474
FXUS61 KCTP 241200
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
800 AM EDT Sun Aug 24 2025

.SYNOPSIS...
* Widespread showers/storms ahead of and along a cold front
  today and early tonight.
* Canadian high pressure will bring many dry days next week with
  below normal temperatures, lower humidity, and gusty northwest
  winds.
* Lake effect rain showers expected Mon-Tues over NW PA.

&&

.NEAR TERM /THROUGH TONIGHT/...
SHRA/TSRA ongoing as a mediocre short wave trough rolls in from
wrn PA. This convection will continue sliding steadily eastward
this morning. We should see ltg continue to decrease over the
few hours as these TSRA try to get too deep into central PA. The
warm air and rising dewpoints today on SE flow backing to the S
will result in rising instability this aftn. The far NW may
actuall stay dry as the next meso forcing comes in later this
aftn - after the best moisture slides east of there. In between
the two waves, the weak subsidence should allow for a relative
lull in coverage and intensity of SHRA...maybe not a total
absence of precip, but a noticeable decrease. By 18Z, the front
should be knocking on the door of our office. The CAPEs rise
into the 1000-1500J range from here on east and as far S as
Harrisburg. Coincident to this maximum of CAPE in time and space
is deep layer shear of between 30-40KT. KIPT NAM soundings paint
a warm mid layer but shear is higher to the east of UNV in the
late aftn and early evening. This should allow a storm or two
to grow tall enough to make strong gusts. The risk for severe
hail is lower, but still mentionable if the storms get tall
enough and the warm layer gets a little cooler due to evap
cooling. WBZ is around 9-10Kft. Lift produced by the front will
be driving through the area at that time. Timing for the deepest
convection to occur should be after the little league champ
game starts (3 PM). But, the poss of a strong/severe storm there
in the 4-8PM time frame does exist. SPC MRGL risk covers our
E/NE third.

As the front moves east in the early evening, the storms should,
too. However, due to timing uncertainty, we`ll taper the PoPs
off slowly from 00Z thru 06Z (midnight). There should be a
decent (few hours) break in the cloud cover for most of the area
before the flow turns wrly enough and wrap around moisture
under the upper low brings clouds into the NW. This should allow
some fog to form, esp in the N. The temps dropping will lead to
a decent lake-air temp difference. Add lift under the upper low
and this will easily make lake effect rain showers. There
should be some in Warren Co before sunrise.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Lake-induced SHRA will be a certainty Monday-Tues, but coverage
will be kind of sparse most of the time. Therefore, we`ve
capped PoPs around 70pct for the far NW. There seems to be a
short period Monday when the SHRA will be anchored close to the
lakeshore or, rather, not far inland. They come back late in
the day as we get a more cross-lake fetch and positive lift
with the arrival of a weak short wave late in the day. The
lake-induced CAPE could get over 1000J if the NAM is spot on
with the physics. Therefore, thunder is more than possible from
a cell or two, and a graupel pellet or two is not out of the
question. Shear of 30KT could even make things more interesting
except that the lowest 12kft will have only 15-20KTs of wind. Of
course, the best (worst) conditions will be closer too the
lakeshore than much our CWA >> Warren Co will hold the most
interesting wx in our CWA.

The problem with the short range forecast (low certainty) will
be trying to time the passage of a few waves dropping in from
the upper Great Lakes over the 48hrs from Mon AM til Wed AM. A
weak backdoor front will also drop in sometime on Tues. So, at
this range, we`ll play a rather broadbrushed set of PoPs for
that whole (short range) timeframe. We`ll try to refine timing
as we get closer and the waves are better-modeled.

Temps do head downhill Mon with the NW losing ~10F from Sun
maxes. The SE will not dip much at all from the prev 24hrs.
Expect mins Mon night in the m40s nrn mtns, and m50s SE. That
is 5-6F below norms. Fog is almost certain with the only neg
there cloud cover. Maxes get 2-5F cooler on Tues with the
bigger change in the SSE than NW (resulting in 5-10F below
norms). Chop off another 3-5F for mins Tues night vs Mon night.
Rather light wind and mainly clear sky could allow for more fog
than Mon night.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Long wave upper trough axis tries to swing to our east for Wed,
but another good shot of energy rotates down across the Great
Lakes and puts us back under the deepest upper heights Fri. Lack
of moisture should limit rainfall potential, though. So, we`ll
cap PoPs in the 20s for the N Fri. Brief ridge builds in for
Sat before flattening again.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Multi-layered MVFR/VFR clouds covered the bulk of Central PA
early this morning, within a deep layer of moderately strong
southwesterly flow aloft and a light SSErly sfc wind in most
places.

Lowest CIGS (IFR to LIFR) and MVFR VSBYS in light fog will be
found on the SE facing slope of the ridges and ridge
tops, generally along and to the east of I-81 this morning and
also across the Laurel Highlands (KJST).

Several bands of focused ascent beneath the southeast quadrant
(right entrance region) of a broad upper level jet core (that
was stretched from Eastern Ohio to NW PA and Western Lake
Ontario at daybreak this morning) will slowly migrate to the
east today and consolidate across the Central Third of the state
late this morning through early this evening (generally
impacting the airfields of KAOO, KUNV, KIPT and KMDT with the
greatest chc for TSRA) with brief reductions into the MVFR and
perhaps even the IFR range.

For now will cover these periods of lower conditions in the
Prob30 and Tempo groups in the 18Z period today through the 02Z
Monday period.

In the wake of the cold front responsible for today`s
convection, bkn-ovc low-end VFR and MVFR strato cu clouds will
occur from late this evening into Monday morning.

Any breaks in the cloud cover tonight will quickly lead to sfc
fog (especially in locations seeing more significant rainfall
today) with possible LIFR VSBYS later tonight/early Monday.

Outlook...

Mon-Wed...SCT SHRA/MVFR for BFD. VFR elsewhere.

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Dangelo
AVIATION...Lambert