024
FXUS61 KCTP 010303
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1103 PM EDT Sun Aug 31 2025

.SYNOPSIS...
* Dry weather is expected to continue through the middle of this
  week, featuring cool nights, and warm comfortable afternoons
* Aurora Borealis may be visible Monday night; Geomagnetic
  Storm Watch in effect
* Next chance for rain comes Thursday and Friday with a cold
  front

&&

.NEAR TERM /THROUGH MONDAY/...
Transient rex block over the NE US and SE Canada overnight and
Monday will maintain dry weather with generally minimal cloud
cover.

Anomalously low PWAT values in the 0.5-0.8 range will be topped
by some high clouds backing NWWD across the NE 1/2 of the state
late tonight and Monday as the weak upper low at the base of the
aforementioned rex block drifts NE over the I-95 corridor.

Minor changes made to the previous forecast for this near term
forecast period.

Previous Disc...

Sprawling high pressure centered over the eastern Great Lakes
is dominating our weather for the rest of this long holiday
weekend and will remain in control through Tuesday.

The result:
spectacular fall- like conditions as we approach the start of
Meteorological Fall on Monday September 1st.

For the overnight, expect a near carbon copy of the last few
with temperatures trending just a couple degrees warmer. As a
result, the risk of frost is lower and should preclude the need
for an Advisories. A mid/upper-level vort max will drift
northward across the Eastern Seaboard overnight, which could
bring some clouds to our eastern zones (mainly east of US-15).
Low temperatures by Monday morning will range from the upper 30s
in northwest PA to the mid 50s toward Harrisburg. Fog is likely
again in the northern river valleys.

More good news for those wanting to be outdoors, and if you
like saving money on your heating/cooling bills. The high
pressure centered just to our N will continue to slide E.
Expect only fair-weather clouds for Labor Day. There should be
more cu on Monday vs the last few days. Middle of the road NBM
temps are looking good. Might have to add more cu to Monday aftn
fcst based on moisture profiles from deterministic model
moisture plots. Highs in the 70s areawide is just about perfect
for this time of year, especially on a day when cookouts and
outdoor activities abound.

&&

.SHORT TERM /MONDAY NIGHT/...
Look for another pleasant night Monday night with a repeat of some
valley fog in northern PA.

The most "exciting" aspect of Monday night`s forecast is the
potential for Northern Lights viewing. The Space Weather
Prediction Center has issued a Geomagnetic Storm Watch for
Monday and Tuesday. Aurora Borealis forecasting is historically
tenuous around here, but it will be worth keeping an eye to the
northern sky Monday night to see if you (or your phone) can get
a good view of the astronomical spectacle.

See our Social Media sites - Facebook, X or Instagram for some
details on this space weather phenomenon.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
The upper-level, synoptic-scale configuration looks to feature
a transition towards an amplified pattern, with a building
western North American ridge axis, a deepening Great Lakes and
Midwestern trough axis, and a western Atlantic ridge for the
long term period. Given consistency of our ensemble prediction
systems in showing this pattern, confidence is relatively high.

At the beginning of the period (Tuesday and Wednesday), with a
deep layer of dry air still in place and continued moderation of
daytime highs over time, minimum afternoon RH values will dip.
Gusty southwest winds ahead of an approaching cold front on
Wednesday could also lead to an enhanced risk of fire weather
concerns.

Later in the week, it is anticipated that the lower-level flow
will turn more southerly and bring increased moisture into the
region. Also, with an approaching cold front from the northwest
and deepening troughing aloft upstream (mentioned above), the
chances for showers should increase. Latest WPC QPF for Thursday
paints a fairly widespread 0.50" area across Central PA, which
would be welcome after a prolonged dry stretch. Unless there is
a well- organized or tropical system, QPF tends to decrease at
shorter lead times (drought begets drought is what we say a lot
around here), but time will tell with this one.

Friday should feature variable amounts of clouds with a
moderately gusty SW breeze, generally dry conditions and max
temps coming in a few to several deg below normal (Upper 60s to
around 70 across the Northern Mtns and Upper 70s in the Southern
Valleys).

A compact shortwave and weak low pressure tracking east across
the Lower Great Lakes will be followed by second push of cooler
air for Friday night into next weekend. The timing of the CFOPA
has 12+ hours of spread between the similar GFS and ICON models
vs the EC (which is the slower solution not pushing the front
through until the daylight hours on Saturday and
preceded/accompanied by a few areas of showers).

The NBM seems to be weighted more toward the slower solution,
but with more diffuse upper dynamics and meager sfc moisture
convergence, yielding only about 20 percent pops for showers on
Saturday.

In the wake of the cold front next weekend, lake effect rain
showers are expected across northwest PA as cold advection
resumes. Latest ensembles indicate another stretch of below
normal temperatures and frost potential across the typical deep
/ protected valleys of northern and central PA.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Clear skies and nearly light winds will prevail overnight and
into Monday evening across the region, as high pressure
prevails. Potential for fog tonight is very low, given how dry
it has been and expected dewpoints.

Potential for fog will edge up some later in the week. after
Monday morning, as dewpoints come up, but then it has been dry,
so would not expect much fog before later in the week, when we
get some showers with a cold front later Thursday and perhaps
lingering into Friday across the east.

Outlook...

Tue...AM valley fog possible; otherwise predominantly VFR.

Wed...Isolated SHRA possible in the afternoon across the far
west at locations such as BFD and JST.

Thu...Widespread SHRA expected.

Fri...Showers lingering, mainly across the east.

&&

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

&&

$$

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