Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 290317
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1117 PM EDT Wed Oct 28 2020

.SYNOPSIS...
The remnants of Hurricane Zeta will combine with a strong upper
level system moving east from the southern Plains to bring
drenching rain and the first snow of the season to central PA
Thursday/Thursday night into Friday morning. Dry and seasonably
cool weather on Saturday will precede a gusty frontal passage
with rain showers likely on Sunday. A brief shot of much colder
air is forecast to blast into the area behind the front Sunday
night into Monday which could trigger widespread and locally
heavy snow showers. Temperatures will moderate quickly and
trend warmer by the middle of next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
Patchy drizzle appears likely late this evening across the
Laurel Highlands, where model soundings show a nearly saturated
0-1km layer and light upslope flow. Otherwise, the remainder of
the evening should be dry.

Rain will spread quickly northward across the region early
Thursday morning, as the remnants of Zeta lift up the
Appalachians and interact with stalled front south of Pa. The
strongest fgen forcing per latest model guidance is across the
southern half of Pa, where rain should fall at moderate
intensity from mid morning through the afternoon. Rain rates
should be diminishing by Thursday evening, as nose of low level
jet shifts east of the Delmarva Peninsula. By 00Z Friday, multi-
model QPF blend yields around 0.75 inch across the northern
tier to ~ 1.5 inches in the southern zones, well below flood
guidance. No concerns for areal or river flooding based on
expected rainfall and abnormally dry preceding conditions.
However, some minor poor drainage flooding is possible, due to
leaf-clogged storm drains.

High pressure parked to the north will funnel chilly air into Pa
on a east-northeast flow Thursday. The steady rain and low level
cold advection will result in a raw day for late October with
highs 5-10F below average, ranging from the mid 40s north, to
low 50s south.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Rain continues area-wide into Thurs night, as the remnant low
of Zeta passes just to our south. As colder air wraps in behind
this system, a changeover to wet snow is expected across the
northern mountains, with some light accumulation expected.
Precipitation will gradually wind down on Friday, as the system
pulls off the East Coast. Rainfall totals have been brought
down a bit, and now range from around an inch across the
northern tier to near two inches over the southeast corner of
the forecast area.

Still holding to a high confidence forecast of fair and chilly
weather Saturday, as surface high builds over the state.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A digging trough and associated cold front are progged to sweep
through the region Sunday. Although is won`t have a lot of
moisture to work with, strong forcing supports a good chance of
measurable rain, especially over the northwest mountains.

A period of lake effect snow showers appear likely Sunday night
through Monday across the Allegheny Plateau, as the coldest air
mass so far this season plunges south across the relatively
warm Grt Lks. NBM suggests several inches of accumulation is
possible across the snowbelt of northwest Warren Co, with a
lighter accumulation possible across the rest of the Allegheny
Plateau. All medium range guidance supports fair weather and
moderating temperatures Tue-Wed, as deep upper trough lifts out
and surface high builds into the region.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Moist upslope flow will hold LIFR conditions at KJST while
conditions elsewhere remain VFR/MVFR tonight. The trend is lower
into Thursday with widespread rain and IFR conditions likely
through Thursday night.

Outlook...

Fri...Improving conditions/VFR.

Sat...VFR no sig wx.

Sun...Gusty FROPA accompanied by rain showers.

Sun ngt-Mon...Gusty winds from 280-310 degrees with snow
showers possible.

&&

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

&&

$$
SYNOPSIS...Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Evanego
LONG TERM...Fitzgerald
AVIATION...Steinbugl/Colbert


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