Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 220840

Area Forecast Discussion
National Weather Service State College PA
340 AM EST Mon Jan 22 2018

A warm front over the Interstate 80 corridor this morning will
lift slowly north today. This weather feature will bring
occasional light rain or drizzle and areas of fog this morning,
with just some lingering isolated to scattered showers for this

A potent area of low pressure moving across the Great Lakes
will push a trailing cold front through the Commonwealth on
Tuesday. Temperatures will rise well above normal today and
stay there through early Tuesday, before falling back to near or
slightly below normal Wednesday and Thursday. A rebound to
above normal temperatures will occur again by next weekend.


Surface warm front extended near the RT22/322 corridor in
south-central PA early this morning with weak isentropic lift
from the southwest producing widespread low stratus to its north
and east, and a dual-multi layer of stratocu and alto cu in the
warm sector across the southern tier of PA.

Expect occasional light rain, drizzle through much of this
morning, before some improvement with just some isolated-sctd
showers leftover this afternoon as the warm front lifts across
the northern mtns and eventually into New York State by late

The weak low-level isentropic...and orographic lift over the
mtns and interface of the shallow cool air and warmer moist air
aloft will yield areas of dense fog through about 14-15Z today
across the higher terrain - AOA 1800 ft MSL.

Temps will remain relatively mild for late January and mainly
in the upper 30s to lower 40s. A few pockets of cooler air
around 35F will persist across the Middle Susq Valley early
today. Blended model guidance points toward a very mild
afternoon with temps ranging from the mid-upper 40s across the
NE to the balmy upper 50s over the southern tier counties. These
highs will depart from normal by 13-15F across the NE and by
nearly 30 degrees over the Laurel Highlands.


Mild weather will continue overnight. A few showers early on
will rapidly expand in coverage from SW to NE across the region
for the second half of the night as deepening uvvel develop
with the approach of the left exit region of a 130 kt upper jet
lifting NE from the tenn Valley. The rain could fall heavy at
times for brief periods just ahead of an approaching cold front.

Cold front crosses central PA Tuesday morning with weak
secondary low forming in the lee of the Appalachians supporting
a period of enhanced rainfall over the eastern 1/2 of PA on the
order of 0.50-0.75" (as front occludes into early Tuesday
afternoon). A rather potent, SW 50kt LLJ could also generate a
rumble of thunder. River ice concerns are addressed in the
hydrology section.

Gusty WSW winds, possibly as high as 40 to 45 mph occur in the
wake of the cold front Tuesday afternoon and evening.


The progressive pattern will keep the mid/late week cool-down
rather brief before temperatures moderate/trend warmer into the
upcoming weekend.

Gusty westerly winds with top values between 35 and 45 mph will
continue Tuesday night, before gradually decreasing through the
day Wednesday.

Occasional snow showers are likely downwind of Lake Erie
Tuesday night and Wed but should only amount to light accums of
a coating to 2 inches in most places.

Dry wx under high pressure Thu- Fri with chilly starts to the
day (especially in the east) with moderating temperatures
heading into the weekend as the next (weaker) low pressure
system lifts across the Great Lakes bringing chances for rain on
Sat increasing into Sunday.


Moist flow, along with calm winds and will continue to have VLIFR
cigs across the northern mountains (KBFD) overnight, while
progressively higher cigs are expected further south. Trapped
low level moisture along with calm winds has allowed fog/mist to
develop overnight. These reduced vsbys, along reduced cigs at
UNV and IPT will continue through the early morning. Light
precipitation south of the front continues with light showers at
times at MDT and LNS. While IPT and SEG are LIFR, areas across
southeast Pa (KMDT/KLNS) at 08Z, are VFR. Latest model
soundings and MOS guidance support the idea of a possible period
of MVFR cigs/vsbys roughly between 10Z-14Z. Expect
predominantly MVFR cigs at KJST overnight, where a southerly
flow results in drying/downsloping off of adjacent higher

Warm front is progged to lift through western Pa on Monday,
resulting in a return to VFR conditions along the spine of the
Alleghenies, including KJST and possibly KBFD/KAOO. Elsewhere,
modest improvement will come slowly across the eastern half of
Pa on the cold side of the front.

LLWS problem will become a concern Monday evening, as a very
strong low level jet overspreads the area ahead of an
approaching cold front.


Tue...AM rain/low cigs poss, then windy with PM shsn poss w mtns.

Wed...AM shsn possible w mtns.

Thu-Fri...No sig wx expected.


Marietta gage /MRTP1/ pretty much steady right now, although ice
effects continue. The Flood Watch for this area lasts into
Monday afternoon. Due to the mild temperatures, there is a
potential for ice movement, but also deterioration/thinning with
time. All locations along rivers and streams that have
significant ice buildup should monitor water levels closely for
the next several days.

The anticipated rainfall totals of 0.5 to 0.8 inches over the
next 48 hrs is much less than we had a few days ago, and the ice
is less pervasive/extensive due to our relatively mild temps
(versus the period leading up to our previous significant


Flood Watch until 1 PM EST this afternoon for PAZ065-066.


NEAR TERM...Lambert/Evanego
SHORT TERM...Lambert/Evanego
HYDROLOGY...Lambert is the U.S. government's official web portal to all federal, state and local government web resources and services.