Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
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FXUS61 KCTP 230846
Area Forecast Discussion
National Weather Service State College PA
446 AM EDT Fri Sep 23 2016
A mainly dry cold front will pass through later today and
tonight. Fair weather with seasonably cooler temperatures is
expected over the weekend. Another cold front will push through
early in the new week and could make some rain.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Lots of high clouds around the northern half of the area this
morning. However, this moisture has no nearby connection to the
surface and dewpoints are still in the m50s for the most part.
Wind does come out of the west later today and could increase
those dewpoints above 60F. The cold front seems to enter the state
sometime before sunset. Most models do produce some very isolated
showers later this afternoon or evening across the northern half
of the area. There is an infinitesimal chance of a thunderstorm,
but not worth mentioning T at this point.
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
All model data pushes cold front all the way through central PA
tonight. But, without upper level support or even moderate
moisture, we expect a mainly dry fropa for much of the area.
Although cooler air will begin flowing in on a northerly breeze,
that band of clouds along and just behind the front will keep
things mild tonight - especially over the south - with mins
between u40s in the northern mtns to around 60F in the south. If
winds drop off to near calm across the north, could see some late
night valley fog, while an active northerly breeze precludes fog
issues elsewhere. Will not mention fog for tonight quite yet.
The clouds should dissipate/slide southward Saturday morning and
leave a mostly sunny day. Maxes will be about 10F cooler than
Friday - right about normal to very slightly above normal. Sunday
morning looks almost certain for fog in the valleys as temps drop
another 10F from Sat AM and the air will be calm. Only the dryness
of the airmass could preclude fog, but am fairly certain of fog.
Sunday is another wonderful but dry day. The maxes may be a few
degs cooler than Sat in the south, and may actually turn out sub-
normal there. But similar and normal maxes will occur elsewhere.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Models remain in good agreement in dry and seasonable weather
this weekend as Canadian high pressure builds southeast into
Pennsylvania. Some of the colder spots in north-central PA look to
dip into the upper 30s Sunday morning, which is not unusual for
this time of year. But some frost is possible.
Main changes for the long term period were to account for
seemingly good agreement on the passage of a cold front Monday
Night. There looks to be some moisture with it as the sfc low
slows down and occludes to our west. But, it could again dry up as
it approaches the region. The deep upper trough/cut off low
rolling through the inter-mountain west looks like it will ride
northward a bit and deepen over the Upper Great Lakes mid-week,
but then the crystal ball gets more cloudy. If the recent GFS
solutions are to be believed, the upper low will drop into the
Lower Lakes and perhaps stall again overhead. That would be a dark
and unstable/showery time for PA during the middle-end of the
week. The ECMWF operational run from 00z takes the low from the
Upper Great Lakes pretty much straight to the east into eastern
Canada. This would be a much brighter and milder outcome. Will
allow for a little of both sides of the coin in the forecast with
a low chc POP in the mid-week. It should be dry by Day8 even by
the GFS progs.
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
High clouds continue to push southeast across the northern
airspace in advance of frontal boundary located over Lake
Ontario. Localized brief restrictions in fog remain possible
around daybreak. Widespread VFR expected for most of the period
with a very low chance for an isolated shower across the northern
1/3 airspace this afternoon into early tonight along the cold
front. Guidance is indicating post-frontal sub-VFR ceilings
reaching the northern airspace late tonight into early Saturday
and have added MVFR FM group 24/03-05z at KBFD/KIPT/KUNV.
Sat-Sun...Patchy AM fog possible with mostly clear days.
Mon-Tue...Increasing risk for showers/thunderstorms ahead of