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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 200319

Area Forecast Discussion
National Weather Service State College PA
1119 PM EDT Thu Sep 19 2019

Anomalous upper level ridging will build east into the region
through the weekend. A cold front will likely push across the 
area Monday, followed by high pressure building in from the 
Great Lakes by the middle of next week.


Rather thick cirrus over the wrn half of the area right now, and
RH progs have it going east slowly before thinning. This could 
keep temps up just slightly from going mins. But, am shy to 
change the mins much at all due to only high clouds. If they 
were lower, say a mid deck, I would have more confidence in 
upping mins. But, the possibility of them clearing away and the 
early cooling we have had already makes me think it is OK to 
hold mins as-is. THV tanked to 50F last hour, but caught a 
little south wind in the last hour, but has gone back to calm. 
THV is back up to 56F. Expect them to drop off once again. SEG 
not disappointing as the best radiational cooling site so far, 
and they are down to 48F. Interesting returns seen on radar 
over Chesapeake Bay over the last few hours - we figure that it
is likely chaff from flight ops around Patuxent NAS.

Mainly clear with just high clouds spilling over the ridge.
These clouds did make for a beautiful sunset. Some low stratus 
is possible with/near the anticipated river valley fog which 
should form again overnight. But, not outside of the immediate
vicinity of the fog. Temps should fall into the 40s to lower 
50s. Just the more sheltered places in the north could touch the
30s much like they did at BFD and in Kane and Coudersport last 
night. While it seems cold - the upper 30s are just 5 or 6 
degrees below normal for the day.


No changes to the going forecast on Friday as the strong surface
high slips south of the region. A return flow of warmer
southward flow will develop, and along with abundant sunshine,
temperatures should jump up to the mid to upper 70s north to the
lower 80s south/southeast.


A building upper level ridge and surface high off of the east
coast will bring a resurgence of summertime warmth across the 
area this weekend. Max temperature departures of +10-15 degrees
are expected Sat-Sun with peak readings in the mid to upper 80s
in the SE. Max temperatures would have to reach or rise above 
90F to challenge daily records in most locations.

The biggest forecast question in the mid range will be the 
presence of a shortwave trough that will move through the Mid 
Atlantic region Saturday. This shortwave should flatten out the 
ridge and bring in some mid to upper level instability. The only
reducing factors is that it will be very dry aloft and their 
should be the presence of a low level cap. Temperatures will 
have to get very warm for the air to be able to be lifted beyond
it. Latest soundings show this is possible but given the dry 
air, less likely. 

So have introduced slight chance to chance POPS to central PA 
Saturday afternoon. 

The models are coming into agreement on the tracking of a cold
front that will move through the area Monday. This system will  
likely be accompanied by a round of showers. It should move
through the region quickly with a return to fair and seasonable
weather appears likely Tue/Wed. High pressure should build  
southeast from the Grt Lks mid next week.


VFR conditions will continue into the early overnight hours,
before patchy fog and low clouds develop. Expect a period of 
IFR/LIFR cigs at KIPT just before daybreak, similar to the past
couple of nights. Also included the possibility of some brief 
vsby reductions in patchy fog at KBFD, KAOO and KUNV.

Any fog and low clouds will burn off quickly Friday morning, 
giving way to another day of VFR conditions. A light
southwesterly breeze around 5 knots will develop as the day

A few showers are possible Saturday. There is a better chance 
for showers/storms Monday, ahead of an approaching cold front.


Fri-Sun...AM valley fog/possible, otherwise VFR. A few shra 
possible Saturday.

Mon...Chance of shra/tsra, as a cold front crosses the area.

Tues...Becoming VFR.


Autumn officially arrives at 3:50 a.m. EDT, on Monday, Sept. 23.




NEAR TERM...Dangelo
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Fitzgerald/Ceru