Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 181945
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
345 PM EDT Mon Mar 18 2024

.SYNOPSIS...
An amplifying upper level trough will drift across Pennsylvania
through tonight, followed by a reinforcing shortwave and
associated cold front with gusty winds between 30 and 40 mph
on Wednesday.

High pressure is likely to build over the area Thursday. A
dying cold front is likely to approach from the Great Lakes late
next week, as a southern stream shortwave passes well south of
the state.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A broad area of mainly light snow showers with vsbys
predominantly over 6SM was sinking gradually SE across the CWA
this afternoon, with dry air and subsidence at llvls helping to
erode/maintain its SE extent across the Southern Valleys and
Lower Susq region.

POPS will stay high for much of the northwestern half of the
CWA through this evening, but for generally very light QPF of
only a few to several hundredths of an inch and equivalent
snowfall of a dusting in the valleys (to perhaps one inch in
spots across the higher terrain where sfc temps were holding in
the upper 20s to low 30s).

Temps are near their forecast high for today, ranging from
around 30F across the ridge tops of the north and west to the
mid 40s throughout the Lower Susq valley where partly to mostly
sunny skies will persist into at least the mid afternoon hours.

For the overnight hours, cloud bases will rise by about 1-2 KFT
across the Central and SE zones, while persistent upslope flow
and the passage of another weak cold front and upper trough
will lower cigs by several hundred feet across the northern and
western mtns and continue the rather frequent/light to briefly
moderate snow showers.

Mins tonight will be in the low 20s over the high terrain of the
North and West, and in the upper 20s to near 30F respectively
from the Central Mtns to the Lower Susq Valley.


&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
After the troughs overhead and at the sfc pass, the subsidence
should quell the SHSN/SQ for at least the next 18 hrs into late
Tuesday. The ridging should also push lake effect snows to our
N. A northern stream wave/Clipper moves across ONT into NY late
on Tuesday and does not bring the coldest of the air across PA
until Wed. The warm advection does nudge into PA. The
associated cold front will not arrive until the overnight. That
will likely touch off SCT SHSN, but squalls should not be very
likely without much instability. Mins tonight will be below
freezing for all. Temps on Tuesday will be very similar to
today/Monday. The warm advection and more clouds Tuesday night
will keep the mins up just a little vs tonight - in the u20s to
m30s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The passage of the trailing cold front Wednesday should be
accompanied by scattered snow showers, a few of which could
survive into the Susq Valley due to strong forcing ahead of the
upper level shortwave. Steep lower tropospheric lapse rates
indicate the potential of some heavier snow squalls, mainly
across the N Mtns. Fair, but still cool, weather appears likely
Thursday, as the trough lifts out and surface ridging builds in
from the Grt Lks.

Medium range guidance suggests a few rain showers are possible
Friday, mainly over the N Mtns, associated with the approach of
a dying cold front. The bulk of guidance tracks a more
significant southern stream shortwave and associated area of
low pressure well south of PA next weekend. Therefore, fair and
seasonal conditions currently appear likely next Sat/Sun.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Mainly VFR will continue into Tuesday across much of the
Central and SE PA airspace under varying amounts of stratocu
based AOA 3500 ft AGL.

There will be occasional to persistent MVFR across PA`s
Northern and Western Mtn airfields late this afternoon and
tonight and even some brief periods of MVFR Cigs at KUNV and
KAOO in -SHSN this into this evening.

West-Northwest winds will be moderately gusty late today and
tonight for all TAF sites.

A dual or multi-layered cloud shield (mainly VFR) will spread
across the region Tuesday as the low level flow backs a bit more
to the west-southwest, helping to confine most of the snow
showers across the far NW zones, with generally mostly cloudy
skies and breezy and dry conditions elsewhere.


Outlook...

Tuesday-Friday...Periodic snow showers and reductions,
primarily across the higher terrain of northern and western PA.
This will be enhanced by reinforcing shots of unseasonably cold
air and gusty W/NW winds. West to northwest wind gusts could
peak in the 35 to 40 mph range on Wednesday.

&&

.CLIMATE...
Astronomical Spring (vernal equinox) begins on Tuesday March 19
at 11:06 PM EDT.

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert
LONG TERM...Fitzgerald
AVIATION...Lambert/Bowen
CLIMATE...Steinbugl


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