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FXUS61 KRLX 212053
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
453 PM EDT Mon Aug 21 2017

.SYNOPSIS...
High pressure continues into Tuesday. Strong cold front late
Tuesday into Tuesday night. Cooler and drier high pressure into
the weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 210 PM Monday...

Mainly dry except in the north where a few isolated showers are
possible this afternoon and evening. High pressure lingers into
Tuesday, but then a well defined system translates through
Tuesday evening.

All indications suggest that there could be some severe weather
with this frontal system though believe it will be north of the
I-64 corridor. Ample moisture, upper and low level forcing, and
wind shear all provide a favorable atmosphere for storm
development and maintenance. Veering wind profiles also suggest
some potential for rotating storms. Timing of the system, with
the front moving through in the late afternoon, is just about
right for maximum realization of CAPE. PW's are also quite high
in the 2.5" arena, so heavy downpours will also accompany these
storms. Luckily they should have enough forward propagation that
only local water issues may result. For now, gusty outflow from
cells looks like the largest threat with damaging winds
possible. The tornado and flash flooding threats are fairly
low, but non-zero.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 350 PM Monday...

As has been described with previous forecast issuances, this
system will feature two distinct surface fronts. The initial
front will be the focus of convection and will be located near
the Ohio River by 8 PM Tuesday. Severe potential will be waning
with the loss of daytime heating and instability, though precip
loading from heavy downpours combined with momentum transfer of
upper level winds can still generate occasionally strong gusts
overnight. This front will clear the CWA by day break Wednesday.

The secondary front, behind which lies the much-anticipated
Canadian airmass, will move through the eastern mountains by
the end of the day Wednesday. Scattered redevelopment of
showers and perhaps storms along the front in the WV mountains
and southwest VA is likely during the Wednesday afternoon hours.
Meanwhile, the remainder of the area outside of the mountains
will enjoy high temperatures 5-10 deg F below normal with
comfortable dewpoints in the 50's under the full influence of
deep northwest flow.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 350 PM Monday...

The region will be under the influence of deep northwest flow to
start the period. Easterly low-level flow from the Atlantic in
the Piedmont will provide some low-level moisture for
disturbances embedded within NW flow to potentially drum up
showers in the mountains during the weekend. Areas west of the
mountains will enjoy persistent dry northeasterly surface
winds. This synoptic pattern will hold while the parent closed
upper- level low struggles to exit eastern Canada. At the very
end of the forecast period, long- term models indicate an
embedded short- wave developing a surface system to increase
precipitation chances to start the work-week.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
12Z Monday thru 12Z Tuesday...
As of 1005 AM Monday...

Weak high pressure prevails thru tonight. An isolated shower
this afternoon is possible across the north. IFR fog will
mainly be in the more protected valleys after 09Z, but not
likely at terminals.

A front moves through Tuesday afternoon with showers and
thunderstorms some of which could be severe.

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

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: More showers and thunderstorms than
currently forecast.

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 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H M
HTS CONSISTENCY H H H H H H H H H H H M
BKW CONSISTENCY H H H H H H H H H H H M
EKN CONSISTENCY H H H H H H H H H H H L
PKB CONSISTENCY H H H H H H H H H H H M
CKB CONSISTENCY H H H H H H H H H H H M

AFTER 18Z TUESDAY...
Dense river valley fog possible each morning.

&&

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

&&

$$
SYNOPSIS...JW/MC
NEAR TERM...JW
SHORT TERM...MC
LONG TERM...MC
AVIATION...JW
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