Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 170317
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1017 PM EST Mon Jan 16 2017

.SYNOPSIS...
A warm frontal system will approach the region tonight and
Tuesday, followed by a cold front Tuesday night and early
Wednesday. High pressure will follow and bring mainly dry
conditions with temperatures several degrees above normal from the
middle of the week into the weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
MRMS RALA showing just a few spotty showers falling across central
Pa at 03Z associated with developing WAA east of storm system
over the Miss Valley. Based on upstream obs, expect precip to remain
very spotty/light through at least 07Z, then steadier precip
slated to overspread the region from the west late tonight, as
shortwave and associated low level jet arrive. All latest model
guidance suggests the main freezing rain threat will be over the
higher terrain of northern Pa, with a diminishing risk in the
valleys and across southern Pa. Will therefore make no changes to
current freezing rain advisory, but will monitor temps across
southern areas for a possible expansion.

QPF will be light so amounts of ice are not expected to be
significant, but as we have seen several times in the past few
weeks, even a little ice on untreated surfaces can cause
significant problems.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
A steady rain will continue Tuesday morning, as the strongest WAA
accompanies passage of low level jet. SREF and NAM both indicate
the possibility of lingering icing through mid morning across the
high terrain of northeast Pa. The mid level shortwave and
associated low level jet are progged to shift east of the area
between 18Z-21Z, causing rain to taper to spotty drizzle.

Surface warm front is progged to push into the Laurel Highlands
during the afternoon, pushing temps into the 50s down there.
Elsewhere, readings expected to top out in the 40s most places and
the upper 30s over the Mtns north of Williamsport.

I kept POPs near 100 pct Tuesday based on latest GEFS/SREF probs
and overall favorable pattern of anomalous PWATS and strong lg
scale forcing ahead of shortwave. Blend of model QPF ranging
fairly close to a third of an inch tonight/Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Winds turn westerly behind the system by Wednesday morning as
flow turns more zonal, but with no real cold air in sight, temps
will remain on the mild side and above freezing during the day.

Ridge re-establishes itself over the eastern U.S. for late in the
week, as mild SW flow persists over the midwest. Guidance
suggests energy will dive south along the west coast eventually
helping to strengthen the building upper ridge over the east.
We`ll be on the eastern side of this, so subtle shortwaves sliding
into the Midwest will bring varying amounts of cloudiness to the
west (less in the east) with low end chances for light showers.

Another wave approaches/lifts into the OH valley late next weekend
into next Monday. Again, temps could be marginal at the start
of pcpn overnight Sunday for some ice or snow, but the bulk of
pcpn looks to be rain at this point.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
A few patches of light rain so far. Still close to freezing in
spots, and the ground is cold, so freezing rain will be possible
overnight. Also dewpoint still on the low side, which will result
in temperatures falling off more in some spots. Freezing rain will
be most likely on untreated surfaces, and on cold objects.

Expect a wide range of conditions into Tuesday. JST already down
to 1/4SM in dense fog, with a CIG of VV002.

Rain will be more widespread on Tuesday, as the cold front moves
toward the area.

00Z TAFS sent.

Outlook...

Wed...MVFR/IFR west; MVFR central to VFR southeast. Rain showers
west ending Wed ngt.

Thu-Fri...No sig wx.

Sat...Sub-VFR developing with the approach of a warm front.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Freezing Rain Advisory until 10 AM EST Tuesday for PAZ004>006-
010>012-017>019-037-041-042-045-046-049>053-058.

&&

$$
SYNOPSIS...La Corte
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/La Corte
LONG TERM...Lambert/Gartner
AVIATION...Martin



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