Lancaster, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

152
FXUS61 KCTP 030015
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
815 PM EDT Wed Apr 2 2025

.SYNOPSIS...
A warm front will lift into Pennsylvania through tonight as low
pressure tracks west of Pennsylvania through the Great Lakes
through tonight. A trailing cold front will push through Central
Pennsylvania late Thursday, then stall out out of just south of
the region late this week. A wave on the stalled front is
likely to lift up the Ohio Valley and across Pennsylvania this
weekend.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
TSRA moving thru JST is making at least small hail (0.5 and
0.75 reports thus far). Marginal reflectivity for severe hail,
though. That cell should shrivel up pretty quickly as it gets
any deeper into the CWA thanks to the very stable air over
most/all of the CWA. The strong winds in the mid layers will
keep things moving and push them down the road early this
evening.

After a short lull, additional weak SHRA may get touched off
over wrn PA and drift in, but die off quickly, too. Then a good
trough aloft will ramp up lift over the NW. The warm front
will still be wrapped around the western and southern borders
of the CWA in the morning. However, the warm front may actually
push through Warren/McKean/Elk counties by morning, followed
quickly by the cold front later Thurs AM. then. Therefore, any
storms moving in before sunrise could contain hail and damaging
wind gusts.

Stability remains high over the east while a surge of deep
moisture will roll in overhead overnight. That should result in
lots of low clouds and fog blanketing the ridges. Some patchy DZ
is also expected. Temps rise after midnight, hitting the 50s
almost everywhere and near 60F in the Laurels at sunrise.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
The low pressure center with this storm will be around the srn
tip of James Bay in mid-day, with a trailing cold front pushing
into the NW in late AM (before noon). The showers/storms in the
morning could still pack a punch, but the prob for SVR wind/hail
is low. The low crud over the east will start to clear out, but
likely be stubborn to leave. The stability will again thwart the
chc for deep convection for much of the area during the daylight
hours. However, the disorganized look to the convection in the
aftn on the HREF guidance may be because of the wide spread in
the members on where and when to pop convection and when the
front moves in/thru. Will keep mentions of SHRA and TSRA in the
forecast for all day in the south, but the nrn tier should
stabilize as the front presses south in the aftn. A large cap is
evident over the srn tier in the aftn up around 7-8kft, so
it`ll have to be strong forcing to overcome it. The front could
do it.

Highest PoPs will come later Thursday night after the cold
front has pushed into MD and perhaps into nrn VA. The
overrunning will also have good/steep lapse rates and
instability aloft over our srn tier. SPC SLGT risk SVR on Day2
is still painted over our srn half, probably more so for the
daylight hours Thurs than the late night (early Fri AM). But,
the cap and initial stability at the sfc are two negatives.

Temps will get into the 70s for many places on Thursday, as 8H
temps get into the mid teens C in the morning, even if they
slide a little in the aftn. A big range will be found for mins
Thurs night, near 40F N and upper 50s SE.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Latest EPS/GEFS indicate cooler and drier weather is likely
Friday/Friday night across most of CPA as sfc high pressure
migrates eastward from the Great Lakes through northern New
England. The most likely area for rain on Friday is over the
southern tier of CPA particularly the southwest mtns/Laurel
Highlands on the eastern edge of the deep moisture plume
extending eastward from the Ohio Valley and in close proximity
to the wavy/pivoting q-stnry frontal zone near or just south of
the MD line.

Waves of low pressure riding east/northeast along the stalled to
lifting frontal boundary will result in periods of soaking
rainfall (with some embedded convective elements) this weekend.
Latest WPC/NBM QPF fcst projects the heaviest rain (0.50-1.50")
over the western and northern Alleghenies with <=0.50" across
the south central ridges into the lower Susquehanna Valley
(where it is needed the most).

There is a broad consensus among the medium range operational
and ensemble guidance that the primary cold front slides to the
east of the area early next week followed by anomalous upper
level troughing building into the northern Mid Atlantic and
Northeast states next Monday-Wednesday. This pattern will be
accompanied by high confidence in below normal temperatures.
The colder cyclonic/NW flow should also favor scattered
rain/snow showers downwind of Lake Erie over the Allegheny
Plateau.

There are some long range model signals that suggest upper level
troughing will reload into the back half of next week which
would favor a continuation of temps below the historical
average for the second week of April. There may also be an
opportunity for frost/freeze conditions as the spring growing
season gets underway in the Lower Susquehanna Valley.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
A few rain showers continue to linger across the area as of the
beginning of the 00Z TAF package. These showers should move out
of the region within the next few hours. The resulting south-
southeasterly flow will lead to increasing low- level moisture
over much of Central PA. This will cause MVFR ceilings to
develop almost everywhere tonight, with the potential exception
of JST. RAP model soundings suggest that the low clouds would
make it there, but the GLAMP and HREF show a less than 40%
chance of MVFR ceilings developing. Given the uncertainty at
that site we kept site borderline VFR overnight.

The other concern tonight will be LLWS as a 45 to 55 knot low-
level jet moves in and surface wind gusts decrease. BFD will be
the first airfield to see wind shear develop and the threat will
spread southeastward through the late evening. The potential
for LLWS will reach MDT and LNS in the 06-08Z timeframe.

A decaying line of convection will reach the central PA area
during the pre-dawn hours Thursday morning. Instability will be
limited the further east these storms move, however sites in the
west such as JST/AOO/BFD could see damaging wind gusts and
rumbles of thunder. As these storms reach eastern PA by late
morning they`ll likely be light or nothing more than drizzle.
Reductions in visibility will still be possible over MDT and
LNS. Latest HREF shows a break in precipitation before another
round of convection initiates across the southern half of PA
with the passage of the cold front. Guidance still is showing a
wide spread of solutions as to the exact timing convection will
initiate come Thursday afternoon.

Outlook...

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

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

Sat...Widespread showers; impacts likely.

Sun...Widespread showers; impacts likely.

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Steinbugl
AVIATION...Bowen