Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
1051 PM EST Tuesday Jan 27 2015
intense low pressure near Cape Cod this evening will lift northeast
overnight. High pressure will build over the region for
Wednesday...followed by an Alberta clipper which will cross the area
Thursday and Thursday night. This system will bring a light
coating of snow to the area. Cold high pressure will follow once
again for late Friday into Sat. Another fast moving low pressure
system may bring some light snow to the area late Sunday...before
another surge of cold air works into the area early next week.
Near term /until 6 am Wednesday morning/...
inverted surface trough across southwest PA still supporting some very light
snow across Somerset Colorado as of 03z. However...visibilities at k2g4 of 3sm
suggests any additional accumulate will be limited to a dusting at
03z infrared loop shows mclear skies across the bulk of central
PA...while stratocu lingers over the Laurel Highlands. Northerly
flow advecting much drier air into the state should cause remaining
low clouds and any flurries to dissipate across Somerset Colorado around
or shortly after 06z.
Clearing skies and diminishing northwest wind will allow temperatures to fall to
the single digits across the Allegheny Mountains...and the low/middle teens
across the lower susq valley. Can/T rule out a few sub-zero readings
across Warren/McKean cos...where weakening gradient will produce
the most efficient radiational cooling.
Short term /6 am Wednesday morning through 6 PM Wednesday/...
high pressure and associated low precipitable water air mass will provide the area
with a mostly sunny Wednesday. Despite the sun...temperatures will remain well
blw seasonal norms...in part due to fresh snow cover. Gefs mean
925temps support highs only in the 20s. A relaxing pressure gradient
will result in a relatively light northwest wind.
Long term /Wednesday night through Tuesday/...
Wednesday night...based on 12z model runs and that with mainly clear
skies and light winds...expect temperatures to drop...with fresh snow
cover. Current forecast still looks good.
Next system will bring some snow showers to the area later Thursday
into Friday. This system not looking like it would result in
a coastal real near the coast.
However...while not real cold aloft...the combination of warm
advection and moderate dynamics should help fire off bands of
snow...especially across the north and west by middle after. Expect
some snow into the southeast late. Most areas should see a dusting to an
inch or two...perhaps 3 inches in a few spots across the west and
Colder air for Friday night...as high builds into the area.
Saturday still not looking too bad.
For Sunday...did up temperatures some. Did not go real warm. Did up
probability of precipitation. Fast moving system will race toward the area late in the
day. For now went with snow. Some mix could try to work into
the area...but think system is moving too fast to get much
warm air into the area.
System moves fast...should be off the coast by late Monday
morning if not sooner.
Colder air will follow for Monday night into Tuesday. Did lower
temperatures Monday night.
Aviation /04z Wednesday through Sunday/...
conditions will continue to slowly improve across central PA as
high pressure moves into the region from the west. Only kbfd
remains sub VFR this evening with upslope ceilings persisting for the next
several hours. Winds will continue to diminish as well.
Widespread VFR conds expected Wednesday as high pressure center moves
over the state by afternoon. Light northwest winds will cover most taf
sites...save for the kmdt and klns where sustained nwrly winds 15
to 20 kts will develop after sunrise and persist into early afternoon.
Thursday...VFR to start...with late day restrictions spreading in from
Thursday night-early Friday...widespread IFR/MVFR in snow.
Sun...VFR to start...with late day restrictions spreading in from