Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 282003
Area Forecast Discussion
National Weather Service State College PA
403 PM EDT Fri Apr 28 2017
A ridge high pressure will slide east over the region today. A
warm front will move slowly north, keeping moist and mild air
in place into early next week. A strong trough should bring
cooler drier weather to the region for the second part of next
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Satellite shows high clouds streaming into the region out of
decaying convection over the midwest.
We will remain dry today, but the chance for rain will increase
this evening and overnight. Guidance indicates that an MCS will
form over the Ohio Valley later today and stream NE into the
region overnight. ECMWF/GFS as well as The SREF and GEFS all
show the MCS decaying as it enters Central PA, while the 12Z NAM
and latest HRRR are more aggressive sliding the convection
through the area between about 03-10Z. I used a blend of POPs
overnight which is not as wet as the HRRR, but wetter than the
other models that break up the showers as they approach. I
favored the north with the best POPs.
Overnight, lows will range from the mid 50s to mid 60s, or
about 15-20 deg above normal.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Guidance agrees in bringing the warm front northward late
tonight and Saturday, but differences exist as to how far north
it manages to progress. Warm and muggy air will pool along and
just to the south of the boundary. Models develop a fair amount
of CAPE, they just differ on whether the most unstable air will
favor the Maryland border areas or extend up into the Central
Mountains. SPC has the region under a marginal risk for severe
storms, and with moderate deep layer shear expected, this looks
reasonable. Look for the best chance of showers and storms to be
from mid day into the afternoon.
Highs will vary from around 70 along the NY border to the
mid/upper 80s over the SE. If we end up with more sunshine than
currently expected, I would not rule out a high temp near 90 in
a couple of places. With dewpoints well up into the 60s over at
least the southern half of the CWA, it will begin to feel humid.
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Upper level ridge tries to builds in for Saturday night through
Sunday but continued southerly flow/instability and a weak warm
front lifting through the Ohio Valley and W PA will lead to
continued chances for showers and even a tstorm - mainly in the
NW half of the area.
Temps remain very warm into Monday. A 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 evening).
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
lift northward. Models showing strength/timing issues so not
getting to specific this far out, but looks like unsettled
weather pattern continues.
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Expect VFR conditions into the evening with localized MVFR/IFR
developing with scattered showers and thunderstorms after about
03Z. Guidance suggests an area of thunderstorms this evening
causing the restrictions.
A slow moving warm front will act as the catalyst for additional
showers and thunderstorms/restricted conditions Saturday. The
best chance for showers and thunderstorms will be during the
afternoon into the evening.
Sat-Sun...Sct showers/Tstorms with periods of sub-VFR.
Mon...Breezy. Showers/thunderstorms likely with periods of sub-
Tue-Wed...Breezy with a chance of showers NW 1/2.
NEAR TERM...La Corte
SHORT TERM...La Corte