Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 220854
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
454 AM EDT Sun Apr 22 2018

.SYNOPSIS...
High pressure will keep us fair through Monday. Developing low
pressure will lift northeast along the eastern seaboard during
the middle of the week. Behind this system, an upper level
trough will set up over the northeast conus.

&&

.NEAR TERM /THROUGH TONIGHT/...
Broken to overcast mid/high clouds are streaming ESE across
southern PA as moisture spinning around the emerging upper low
over southern Nebraska gets caught up in the upper deformation
zone.

Previous shift pondered a Frost Advisory, but decided against
given the proximity of the clouds.

Deformation cloudiness will affect the far southern zones,
otherwise it will be another fine day with temperatures managing
to top 60 over most of the area...for a change.

The overnight will be clear to partly cloudy with temperatures
generally dropping back into the 30s.

&&

.SHORT TERM /MONDAY/...
Monday will be the last of the dry days in this recent string.
Highs will be in the mid to upper 60s with a SE wind being the
harbinger of the clouds and rain that will follow.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The slow moving upper low over Nebraska is slated to continue
crawling eastward under the Rex Block with the first showers
expected to reach SW PA by Tuesday morning.

The low is forecast to open up and track NE through the region
Tuesday-Wednesday accompanied by periods of rain...no snow!

Several other shortwaves are stacked up in the flow well to our
west and they will eventually conspire to carve out a new long
wave trough over the eastern US by the end of the week and
weekend.

In the meantime there are differences in the timing details as
we move into Thursday and Friday. The GFS/GEFS are faster with
the upstream wave dropping out of the upper Gr Lakes,
suggesting rain makes a rapid return by Friday. The EC is again
slower on Friday, suggesting a dry and mild day. With such low
confidence, I leaned toward the model blended guidances which
give chance POPs.

The differences continue into the weekend with the EC making the
eastern trough less intense than the GFS/GEFS. The deeper/colder
GFS/GEFS would lead to a chance of snow showers over the
western and northern mountains Saturday and Saturday night. Too
early to bite on that as yet.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
No large changes for the 09Z TAF package.

Earlier discussion below.

Looking at some mid and high clouds today into late Monday
afternoon.

06Z TAFS adjusted some.

Earlier discussion below.

VFR conds to prevail into Monday with a thin veil of cirrus
slowly sagging further southward as high pressure builds into
the area. No impediments to flight ops are foreseen in the near
term.

A slow-moving storm system will affect the area midweek. Cig
restrictions may slide northward into JST late Monday night,
with expanding ceiling restrictions over the west Tue - and
areawide Tue night into Wed night in rain.

Outlook...

Mon...No sig wx expected.

Tue...Rain/low cigs becoming likely PM from S-N.

Wed-Thu...Rain/low cigs.

&&

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

&&

$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...La Corte
LONG TERM...La Corte
AVIATION...Martin


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