Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 211929
Area Forecast Discussion
National Weather Service State College PA
329 PM EDT Tue Mar 21 2017
Look for a relatively short lived but significant change in the
weather later tonight and Wednesday as a frontal system bring
much colder air back to the region for Wednesday and Thursday.
A period of snow or ice is possible ahead of the returning warm
air later in the week. A milder pattern will persist through
the weekend with opportunities for rain into early next week.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Big temperature changes later this evening as strong cold front
will push across the region. The front will bring gusty winds
but will be mainly dry with just a few mainly light snow
showers over the usual spots in NW PA. A short northerly fetch
and dry air should limit any accumulation to a brief coating
over Northern Alleghenies.
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
It will be cold with a good deal of the area not breaking
freezing /15-25 degrees below average/. A strong ridge of
surface high pressure will build into the area with decreasing
winds and clear skies by afternoon. This will set the stage for
strong radiational cooling and very cold temperatures by
.LONG TERM /THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --WAA pattern quickly follows what could be winter`s last gasp
with moderating temperatures into the second half of the week.
Models indicate risk for snow/ice mix ahead of the warm air as
pcpn spreads into retreating shallow low-level cold layer
(associated with 1035mb high pressure area that briefly pauses
along the coast) Thursday night-AM Friday. Max POPs are over
the NW 1/3 of the area based on a multi-model consensus blend
but ZR risk extends into the interior zones based on WPC
probabilistic winter pcpn guidance.
Risk for mix/ZR continues into mid Friday morning before
temperatures warm above freezing. Models continue to show the
warm front lifting north into NY by Friday night, becoming
quasi-stationary and setting up a west-east oriented baroclinic
zone. Location of this boundary will be key as it will be a
focus for pcpn into the weekend.
Models and ensembles are in decent agreement with the general
synoptic pattern evolution across the CONUS with a series of
upper troughs moving into the Southwest U.S. and losing
amplitude as they eject/dampen out downstream across the Central
Plains and east of the MS River. The lead wave and associated
frontal system is progged to reach the area by Sunday which
coincides with max POPs based on NBM/WPC/ECENS blend.
The first wave will plow the path for a weakening second wave
lifting through and bringing chances for showers early next
week - though by then precip type looks to remain plain rain.
Above average temperatures are expected over the weekend with
the warmest day likely on Saturday with some sites approaching
70F over southern PA. Sunday should also be mild but a bit
cooler due to likelihood of rain. Operational EC/GFS/CMC are
somewhat at odds early next week with EC/CMC more bullish than
GFS with shallow cool air to seeping southward east of the
-- End Changed Discussion --
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
The arrival of high pressure and drier air will maintain
widespread VFR conditions this afternoon into early this
A stronger, secondary cold front will push SE across the
commonwealth tonight followed by periods of MVFR across the
Central Ridge and Valley Region, with areas of IFR-low end MVFR
across the western mtns with flurries and brief light snow
showers. Expect gusty NW to follow tonight`s front with gusts
Wed-Thu...No sig wx expected.
Fri-Sat...Showers/reduced CIGS possible, mainly BFD.