084
FXUS61 KCTP 260259
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1059 PM EDT Fri Apr 25 2025

.SYNOPSIS...
* Periods of rain showers and a few thunderstorms this afternoon
  through Saturday morning bring beneficial rainfall for most
* Gusty northwest winds accompany cooler temperatures and dry
  weather Saturday evening through Sunday
* Patchy frost Monday morning precedes a nice warmup through
  Tuesday ahead of a risk of severe weather Tuesday afternoon
  and evening.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
7 pm update... Regional radar animations this evening show the
coverage of showers and thunderstorms increasing across south-
central and western PA, tied to strong low-level moisture
advection within a slowly advancing surface warm sector. As
moisture further deepens this evening across the Commonwealth,
showers should continue to blossom, especially for our western
areas closer to the Allegheny plateau. Given slowly waning
instability, it is anticipated that thunderstorms will become
more isolated.

Given thick cloud cover and modest warm air advection,
readings will not fall much more overnight, with low
temperatures not far from 60 by daybreak.

Previous discussion... Overcast skies across the region
accompany scattered showers and a few rumbles of thunder this
afternoon across PA. A wavy, quasi-stnry boundary is evident
along Lake Erie`s South shore as a series of compact upper speed
maxes push a couple areas of rain across much of Central PA
this afternoon and early this evening as PWAT Values climb to
slightly over one inch by 00Z Saturday.

High temps this afternoon are still on track to range from the
upper 60s to low 70s across the NW Mtns and Laurel Highlands, to
the mid and upper 70s across the Eastern half of the CWA. Cloud
cover has helped keep temperatures and relative humidity in
check today as well, lessening the risk of rapid wildfire spread
to some extent.

Showers of varying intensity will fall through the night,
hopefully suppressing ongoing wildfires in south central PA, as
low pressure near KDTW moves east to Western New York by the
mid morning of Saturday. Forecast rainfall amounts are generally
0.7 to 1.0 over the Northern Half of the Fcst Area, to just
under 0.50 inch in the far SE. The combination of PW values
between 1-1.5 inches, relatively strong IWT and some elevated
instability suggesting the potential for locally heavy rainfall,
particularly across the northwest part of the forecast area, WPC
has maintained the D1 MRGL ERO with increased soil saturation
and lower FFGs there. Really think it will be beneficial
rainfall for all, but some localized ponding of water cannot be
ruled out.

Tonight will be quite mild thanks to persistent cloud cover and
rain. Lows will range from the upper 40s in extreme northwest
PA (behind the front) to lower 60s in southeast PA, with most of
the region only dropping into the mid to upper 50s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
Models continue to show low pressure developing over Lower
Michigan and strengthening as it tracks into northern New
England by Saturday night. The parent h5 trough amplifies
through the Great Lakes as the attendant/trailing cold front
sweeps through CPA. This feature will drive periods of rain and
possibly a few t-storm downpours. The main batch of rain should
be east of I-99 by midday with some lingering lake
enhanced/upslope showers possible in the Laurels and northwest
mountains in to the afternoon.

Farther south and east, a strong thermal gradient/CAA in the
850-500 mb layer advecting across Central PA late Sat morning-
mid afternoon poses the threat for a brief gusty shower (or even
a short bkn line of showers. Several high res models indicate
this between 15-18Z Sat, mainly impacting the northern half of
PA. Majority of guidance depicts all convection clearing
Lancaster County by dinner time. Do think that the drying trend
will be fairly quick in the wake of the cold front, though a
strato cu deck will likely linger west of I-99 and north of
I-80. This deck of clouds will be quite shallow and unable to
produce much more than sprinkles.

Accompanying the cold front will be a quick wind shift and
gusty (25-35 mph) West- Northwesterly post frontal flow late
Saturday morning and afternoon, continuing into Sunday. Clearing
skies southeast of the Allegheny Front and strong cold air
advection will support a chilly night Saturday night. Min
temps Sunday morning in the 35-45F range will be 10 to 20
degrees lower vs. Friday night/AM Saturday. The NW breeze will
preclude frost formation.

