National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS61 KCTP 170329
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1129 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/...
Most model guidance indicates a closed upper low will pass north
of the region Friday, with a trailing occluded front coming
through Central PA Friday afternoon/evening. The triple point
low is progged to pass south of the forecast area, so the severe
weather threat looks very low. A decent plume of moisture with
pwats close to +2SD should support POPs close to 100pct and some
heavier showers. However, the best large scale forcing as
inferred by model 300-500mb qvec convergence fields passes well
north of PA, so expect overall rainfall to be less than
impressive. Latest plumes support amounts between 0.1 and 0.2
inches in general.

Upper level troughing in the the latest EPS/GEFS supports
slightly below average temps through next weekend. Surface
ridging and low-pwat air building into PA should result in dry
weather Sat/Sun with afternoon dewpoints likely a bit below NBM.
Light wind, dry air and mostly clear skies associated with the
surface ridge is likely to result in areas of frost Saturday and
Sunday nights. The risk of frost is greatest over the N Mtns,
but areas in the growing season further south could also be
affected.

Moderating temps are expected by Tuesday, as the surface high
slips off of the east coast. However, and approaching
shortwave/cold front will bring the next chance of showers by
Tue PM.

&&

.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
Late evening update.

Current fcst in good shape.

More information below.

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...Fitzgerald/Bauco
AVIATION...Martin