York, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

083
FXUS61 KCTP 301913
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
313 PM EDT Sun Mar 30 2025

.SYNOPSIS...
Low pressure over Lake Michigan will track north of PA early
Monday, with the trailing cold front pushing through the region
Monday afternoon and evening. Another low is likely to take a
similar track west of Pennsylvania through the Great Lakes
Wednesday night into Thursday. The front with that mid-week
storm will stall just to our south and provide a few more days
of rain at the end of next week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Subtle short wave trough rolling through wrn PA is generating a
broad patch of SHRA/RA which will get almost everyone wet in the
next couple of hours, including many places N of MDT, but LNS
may stay dry. Instability to the E of AOO is weak and could mean
a rumble of thunder, but it is doubtful, so we have not
included any mention of T at this time. After a very short
2-4hr break this evening, though, the chc T comes in from the W,
esp into the NW zones. Instability will be noticeable aloft and
perhaps sfc-based. 0-6km shear in the 35-40KT range per RAP
sounding at BFD does give rise to the possibility of SVR gusts.
SPC has continue to mention a slice of the wrn zones in the MRGL
risk SVR and Warren Co in SLGT risk SVR for tonight. Best
timing is generally around 04-07Z at BFD, so it won`t be that
late at night for SVR to be unusual. However, the support for
storms does wane after 06Z, so anything that does reach the wrn
zones will probably fall apart or at least diminish in intensity
and may not make thunder thru the rest of the night. Given the
high moisture (m50s dewpoints) and weak forcing lingering into
the latter half of the night, the showers should be persistent,
mainly across the N. Temps will stay very mild all night thanks
to the high dewpoints and srly flow. Some places, the temps may
not dip more than a deg or two.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Monday will be active, at least across the SErn third to half
of the area. Low pressure passes well to our N during the
daylight hours, dragging a cold front thru the entire CWA. The
early AM SHRA and clouds expected over the N&W will likely keep
things more- tame before/as the front moves through. Timing of
FROPA seems like roughly 16-17Z at BFD, 20-21Z JST/UNV/IPT, but
not until around 03-04Z Tuesday in MDT/LNS. Mstr profiles/plan
views yield some breaks in the cloud cover in the morning/early
aftn for the SE half of the CWA. This should help things heat
up and bubble some tall convection.

CAPE is kinda thin, but the shear is big. Deep layer shear of
around 40KT in the aftn/evening in the SE and tall, skinny CAPE
of 500+ J/kg will be plenty to keep the risk of SVR storms in
the forecast. There is a small chc of tornadoes (SPC 2% area now
covers the SE half (and even into BGM`s area), esp early in the
event when supercells are more-likely. Expect the combo of
moisture, lift and instability to coincide in the Lower Susq.
With little confidence in the ability for the Ridge and valley
region (IPT- UNV-AOO) to destabilize sufficiently, the tallest
convection will likely develop and stay SE of those stations.
The orientation and slow progress of the front across the far
srn tier will mean that the threat for storms will last until
close to midnight in Lancaster Co.

Rainfall could be heavy for a brief time (<1hr) from some storms
due to the highly moist atmos and tall convection. However, the
shear and forward speed of the storms will hold the risk very
low for anything but for the smallest of stream to get out of
their banks. Puddles will grow large. Green up in the SE is
well-underway and the dryness of the past 3-4mos there means
that the rain will likely be welcomed by many. Widespread
1-1.25" QPF is seen in the SErn third of the CWA.

As the front passes, the temps will start to cool off in the NW
(after a balmy 55-60F start to the day). The temps will get into
at least the m70s in the SErn cities. Temp profile may be cold
enough in the nrn tier Mon night to turn any wrap around SHRA to
SHSN or at least mix some flakes in. Air temps dip into the u20s
in the nrn tier. No need for more than a 30 PoP or any accums,
though. The ground will be warm and SHSN isold/sct at worst.
Mins elsewhere will get into the 30s. Only the lower elevations
SE of I-81 will stay AOA 40F.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Cooler and dry conditions are forecast to start April on
Tuesday and continue into early Wednesday as high pressure
moves across PA. Guidance then tracks another surface low west
of PA through the Great Lakes next Thursday. Rain along the
attendant warm front could spread into Central PA by Wed PM,
with a chance of showers accompanying the trailing cold front
Thursday.

