Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 120123 AAB
AFDRLX

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Charleston WV
923 PM EDT Tue Aug 11 2020

.SYNOPSIS...
Weak cold front nudges into the region tonight and will stall
over the area through the rest of the week. Weather remains
unsettled through the upcoming weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 916 PM Tuesday...

Adjusted hourly temps and dewpoints slightly, for this evening,
to account for current nocturnal trends. Otherwise, forecast
remains on track. It will be a battle between river valley fog
or a cloud deck tonight. Potential exists for some dense river
valley fog tonight if the cloud cover is too slow to
develop...although latest GOES 10.3-3.9 micrometer imagery
indicates cloud cover is currently trying to develop across SW
VA and the eastern CWA. Aside from fog/clouds, it will feel
noticeably more humid tonight.

A look forward to tomorrow indicates current forecast POPs may
be a little on the high side. Will allow incoming shift to
analyze full 00z data suites before making any changes to Wed`s
precip forecast.

As of 345 PM Tuesday...

Have made substantial changes to this afternoon and evening`s
forecast. Increased cloud cover significantly for the rest of
this afternoon, lowered max temps for this afternoon, and
reduced POPs across the board for this afternoon and tonight.
Cloud cover has kept the area rather more stable than previously
expected, which should aid in precluding much in the way of
precip development (aside from ongoing showers across the
mountains).

As of 225 PM Tuesday...

A cold front will arrive tonight from the northwest, and stall over
the area through the rest of the period. However, models are not too
excited with this front bringing little or no pcpn as it moves in
tonight. Showers and storms can not be ruled out with H500
shortwaves passing overhead through Wednesday. Therefore, kept low
PoPs tonight, re-emerging Wednesday afternoon and evening.

Low temperatures tonight should reach the upper 60s lowlands ranging
into he lower 60s highest elevations. Max temperatures for
Wednesday will generally be in the upper 80s, with some spots across
the lowlands reaching the 90 degree mark.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 237 PM Tuesday...

A weak upper level low across the mid Mississippi Valley will
gradually open to a upper trough by Thursday. This feature will
slowly drift to the ENE towards the middle Ohio Valley by the end of
the week. As this feature slowly pushes towards our area and
interacts with a weak frontal boundary draped across the region,
scattered showers and storms are expected both Thursday and Friday.
Orographic lift should help keep highest PoPs in the mountains and
thus, WPC has a Marginal Risk for Excessive Rainfall across the far
eastern portions of our area on Thursday. While dry antecedent
conditions should help mitigate a more substantial flood risk, slow
storm motions and PWATs around 1.75 to 2 inches should support
torrential downpours and if any areas receive repetitive rounds of
convection, localized water issues could be possible late this week.
Otherwise, it will be warm and humid with highs around 90 on
Thursday and Friday across the lowlands.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 237 PM Tuesday...

The aforementioned upper level trough will continue to slowly drift
across the region this weekend and with better shortwave support,
coverage of showers and storms should increase this weekend with
activity most numerous in the afternoon and evening hours. By early
next week, an upper level trough will drop into the Great Lakes and
push a cold front towards our area Monday night into Tuesday.
This will result in additional rounds of showers and
thunderstorms across the area. Surface high pressure in the
Upper Midwest is then expected to start to build into the area
by Tuesday in the wake of the departing frontal passage, but
will leave PoPs in the forecast through the end of the period as
there are timing differences in exactly when the front will
clear the area. We also should see a gradual return to more
normal temperatures by the end of the long term period as the
surface high brings a more northerly flow into the area.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
As of 723 PM Tuesday...

VFR early in the TAF period with IFR or worse conditions
possible overnight due to river valley fog.

Diurnally driven Cu along with persistent mid level deck are
both diminishing in coverage this evening. Thus, VFR should
prevail areawide during the first several hours of the TAF
period. Later in the night, river valley fog is likely to
develop across/vicinity of most aerodromes with nearly all
guidance indicating IFR or worse restrictions by late in the
night. Thus, have carried poor flight rules for most
areas...although there are a few hints that wind speeds just off
the sfc may help negate fog severity to an extent. We`ll see...

Poor flight rules should gradually improve back to VFR by mid
morning Wednesday with a Cu field developing by afternoon. Sct
SHRA/TSRA likely to develop in the afternoon along the WV mountain
spine and gradually drift northwest by early evening. Have
carried PROB30s for KBKW/KEKN and VCTS late in the period for
KCKB/KCRW to account for expected convection.

Weak/vrb wind fields through much of the TAF period. Perhaps a
little more Nrly during the day Wednesday.

Winds should remain light throughout the period.

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

FORECAST CONFIDENCE: High this evening. Medium overnight.

ALTERNATE SCENARIOS: Severity of fog may differ from TAFs.

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 08/12/20
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    L    L    M    M    M    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    L    M    M    M
BKW CONSISTENCY  H    H    H    H    H    H    M    L    L    L    M    L
EKN CONSISTENCY  H    H    H    H    H    H    H    L    M    M    M    M
PKB CONSISTENCY  H    H    H    H    H    H    H    L    M    M    M    M
CKB CONSISTENCY  H    H    H    H    H    H    H    L    M    M    M    M

AFTER 00Z THURSDAY...
No widespread IFR conditions are expected at this time.

&&

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

&&

$$
SYNOPSIS...ARJ/RG
NEAR TERM...RH/ARJ
SHORT TERM...RG
LONG TERM...RG
AVIATION...RH


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