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814
FXUS61 KCTP 240818
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
418 AM EDT Sat Sep 24 2016

.SYNOPSIS...
High pressure will move down from Hudson Bay into the northeastern
states this weekend. Expect fair weather with seasonably cool
temperatures over the weekend. A cold front will push through
early in the new week and should make some rain late Monday into
early Tuesday. Dry weather will return for the rest of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Winds are north/easterly now all the way to the Turnpike, but the
dry air is only about a third of the way into the CWA. The
feature/thin-line on radar closing in on the RDA is most likely
the real dry air as it`s passage coincided with a one-hour 7
degree drop in dewpoint in Wellsboro. This dry air will continue
to slide south and west through the morning. Barely a tick on
radar otherwise. But, a stray shower is still possible through
mid- morning in the southern tier. Sky trends match the going
forecast with almost all of the area cloudy at this point, but we
can see the Finger Lakes on the IR satellite pics, and those
breaks/that clearing should work southward through the morning. By
sunrise the northern tier could be clear, but will hold onto
patchy clouds there for a few hours. The clouds look like they
could hang tough in the southern tier for much of the morning or
even just past noon. Will then clear it out. Maxes should be
10-15F cooler than yesterday`s lofty temps. But, they will still
be just at normal or a deg or two warmer.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
clearing will complete very early this evening and PWATs will be
below normal under the subsidence of the advancing high pressure
bubble. This airmass change will make it really feel like autumn
as temps drop off into the m-u30s in the northern mountains, and
40s elsewhere. With the prolonged period of very much above
normal temperatures, this will be quite a shock to some. There
could be just a little bit of the north wind left tonight and a
few wisps of high clouds. But otherwise, these conditions are
very good for frost. It is also difficult to shake the idea of
abnormal warmth from the forecast, as well. Forecaster bias tells
me that it may not get quite that cold when temps got 5F higher
than forecast at IPT yesterday. But, it is a new airmass. This
may be a case where the current temp anomaly clouds forecaster
judgment. Will mention patchy frost for now and stay barely on
the high side of the MOS temp guidance for mins. Dayshift may have
more certainty on frost formation. But the cold air draining into
the river valleys will then set up a battle between the river
valley fog and frost. These two phenomena are rarely coincident.

Sunday should be stellar with low dewpoints, few clouds after the
valley fog lifts, and temperatures almost normal. Some high clouds
will slide down from the NW Sunday night. These may have a tiny
effect on temps, but there may be a little bit of an east wind.
Guidance says that it should be quite a bit milder in the west
Sunday night vs. Sat night. Will stay close to these numbers.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Clouds increase Monday ahead of significant cold front headed our
way. Recent guidance has hurried up with the timing of the front.
Have adjusted things by 3-6 hours faster. This then puts the
timing of showers during the afternoon/evening in the west. Will
add a slight chc thunder in there due to the peak heating/lower
stability possible with this timing. Certainty of rainfall for
most of the area has climbed into the 60-70pct range. This will
be much needed rainfall, centered on Monday Night. The front
should be through by Tuesday morning. Will linger only chc POPs in
the far SE and keep them in the far NW for lake-effect and/or
cool air aloft instability showers for mid-week. Temps should stay
very normal for the balance of the week - but the dryness returns
for a long period.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
Post-frontal low ceilings ranging from IFR to low VFR will impact
the airspace this morning. IFR cigs ongoing at KBFD with period of
sub-1000ft cigs likely at KJST toward daybreak. Arrival of high
pressure and associated dry air mass via northerly flow should
ensure widespread VFR conds by the afternoon. VFR with clear skies
and light winds overnight could lead to some patchy fog by Sunday
morning.

Outlook...

Mon...PM showers/cigs reductions possible.

Tue-Wed...No sig wx expected.

&&

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

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Dangelo
AVIATION...Steinbugl