Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 krlx 121119 
afdrlx

Area forecast discussion
National Weather Service Charleston WV
619 am EST Tue Nov 12 2019

Synopsis...
snow showers at times this morning, becoming more confined to
the mountains. Near record cold temps possible tonight. Dry for
the second half of the work week.

&&

Near term /through tonight/...
as of 607 am Tuesday...

Last significant snow band exists from Charleston to Clarksburg
and is pushing east. Once this band shifts east, a lull in
precip should occur before new sct snow showers develop by
mid/late morning, primarily across the northern/northeastern
County Warning Area. Infrared thermometer at our office indicates asphalt temps
are now lowering to around freezing in the Southridge area. In
general, Road temps should continue to lower across the entire
County Warning Area and the threat of hazardous Road conditions should increase
some from now through at least mid morning.

As of 222 am Tuesday...

As of writing, surface cold front has cleared the County Warning Area with
nearly all areas having changed over to snow. 850 mb front is
roughly Half Way across the cwa, with 800 mb-700 mb layer equivalent
potential vorticity values trending slightly negative across
West Virginia. The combination of these features should result
in some SW to NE oriented banding of snow over the next few
hours...until the 850 mb front shifts farther southeast. As such, there
should be some pockets of moderate to briefly heavy snow across WV
and SW Virginia before sunrise. Closer to sunrise, most of the locally
heavier bands of snow should become more confined to the
mountains. After sunrise, the parent 500 mb trough axis should move
overhead and eventually east with snow gradually tapering off at
that time. However, Post frontal snow showers should be a good
possibility through the day, especially across the
northern/northeast County Warning Area where some low level moisture fetch from
the Great Lakes initiates and some modest instability is prog to
exist. Could see a few bursts of brief heavy snow with any snow
showers during the day, resulting in brief rapid drops in
visibility.

Entire storm system eventually shifts far enough to the east
tonight to allow surface high pressure to settle more into the
area. Skies will try to clear by this evening, but only a slow
erosion is expected today and tonight.

Temps today should continue to slowly fall through mid/late
morning, then hold steady a bit around midday/early afternoon,
and then fall further during the afternoon. Nearly all areas
should remain below freezing during the day. Near record low
temps are expected to occur late tonight. Low temp forecast is a
bit tricky, however, as values are strongly dependent upon how
much clearing occurs...and also how much snow is on the ground.
Have gone a little conservative with the forecast values for now,
as I think cloud cover should stick around for quite awhile. If
skies clear faster than forecast, then values will be even
colder.

No changes are being made to the Winter Weather Advisory at
this time as snow is ongoing and Road conditions are gradually
becoming more hazardous.

&&

Short term /Wednesday through Friday night/...
as of 200 am Tuesday...

Surface high transitions to the East Coast Wednesday with weak
warm air advection allowing for temperatures to moderate. However, it will
remain quite chilly as a Stout inversion will likely limit the
amount of recovery we would otherwise see.

Temperatures Wednesday nigh are tricky and hinge on how much of
a cirrus canopy overspreads the area ahead of an approaching S/W
trof. Current thinking is we will have an opportunity to
realize decent radiational cooling in the evening with
temperatures leveling off or perhaps rising overnight with
arrive of high clouds. Even with the expected arrival of cirrus,
I undercut nbm by several degrees across our typical cold
spots. This results in the mountain valleys dropping well down
into the teens with some single digits possible should cirrus
not be as dense as forecast.

Aforementioned S/W trof will cross later Thursday with little
fanfare, other than some clouds. Temperatures will continue the
moderating trend, though still well below normal for mid
November.

Upper level energy is progged to hang back across the Red River
valley Friday as the mean longwave trof lifts northeast into
eastern Canada. This will help to induce weak cyclogenesis along
the Gulf Coast, along the old baroclinic zone with no impact to
our sensible weather. Weak cold air advection will temporarily mitigate the
moderating trend from previous days.

&&

Long term /Saturday through Monday/...
as of 211 am Tuesday...

Weak wave along the Gulf Coast will track along the southeast
coast over the weekend before becoming better organized and
lifting northeast. Meanwhile, we will essentially remain between
that system and an upper level trof amplification along the MS
valley. This will keep a dry regime in place this weekend with
temperatures remaining a bit below normal amid intervals of
clouds.

&&

Aviation /11z Tuesday through Saturday/...
as of 603 am Tuesday...

Last significant band of snow is currently pushing east and
extends from kcrw to kckb. This band should move into the
mountains early in the taf period, possibly resulting in IFR or
worse conditions for kbkw to kekn. After this last band moves
through, cigs should improve to MVFR with generally VFR vsbys
prevailing. However, by mid/late morning, additional sct shsn
may develop, especially across kpkb/kckb/kekn. Have included
tempo groupings for reduced flight rules for those aerodromes to
account for these snow showers. Elsewhere, chances of snow
showers will be too low to mention in tafs.

Aside from impacts from precip, MVFR cloud deck will be slow to
erode today, but should eventually transition to VFR by late in
the day and especially overnight.

Brisk wnwrly sfc winds 10 to 15 kts today, peaking around midday
to mid afternoon...then becoming much lighter tonight.

Forecast confidence and alternate scenarios through 12z
Wednesday...

Forecast confidence: medium.

Alternate scenarios: coverage of snow showers may not be as
great as currently expected. Lower confidence exists with kbkw
taf.

Experimental table of flight category objectively shows consistency
of weather forecast office 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 Tuesday 11/12/19
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 M l h h h h h h M h h h
heights consistency h M h h l h h M h h h h
bkw consistency h h h h h h l h h h h l
ekn consistency M M M h h h h h h M h l
pkb consistency h h h h h h h h h M h h
ckb consistency l h h h h h h h h h h M

After 12z Wednesday...
no widespread IFR conditions are expected at this time.

&&

Climate...
record low temperatures may be challenged Wednesday morning.
Below are the records for Wednesday November 13th.

Charleston 16 1911
Huntington 17 1911
Parkersburg 17 1986
Clarksburg 15 1926
Elkins 10 1920
Beckley 12 1986

&&

Rlx watches/warnings/advisories...
WV...Winter Weather Advisory until 7 PM EST this evening for wvz032-
039-040-520-522>526.
Winter Weather Advisory until noon EST today for wvz005>011-
013>020-024>031-033-034-515>519-521.
Wind Chill Advisory from 7 PM this evening to 8 am EST
Wednesday for wvz523-526.
Ohio...Winter Weather Advisory until noon EST today for ohz066-067-
075-076-083>087.
Kentucky...Winter Weather Advisory until noon EST today for kyz101>103-
105.
Virginia...Winter Weather Advisory until noon EST today for vaz003-004.

&&

$$
Synopsis...rh/30

National Weather Service Glossary of Abbreviations