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000
FXUS61 KCTP 162326
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
726 PM EDT Tue Apr 16 2024

.SYNOPSIS...
-Periods of rain Wednesday-Friday with limited/no flood risk
-Weekend cooling trend; monitoring frost/freeze potential

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Upper level ridging over PA will provide most of the forecast
area with fair weather tonight. However, a closed upper low
lifting through the Upper Midwest, combined with an approaching
warm front over the Ohio Valley, may spread showers into the
western counties around dawn. Although the warm front will
remain well south of the region, surging thte along the low
level jet and some elevated instability supports the chance of a
tsra in addition to the showers.

Mostly clear skies, light wind and dry air should result in
fairly efficient radiational cooling tonight. Thus, have
undercut NBM guidance slightly. Thickening cloud cover late
tonight may cause readings to rebound before dawn over the
Alleghenies.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
The closed upper low is progged to lift northeast across the Grt
Lks Wednesday. Falling heights and surging pwats ahead of this
feature will produce showers and isolated tsra during the
daylight hours. However, latest convection-allowing model
guidance indicates the bulk of the activity will have shifted
into the eastern part of PA by late afternoon. Strong large
scale forcing and PWATs close to +2SD support high POPs.
Ensemble plumes indicate most likely rainfall Wednesday will be
between 0.10 and 0.25 inches, with the higher amounts over the
N Mtns.

An additional round of showers appears likely Wed evening
associated with the passage of a shortwave rotating through the
base of the upper low over the Grt Lks. Central PA should remain
on the cool side of the approaching occluded front. However,
model soundings indicate enough elevated instability with the
passage of the low level jet to support possible tsra, mainly
over the western half of the forecast area. The progressive
nature of the showers should keep the risk of even minor flooding
low.

Rising heights noted in the model guidance Thursday, as the
remnants of the upper low pass well north of PA and the plume of
deep moisture shifts east of the forecast area. Residual low
level moisture, combined with upslope flow, may yield a bit of
lingering drizzle, mainly over the N Mtns and W Poconos, where
model sfc-850mb remains near 100pct. At the surface, a slow-
moving occluded front is progged to push into the central
portion of PA. A drier westerly flow behind it should result in
partial clearing. However, a lingering inversion in the model
soundings suggests afternoon showers are unlikely.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A cold front will pass through on Friday before stalling out to
the south for the weekend into early next week. Showers and
potentially a thunderstorm are possible Friday with the frontal
passage, though rainfall generally looks to be light as the
front pushes through fairly quickly. Ensembles suggest that
rainfall will generally be in the 0.25 to 0.5 inch range, with
the highest amounts expected across the western mountains.

Canadian high pressure will approach the region behind the front
into early next week while a series of disturbances track along
the boundary that is stalled to our south. There are significant
timing differences in the models with regard to these
disturbances, but each will bring at least a chance of showers
to the area. Some frost will also be possible Saturday and
Sunday night, as light winds and mainly clear skies will support
temperatures falling into the low to mid 30s.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
A nice mid Spring afternoon outside with just a few high clouds.

A warm front will push eastward toward western PA Wednesday
morning, resulting in a few showers into central PA toward
sunrise. These showers will spread eastward and overspread
most of the Susquehanna Valley by late morning or early aft.
Conditions will lower some, but given the amt of dry air at
low levels and time of day, expect most areas to be MVFR or
higher.

The first batch of showers may taper to nothing for a brief
time before more showers arrive later in the afternoon and
evening. There could be a thunderstorm as well, mainly across
the far west, closer to the warm sector. Would expect visbys and
cigs to drop into IFR for brief periods Wed night and early
Thurs.

Outlook...

Thu...Post-fropa wrly flow. MVFR cigs sct SHRA NW, VFR SE.

Fri...CFROPA. Occnl dips to IFR.

Sat-Sun...No sig wx.

&&

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

&&

$$

SYNOPSIS...Dangelo/Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Dangelo
LONG TERM...Lambert/Banghoff/Bauco
AVIATION...Martin