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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 250958

Area Forecast Discussion
National Weather Service State College PA
558 AM EDT Mon Mar 25 2019

Low pressure over southern Indiana will track south of
Pennsylvania late today. 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 loop at 09Z shows diminishing pre-frontal showers 
across central/southern Pa, as parent shortwave and best forcing
shifts east of the state. By dawn, expect the dying cold front 
to have settled south to near the Mason Dixon Line and the 
showers to have dissipated due to the arrival of large scale 
subsidence behind shortwave.

The remnants of Miss Valley upper low and associated surface 
low are progged to track south of Pa later today. The latest 00Z
operational models and Hrefv2 are supporting increasing 
confidence in the southern tier of the state being impacted by a
period of light rain, beginning around midday and lasting until
early evening. An examination of model soundings indicates 
some wet snow is likely on the ridge tops of southern Pa, 
mainly at elevations above 2000ft. Surface temperatures appear 
to be the limiting factor for any accumulations, but wouldn't 
be completely surprised if an inch or so was reported on the 
highest ridgetops south of the turnpike. 

After a cloudy start, surface ridging and much drier air mass 
building in from upstate NY should result in mostly sunny skies
across northern Pa today, while model RH profiles indicate overcast
conditions all day in the south.


Clearing skies will advance south tonight, as low pressure 
passes off the coast and high pressure builds south from NY 

Canadian high pressure will build into the region Tuesday,
accompanied by abundant sunshine and a light northerly breeze.
Mixing down model 850mb temps yields expected max temps ranging
from the upper 30s over the northern mountains, to the mid 40s
across the Susq Valley.


Med range guidance continues to support a high confidence of
fair weather through midweek, as Canadian high pressure drifts 
southeast over the area. Nearly ideal conditions for radiational
cooling Tuesday night with high directly over the area, so have
leaned toward the colder Eco and MAV MOS over the NBM min temp

Med range guidance all indicating a dying cold front will either
approach or push into northwest Pa late Thursday into Friday,
accompanied by a chance of showers. Both the 00Z ECENS and
operational EC/GFS suggest the front lifts north of the region
late Friday and Saturday, as wave of low pressure forms over 
the Miss Valley and tracks northeast through the eastern Grt 
Lks. All guidance continues to suggest the best chance of 
showers comes next weekend, when east coast ridge breaks down 
and cold front pushes across the state. 

Above normal temperatures appear very likely Thu-Sat in the 
deep southwest flow between east coast ridge and approaching 
front. A transition to drier and colder conditions appears 
likely Sunday, as the front pushes east of the state.



VFR conditions continue to prevail across the region this
morning, save for KJST where low level moisture and the upslope
flow into the mountains is producing MVFR ceilings. Latest radar
imagery shows spotty light precipitation moving east.

Later this morning, a weak wave will slide south of the airspace
bringing light rain into the southern half of the region. 
Models generate limited moisture with this feature as it 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.


A weak weather system will move south of the state today through 
tonight producing light precipitation, mainly over the southern 
half of the district. Behind this system, a large area of high 
pressure will build across the eastern third of the country 
through mid week. 

***This area of high pressure contains very dry air. Dewpoints
 in the single digits are expected today, Tuesday and Wednesday
 across the northern half of the district. Dewpoints in the 
 teens are forecast across the southern half on Tuesday and 
 Wednesday. This will result in afternoon relative humidity 
 below 30 percent all three days. Given sufficient mixing, quick
 drops to below 20 percent are possible in some locations.

Winds are expected to remain on the light side, less than 
10mph, during this period.




NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Fitzgerald