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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 151954

Area Forecast Discussion
National Weather Service State College PA
354 PM EDT Sun Sep 15 2019

A ridge of high pressure over Pennsylvania will slide east 
to the Mid Atlantic Piedmont tonight. Clouds will increase 
across the state late today and tonight as an area of low
pressure and its preceding warm front moves out of the 
midwest and crosses Pennsylvania Monday night. 

A large area of high pressure over the Upper Great Lakes and
southeastern Canada will build south into the region Tuesday 
and usher in several days of dry weather with temperatures at 
or above normal.


Ridge of high pressure at the surface was nearly bisecting PA
from SW to NE, providing abundant sunshine across practically 
all of the state. The exception was across the far NW where
gentle westerly mid-level isentropic was leading to a bkn deck
of alto cu, that will spread across the rest of NW and Ncent 
mtns through dusk. 

Temps in the 70s, to low 80s across the southeast zones, are
within about 1 deg F of their highs and will beat our normal 
highs for today by 5 degs in many places.

A weak area of low pressure and shield of thick mid level clouds 
will spread gradually ESE across the region late today and 
tonight as the entrance region of a compact 80 KT 300 mb speed 
max slides by across southern New York. A few very light showers
will occur over the north late in the day. 

Additional, albeit scattered at worst, showers will occur 
overnight generally north of I-80. 

Mins temps in the u50s to m60s will be much above normal, 
thanks to the blanketing effect of the clouds.


Weak area of sfc low pressure will cross the area on Monday, 
generating scattered showers across the NW mtns in the morning,
and more numerous small/brief afternoon showers elsewhere 
(though the actual areal coverage will be scattered). Many of 
these probably won't make it SE of the I-81 corridor. 

Maxes will range from 70F across the far north (north of the 
warm/quasi-stnry from) to the mid and upper 70s throughout much 
of Central PA, and low-mid 80s in the Lower Susq Valley.



The weakening cold front could have just enough moisture Monday
evening to continue showers through the Laurels. That moisture
will dry up as a large upper level ridge will build over the
Great Lakes which will dominate the weather pattern through the
This should keep central PA generally dry through the week. 
After a brief cool down behind the departing cold front, 
temperatures should slowly begin to moderate later in the week.


Clouds from an upstream wave will start to thicken over mainly 
the nrn tier of PA late today, and a couple of very light 
showers could dip into BFD before sunset or during the evening. 

However, it should remain VFR for much of the night. The cloud 
cover will probably be a benefit to the nrn mtns, keeping fog 
unlikely tonight.

A weak low pressure area, its preceding warm (or near 
stationary boundary) extending from KDUJ to KSEG and a nebulous
cold front crossing SW and SCENT PA with meager moisture will 
be the main weather maker for Monday. 

The low and associated fronts will create iso/sct SHRA, but 
mostly over the nrn terminals. Low-end VFR (3-5kft) clouds will
cover a good portion of the area on Mon, but IFR is unlikely.


Tue-Thu...AM valley fog until around 13Z throughout the valleys
of central and northern PA. Otherwise, VFR.




NEAR TERM...Lambert
SHORT TERM...Lambert/Gartner
LONG TERM...Ceru/Evanego