Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 292328
Area Forecast Discussion
National Weather Service State College PA
728 PM EDT Sat Apr 29 2017
A nearly stationary frontal boundary will remain over the
forecast area for much of the weekend. A strong Cold front will
move across the region on Monday, followed by cooler air for
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Weak shortwave, which brought showers to northern Pa late this
afternoon, has passed into New England this evening. In its
wake, expect a dry evening beneath building upper level ridge
centered off the southeast coast. At the surface, a shallow cold
front along the I-80 corridor is pushing south across the
region. Temperatures at 21Z ranged from 54F at BFD to 85F at
HGR. This boundary is progged to stall out as it reaches the
Mason Dixon Line around midnight.
Increasing WAA is indicated by late tonight, as southerly low
level jet works eastward from the Ohio Valley. Have used
blended POPs to bring a small chance of showers/tstorms back in
for the second half of the overnight, mainly across the western
counties. Blend of latest HRRR/LAMP support min temps from the
chilly mid 40s along the NY border, to the low 60s near the
stalled front along the southern border.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
The stalled front will try to crawl back north into the CWA
Sunday, presenting a high temperature forecast problem. Near
term deterministic models show a cool-air damming scenario
hanging rather tough. The surface based LI field is usually a
great indicator of this. The ECMWF/NAM/GFS are all in good
agreement with the warm air working into my western higher
elevations while the ridge-valley areas east of the Alleghenies
stay in the clouds and cooler air. If things work out as
expected highs will vary from around 60 in the Poconos to around
80 in Somerset county.
Again the main focus for Sunday will be for
showers/thunderstorms to once again develop and/or move into
the region. With the most unstable air expected to be over the
western sliver of my CWA, that`s where I would expect the best
chance for measurable rain. Once again I used blended MOS POPs
for this given that the best focusing mechanism will be well
west of the region.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Upper level ridge builds across the Mid Atlc Region Sunday
night and Monday and a warm front will be lifting through the
Ohio Valley and W PA. This weather feature will lead to
continued chances for showers and even a tsra - mainly in the NW
half of the area. Upper low now over the four corners region is
forecast to lift through the central Plains on Sunday then the
Great Lakes on Monday. This will serve to send pieces of energy
along the surface boundary.
Temps should return/rise to very very warm levels on Monday. The
massive and deepening cyclone lifting into the western Great
Lakes Sun night into Monday will push a strong cold front
through PA Mon into Mon night, accompanied by a round of
potentially potent showers and thunderstorms (likely reaching
western half of CWA in the afternoon and eastern half during the
Once this front passes by much chillier air will advect into PA
on cyclonic flow with unsettled light showery weather persisting
mainly for the northern part of the state right into Wednesday.
Chance for a more widespread light rain arrives Thu into Fri as
a low progged to develop along the southern Appalachians and
the lift northward. Models showing strength/timing issues so
not getting to specific this far out, but looks like unsettled
weather pattern continues.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --Experience normally shows that lower clouds work in toward
sunrise after a wind shift in the evening with a cold front.
In this case, looks like there is enough support to bring
in the lower clouds rather fast. Will keep timing close to
what we have.
Most of the showers gone now. Showers over the Great
Lakes line up better with the 850 mb front. Thus for
Sunday, went with VCSH, based on this.
It may take much of the day for the lower clouds and
fog across the east to mix out on Sunday.
Showers and storms with the cold front on Monday. Windy and
cooler into mid week.
Some variation in models for later next week.
Mon...Breezy. Showers/thunderstorms likely with periods of
Tue-Wed...Breezy with a chance of showers NW.
Thu...Widespread sub-VFR developing ahead of a warm front.
-- End Changed Discussion --
SHORT TERM...La Corte