Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
932 am EST Sat Feb 6 2016
high pressure builds into Sunday...with a tranquil February
environment. Cold front Monday. Unsettled/colder Tuesday and
Wednesday under middle/upper level low...with rounds of snow showers.
Near term /through tonight/...
930 am update...just minor changes to temperatures with this
forecast update to align them with current observations and
trends. Other than that...pretty basic forecast for the weekend
with cool high pressure overhead and scattered clouds.
a surface high pressure remains in control with dry and cool weather.
Satellite images and surface observation show high level clouds moving
northeast across the area. Expect these clouds to continue
covering the skies through tonight.
Temperatures will be near normal. Generally in the middle 40s
lowlands to upper 30s highest elevations for highs. Lows will
depend on cloud cover tonight. Since expecting mostly clear
skies...light and variable to calm winds after the lower
atmosphere decouples...temperatures will drop into the middle to
Short term /Sunday through Tuesday/...
significant changes in airmass and precipitation characterize the
short term forecast with a well advertised upper level low diving
into the southern Great Lakes from the upper Mississippi Valley.
Since the operational NAM/GFS/ECMWF are in fairly good
agreement...relied on the NAM for the details for the upper level
system and the surface system counterpart as they traverse the Ohio
Initial band of showers expected with the front...and once
again...have used low to middle level deformation to time the arrival
and passage of this feature. Expecting a sliver of dry air behind
the cold front...and tried to represent this in a marked decrease in
cloud cover and dropping probability of precipitation to slight chance. Timing of this is
always tricky...however. Should be completely resaturated in the
lower levels across the entire County Warning Area by 06z Tuesday in the cold air
advection. Have snow chances increasing early Monday night into the
likely/categorical through much of Tuesday...but this is more of an
autoconvective scenario as opposed to an upslope condition due to the
1000-850mb streamlines that are more westerly than
northwesterly/perpendicular to the mountains. Not discounting the
terrain influences completely though. 850mb temperatures drop into
the lower minus teens Monday night through Tuesday.
Due to the timing...expect very little temperature recovery Monday
with the frontal passage during the day. Also...have taken the maximum
temperatures for Tuesday down from the guidance numbers a few
notches...with the thinking that above freezing values will not be a
good play here. Guidance tends to overplay these situations and have
the area too warm...so will keep it cold area wide.
For amounts...not too many changes in snow from the previous
forecast. Despite it not being a perfect upslope situation as
previously mentioned...think there will be better enhancement of the
snowfall in the higher elevations. But for the most part...this will
be a slow accumulation of snow over time in off and on snow showers
and squalls over The Lowlands. As far as future headline
considerations GOES...a lot will depend on duration/how long it
takes to get the accumulations...which as of right now...spans
well into double digit hours. Severe weather potential statement will be highlighted as such.
Long term /Tuesday night through Friday/...
after the initial support swings through on Monday...probability of precipitation increase
again Monday night...with Upper/Middle level low dropping into Ohio
and surface low trying to take shape toward Delaware-Maryland-Virginia.
GFS and European model (ecmwf) similar now...with 500 middle level low in our vicinity
around 18z Tuesday. Old solutions over the past few days...of middle
level low going to our south...seems less likely now. Weakening 500
mb trough remains in vicinity into Wednesday...with the colder 850 mb
temperatures still advecting in on Wednesday. Have min temperatures near zero
at or below 4 thousand feet Wednesday night. Only apparent temperatures at Wind
Chill Advisory also mostly at or above 4 thousand feet. So not Worth highlighting
in the hazardous weather potential.
Rounds of snow showers still expected Monday night into Wednesday.
Also still tried to keep our probability of precipitation higher than guidance in the moist low
level thermal trough and moisture depth still up to 10 thousand feet.
Picturing at this distance in time...a lot of 1 to 3 inches of snow
in lowlands over 12 hours...and 2 to 4 inches over mountain counties
Monday night into Tuesday night. So thinking more toward winter weather
advisories than taking the Winter Storm Watch/warning Avenue. Of
course...over 48 hours amounts will add up over the mountains. Will
include in hazardous weather potential.
Low confidence for day 6 and 7...in the 100+ knot 250 mb flow from the
west northwest. Could easily see some clipper action...but
uncertainty is in the timing. Included 20 probability of precipitation for now for
Thursday night and Friday.
Aviation /15z Saturday through Wednesday/...
surface high pressure will provide dry weather...with light
southerly winds through the period. Despite of a dry
atmosphere...high cirrus clouds will be common Saturday.
VFR conditions will prevail as a surface high pressure remains in
control through Saturday night. BUFKIT soundings and surface observation show
a very dry atmosphere in the boundary layer.
Surface flow will be light mainly SW today.
Forecast confidence and alternate scenarios through 12z Sunday...
Alternate scenarios: none.
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 12 13 14 15 16 17 18 19 20 21 22 23
EST 1hrly 07 08 09 10 11 12 13 14 15 16 17 18
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 12z Sunday...
MVFR to IFR conditions possible in rain/snow showers Monday into
the river gauge at Parkersburg...along the Ohio River...has been