Duncott, Pennsylvania Weather Forecast Discussion

431
FXUS61 KCTP 061613
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
1213 PM EDT Mon Oct 6 2025
.SYNOPSIS...
* Warm and dry again today
* Showery weather will cross the Commonwealth Tuesday and
  Tuesday night, associated with an incoming cold front
* Drier and much cooler weather for the latter part of the week
&&
.NEAR TERM /THROUGH TONIGHT/...
Previous forecast is right on track. Did tweak the nearest few
hours with T/Td/Sky trends accounted for. Already see a little
cu popped over Lanc/York Cos., and expect some to form other
places - mainly higher elevation sites S of US 22.
Prev...
Another clear morning is upon us, under the influence of an
expansive surface ridge axis along the eastern seaboard. Valley
fog has been less extensive this morning compared to the last
couple of days, and at this point only isolated instances of fog
are anticipated.
This all leads into another sunny and very warm day for early
October. Afternoon highs should range from the upper 70s over
the higher terrain, to the low-mid 80s in valley locales.
A deep layer of dry air is noted over the Commonwealth, in view
of lower-level water vapor animations. This will likely lead to
efficient vertical mixing this afternoon, dropping minimum RH
values as low as 25-35%. Luckily, light surface winds should
mitigate any fire weather concerns.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
Model guidance remains consistent in slowly tracking an axis of
higher moisture into northwest PA late tonight, then gradually
across the Commonwealth Tuesday and Tuesday night, owing to a
S-SW low-level jet. Although frontal convergence, mid-level
height falls/DPVA, and modest upper jet support all argue for a
period of pre-frontal showers, the strongest large-scale lift
appears pointed towards areas well north and west of PA, while
the deepest moisture supply appears to stay south of the Mason-
Dixon line. As a result, a soaking rainfall (which we certainly
need) is not foreseen.
Model sounding profiles show a narrow axis of mostly mid-level
instability on Tuesday, so we maintained the mention of isolated
thunder.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
For the latter part of the work week (Wednesday through Friday),
there is reasonably high confidence that a surface cold frontal
passage early Wednesday will be progressive in nature, pushed on
by a kicker northern stream short-wave trough in the upper
levels of the atmosphere. This should limit clouds and any
lingering showers to early in the day Wednesday, with
improving/clearing conditions by afternoon.
Fairly strong low-level cold advection is likely later Wednesday
into Thursday under a deep NW flow aloft over PA. This,
combined with clear skies and slackening winds in the overnight
hours, should lead to a high probability (70+%) of frost/freeze
conditions both Wednesday and Thursday nights.
From Wednesday afternoon through Friday, conditions look rain-
free, given the likely advance of a very dry air mass across the
eastern U.S. Especially by Thursday, minimum RH within this type
of air mass should efficiently drop as low as 25-35%, perhaps
even locally lower. At this early juncture, surface winds should
be dropping off by Thursday, owing to the approach of a surface
ridge axis, but this timing will have to be watched for fire
weather concerns.
By next weekend, the large-scale flow at least temporarily is
progged to amplify, with a building upper ridge axis over the
central CONUS and south-central Canada, and the potential for a
trough axis along the east coast. Clustering analyses with the
mid-level height fields show a piece of short-wave energy
topping the aforementioned and upstream upper ridge as holding
the key. One solution keeps this wave more progressive over
eastern Canada, with less troughing along the east coast and
drier weather for PA, while an alternate scenario digs this
same wave down into the Mid-Atlantic, with the potential for a
closed low along the coast and at least somewhat higher rain
chances for parts of the Commonwealth. Given relatively equal
model membership between these two scenarios, each are about
equally likely from this early vantage point, and thus we have
low chances (20-30%) for showers indicated.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
Low clouds/fog dissipated nicely in the Lower Susq, leaving
great flying weather all over the Commonwealth. Just some
isolated/scattered fair-weather cu in the SE and on the hill
tops, and some mid-high clouds (no precip) moving in from the
west through the day and into the evening. Timing of precip may
use to be hurried up a little in the W (starting
Prev...
Low clouds across the Lower Susquehanna Valley are the main
aviation concern in the near-term with MDT/LNS currently
observed MVFR conditions. There remains some uncertainty with
respect to lower-bound restrictions; however based on downstream
observations at KFDK, it seems plausible that a brief period of
IFR conditions can be expected at MDT with slight chance of the
lower-level cloud deck expanding towards LNS. Restrictions are
likely (70-80% chance) to begin lifting in the 12-13Z timeframe;
however, lower probabilities of restrictions continuing through
14Z will remain at MDT/LNS.
Widespread VFR conditions are expected to prevail after the
low-level cloud deck begins to dissipate, with high pressure
allowing for clear skies and light/variable winds. Next aviation
concern for the 12Z TAF package is progged fairly well by
GLAMP/HREF model guidance with respect to rainfall entering the
western airspace after 08Z Tuesday. There does remain some
timing disparities in model guidance, so have trended towards a
combination of GLAMP/HREf model guidance this cycle, but will
need to continue to refine in future TAF cycles.
Outlook...
Tue...Sct SHRA. TSRA poss W & S late.
Tue PM...CFROPA. SHRA/TSRA. IFR fog poss mainly NW.
Wed...Sct AM SHRA SE. Otherwise becoming VFR.
Thu...AM fog then VFR.
Fri...AM fog, otherwise clear with VFR conditions.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Jurewicz/Dangelo
NEAR TERM...Jurewicz/Dangelo
SHORT TERM...Jurewicz
LONG TERM...Jurewicz
AVIATION...Dangelo/NPB

NWS CTP Office Area Forecast Discussion