Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 231038
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
638 AM EDT Mon Oct 23 2017

.SYNOPSIS...
Strong cold front and low pressure system cross today and
tonight. Much cooler weather by midweek. Another cold front next
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM Monday...

A strengthening low pressure system will lift through KY/IN and
into MI today. This will push a strong cold front through the
Ohio River Valley and Central Appalachians this afternoon into
tonight. Models also showing a wave of low pressure along the
front lifting up the spine of the Appalachians this evening.

Southeast winds already picking up ahead of the front. A stout
low level jet in place today -- with 850mb winds increasing to
50-60kts. This will translate to gusty winds at the surface. A
blend of hi-res models yielded gusts of 25-35 kts from late
morning through the afternoon. Gusts along the highest peaks
could even be a bit stronger.

Precipitation will be on the increase as moisture pumps into the
forecast area today. First radar echos arriving from the south
as of 10Z. Heaviest rain will be with the cold front late this
afternoon into this evening. Did not include any mention of
thunder, due to little to no instability. However, cannot rule
out a stray dynamics driven rumble. Even without the
instability/thunder, stronger showers could mix down stronger
winds, which could be capable of damaging weak trees, etc. PWAT
values top out in the 1.5-1.75 inch range late today. A band of
heavy rain is expected near the front. The ground is generally
pretty dry and the entire system will be moving nicely, so not
anticipating any widespread or significant water issues. But
heaviest rain could still lead to some local ponding. In total,
have a widespread 1-2 inches forecast today into tonight.

Cold front departs to the NE overnight, with POPs decreasing.
Kept some 20 POPs going to account for timing and any lingering
showers, however it looks like we should have a decent dry
period overnight with a dry slot rotating through.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
As of 230 AM Monday...

Models indicate a deep low pressure system over the Great Lakes
region with a cold front extending south, well east of our
eastern mountains Tuesday. An upper level trough will cross
Tuesday and Wednesday. This trough will provide some moisture
and lift, allowing for a chance of showers. With colder air
aloft, could see some snow flakes in the higher elevations of
the northern WV mountains. By Tuesday night, models show H850
temperatures reach minus 2-3C, suggesting a widespread area
with surface temperatures at or below 36 degrees over the
lowlands. This poses a threat for a widespread frost event
Tuesday night into Wednesday morning. Mainly dry Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 230 AM Monday...

A high pressure system will build over the area, to provide dry
weather conditions Thursday and Friday.

Strong cold front will move into the area from the west over
the weekend. There are minor differences in the arrival timing
among the GFS and ECMWF models. This looks like a progressive
system, so rainfall accumulations, although heavy at times,
could be minor.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 630 AM Monday...

A strong cold front will cross late today. Ahead of the front,
clouds and precipitation will be on the increase driven by
strong southeasterly flow. Winds at 850mb will be increasing to
50-60kts by this afternoon, and have included gusty conditions
in each TAF. Strongest surface winds will be at higher elevation
terminals.

Have included a one hour slot of IFR visibilities at each TAF
site to account for strongest showers just along and ahead of
the cold front. Timing on this may be off, but can be tweaked as
things progress today.

With a fair amount of cloud cover and some lingering flow
expected tonight, did not include any post rain fog -- however
if any breaks develop and winds decouple, fog will become more
likely.

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

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Timing of showers may vary by an hour or
two. Could get valley fog tonight if clouds break.

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

AFTER 12Z TUESDAY...
River valley IFR fog possible Wednesday and Thursday mornings if
frost does not occur.

&&

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

&&

$$
SYNOPSIS...ARJ/MZ
NEAR TERM...MZ
SHORT TERM...ARJ
LONG TERM...ARJ
AVIATION...MZ



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