Wilhelm, Pennsylvania Weather Forecast Discussion

204
FXUS61 KCTP 291736
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
136 PM EDT Mon Sep 29 2025
.SYNOPSIS...
* Very warm to close out September; brief cool down to start
  October
* Frost/freeze risk focused across the northern tier Wednesday
  night
* Dry pattern stays locked in place for the 7-10 days
&&
.NEAR TERM /THROUGH TONIGHT/...
Midday satellite imagery shows an impressive plume of clouds
extending from Tropical Storm Imelda all the way up into
Pennsylvania. Cirrus clouds are helping to filter the sunshine,
but a pleasant day is underway. Clouds will continue to increase
this evening and overnight as Imelda continues her northward
trek. Despite a partly sunny to mostly cloudy day on balance,
it will be very warm for the end of September with max temps in
the 75-80F range or +7-15 degrees above the historical average.
Canopy of mid and high cloud cover should limit fog formation
tonight into early Tuesday morning. Only real threat for fog
appears to be in the deepest river valleys across northern PA
where high clouds may still be scattered for some of the night
and support sufficient radiational cooling. It will be another
relatively mild night vs. climo (+5-10F) with lows generally in
the upper 40s NW to low 60s SE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
September ends very mild on Tuesday with max temps fcst in the
70-80F range. Shield of mid and high clouds are projected to
gradually clear from NW to SE through Tuesday night. Backdoor
cold frontal passage later Tuesday will open the door for
seasonably cooler and drier air to filter into CPA behind a
steady breeze from the N/NE. Low temps Tuesday night will be
5-10 degrees lower vs. Monday night ranging from the upper 30s
in the northern tier to low 50s in the Lower Susquehanna Valley.
October will start with seasonably strong 1030+mb Canadian HP
migrating southeast from Hudson/James Bay into northern New
England. The cooler and drier llvl flow from the N/NE will
bring a noticeable cool down through midweek with highs on
Wednesday 5-10 degrees lower vs. Tuesday in the low 60s/70s.
Clear and cool Wednesday night; high confidence in frost/freeze
risk across the northern tier with decreasing wind and min temps
in the low to mid 30s. GFS MOS guidance spits out 32F for
Bradford on Thursday morning, which supports the idea that an
anomalously dry airmass underneath high pressure this time of
year can yield under-performing temperatures. A Freeze Watch may
be needed for portions of northern PA in the next 24 to 48
hours, and frost is nearly a sure bet for a stripe of counties
along the NY/PA border at this point.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Slow moving and blocky pattern under deep layer ridging over
the Mid Atlantic and Northeast states will lock-in the renewed
run of dry wx through the first weekend of October. NBM/WPC QPF
is 0.00" in CPA for the next 7+ days.
Thursday night also looks chilly with some frost possible again
over the northern tier. As high pressure moves just each of the
region later this week, southwest flow will usher in slightly
milder temperatures each day. Temperatures moderate back to
well-above normal by the second half of the weekend. Calm winds
combined with clear skies and a gradual uptick in surface
moisture will likely lead to daily occurrences of fog in the
typical river valleys across northern PA. The return of the
multi- day/persistent parched pattern could offset any short
term improvement in the low-end drought conditions from much
needed/beneficial rainfall last week.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR conditions prevail through the TAF period as high clouds
associated with a tropical storm off the Atlantic Coast of
Florida continue to stream in. Light winds today and overnight
will be replaced by north/northeast winds that could
occasionally hit 8-10kts on Tuesday afternoon.
Despite fog in a few spots this morning, an uptick in cloud
cover should limit the potential for any airfield visibility or
ceiling restrictions tonight. Would not be surprised to see fog
by daybreak Tuesday in the river valleys north of I-80 where
clouds will be relatively thinner, but only a low (

NWS CTP Office Area Forecast Discussion