Area Forecast Discussion
Issued by NWS Charleston, WV

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996
FXUS61 KRLX 201825
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
125 PM EST Sat Jan 20 2018

.SYNOPSIS...
Mild temperatures this weekend and then a strong cold front
crosses late Monday. This will bring widespread rainfall to the
region. Cooler behind the front, but another warm up late next
week with high pressure building in.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 1100 AM Saturday...

Previous forecast on track.

As of 600 AM Saturday...

Adjusted temperatures and sky cover for this morning based on
current obs and trends. Non-diurnal trend now in full swing --
it even appears that the more sheltered valleys have broken
through the inversion with temperatures on the increase.

As of 1250 AM Saturday...

Tricky temperatures again early this morning, as some areas have
decoupled and cooled quickly, while others remain mixed. In
general, have temperatures bottoming out in next couple hours
before starting to warm with incoming clouds and continued SW
flow. In a somewhat odd synoptic setup, our SW flow is actually
producing some mid level cold advection with closed upper low
near the Gulf Coast. So did not start warming higher elevations
until after sunrise.

Clouds should be on the increase today. Initially, expecting a
layer of cirrus which is already spreading in from the west. But
with the SW flow, the low to mid levels begin to saturate, with
a stratus deck forming/moving in from the SW. As moisture
continues to pump in, eventually we will see some
drizzle/sprinkles/light rain as a warm front lifts through.
Blended in ECMWF MOS for highs, which bumped up highs a degree
or two across the south.

The warm front departs to the north overnight, so cut back on
POPs. However still lingered slight chance to chance across the
north with GFS/ECMWF a bit slower than the NAM lifting the front
through. Went with a non-diurnal temperature trend tonight,
especially across the south after midnight.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 125 PM Saturday...

Looking at well above average temperatures to start the period
as we sit well within the warm sector or low pressure tracking
northeast into the Great Lakes. This system will drag a cold
front through the region on Monday. Strong SW return flow will
send temperatures soaring and carry some decent moisture into
the area. Models agree that front moves through fairly quickly
late Monday night, and not expecting a ton of QPF out of it,
even with slightly anomalous PWATs for the area. Still looking
at a widespread half inch rainfall, with possibly some higher
amounts nearing an inch in the the mountains. Colder air rushes
in behind the front, but with only some lingering low level
moisture, not expecting much in the way of snow. Even in the
mountains, only about a half inch of snow accumulation is
expected. Orographic accent will be limited with flow generally
staying WSW to straight westerly behind the front, so this will
help keep accumulations light.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
As of 225 PM Saturday...

Model guidance is in fairly good agreement as we head later in
the week. May see a few snow showers in the mountains Wednesday
into Thursday in NW flow and upper trough swinging through.
However, after that, the trend has been for another warm up as
we close out the period. Large high pressure and upper ridge
build over the area at the end of the period and beyond with
return flow over the Ohio Valley.


&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 1230 PM Saturday...

Morning MVFR stratus have lifted leading to mostly sunny skies.
Satellite and sfc obs suggest there is broken thin cirrus across
the area. In addition, a mid level deck is evident in satellite
images to affect southern WV including BKW through this evening.

High pressure will continue in control with widespread VFR
conditions through the period.

A warm front will lift across the area overnight tonight.
Although light drizzle or sprinkles can occur with this feature,
confidence is low, and were not included in TAF.

Flow will continue out of the S to SW through the TAF period.

A cold front will approach Monday capable to produce IFR/MVFR
conditions and gusty winds along the heaviest rain showers.

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

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: May need to add IFR visibilities if
drizzle or rain materialize tonight.

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
EST 1HRLY       13   14   15   16   17   18   19   20   21   22   23   00
CRW CONSISTENCY  M    M    H    H    H    H    H    H    H    H    H    L
HTS CONSISTENCY  H    H    H    H    M    M    M    H    H    H    H    L
BKW CONSISTENCY  M    M    M    M    M    M    M    M    M    H    L    L
EKN CONSISTENCY  M    M    M    M    M    M    M    M    M    M    H    M
PKB CONSISTENCY  M    M    M    M    M    M    M    M    H    H    H    M
CKB CONSISTENCY  M    M    M    M    M    M    H    M    M    M    H    M

AFTER 18Z SUNDAY...
IFR possible Monday/Monday night under rain showers.

&&

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

&&

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



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