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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 212259

Area Forecast Discussion
National Weather Service State College PA
659 PM EDT Sun Apr 21 2019

An upper low overhead will slide south and east tonight. A 
ridge of high pressure will then build in and provide us with 
fair, dry weather for much of Monday and Tuesday. A cold front 
will bring a few showers or a thunderstorm late Tuesday and 
Tuesday night. Wednesday and Thursday should feature mainly dry 
conditions once again under the influence of another area of 
high pressure.


Scattered showers persist over eastern portions of the Central
and North Central Mountains this evening. Isolated spritzes
detected by radar down to the Maryland border and eastward to
the Pocono Plateau, with more numerous showers along the
Delaware River Valley along the NY/PA border. 5H shear axis lies
from north to south from the N Central to S Central Mountains,
and will pivot westward and southward overnight, with best
forcing shifting west and especially southwest of the Laurel
Highlands in the pre dawn hours. 

Loss of heating will decrease the showers through mid evening.
Not expecting much more than a sprinkle in spots late tonight
through Monday morning. The western highlands should remain 
dry, but mainly cloudy. Clouds over the NErn mtns and 
Alleghenies should last much of the night, but clouds will be 
thinning over the SE and SC counties. Mins should range from 
u30s NW to 50F in the SErn cities as the wind gets lighter out 
of the NW, but not die off totally.


Clouds should decrease nicely in the morning, with only the
smallest chc of a SHRA in the aftn over the extreme eastern
towns. This will be due to the old upper low spinning back to
the north up/off the East Coast. Maxes should be 10F higher than
Sunday as 8H temps rise from 3-4C to about 6-8C through the day.
The wind will pick up to 5-10MPH out of the NW, strongest in the


There is decent model agreement in the next cold frontal system
moving through the area during the midweek period. Ahead of the
front on Tuesday, increasing clouds and mild as temps peak in
the 70s. Showers and sct tstms impact mainly NW areas Tue 
night, with diminishing showers surviving into the SE through 
early Wed, followed by a breezy and cooler day.

Beyond Wednesday, the weak frontal boundary washes out as it
gets nudged further south, keeping dry weather in place through
Thu. Thu will start of chilly, with dry air in place and light 
winds, lows likely dip into the upper 30s in the valleys of the
northern mountains.

Models then focus on a digging trough shifting eastward
across the GLakes for late week, with a transition to SW flow 
ahead of it as a weak surface low lifts up the Appalachians. 
Combined with a potent shortwave progged in on Friday, this  
will bring the next shot for showers/tstms followed by another
shot of cooler air and breezy conditions to start the weekend
with temps recovering back to normal by Sunday.


Upper low is right overhead and has helped SHRA form over the 
airspace between KIPT-KBFD-KUNV. These should expand a bit for
the next few hours to the space between KAOO and KMDT. Showers 
should end this evening, as the upper low slides south and east
of the area and we lose the heat of the day. Expect that the
only flight trouble overnight will be the possibility of low
clouds and a little fog over KBFD and KJST. But, the dry air and
plenty of drying time from this morning's rain until nighttime
stratification argues against it. Will include the first hints
of IFR for a few hours late tonight/early Mon. But, won't hit it
too hard.

Monday looks like widespread VFR as high pressure builds in 
despite the old upper low circling back north along/off the 
East Coast. Any light showers Mon should remain to the east of 


Tue...Mainly VFR. Scattered SHRA/TSRA possible far NW late.

Tue PM...Cold frontal passage, with accompanying SHRA/TSRA.

Wed-Thurs...No sig wx.

Thurs PM-Fri...SHRA/TSRA. Restrictions probable.




NEAR TERM...Dangelo/DeVoir
SHORT TERM...Lambert