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000
FXUS61 KRLX 181135
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
635 AM EST Tue Dec 18 2018

.SYNOPSIS...
High pressure today into Wednesday. A strong system moves
across Thursday through Friday, with another soaking rain.
Colder next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 635 AM Tuesday...

Forecast on track. GOES-R imagery shows stratocu in the
mountains slowly eroding, and river valley fog in the southern
lowlands.

As of 310 AM Tuesday...

High pressure builds into the area today, and then shifts to
the east of the area tonight. Low level moisture beneath strong
subsidence inversion, mainly in and near the mountains, mixes
out later this morning, with nothing more than a few cu this
afternoon.

Cirrus against upper level ridge over the Tennessee, lower Ohio
and mid Mississippi valleys early this morning, follows the
ridge and crosses the forecast area later today and tonight.
This may temporarily interfere with radiative cooling and fog
formation tonight. Either way, do not expect much fog tonight,
Guidance indicates none but think some fog is possible along the
rivers with clear, calm and chilly conditions late.

Temperatures close to MOS and near term guidance, a little
higher than previous forecast for today, and then a little lower
in the valleys tonight. Highs in the lower to mid 40s across
much of the lowlands today with sunshine and h85 temperatures
around 2-3C reflect the colder air beneath the shallow
inversion, which essentially evolves into a radiation inversion
tonight.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 155 AM Tuesday...

Warmer on Wednesday, as surface high pressure slides off to the
east, and upper heights build in response to deepening trough
across the eastern U.S. Clouds however will be on the increase,
as moisture streams northward into the area, as an upper low
forms in the base of the trough over the southern Mississippi
Valley region. Rain will overspread the area by early afternoon
Thursday, as atmosphere gradually moistens enough for precip to
reach the ground. Heavier rains are expected in the long term
period.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 200 AM Tuesday...

Moisture will continue to stream northward from southern stream
low over the MS valley region at the start of the period.
Precipitation will continue on Friday, becoming heavy at times,
along with gusty winds, as the southern stream low phases with
northern stream trough Friday, before kicking off to the east
Friday night/Saturday, with a cooler northwesterly flow taking
hold. Have a general 1.3 to 1.7 inches of QPF coded so far with
the system, and continue to be concerned with flooding issues.
PW values are progged to rise to around an inch, well above
normal for this time of year considering mean is around 0.4 for
December. Will continue the mention in the HWO.

As the low kicks off to the northeast over the weekend, will see
a change over to -shsn, particularly across parts of southeast
Ohio, KY, and the mountainous counties...but it will be brief
at least for lowland locations if at all, as moisture is quickly
lost in DGZ. Mountainous/northwesterly upslope favored
locations will be more likely to see an actual snowfall, with
light accumulations possible. No accumulations expected across
lowlands at this time.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
As of 635 AM Tuesday...

River valley fog in the southern lowlands will dissipate by
14-15Z.

Stratocu over the mountains this morning may spread westward a
bit as a SCT-BKN layer on the morning cu effect, before mixing
out into a FEW-SCT afternoon cu field near 4 kft.

Tonight will be VFR, save for river valley fog formation toward
dawn Wednesday, once a cirrus deck goes by.

Other than light north to northwest winds in the mountains
early this morning, surface flow will be light and variable to
calm today and tonight, as high pressure crosses. Light to
moderate north to northwest flow aloft this morning will become
light north by afternoon, and then switch to light southwest
overnight tonight.

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

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: Dissipation of MVFR stratocu this morning
could vary from forecast. River valley fog forming overnight
tonight or toward dawn Wednesday morning is in question,
depending on high cloud and boundary layer flow, which is likely
to be in the borderline 15 to 20 kt range.

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 12/18/18
UTC 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
EST 1HRLY       05   06   07   08   09   10   11   12   13   14   15   16
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  M    M    L    L    M    H    H    H    H    H    H    H
BKW CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  M    M    M    M    M    M    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z WEDNESDAY...
IFR possible in rain late Thursday through Friday, and in snow
showers in the mountains Friday night into Saturday.

&&

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

&&

$$
SYNOPSIS...TRM/SL
NEAR TERM...TRM
SHORT TERM...SL
LONG TERM...SL
AVIATION...TRM