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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 250016

Area Forecast Discussion
National Weather Service State College PA
816 PM EDT Sun Mar 24 2019

An upper low over the Miss Valley will weaken as it pushes east
and merges with a shortwave diving southeast across 
Pennsylvania Monday. Canadian high pressure and associated dry
air mass will settle south across the area during midweek. A 
cold front is then likely to push southeast across the region 
next weekend.


Radar shows some scattered disorganized light echoes, so far
no rain reaching the ground all the way back into Central OH.
The HRRR keeps the precip disorganized and suggests the best 
chance for some small measure of rain will be over the SW and 
along the Mason Dixon line overnight. In general I trimmed back 
the already low POPs and QPF.


A shortwave over the Midwest will get absorbed into the very
fast WNW flow aloft, causing the surface wave to get squeezed
mainly south of the forecast area. The HREF shows mainly light
rain moving across the southern stripe of counties tomorrow
afternoon into the early evening. 

Surface ridging and much drier air mass over upstate NY will 
build back in for Monday night.


The axis and SWWD extend of an upper trough over southeastern
Canada and deepening cold air will extend across PA Monday
night. At the same time, the northern extent of light precip 
(from a weak sfc low and southern stream trough) will brush our
southern zones and will transition into a light rain/snow mix 
for a short period prior to ending by 04Z Tuesday. No snow accum
is expected as sfc temps will be in the mid to upper 30s. 

NW flow aloft and dry conditions with below normal temps will
follow for Tuesday, with strongly anticyclonic flow/subsidence 
at llvls. 

The NW flow aloft will abate for midweek as a large area of sfc
high pressure builds across the Commonwealth. Mainly clear 
skies are expected for later Monday night right through 

A slow-moving frontal boundary, draped to our northwest across 
the Grt Lks, may sink SE into the region Thu night or Friday 
before stalling out as a weak northern stream trough slides 
from the Upr Glakes to the Canadian Maritimes. 

A deepening upper trough and 1000 mb sfc low over the Central 
Plains and Mid Miss Valley respectively late Fri Night/Sat will 
lead to a quickly expanding rain/snow field from the Central 
Plains to Upper Glakes, with a building ridge along the East 
Coast keep us very mild and mainly dry under south-southwest 
flow at the sfc and aloft.

Near to slightly above normal temps are forecast for Wed under
the central of the high. Afterward, temps will rebound to 7-10F
above normal Thursday, and peak at 15-18F above normal Friday
and Saturday. 
Will maintain a chance of showers across northwest Pa late in 
the week through Saturday to account for model differences with
regard to the exact location of the quasi-stationary/warm front
that's expected to stretch from Lake Erie NE across the St.
Lawrence Valley.

The greatest prob for rain showers comes for later Sat and
Saturday night, when east coast ridge breaks down and a cold 
front pushes across the state. Above normal temperatures should
hang on Sat before dropping back to near normal for Sunday with
scattered rain/snow showers possible across the Mtns and
isolated-sctd rain showers in the Valleys.


VFR conditions prevail across the region this evening. A cold
front will slip southward through Pennsylvania overnight. A 
shift to northerly winds will accompany the frontal passage. 
While actual precipitation will be spotty overnight, increasing 
low level moisture and the upslope flow into the mountains will 
likely generate some MVFR ceilings.

On Monday, a weak wave will ride eastward along the front, which
should be south of Pennsylvania. Models generate limited
moisture with this feature as is is sheared, but threat exists
for some light precipitation and ceiling restrictions across the
southern tier during the day.

High pressure will then prevail through Thursday, with a frontal
system approaching for Friday.


Mon...AM rain/snow. Restrictions possible, mainly northern and
western mountains.

Tue-Thu...No sig wx expected.

Fri.....VFR, but with some scattered showers possible northwest.




SYNOPSIS...Fitzgerald/La Corte
NEAR TERM...La Corte/Ceru
SHORT TERM...Fitzgerald/Ceru
LONG TERM...Fitzgerald/Lambert