Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 041026
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
526 AM EST Sun Dec 4 2016

.SYNOPSIS...
High pressure will slide quickly off to the east on Sunday. A
weak frontal boundary will pass through Sunday night. Another
storm system will affect the area during mid-week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Stratocu not letting go. Therefore, the temps today will likely
stay rather cool as they did on Sat. Diurnal swing will likely be
only 5-10F. The SE will still have the best chance to see sunshine
today. Wind should go light from W-E through the day as ridging
aloft and at the surface calms things down. However, the fast flow
aloft will bring in a good deal of moisture for tonight. The
system is slightly disorganized without a sfc low of any repute
developing. Jet structure is just not well-enough aligned tonight.
Precip should arrive this evening in the SW and spread steadily
across the rest of the region. A 3-6 hour period of precipitation
is expected - starting as snow/sleet in most places. The most
challenging part of the near term period is the type of precip and
how much if any accumulation of snow - or even some freezing rain
- there will be. Temps seem to stay just a bit too mild for much
of an accumulation of either. However, the Laurels may drop below
freezing for a period in the middle of the night as the temps
begin to rise aloft and turn the precip to rain. This could allow
for some FZRA in the southwest - most likely confined to the
highest elevations. Not enough confidence in temps being below
freezing for very long where it does turn to rain in order to post
a FZRA (or winter wx) advisory just yet. Have mentioned it in the
grids, but kept out mentions of FZRA accretions. Temps will likely
be mildest overnight in the SCtrl/SErn counties. Otherwise, there
is enough QPF and will likely be enough of a cooling effect from
the precip falling into the 20-something dewpoint air to make a
light coating of snow/sleet across much of the area. Have kept a
general 1-2" in the north and an inch or less in the central and a
little less still in the south. The precip could turn to rain at
the very end, but will likely just decay into some patchy drizzle.
This, too, could spell trouble if it lingers into rush hour Monday
morning and if temps can stay below freezing.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
The fast flow aloft takes the best forcing for precip off to the
east of the area early Monday. Will linger some sct -SHSN/RA in
the east and along the west/high elevations during the morning. It
should dry out through the day. But, much like today, Monday will
be just a brief break from precip. Another system will try to gel
to our west. This one will have a former cutoff low from old
Mexico as it`s forcing mechanism. The low will cross the border
early Monday and open up as it slides NE into the OH valley Mon
night and overhead on Tuesday. A broad but weak low will form over
the lower MS valley and perhaps do a split with one spot of lower
pressure going up the OH river and another one more to the south
which would eventually move over the DelMarVa peninsula.

Without a very solid low moving to our south, I have a low
confidence in keeping all the precip frozen. Similarly, without
a distinct low going to the west of us, I also have trouble
pushing the warm air over the entire area and turning things to
all rain - as it looked like would be possible when I saw the
model output last night. At this point, it seems like there will
be a transition from a very brief period of mixed precip to a
longer period of rain. However, the NEthird of the area may stay
cold enough to allow for an inch or so of snow. Another small
chance for freezing rain does exist - but the precip will be
falling during the day, and temps should rise above freezing after
the precip begins but probably before noon passes. Even the
northern mountains should get into the m-u30s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The end of the week brings some model disagreement with the
GFS/GEFS being faster than the ECMWF with the next large upper
trof and frontal system. Either way, precip looks like a good bet
around the Thu/fri period as all solutions eventually bring this
trough through. So predictability is increasing, but timing issues
remain. Best bet for precip at this point is mainly rain over the
SE as decent push of warm air lifts ahead of the system, with a
rain/snow mix further north where warm air will not infiltrate as
much.

Behind the trough, looks like a chilly weekend in store with a
potential sharp dropoff in temps.

&&

.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
Extensive stratus continues to prevail across Central Pennsylvania
overnight. Typical WNW flow regime, with MVFR ceilings across the
Western and Northern Mountains, with VFR ceilings across central
and eastern airfields. Lake effect streamers continue to become
less organized and diffuse. While these will likely only affect
KBFD and vicinity, there is a slight chance of conditions dipping
into IFR category from time to time.

High pressure approaching from the west will cause snow showers
to diminish overnight. Additionally, the high building in will
allow winds to continue to diminish overnight.

Light precipitation moves in Sunday Night. Mainly rain in the
southeast...a rain/snow mix in central areas...and mainly snow in
the north and northwest.

Outlook...

Sun...Morning restrictions in mountains, then VFR.

Sun Night...Mixed rain/snow event with restrictions. Lowest
conditions in the mountains north and west.

Mon...No sig wx expected.

Tue...Mixed precip/low CIGs possible, especially late.

Wed...Lingering low CIGs possible.

Thu...Mixed precip/low CIGs possible.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Gartner/RXR
AVIATION...Jung/Gartner


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