A cold air damming scenario ahead of the approaching warm front
with surface high east of New England supports undercutting NBM
max temps slightly Wed. However, much milder conditions are
likely Thursday, with the region potentially breaking into the
warm sector south of the surface low.

A trailing cold front is currently progged to stall out just
south of PA Thursday night. A potential wave on this boundary
looks increasingly likely to result in a period of rain Thursday
night into early Friday, especially across Southern PA. Latest
EPS/GEFS suggest a brief period of cool and drier weather is
likely Friday PM into early Saturday associated with a surface
high passing north of PA. However, another wave of low pressure
approaching from the Ohio Valley could spread rain back into the
region by Saturday PM.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
A widespread patch of SHRA over the wrn half of PA is sliding
eastward. The weak upper trough driving this rain will lift N&E
over the next few hours. Expect the SHRA to try and get MDT and
LNS wet, but LNS has the lowest chc of any dip in visby. Have
not yet seen any of the terminals dip to MVFR cig or visby. But,
have carried MVFR cigs at BFD and JST for the next couple of
hours. The wave will pass and take this batch of SHRA with it.
We`ll likely have 3-4hrs at BFD before the next decent forcing
arrives, pushing the weakening convection in from the W after
00Z. The peak timing of possible TSRA at BFD is between 03-07Z.
The storms will weaken as they move eastward and encounter a
more stable environment. MVFR ceilings will develop pretty much
area-wide through the night, with MDT and LNS last/late tonight.

A 45 knot low-level jet dropping southeastward will lead to
LLWS developing initially at BFD, JST, and UNV late today and
during the evening at all other sites.

Expect SCT-NMRS showers and MVFR cigs/visby before CFROPA all
over Central PA. FROPA timing roughly 17Z at BFD, 21Z
JST/UNV/IPT, but not until around 03-04Z Tuesday in MDT/LNS.
The best instability will develop across SE PA Mon aftn. 50+KT
wind gusts are poss in SE PA (primarily LNS, MDT, CXY) as SCT
TSRA tap higher wind aloft. The timing of front and
clouds/showers before 17Z at JST/AOO/UNV/IPT may not allow
sufficient heating/instability for severe wind gusts, but G40+KT
still possible at those airfields if a storm hits. A PROB30
mention of TSRA from 16-18Z (the tail end of this fcst pkg) is
all that confidence allows at this point, mainly due to timing
uncertainty in the SE. Later TAF pkgs will be refining the
timing and coverage of the expected storms.

Colder air immediately behind the front could make a SHSN at BFD
Mon night - with reductions to cigs/visby (mainly MVFR) likely
(70%) there. Other terminals should be MVFR for a few hours Mon
night, but at least MDT and LNS should improve to VFR if not
even clear out. NW winds behind the front will gust into the
18-28KT range.

Outlook...

Tue...No significant wx or restrictions expected.

Wed...Rain moves in west-to-east late. Restrictions likely PM.

Thu...MVFR poss in widespread rain showers. TSRA poss, mainly S.
CFROPA aftn/eve.

Fri...MVFR cigs and visby expected, mainly S.

&&

.FIRE WEATHER...
Cooler and drier conditions are forecast to start April on Tuesday
as high pressure moves across PA. Dry air should support relative
humidities Tuesday afteroon falling into the 30 percent range,
and possibly lower, across most of central PA. Moderately strong
and gusty northwest winds are also possible Tuesday, but at
this time it appears the strongest winds will be in the morning.
Will continue to monitor the forecast and coordinate with BOF
and ANF for any potential need for fire weather statements and
or FWW/RFWs.

&&

.CLIMATE...
Record high minimum temperatures for 3/30:

Harrisburg         59 in 1910 and 1945
Williamsport       54 in 1905
Altoona            60 in 1986
Bradford           53 in 1998
State College      52 in 1910

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Fitzgerald/Gartner
AVIATION...Dangelo
FIRE WEATHER...Gartner
CLIMATE...Banghoff