Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 240517
Area Forecast Discussion
National Weather Service State College PA
117 AM EDT Mon Oct 24 2016
A cold front and potent disturbance aloft will pass through
tonight and early Monday bringing a cold rain to the northern half
of the state. A reinforcing shot of cold air will follow and last
through mid week.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Weak sfc low located over the northwest mountains early today...
will traverse the rest of the North Central and Endless Mountain
region in the pre dawn hours...spreading showers along and north
of the I80 corridor through 12z. .
Energetic system aloft with broad upper level diffluence
associated with the left exit region of a 110 kt 300 mb jet...and
strong southwesterly 925-850 mb theta-e advection will bringing a
stripe of rain of light to moderate rainfall (0.10-0.25") across
the northern third/quarter of the CWA (with maybe around 0.4"
along the NY state line), while a sharp gradient to lower amounts
(or no rain at all) will occur just to the north of Interstate 80.
Will keep a few hundreths in the QPF grid in the central mtns for
06-12z. NW flow will make isold-sct shra in the Laurels in that
same time frame. POPs will be near zero overnight across the
southern mtns and Lower Susq Valley.
Temps will be cooler and in the 40-45F range for overnight lows
across the north where the steadier rain falls (and cfropa occurs
earlier), while mins in the south will be mainly in the upper
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
NW post-frontal flow will keep isold-sct shra for the usual
suspects on Monday. High pressure stays to the W thru the short-
term and the tight pres grad will keep it breezy. Temps will only
rise 6-8F on Mon in the NW, and 10-15F in the SE under constant
but weak cold advection. The flow lasts into Mon Night, and the
temps get cold enough then to get a mix or plain ol` --sn for
precip type in the higher elevation of the nrn mtns. As with last
night, no accums expected with still-warm ground and very
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Surface high pressure gradually works in from the Great Lakes Tue
into Wed keeping below normal temperatures in place. Cyclonic
flow/cold air aloft on Tue may bring enough instability to kick
off a few light showers in the NW mountains.
CAA comes to an end on Wed as weak progressive upper ridge
moves through as low-level flow turns back to the S/SW. Could see
a decent frost Wed morning as dewpoints bottom out.
A compact low developing over the Midwest will already be
knocking on our door by Thu. Drier air remains in place over the
east Wed night, but expect showers to work into the west
overnight. Rain becomes likely for much of the area on Thu.
Model guidance continues to diverge after that, especially at the
surface, so confidence in next weekends forecast remains rather
low. But a look at the upper pattern suggests general NW flow
keeping a steady stream of cooler air feeding into the region,
with a series of shortwave troughs sliding through.
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
A fast-moving low pressure system tracking across Northern Pa
will bring a period of showers and sct tsra to that part of the
state overnight. A core of strong winds aloft will precede this
system, likely resulting in LLWS overnight across much of Central
Pa. The exception may be at KJST, where climatology and model
soundings suggest the strong winds will mix to ground level,
resulting in wgusts to near 35kts. The threat of LLWS should end
from north to south after midnight, as strong winds aloft slip
south of the state.
The other concern will be the possibility of low cigs overnight
at KBFD and KJST, as plume of low level moisture ahead of trailing
cold front ascends the higher terrain of West Central Pa. Model
soundings indicate a possibility of tempo IFR cigs at KBFD between
04Z-12Z and at KJST between 08Z-14Z.
Moisture flowing off of Lk Erie will produce fairly widespread
stratocu across Central Pa on Monday. Model soundings suggest MVFR
cigs could linger most of the day at KBFD/KJST, while predominantly
VFR conds expected elsewhere.
Tue...No sig wx expected.
Wed...Patchy AM fog possible.
Thu...Rain/low cig possible.
Fri...MVFR/sct -shra N/W. VFR elsewhere.