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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 191319
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
919 AM EDT Mon Apr 19 2021

.SYNOPSIS...
Warmer south to southwest flow around high pressure to the
south today through Tuesday. Strong cold front Wednesday. High
pressure late week, followed by a wet system this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 915 AM Monday...

Added showers over the western zones with the vort max/trough
axis rolling in. May need to expand this eastward in the next
update.

As of 640 AM Monday...

Forecast on track, with nothing more than isolated light showers
grazing far southeastern portions of the forecast area early
this morning.

As of 355 AM Monday...

A deep mixed layer to h75 prevails this period, maintaining a
dry boundary layer that allows RH values to dip into the 20s
this afternoon, but amid light flow. An upper level short wave
trough exiting first thing this morning, will take isolated
showers skirting southeast portions of the area with it.
Meanwhile, there may be a touch of valley frost in east-central
Ohio early this morning.

Otherwise, a nice spring day is on tap as high pressure builds
south of the area in the wake of the exiting short wave. The
deep mixed layer, and h85 temperatures of at least 5-6C,
support lowland highs of 68-70 amid rather uniform low level
thermal fields. Favored the higher MOS over the lower central
guidance and previous forecast. Unlike Sunday morning, the deep
mixed layer will preclude the low morning stratocu.

A mainly clear and tranquil night is on tap tonight, with light
south to southwest flow across the area, north of the high.
This will promote somewhat of a ridge valley split, and
otherwise again close to a MOS blend on average. With the bottom
of the column so dry, fog should by and large be precluded
again tonight.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 358 AM Monday...

     STRONG COLD FRONT TO IMPACT THE AREA WEDNESDAY...

Enjoy Tuesday`s weather as a blast of winter is set to occur
for Wednesday.

Strengthening SSW low level flow Tuesday will aid in good diurnal
mixing and associated sfc warming across the entire region. Given
the expected mixing, increasingly higher mid-April sun angle, and
rather dry soil moistures our afternoon highs should easily warm
into the 70s for nearly all locations below 2kft (50s/60s for the
mountains). By Tuesday evening, a powerful cold front will be
knocking on our northwest doorstep with a deepening sfc low
shifting NE roughly along the Ohio River. This will aid in a
strengthening LLJ overnight and allow for temps to remain rather
mild for much of the night. The front should rapidly cross from
NW to SE during the second half of the night and be moving into
(or possibly already cleared) the mountains by sunrise Wed.
Rain showers will likely accompany the front, but brevity of the
precip should result in rather low rainfall amounts. Mild temps
ahead of the front will crash after FROPA with temps likely
continuing to fall through at least late morning for the lower
elevations (and fall the entire day for elevations roughly 3kft
or higher). Given this, there should be a small one to three
hour window late Wed morning where the entire region is in the
30s. Temps for the lower elevations should then moderate
slightly (low 40s) during the afternoon. As temps fall during
the morning, rain showers may briefly mix with snow showers for
the lower elevations...and transition to all snow showers for
the highest elevations. Again, precip duration should be rather
brief and minimal to nil snow accumulations are expected for the
mountains.

A cold night will occur Wednesday night as strong sfc high
pressure tries to build into the area. Given expected cloud
cover and continued near sfc wind flow, I have not gone as cold
as some guidance indicates. Still, some locations where the
growing season has already begun will likely experience a brief
light advection freeze around sunrise Thursday. Thursday itself
will still be rather cool. Isolated to scattered rain and snow
(mountains) showers will likely dot the area during the day as
the final/parent H5 s/w trough axis advects across. Calmer sfc
winds and clearer skies Thurs night may allow another night
with temperatures around freezing.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 406 AM Monday...

Friday should be a rather quiet weather day as high pressure slowly
shifts east and temperatures start to moderate better. Forecast
certainty then decreases significantly for the upcoming weekend. All
guidance suites indicate another storm system will impact our area
Saturday into Sunday. There continues to be significant
discrepancies with synoptic feature placement and timing, but
there are good signals for wet weather to impact the area at
times over the weekend.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
As of 640 AM Monday...

VFR conditions are expected this period, with scattered high
stratocu / low altocu atop a deep mixed layer.

Light and variable to nil surface flow early this morning will
become light west today, and then light southwest tonight.
Light west to northwest flow aloft this morning will become
light west to southwest this afternoon and tonight.

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

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: None.
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       12   13   14   15   16   17   18   19   20   21   22   23
EDT 1HRLY       08   09   10   11   12   13   14   15   16   17   18   19
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    H    H    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 12Z TUESDAY...
IFR possible in showers Wednesday morning, mainly on ceilings.

&&

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

&&

$$
SYNOPSIS...RH/TRM
NEAR TERM...26/TRM
SHORT TERM...RH
LONG TERM...RH
AVIATION...TRM