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

&&

SYNOPSIS...JSH
NEAR TERM...JSH
SHORT TERM...99
LONG TERM...99
AVIATION...99

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