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Rain and High Winds Return to the Northwest; Fire Weather Conditions in Southern California

Heavy rain will bring localized areas of flash flooding cross parts of Washington. Another high wind event is expected to impact portions of Montana and Wyoming. Locally critical fire weather concerns are likely for southern California. A powerful storm will impact parts of Alaska with rain, snow and gusty winds the next several days. Read More >

Here is the latest Area Forecast Discussion for Central PA

This text statement is the latest forecast reasoning from the NWS in State College, PA

See the links at the bottom of the page for previous issuances/versions of the statement as well as our other text statements.


000
FXUS61 KCTP 300027
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
727 PM EST Mon Nov 29 2021

.SYNOPSIS...
Another fast-moving upper level shortwave (aka Clipper) over
the Upper Mississippi Valley and Northern Great Lakes early
this evening will race southeast and spread a several hour
period of light snow across our region late tonight and Tuesday
morning, followed by scattered snow showers late Tuesday and
Tuesday night.

Every 24-36 hours, a new Clipper will cross the Lower Lakes,
but the ones moving through during the mid to late week period
will have minimal impacts on the weather in Central PA as they
take more northerly tracks resulting in mainly rain showers.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Timing of the next event on course.

Clouds held onto western areas late this afternoon, but
much of the region had some sun.

Earlier discussion on the next system.

Arriving quick on its heels from the NW will be a thickening
layer of clouds and a period of light snow late tonight and
Tuesday morning, thanks to an area of of weak to mdt low-mid
level warm advection, beneath the left exit region of a
110-120kt 300 mb jetlet.

Expect between 1-1.5 inches of snow to fall across the northern
and western mtns per consensus high res model qpf output and a
10-12:1 SLR, with a coating to 0.75 of an inch across the Ridge
and Valley Region of the state.

Although the snow accums will be light, the period of nuisance
winter weather will target the morning rush hour across much of
the CWA. This will likely slicken-up many untreated roads with
overnight min temps in the low to mid 20s over the higher
terrain, and upper 20s throughout the Central Valleys.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Timing and amount of snow on track.

Earlier discussion below.

The period of light snow and a thick overcast will diminish/move
off to the east during the late morning and early afternoon as
the weak warm front causing the isentropic upglide pushes
through.

Our time in the warm sector will be brief, as a weak cold front
slides SE across the Commonwealth late Tuesday into early Wed
with little more than some scattered flurries.

The southern half of the state should see some sunshine during
the afternoon, while mostly cloud to overcast skies persist
across the Nrn Mtns.

Most of the light snowfall should melt in the valleys during the
afternoon as temps climb to the upper 30s/low 40s over the
Central and South, while max temps will be in the mid 30s over
the Northern Mtns.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
An Alberta Clipper pattern (relatively weak, fast-moving storm
track from south-central Canada across the Great Lakes through
the Northeast states) is expected through the end of the week.
We are leaning toward a faster onset with light snow arriving
Wednesday evening in the western zones. Milder trend should
transition snow over to more rain/snow mix or plain rain showers
through Thursday as the system departs. Precip should end
(outside of the lake effect zones) Thursday night with the next
weak system possibly bringing another shot of light rain/snow on
Friday into the weekend. After a brief warm up Thursday, temps
trend seasonably colder into the weekend. Clipper precip pattern
seems to hold on through the weekend with some potential for a
larger scale storm system around early next week. Still lots of
question marks surrounding what evolves this far out in the
forecast period.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
MVFR to low end VFR stratocu clouds will linger late today and
this evening, before being topped by a large area of
thickening/multi-layered clouds and a several hour period of
IFR Cigs and Vsbys in light snow late tonight through much of
Tuesday morning.

Outlook...

Tue...Improving conditions to MVFR or VFR across Southern PA
Tuesday afternoon, with lingering MVFR and flurries across the
Mtns of northern PA. Breezy with SW winds of 10 to 20 mph in the
late morning and afternoon hours Tuesday.

Wed...Becoming VFR areawide.

Wed night-Thu...Rain showers developing with a period of MVFR to
IFR Cigs. Rain showers changing to snow showers across the
Western Mtns later Thu afternoon with areas of IFR cigs and MVFR
to IFR vsbys at KBFD and KJST. Southwest to Westerly wind gusts
of 25 to 30 mph likely during the day Thursday.

Fri...Mainly VFR Central and SE valleys, with MVFR cigs and
flurries across the northern and Western Mtns.

Sat...Perhaps some rain and snow showers across the west.

&&

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

&&

$$
SYNOPSIS...Lambert/Martin
NEAR TERM...Lambert/Martin
SHORT TERM...Lambert/Martin
LONG TERM...Steinbugl
AVIATION...Lambert

 

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