Scientific Forecaster Discussion
fxus61 krlx 121742
Area forecast discussion
National Weather Service Charleston WV
1242 PM EST Thu Dec 12 2019
high pressure through early Thursday night. Mixed precipitation
system late Thursday night and Friday changing to rain. Active
pattern persists through the weekend and into early next week.
Near term /through tonight/...
as of 1240 PM Thursday...
No changes needed through this afternoon.
As of 625 am Thursday...
No changes necessary, the forecast remains on track this
As of 215 am Thursday...
High pressure and rising heights overhead early this morning
will support quiet weather for the majority of the near term
period. The surface high will progress into New England through
the day Thursday, encouraging low level winds to shift out of
the south by the afternoon. A surface trough feature aligning
along the mountains will favor breezier downslope winds after
midday to around 15 mph.
A chilly night is in store tonight with the high in close
proximity to the forecast area and efficient radiational cooling
can take place. Temperatures at the time of this issuance had
already dropped down into the low 20s, with the exception of the
northeast WV mountains, who has some catching up to do now that
lingering evening clouds are no longer blanketing the area. By
dawn, I expect portions of southeast Ohio and the mountains to
fall into the upper teens. As surface winds shift into a return
flow regime during the day Thursday, we should see a decent
diurnal uptick by peak heating hours, leading to Max
temperatures in the mid to upper 40s in The Lowlands and 20s/30s
for the higher terrain.
Unsettled weather sneaks in for the final few hours of the near
term in the form of a low pressure system developing along the
Gulf Coast Thursday evening. This feature will travel across the
Mississippi Valley and eventually up the eastern Seaboard for
the end of the work week. Moisture feeding into central
Appalachia via return flow will promote a conglomeration of
showers and associated precip types, first encroaching on our
southwest Virginia counties around midnight. A nose of warm air
aloft traveling up the I-79 corridor will quickly change over
subfreezing temperatures in the southern coalfields and across central
West Virginia, bolstering rain showers by the morning rush hour
Friday morning. Meanwhile, areas along the Ohio River valley
and West Virginia mountains undertake a wintry mix beyond the
near term period.
Short term /Friday through Sunday/...
as of 255 am Thursday...
Shortwave over the deep south tracks northeastward into the mid
Atlantic region with one surface low over the mountains,
transitioning to a low further east that will push into upstate
For the western lowlands, and freezing rain/snow combination
should transition quickly to all rain, so any of these elements
prior to all rain should be short lived. Where the cold air
damming is strongest on the eastern slopes, and extended
freezing rain event is likely as 925mb-sfc temps are much
slower to warm to above freezing values. Transition to all rain
for these areas and the highest ridges will be in the 15-18z
Friday time frame. With this transition, and inch plus of rain
is possible in the mountains. Snow amounts should be negligible
overall, but some flakes are possible as this system evolves and
arrives in the overnight hours into Friday morning. Secondary
trough aloft and northwest flow keeps precipitation chances
going through the weekend in an unsettled synoptic pattern for
Long term /Sunday night through Wednesday/...
as of 255 am Thursday...
Active pattern continues in the long term with another southern
stream system moving in for the beginning of the work week. A
look at the lower level temperature profile suggest another
potential mixed precipitation event, but will keep the types
more generic this far out. Pattern shift and colder through the
middle of the week.
Aviation /18z Thursday through Tuesday/...
as of 625 am Thursday...
VFR conditions will prevail through early Friday morning with
increasing upper level cloudiness late this afternoon into the
early overnight. Southeasterly downslope winds will yield gusts
12-16kts at bkw with the remaining terminals staying under 6kt
sustained through morning. Winds aloft increase toward morning
in response to southern stream system coming up the mid-Atlantic
which could yield a few hours of low level wind shear at ekn, although may see
enough mixing to mitigate this.
Light rain overspreads the terminals early Friday morning with
ceilings lowering to 025-040. A brief period of freezing rain is
likely at bkw 10-13z before temperatures rise above freezing,
but current thinking is the remaining terminals recover/remain just
above freezing prior to arrival of the rain.
Forecast confidence and alternate scenarios through 18z Friday...
Forecast confidence: high.
Alternate scenarios: timing of rain may vary by an hour or so.
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.
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 h h h h h h h h h h h h
heights 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 18z Friday...
IFR possible in rain Friday evening.
WV...Winter Weather Advisory from midnight tonight to 7 PM EST
Friday for wvz516-518-520-523-524.