Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
725 PM EST Monday Nov 24 2014
gusty winds will diminish this evening as colder air enters the
region. A storm system may bring snow accumulations to the ridges
east of Pittsburgh Wednesday.
Near term /through Tuesday/...
quick 730pm update to end the Wind Advisory. All sites have been
below the advisory criteria of 45 miles per hour wind gusts for two
hours...and do not expect wind gusts to ramp up again.
With 615pm update...have pulled chances for precipitation during
the evening with things looking calm on the radar. Anticipate
being able to bring the Wind Advisory down before 10pm...but with
gusts having remained high during the last one to two hours...will
not make any changes at the current time. Also updated for hourly
temperature trends as colder air begins to push in from the west.
Previous discussion follows.
Front will cross region this evening with gusts around 45 miles per hour
still expected early tonight. Only stray showers now as the
front and shortwave head east and much drier air works in. Weak
surface ridge will move into the Ohio Valley Tuesday with much
cooler temperatures and partial sunshine.
Short term /Tuesday night through Thursday/...
Tuesday night southern stream storm system will develop off the
Carolina coast as northern stream shortwave digs into the Great
Lakes. Models agree there will be a coastal storm but how far
west precipitation shield will reach is the main issue. With an open wave
aloft system will be a fast mover. Using a blend of models brings
the chance for accumulating snow to the southeast ridges...with
best chance for 6 inches across Garrett and Tucker counties where
highest quantitative precipitation forecast will be forecast. Lesser amounts for the ridges of
Westmoreland and Fayette where an advisory may be needed for
lighter snow accumulations. Looks to be quite a sharp cutoff to
northwest edge of precipitation shield with only low chance probability of precipitation for rain of
snow east of Pittsburgh to Morgantown. Still early for this system
and the track still could change quite a bit as we get closer to Wednesday.
For Thursday coastal exits and deeper upper level trough and
shortwave move in for Thanksgiving with snow showers and well
below average temperatures. Lake enhanced snow showers look to
develop Thursday afternoon as 850mb temperatures fall toward -10c.
Long term /Thursday night through Monday/...
northwest flow and remnant moisture from the exiting middle-week
system will produce snow showers Thanksgiving night...enhanced
just downwind of Lake Erie and in the upslope regions of our southeast
ridges. These showers should quickly taper off early
Friday...however...as subsidence occurs with high pressure moving in
from the west. This will effectively lower inversion heights and
choke out the remaining bl moisture by late Friday morning.
From that point the extended period gets a little tricky as model
guidance diverges greatly. Primarily stuck close to wpc guidance
based heavily on the operational GFS. This briefly holds the surface
high over the area into the early part of the weekend before an
upper trough propels a surface low pressure system through the northern Great
Lakes. The associated moisture-starved cold front will stream across
the forecast area sun resulting in some showers. Raised temperatures ahead
of the front which means that rain and rain/snow come into
play...but any quantitative precipitation forecast associated looks light.
Aviation /01z Tuesday through Saturday/...
genl VFR conds are expd Erly this evening behind an exiting cold front.
Winds are expd to dmnsh...but gusts from the west-southwest around 20kt are still
expd. MVFR SC is epxd to work slowly eastward into the area north of the
PA/WV border as cold advection begins. Experimental an increase to VFR by morning
with VFR cumulus/SC ceilings...though duj will likely hold on to MVFR into
Outlook.../Tuesday night through Saturday/...
coastal low pressure could bring possible rstrns into middle weak. Periodic
rstrns are possible into the weekend with several weak crossing disturbances.
the one record high tempreature that was set today was
DuBois...with an observed high temperature of 67 degrees. The
previous record was 61...set in 1979.
Maryland...Winter Storm Watch from Wednesday morning through Wednesday
afternoon for mdz001.
WV...Winter Storm Watch from Wednesday morning through Wednesday
afternoon for wvz041.