Scientific Forecaster Discussion
fxus61 krlx 220635
Area forecast discussion
National Weather Service Charleston WV
235 am EDT sun Oct 22 2017
high pressure continues through Sunday. A strong cold front and
low pressure system crosses Monday and Monday night, with much
cooler weather by midweek. Another cold front next weekend.
Near term /through tonight/...
as 120 am Sunday...
Forecast on track.
As of 1000 PM Saturday...
As of 200 PM Saturday...
Intervals of cirrus through Sunday as high pressure shifts to
the east. Patchy dense River Valley fog overnight, but thinking
the combination of cirrus and boundary layer winds will keep
much of it confined to the mountain valleys.
The smoke plume from the large Industrial site fire in
Parkersburg should back more toward the north overnight and
perhaps into the city of Parkersburg. Should more decoupling
occur than forecast, poor ventilation rates and lack of
dispersion overnight could result in reductions in visibility.
Having said that, this is a low confidence scenario, especially
considering the uncertainty regarding how much smoldering will
Overnight lows were hedged a few degrees below guidance with
highs tomorrow on the warm side of the guidance envelope.
Short term /Monday through Tuesday/...
as of 230 am Sunday...
Main feature for the short term is the cold front which will
push through late Monday and Monday night. Models have come into
a bit better agreement on the synoptic features. A surface low
should cross from central Tennessee through central/western Ohio Monday
and Monday night. Some small differences in the models at 500mb,
namely on when the associated closed low opens and accelerates
to the NE. Generally looking at 1-2 inches of rain...mainly
Monday night. Will probably see some lingering showers behind
the front on Tuesday, but main upper level forcing holds of
until Tuesday evening.
Long term /Tuesday night through Saturday/...
as of 230 am Sunday...
In the wake of the cold front, much cooler weather is expected
mid week. Will also have an upper level trough passing over
Tuesday night through Wednesday night with showers. 850mb
temperatures continue to look cold enough for show showers
across the northern mountainous counties.
Surface high pressure passes Thursday and Friday with another
decent cold front expected Saturday per GFS -- or Saturday night
per European model (ecmwf).
Aviation /07z Sunday through Thursday/...
as of 120 am Sunday...
High pressure will continue to provide dry conditions through
the Sunday night. Satellite images show few to scattered cirrus
moving across the area overnight. Smoke plume from fire just
south of pkb had will likely shift northwestward and lower
across the area tonight as winds turn very light southeasterly.
Should this occur, vsby and/or cig restrictions may be realized
given the lowering ventilation rate and developing low level
inversion. So, for now, will code 4sm in smoke for pkb
overnight due to very low confidence on impact of and duration
of this plume.
Otherwise, the NAM and rap models show boundary layer winds of
15 to 20 knots from the south. This winds will keep good
ventilation preventing dense valley fog formation overnight. The
exception will be at site ekn which is more protected where IFR
visibilities of ceilings are expected during the 10z-13z time
Widespread VFR conditions are expected on Sunday as the high
pressure drift east.
Forecast confidence and alternate scenarios through 06z Monday...
Forecast confidence: high except at pkb.
Alternate scenarios: smoke may restrict vsby and/or cigs more
than forecast at pkb tonight.
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 sun 10/22/17
UTC 1hrly 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1hrly 02 03 04 05 06 07 08 09 10 11 12 13
crw consistency h h h h h h h h h h h M
heights consistency h h h h h h h h h h h M
bkw consistency h h h h h h h h h h h M
ekn consistency h h h M l l l l h h h M
pkb consistency h h h h h h h h h h h M
ckb consistency h h h h h h h h h h h M
After 06z Monday...
A strong cold front will cross the area Monday and Monday night.
IFR conditions and gusty winds can be expected along the heavier
showers or storms.