-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 220633
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
233 AM EDT Tue Aug 22 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 TONIGHT/...
As of 1000 PM Monday...

Made some minor tweaks to temps and dewpoints this evening, but
no other changes made with forecast on track.

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 /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 220 AM Tuesday...

The post frontal environment will dry out quickly in northwest
flow with broad scale surface high pressure building into the
Ohio Valley. Some low level moisture advects back into the area
in wrap around moisture, which would suggest sprinkles to
isolated shower chances over the far northern CWA. However,
leaving this out for now, and should be firmly entrenched north
in the PBZ area.

Temperatures give a slight hint to the twilight of summer with
lowland 70s and dewpoints in the 50s for the short term.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 220 AM Tuesday...

Outside of some isolated mountain showers, the extended is dry
on the front end, with high pressure centered over eastern
Canada controlling our forecast area. An upper level low will
dig into the upper Mississippi Valley, meander eastward as it
becomes cut off, and slow advects chances for showers into the
western zones. As mentioned in past discussions, the dominant
ridge/trough pattern across the CONUS from west to east will
remain dominant. Expecting a slight increase in temperatures
from the short term.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
06Z Tuesday thru 06Z Wednesday...
As of 215 AM Tuesday...

Strong cold front moves across the area late this afternoon and
tonight, well preceded by a line of strong to severe
thunderstorms.

Thru 13Z...
Cirrus on the increase early morning. This, and some flow
should keep dense fog in only the most protected valleys. Did
include LIFR at EKN in the deeper valley and with the thinest
clouds til 13Z. Elsewhere, marginal MVFR valley fog at best possible.

Today after 13Z...
Out ahead of aforementioned line of thunderstorms, VFR with
generally cirrus this morning, then SCT-BKN clouds 4000-6000
feet AGL after 17Z with isolated thunderstorms mainly west.
Light south winds becoming southwest 10 to 20 KTS and gusty by
late morning.

Best estimate. Line of TSTMS expected to arrive at Ohio River
20Z-22Z and CKB-CRW line 23Z-01Z and into the mountains 01Z-
03Z. Conditions varying greatly within this line, lowering to
IFR at times, so will put PROB30 in TAFS at this distant time
frame, with strong gusty west winds and hail possible.

Behind this line, outside of mountains generally VFR ceilings
3500-5000 feet with scattered showers for 1-3 hours, then clouds
decreasing in the west. In the mountains, MVFR ceilings and
showers will linger thru rest of period. Winds becoming west 5
to 8 KTS behind the front which will reach the mountains around
06Z.


FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Main line of storms with cold front
later today could arrive a bit earlier than 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.

DATE                              TUE 08/22/17
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
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  M    L    L    L    L    L    L    M    H    H    H    M
PKB CONSISTENCY  H    H    H    H    M    M    M    H    H    H    H    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M

AFTER 06Z WEDNESDAY...
IFR possible in low stratus and showers/fog into early
Wednesday for mountains. River valley fog possible each morning
through the weekend.

&&

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

&&

$$
SYNOPSIS...JMV/26
NEAR TERM...JW/MZ
SHORT TERM...26
LONG TERM...26
AVIATION...JMV