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000
FXUS61 KCTP 201012
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
612 AM EDT Sat Apr 20 2024

.SYNOPSIS...
An upper level trough will swing through eastern Canada and the
northeastern states today and Sunday, resulting in cooler and
breezy conditions. Frost is possible Sunday morning, but more
likely on Monday morning as high pressure moves overhead and
the sky clears.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
While the dewpoints are crashing into the 20s over wrn PA, a
wide deck of mid clouds have surged northward over the western
zones. The low crud is sticking around the SE. A little --RA
may even be falling out of the mid deck in NW PA. Some breaks in
the clouds here and there, but we bumped up the clouds for the
next 5-6hrs until the wind goes more westerly.

Still planning on seeing the clouds break up over all of the
area through the daylight hours. As we mix fairly deeply today,
the wind will get rather gusty with sustained 15-20MPH and
gusts into the U20s-L30s. A spoke of vorticity drops across the
area this afternoon, right about peak heating. The cold air
aloft and residual moisture will allow a few fast-moving, high-
based
-SHRA to form. While few models pump out any measurable QPF,
there will likely be some raindrops falling on some heads, esp
in the nrn tier. Feel it is better to mention them with a chc
PoP rather than to leave it out of the forecast altogether.

Temps will struggle to rise more than 3-4F in the NWrn mtns
today. Even the downslope-aided SE will only have diurnal rises
of 10-12F.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Interesting dance tonight with regard to the frost/freeze
potential. Not all of the CWA is deemed to be in the growing
season yet. The Alleghenies, Laurels and Schuylkill Cos are not
yet in the growing season, but those are the places most likely
to freeze tonight.

Those zones which will be active Sunday morning will
have a complicated set up factors that could/not make it frost.
The threat of widespread freezing temps is not there for any of
the SE half of the CWA. The 2m temps probably get into the
m30s over a good chunk of the SE, which is usually good for a
frost. However, the atmosphere can trick us in a few different
ways. Clouds can inhibit frost formation by keeping temps up.
Clouds may be lacking at first tonight, but lower clouds move
into the N & W while high/cirrus clouds move overhead from the
S. The wind can also a detrimental effect on frost formation,
also as the wind keeps the air near the sfc mixed, helping to
keep the ground temps more in-line with the 2m temps. m30s won`t
cut it if there is a sufficient wind blowing. But, it doesn`t
take long for frost to form if the wind can go calm for an hour
or so. At this point, we`ll issue no frost/freeze products and
allow the dayshift to continue discerning the best course.

The wind picks back up on Sunday. Another weak vort max rolls
overhead in the middle of the day, and could make a few clouds,
but not likely any precip. Did add a 10 PoP for the nrn mtns,
though. Temps should get back into the 50s for just about
everyone which is 5-8F below norms.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Model guidance all supports dry conditions Sunday through
through Tuesday morning, as high pressure and an associated
low-pwat air mass builds into the area. However, upper level
troughing does support below average temperatures into early
next week.

The combination of light winds, dry air, and mostly clear skies
associated with surface ridging is likely to result in good
chance of frost Sunday night. The greatest risk of frost is
over the northern mountains where the growing season is not
active, but areas in the growing season farther south could
also be affected.

A decent warmup looks likely Tuesday, as high pressure passes
off of the east coast. However, medium range guidance all points
to a chance of showers and a subsequent cool down associated
with a cold front passage Tuesday night into Wed AM. The
moisture return ahead of the front looks unimpressive, but
strong forcing ahead of a potent upper level shortwave suggests
a good chance of rain. Latest plumes support a general 0.2 to
0.4 inch rainfall.

It appears there will be another chance of a frost/freeze Thu
and Fri AM, as Canadian High Pressure builds over the region.
Those with agricultural interests should keep an eye on the
forecast for the end of next week.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
Expect improvement at all airfields to VFR over the next couple
hours and prevail through 00Z Sunday. The main concern will be
a gusty WNW (270-310) wind with sustained 15-20KT speeds and
G25-33KT developing for the late morning and afternoon hours and
continuing into the early evening hours.

Outlook...

Sun-Mon...No sig wx expected.

Tue...Slight chance of evening showers/cig reductions NW Mtns.

Wed...Showers move in west-to-east from rain early, continues
throughout the day. TSRA possible SW late PM.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Lambert/Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Fitzgerald/Banghoff
AVIATION...Gartner/NPB