Breezy start on Sunday with perhaps some low clouds lingering
downwind of Lake Erie. Temperatures only get into the mid 50s to
mid 60s on Sunday, but ample sunshine and a very dry airmass
should make it feel like spring. Locations that don`t get much
rain tonight and tomorrow could see an elevated risk of wildfire
spread. See the Fire Weather section for more details.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Late Friday evening update... On the large-scale, a progressive
and energetic pattern across the CONUS at upper-levels will lead
to a roller-coaster ride in temperatures next week for the
Commonwealth, along with at least one, and possibly two active
rainfall/convective episodes.

On Tuesday into Wednesday, an amplified upper trough progressing
across the northern tier of states will push a warm front/cold
front progression through the Commonwealth. This should lead to
notably warmer temperatures within the surface warm sector
Tuesday afternoon, followed by potentially active showers and
thunderstorms ahead of an approaching cold front later Tuesday
into Tuesday evening. Wednesday should be breezy and cooler,
with cyclonic flow aloft tied to the aforementioned upper trough
perhaps bringing some hit and miss showers to the northern tier.

Surface high pressure and short-wave ridging should bring dry,
seasonable conditions Wednesday night through most of Thursday.

The next phased upper system makes a run at the eastern CONUS by
Friday, with another round of showers and thunderstorms likely
to close out the work week.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Late evening update.

Cluster of heavier showers and isolated thunderstorms lifting
across the northwest mountains this evening, thus I added
thunder to the BFD TAF for the next few hours.

Earlier discussion below.

Not a lot of change for the 00Z TAF package. Much of the area
is still VFR conditions. Storms have been mainly to the west of
our area so far, where temperatures were a bit warmer, and the
airmass became more unstable.

Thus left storms out of our TAFS for now. Expect showers to
become more widespread overnight, which will result in MVFR
and IFR conditions later.

Still expect showers to end from west to east during the
afternoon hours on Saturday, with a gusty northwest wind
developing.

Lower CIGS could linger across the north and west into Sunday
morning, as the airmass cools aloft. Main chance for low CIGS
will be BFD, perhaps JST. Anyway, conditions should improve
to VFR everywhere by late morning on Sunday. Gusty winds will
persist into Sunday.

Earlier discussion below.

Flow turns northwesterly behind a cold front that will track
through the region late Saturday morning/early afternoon and low
ceilings will be slow to rise. Model RH profiles suggest that
all TAF sites will remain either MVFR or IFR through 18Z
Saturday.

Outlook...

Sun-Mon...VFR/No sig wx expected.

Tue...Showers and possibly a few t-storms with sub-VFR probable
into Tuesday night.

Wed...Lingering showers across western PA.

&&

.FIRE WEATHER...
Dry fine fuel and 10-hr fuel moisture hovering near 10 percent
will combine with moderately low min RH values of 35 to 45
percent and a freshening southerly breeze (gusting into the
mid and upper teens this afternoon) to create and elevated
threat for wildfire spread across the SE third of the CWA today.

Thick mid and high clouds will trim vertical mixing today and
the onset of rain during the late afternoon and early evening
hours will lead to a relatively narrow, 3-5 hour window of
elevated fire weather conditions.

A Special Weather Statement was issued (similar to Thursday) for
the moderate threat and details can be found there.

Sunday is the next day of concern as northwest winds gust 20 to
30mph and RH values drop into the 25-35% range. A soaking
rainfall tonight and Saturday will hopefully help mitigate the
wildfire risk to some extent, but locations that receive little
rainfall may be particularly at risk. RHs will drop into the 20s
again on Monday, though winds will be much lighter than on
Sunday.

&&

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

&&

$$

SYNOPSIS...Banghoff
NEAR TERM...Jurewicz/Banghoff
SHORT TERM...Lambert/Banghoff
LONG TERM...Jurewicz/Banghoff
AVIATION...Martin/Bauco
FIRE WEATHER...Banghoff