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FXUS61 KRLX 172322
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
622 PM EST Sat Nov 17 2018

.SYNOPSIS...
High pressure tonight. Next cold front Sunday night through Monday
night. Remaining cool through mid week, but modest warming for
the end of the week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 220 PM Saturday...

Clearing line working north through the area this afternoon,
all while stratus evolves into a broken stratocu field across
southeast Ohio and northern West Virgina. This trend will
continue into the early evening hours, as low level WAA
continues. Meanwhile some cirrus will be traversing the area
from the west, well in advance of an approaching s/w trof.
Based on model soundings and satellite imagery upstream, I do
not believe this will temper overnight lows. As such, I have
relied more on the colder guidance, especially in the typical
cold spots.

The upper s/w trof pivots closer Sunday, with mid and
eventually low level moisture advecting into the area. This
looks to affect primarily southeast Ohio until very late in the
afternoon. A low level baroclinic zone will develop across
portions of southeast Ohio, with lift increasing enough for
a few light showers late in the afternoon. Temperatures will be
warmest across the West Virginia lowlands, where mid to upper
50s look reasonable.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 245 PM Saturday...

A surface front forms over the baroclinic zone and is initially
draped along the northern side of the Ohio Valley, then begins
to drift South and East during the period into our area, helped
along by a wave aloft. The wave also enhances cyclonic
flow/low- level cyclogenesis; our location South of the front
means an influx of warmth and moisture Monday. The surface front
drifts southeastward through Monday with light rain shower
activity along it. Models differ on the extent of cyclogenesis
along the surface front, and thus differ on the extent of warm
air/moisture advection. For instance, the NAM brings a healthy
surge of 0.75" PWAT moisture into the Middle Ohio Valley as a
result of a stronger low level wave. The ECMWF is similar vs the
more subdued GFS. So, while a general blend is erred toward,
there is potential for more widespread stratiform rain Monday in
the Ohio Valley especially if southerly inflow overrides the
surface front.

Mid-level cooling largely holds off until early Tuesday morning,
maximizing between roughly 06-12Z Tuesday as the trough axis
aloft rotates through. A few flakes are possible in SE Ohio as
cold air pushes moisture out, and only light snow accumulations
are possible across the higher elevations. The factors limiting
accumulations across the mountains are mainly a) not the
greatest upslope low-level wind directions and b) scarce
humidity in the DGZ, although a seeder/feeder layer aloft could
help dendrite growth.

Maintained precipitation chances through the first part of Tuesday
with continued troughing and cold air advection coincident with
saturated low levels beneath very dry air aloft. A stronger,
albeit dry cold front associated with another short wave moving
through the mean trough aloft Tuesday night. Strong cold air
advection behind the front brings 850 temps down to -6C across
much of the area yielding low temperatures Tue PM into early
Wednesday in the 20's to near 30.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 300 PM Saturday...

After a brief afternoon warm-up between waves on Wednesday,
another dry cold front comes Wednesday Night. Behind the front,
stout high pressure builds over SE Ontario/S Quebec and extends
into Appalachia. A north wind develops as a result through
Thursday. High pressure only strengthens in the Piedmont /Mid-
Atlantic by early Friday, setting up a downslope SE wind down
into the western lowlands.

Friday, warm advection returns with an approaching ridge aloft.
Expect warmer afternoon temps as a result and upper-level
cloudiness later in the day. Rain showers approach from the SW
later Friday and expand across the area Friday night into early
Saturday. Cool temperatures in the mountains means a snowy start
(and perhaps icy in the highland valleys) is possible with the
current timing before switching to rain. But, still a bit early
to pin point specific conditions.

&&

.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
As of 612 PM Saturday...

VFR expected to prevail nearly areawide through the TAF period.

Cirrus continues to increase from west to east across the region
this evening and should prevail through much of the night as an
upper level jet remains nearly overhead. This cirrus should
negate much in the way of fog development overnight. Exception
may be across the higher terrain of West Virginia where some low
clouds and visibilities may develop late tonight. No reduction
in visibilities currently expected at the primary TAF sites,
however.

Mid level cloudiness is then expected to develop from NW to SE
during the day Sunday, but VFR should continue to prevail.

Weak sfc winds overnight becoming more SWrly around 10 kts on
Sunday.

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

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: Fog may develop late tonight if cirrus
thins more 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 22 23 00 01 02 03 04 05 06 07 08 09
EST 1HRLY 17 18 19 20 21 22 23 00 01 02 03 04
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 M M 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 00Z MONDAY...
IFR may occur in areas of rain Sun night and Monday.

&&

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

&&

$$
SYNOPSIS...30/MC
NEAR TERM...30
SHORT TERM...MC
LONG TERM...26/MC
AVIATION...RH/JZ
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