Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Blacksburg Virginia
612 am EST Thu Nov 21 2019
high pressure will move southeast cross the Appalachians today
into tonight. A cold front will move south through the mid
Atlantic region on Friday. Low pressure will form along this
front, tracking from the tennesse valley Friday night, to off
the mid Atlantic coast by Sunday morning.
Near term /through tonight/...
as of 212 am EST Thursday...
The upper ridge will build across our region today and flatten
tonight into Friday. High pressure overhead this morning will slide
southeast this afternoon into tonight. A dry warm front will lift
north into New England today as cold front approaches US from the
west. Mid and high clouds associated with a northern stream
shortwave will cross the mid Atlantic region today into tonight.
High temperatures this afternoon will range from the lower 50s in
the mountains to around 60 degrees in the Piedmont. A cold front
approaches from the west tonight. Clouds will increase tonight as an
approaching shortwave trough in the northern stream passes over
Pennsylvania. Increased winds and wind gusts across the higher
terrain tonight into Friday morning as supported by NAM and
GFS. Utilized a blend of consall and nbm to adjusted pops and
weather in the western mountains late tonight. Some rain will
enter the mountains late tonight into Friday morning. Low
temperatures tonight will vary from around 40 degrees in the
mountains to the mid 40s in the Piedmont.
Medium confidence in the near term period.
Short term /Friday through Sunday night/...
as of 200 am EST Thursday...
A lazy front moves through the Appalachians and central ID Atlantic
region on Friday with some showers and gusty winds, especially west of
the Blue Ridge. High pressure then slides in behind the front and
wedges down east of the mountains Friday night.
Guidance remains fairly consistent in handling evolution of weather
systems for the weekend. The northern and southern streams of the split
upper level pattern will begin to phase and drive development of a low
pressure system that will move across the region Saturday. May see some
precipitation Friday night with increasing isentropic lift over The
Wedge, but the main push of precipitation will be on Saturday into
Saturday night. Big Warm nose evident in BUFKIT and in-situ wedge will
make for a cold rain. Guidance is starting to hint at a colder solution
in The Wedge that may allow for some freezing precipitation at the
higher elevations but this is low confidence so believe the most likely
scenario still favors all liquid until deeper cold air gets pulled in
behind the departing low Saturday night generating upslope rain-to-snow
showers in the mountains. Could be a wet coating of snow for the higher
elevations before daybreak Sunday morning. Seeing trends toward holding
lingering snow showers west of the ridge through Sunday though
insolation will work against any potential accumulations.
Winds will also become quite blustery with strong wind gusts developing
late Saturday night and continuing through Sunday. Gusts over 45mph may
be possible along and west of the Blue Ridge, mainly at the higher
elevations, so will be watching later guidance closely to see if winds
continue to escalate.
Temperatures will generally be at to slightly above normal on Friday
with highs near 60 east of the Blue Ridge and in the low/mid 50s to the
west. However, Saturday continues to look quite chilly in The Wedge
with a cold rain. Temperatures will be a bit below normal on Sunday
behind the front with low/mid 50s east to low/mid 40s west.
Long term /Monday through Wednesday/...
as of 330 PM EST Wednesday...
Dry conditions are anticipated for Monday and Monday night.
As high pressure heads offshore on Tuesday, a new low pressure
system should organize over the Central Plains. This system appears
more progressive in the European model (ecmwf) as compared to the GFS, but both
models agree on the main area of low pressure tracking well to our
north by Wednesday. While the timing of this system remains somewhat
questionable, confidence is increasing for the next chance of rain
coming to our area by Tuesday night and Wednesday. However, the
dynamical energy appears to be far displaced to the north, so the
rain could stay rather light.
Aviation /12z Thursday through Monday/...
as of 612 am EST Thursday...
Scattered to broken MVFR clouds in the western mountains should scour
out this morning. Otherwise, mainly high clouds are expected
this morning into this afternoon. Isolated pockets of MVFR fog
are possible for the next couple of hours. However,these should
burn off quickly this morning. VFR conditions should prevail
this afternoon into tonight. Late tonight into Friday morning as
the cold front approaches, MVFR condition will slide into the
Winds today should back to the southwest as high pressure
passes toward the Atlantic coast. Winds are expected to be
light, but toward this evening some gusts to 20kts possible at
Medium confidence in ceilings,visibilities and winds during the
Extended aviation discussion...
A cold front and low pressure system will bring a widespread
threat of rain and sub-VFR conditions for Friday and Saturday.
Winds will be gusty from the southwest ahead of this system and
from the northwest behind this system on Saturday night and
Sunday. VFR and dry conditions are expected by Sunday night east
of the Blue Ridge with MVFR ceilings and snow showers in the
mountains. Dry weather is expected for Monday.