Scientific Forecaster Discussion
fxus61 kctp 130343
Area forecast discussion
National Weather Service State College PA
1043 PM EST Tue Nov 12 2019
a northwest flow of very cold air will continue across the
region into tomorrow resulting in snow showers over the northern
and western mountains, and much below normal temperatures. A
warming trend on Wednesday and Thursday will return temperatures
to near normal with mostly dry conditions.
Near term /through Wednesday/...
dry, Arctic air mass flowing into the region has caused skies to
clear across most of central PA this evening. At 03z the only
areas seeing snow showers are immediately downwind of Lake Erie
over parts of Warren/McKean counties and across the Laurel
Highlands, which is being affected by a dying lk Huron band.
In general expect lake effect to gradually diminish overnight,
as inversion heights fall. Backing boundary layer flow should
cause the focus of remaining snow showers/flurries to lift
northward, resulting in an end to the snow showers over the
Laurel Highlands after midnight. The relatively Shallow Lake
effect cloud layer is progged to fall within the dgz, supporting
high snow/water ratios, which could translate to additional
overnight accumulations as high as 2 inches over a few spots of
western Warren County. Elsewhere, expect any additional
overnight accumulations to be less than an inch and confined to
the Allegheny plateau. By dawn, expect remaining snow
showers/flurries to be limited to the northwest mountains.
Flow will back to the southwest by midday Wednesday, ending any
remaining lake effect and causing stratocu to diminish. However,
expect a veil of cirrus to overspread the area during the
afternoon, as waa aloft spreads in ahead of shortwave over the
plains. Mixing down model temps from the top of the boundary
layer results in expected highs ranging from the mid 20s over
the northwest mountains, to the mid 30s over the lower susq
Short term /Wednesday night through Friday/...
short wave will pass north of the area Wednesday night
increasing the warm air advection but with upper support well
north, not expected to drop any precipitation. System is trailed
by a weak cold front late Thursday and early Friday which will
have little effect on the weather as the weakening front has
little cold air behind. Overall result will result in the area
being under a west-northwest flow aloft and surface high pressure nosing in
from the Ohio Valley. So, expect dry conditions and near normal
temperatures at the end of the week.
Long term /Friday night through Tuesday/...
little change to the extended forecast at this update. Models
are still struggling in the resolution of a potential East
Coast low developing over the weekend. Latest runs of the
operational GFS and Euro build a blocking high over New England
and hold the low at Bay well south and east of the region. Will
continue the generally dry and seasonal forecast for the
extended making only minor temperature and pop adjust according
to the latest guidance and surrounding offices.
Aviation /04z Wednesday through Sunday/...
northwest flow will bring lake effect snow showers to bfd and
jst through tonight at least, with occasional IFR conditions.
Elsewhere, general VFR conditions are expected with
quickly decreasing quickly overnight as high pressure builds
into the region.
Fri...perhaps a snow shower and brief restrictions at kbfd, but
otherwise mostly VFR.