FXUS61 KCTP 191527
Area Forecast Discussion
National Weather Service State College PA
1127 AM EDT Tue Jun 19 2018
A cold frontal boundary will drift just south of the Mason
Dixon line this afternoon before stalling out late today through
Wednesday. More normal early Summer temperatures and lower
humidity will return for this afternoon through Wednesday
morning. A weak wave of low pressure will ride east along the
stalled out front and bring periods of rain along with below
normal temperatures for Wednesday afternoon. The rain will end
from west to east Wednesday night, but not before totaling
between one half of an inch...and one inch across the southern
half of the state. Lesser amounts of rain area expected over
northern Pennsylvania. The risk for showers and thunderstorms
will outnumber dry days as the pattern remains fairly active
through the weekend.
.NEAR TERM /THROUGH TONIGHT/...
Surface cold front with a fairly narrow west-east, bkn line of
showers was located just north of the PA Turnpike in southern PA
and pressing slowly south.
Notably more comfortable/drier dewpoint air and cooler temps
will advect into the region this afternoon on a 8-12kt North to
NNE wind with gusts into the teens.
Rainfall overnight was locally heavy across parts of south
central PA with MRMS/IRIS 3-6hr precip totals showing a stripe
of 1-3 inches from southern Clearfield/Cambria southeast across
Blair and Huntingdon counties.
The hires models support the highest POPs over the southwest
Alleghenies into western MD this afternoon, where the HREF
members are unanimous in developing scattered convection invof
the quasi stationary boundary. Need to watch this area (WPC MRGL
to SLGT ERO) for potential FF threat given high PWs and
Most locations should anticipate generally improving conditions
from north to south by later today with highest confidence
across the northern 1/2 of the CWA.
Rain risk/probs should increase into Wednesday morning across
far western areas as the next wave approaches from the OH
Valley, with increasing large scale UVVEL developing beneath the
Right Entrance Region of an anomalous westerly upper jet
stretched from the Upper Glakes to New England.
Max/min temps will be about 10-15 degrees lower than yesterday
with less humidity.
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Short term/hires model blends generally agree in bringing rain
back into central PA on D2. Increased POPs to high likely and
categorical in most places Wed afternoon and evening.
Temps should be a few to svrl deg F below normal, especially if
clouds thicken and rain moves in from the west a few hours
earlier than currently forecast.
PWs remain high invof the quasi stationary boundary draped near
the MD line. WPC MRGL/SLGT ERO covers the southern 1/2 of the
area and will mention in HWO. Thursday (D3) looks like a dry day
(for now) as the front gets shunted to the south, allowing high
pressure to briefly take control of the pattern. Thursday night
could get relatively cool with mid-40s fcst across north-
.LONG TERM /FRIDAY THROUGH MONDAY/...
A shortwave trough and associated surface low pressure is fcst
to track north from the Midwest through the Great Lakes into
southeastern Canada Fri-Sun. Rounds of showers and thunderstorms
appear probable during this time. High pressure should return
dry weather early next week.
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
Improving and mainly VFR conditions are expected late this
morning and afternoon, as drier air pushes into the region from
the north. A few showers will impact KJST and KAOO with MVFR
conditions through about 17-18Z.
Wed...PM rain/cig reductions possible southern Pa.
Thu...Early AM rain/cig reductions possible southern Pa.
Fri...PM showers/cig reductions possible central mountains.
Sat...AM showers/cig reductions possible. Sct PM tsra impacts
Williamsport tied the record high yesterday of 97 degrees set
Astronomical summer begins Thursday, June 21st at 607 AM.
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