Lancaster, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

338
FXUS61 KCTP 230536
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1236 AM EST Tue Dec 23 2025

.SYNOPSIS...
* A quick-hitting system will bring up to a several hour period
  of snow with a coating to 1 inch across central and northern
  PA tonight with some light mixed precipitation early Tuesday
  morning; travel impacts possible
* Breezy conditions Tuesday night precede a sunny and seasonable
  Christmas Eve (day)
* Light rain possible (mainly SW) later Christmas Eve and
  Christmas morning; light mix possible in central mountains
* Monitoring the potential for an impactful winter system on
  Friday, with snow, sleet, freezing rain, and rain possible.

&&

.NEAR TERM /THROUGH TODAY/...
A band of mid level lift has drifted across the area late this
evening generating returns on radar but no more than a flurry at
JST. The main, 3-5 hour period of light snow will hold off
until 2 to 4AM in most places. Afterward, the nose of a 45-50
kt, WSW 850 mp jet moves into the CWA and enhances WAA/UVVEL
over the dome of llvl cold air across the CWA as quickly
blossoms/expands the snow through the late night/predawn hours
of Tuesday.

The precip type across the north and east will remain snow for
much of the night and early morning. So, accumulations are
likely - mainly N of a MDT to AOO line. The QPF is unimpressive
with at most 0.20" of frozen in the NE where SLRs will be 10:1
at first, but slide lower thru the night, eventually finishing
around 5:1 around noon Tues. Thus, max snow/sleet amounts will
likely be ~2" from Potter to Sullivan counties. Up to an inch is
possible down to I-80, tapering off to nothing by the MD
border. Whatever does fall as frozen or freezing precip should
melt away.

BUFKIT soundings indicate the potential for precipitation to
start as freezing rain in a few locations, which could bring a
glaze of ice to elevated or untreated surface in the northern
Laurels up through the northern mountains, including I-99 and
I-80. Issued a Winter Weather Advisory this evening for the
potential of hazardous conditions, mainly on untreated roadways
Tuesday morning. If precipitation starts as snow and then
transitions to freezing rain, impacts will be lower with a glaze
of ice simply crusting the snow accumulation on sidewalks and
untreated surfaces.

Temperatures will warm during the day on Tuesday, getting into
the mid 40s across the south central mountains but increasing
more slowly across the northern tier and only topping out in the
upper 30s. Rain/drizzle may linger into the afternoon,
especially in the Laurel Highlands.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
WNW wind gusts will increase Tuesday evening to the teens and
20s (with some gusts into the 30s possible early Wed) as
building high pressure creates a tightening pressure gradient
with a retreating wave of low pressure. Winds shouldn`t be much
of a factor by late Wednesday morning as high pressure moves in
and the pressure gradient weakens.

Wednesday holds some potential for temps to get warmer than
expected, but will be a milder day as 8H temps rise to the mid-
single digits (C). But, the subsidence inversion will be
holding the top of the mixed layer down around 2kft. Therefore,
we`ll hang close to the NBM guidance for the time being. Highs
range from the mid 30s north to upper 40s south. The fast flow
will keep pushing high clouds in from the NW. Forcing comes
over the top of a ridge over TX and the Deep South after coming
ashore in SoCal.

Clouds will thicken up Wed night (Christmas Eve) and eventually
could bear some precip - mainly for the SW half of the CWA. The
timing is still moderately uncertain, but the trend on the GFS
is centering on any precip starting after 06Z. The ECMWF is much
drier and would delay precip until Thurs. Temps Wed night will
probably be very much like Monday night, but the precip lighter.
So, there is a chc for --ZR over the NErn half of the CWA early
Christmas morning. However, the moisture feed and precip
amounts are still suspect.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
The main weather features for this period are #1 - the minor
shortwave/warm-cold front tandem that brings very minimal light
mixed precip Christmas morning and #2 a stronger upper shortwave
and surface low with even a several hour period of llvl easterly
flow ahead of a warm front leading to a several hour period of
wintry precipitation on Friday.

Concerning #1 - The majority of models keep the measurable
precip late Christmas Eve and Christmas morning to the SW of FIG
and AOO. It would also be just warm enough to be mainly -RA.

Any light precip will quickly turn to plain rain before ending
later Christmas morning. Temps soar on Christmas Day with upper
30s NE and mid 50s SW.

By Friday, models have shifted considerably colder and wetter
than they were just 24 hours ago. GEFS and ECENS ensembles
paint 0.3 to 0.6 inches of liquid across Central PA between 12Z
Friday and 06Z Saturday. Temperature profiles at this point
favor snowfall (potentially significant) in northeast PA and a
formidable threat of freezing rain in southwest PA. In between,
across much of our forecast area, a wintry mix of precipitation
types is favored. With how much the forecast has shifted just in
the last 24 hours, anticipate additional changes in the coming
days. In the meantime, continue to monitor the forecast and
consider arranging alternative plans if you intend to travel on
Friday.

In the wake of Friday`s system, unsettled weather will likely
continue into the weekend with a chance for rain and/or snow
showers Saturday and Sunday. QPF amounts look unimpressive at
this juncture.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Clouds are continuing to thicken and precipitation has begun to
appear in radar reflectivity returns, however air at the surface
is incredibly dry, so it is unlikely anything is reaching the
surface as of right now. Once the moisture overcomes this dry
slot(around 08Z starting in the west) An initial area of light
snow will move through this evening, but remaining dry air in
the low levels should limit just how heavy the snow gets.

Restrictions will quickly develop as mixed precipitation enters
from the west after 08Z, though there is still quite a bit of
uncertainty regarding precip type at most TAF sites. After an
initial mix of rain, snow, and freezing rain at BFD, UNV, and
AOO, expect light freezing rain or freezing drizzle to become
the predominant ptype after sunrise. Model soundings show warmer
air reaching JST quicker, likely resulting in a quick
transition to plain rain. IPT has the best chance of seeing
steady snow with this system as they should stay coldest the
longest. MDT and LNS will likely see a few hours of rain or
snow, but it will be fairly light. Confidence in this forecast
is low with medium impacts expected and adjustments to precip
type and visibility will likely be needed.

Precipitation decreases in intensity after 18Z though drizzle,
low clouds, and reduced visibility will linger through the rest
of the day. A 45 knot low-level jet will move into southwest PA
during the afternoon resulting in a period of LLWS for JST, AOO,
and UNV.

Outlook...
Wed...Lingering restrictions in the west, otherwise VFR with
plenty of sunshine. Increasing clouds late.

Thu...Scattered rain showers, some FZRA possible.

Fri-Sat...Widespread -SN developing (with restrictions),
possibly changing to sleet or a brief period of -ZR Friday
night.

&&

.CLIMATE...
Astronomical winter (solstice) began at 10:03 a.m. on December
21st. Daylight lasted 9 hours and 15 minutes. We can look
forward to the following milestones:

10 hours of daylight: January 29th
11 hours of daylight: February 22nd
12 hours of daylight: March 17th
13 hours of daylight: April 9th
14 hours of daylight: May 2nd
15 hours of daylight: June 6th

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 AM EST this morning for PAZ004-
025>028-034-035.
Winter Weather Advisory until noon EST today for PAZ005-006-
010>012-017>019-037-041-042-045-046-049>053-058.

&&

$$

SYNOPSIS...Lambert/Banghoff
NEAR TERM...Lambert/Banghoff
SHORT TERM...Lambert/Banghoff
LONG TERM...Dangelo/Banghoff
AVIATION...Bauco/Bowen
CLIMATE...Banghoff