Area Forecast Discussion
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FXUS61 KCTP 201222
Area Forecast Discussion
National Weather Service State College PA
722 AM EST Fri Jan 20 2017
A weakening warm front will push across the state today.
Relatively mild conditions will persist through the weekend
before cooler air makes a return next week.
A complex storm system is expected to move off the Mid Atlantic
coast Monday and Tuesday and could bring a return of wintry
.NEAR TERM /THROUGH TONIGHT/...
A weakening warm front extends from northern KY eastward
through southern Va. Milder air is making progress northeastward
bringing a shield of rain along with it.
Guidance suggests the rain will overspread the region around or
shortly after sunrise. The biggest issue with the advance of
the rain is whether surface temps rebound enough to prevent a
period of freezing rain. Latest HRRR is colder and shows spotty
Freezing rain along the leading edge as the rain progresses
northeast. Being the hours of the morning commute, we have
issued an Advisory for a few hour period of freezing rain to
cover the possibility of some light icing.
The precip will continue off to the northeast with improving
conditions expected for the afternoon as the steady rain turns
to just scattered showers.
As we have seen so many times this season, the low level cold
air will be stubborn to dislodge, so while it will be quite mild
over SWRN Pa today, the ridge-valley area of central Pa will
stay locked in with temps only in the upper 30s to mid 40s.
With just some scattered showers early tonight, the overnight
temperatures will stay steady or only fall back slowly as we
become ensconced in a mild SW flow between high pressure over
the Mid Atlantic and a stronger low moving through the upper
Midwest. Lows in the 30s and 40s will be some 15-25 deg above
normal for the dead of winter.
.SHORT TERM /SATURDAY/...
Saturday will be mild with a fair amount of cloudiness, but
mostly rain free. I cannot rule out a stray shower, especially
over the NW, but the chances are very low and I chose the more
optimistic forecast not mentioning rain.
Highs will average in the 40s and 50s, well above normal.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
The upper ridge is forecast to re-establish itself over the
eastern U.S. early in the period, as a very complex storm
system gathers over the southern Rockies by Saturday evening.
This southern stream low is tracked through the southern states
before turning northeast over the eastern US early next week.
Meanwhile the models build high pressure over eastern Canada and
gradually ooze colder air south into the NERN US.
By late Monday into Tuesday morning, the parent upper low is
made to track into the Mid Atlantic states. The deterministic
GFS has the southernmost track, through eastern NC then up just
off the coast. The GEFS has a slightly more northern track
The ECMWF and its ensemble partner are more north taking the
storm up through eastern PA. The ECMWF tracks its sub 990mb
surface low through the Del Marva up along the NJ coast is what
we look for as a "sweet spot" for snowstorms locally.
Temperatures are marginally cold so it`s still questionable what
the precip type will be. But it`s the most interesting pattern
we have seen this winter for the snow-birds among us.
After our early week storm system, the eastern ridge is made to
make a rapid rebound, even if for just a short time around
midweek. A fast moving shortwave quickly chews the top off the
ridge we are made to evolve into a cyclonic westerly flow by
week`s end. It will turn cooler, but not especially so as there
really is no truly cold air over North America at the current
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
12Z TAFS sent.
Area of rain to the west. The concern for the next few hours
will be for the potential for freezing rain until around 10 AM.
Otherwise, the main thing will be a wide range of conditions
today, as things get better for a few hours here, before the
rain moves in.
Some clearing tonight, but there will still be some potential
for a shower or two, low clouds, fog.
Most of Saturday and early Sunday looks ok at this point,
but some rain possible again later Sunday, mainly across
Looks like Monday and Tuesday will be wet days.
Sat...Low CIGs likely, mainly in the morning.
Sun...IFR/MVFR CIGs likely. Rain advances fm S-N.
Mon...Rain/low CIGs likely with snow possible central Mtns.
Tue...AM rain/snow and low CIGs possible.
Freezing Rain Advisory until 10 AM EST this morning for
NEAR TERM...La Corte
SHORT TERM...La Corte
LONG TERM...La Corte