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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 231903

Area Forecast Discussion
National Weather Service State College PA
303 PM EDT Fri Aug 23 2019

A large area of high pressure over the Great Lakes will drift 
gradually to the east, reaching northern New England on Sunday. 
This weather feature will bring us a several day string of dry 
and cooler weather with low humidity right into early next week.


The wave riding the front is finally moving far enough to the 
east to take the rain away from the SErn counties. Lower clouds 
are diurnal in nature and should die off quickly this evening, 
perhaps before sunset. The high clouds should linger thru 
midnight in the SE, but will be diminishing on the whole 
elsewhere. Air/river water temp difference to night will likely 
lead to the dendritic fog in the northern valleys. Some of the 
central valleys may also see fog try to form. Fog elsewhere is 
unlikely due to the dry air. Ought to be refreshing air. A small
taste of autumn, esp across the northwest half of the CWA. 
Thank the Canadians for this night's comfortable sleeping 


Fog burns away after an hour or two, and a mostly sunny day
results. Just a few cu over the mtns. Modified CP airmass 
visits for the weekend. Tough to beat guidance on maxes on days 
like Sat. Mixing gets up near 8H where Temps are 6-9C. We should
end up in the u60s across the higher hill tops of the west and 
north, and m70s in the warmer valleys of the east. These values 
are generally 4-8F below normal.


Patchy valley fog is possible once again Saturday night, as high
pressure provides mainly clear skies and light winds. Any fog 
should burn off quickly Sunday morning, giving way to partly to 
mostly sunny skies. Temperatures will remain slightly below 
normal for late-August.

Heading into next week, the main question will be how quickly 
return flow develops and brings moisture back into the area. 
The GFS continues to be a bit more bullish, although it is 
slowly coming more in line with the ECMWF in keeping central PA 
mainly dry until Tuesday. Given the uncertainty, went with a 
model blend and gradually increase PoPs later Monday into 
Tuesday. PoPs should peak on Wednesday with a frontal passage, 
with a drying trend for the later part of next week.

The temperature forecast is less certain early next week, as 
an increasing southeasterly low-level flow may advect some 
clouds into the area and result in another relatively cool day 
on Monday. Some moderation in temps is expected ahead of an 
approaching cold front Tues into Wed. Following the midweek 
frontal passage, cooler and drier weather should return late 
next week.


LE region of the strong jet streak and it's assocd wave along 
the front are sliding east and taking the rain to our east. Dry
air will win out and VFR will prevail for most of the next 60
hours. Some early morning fog is a given in the northern 
valleys. If it gets cold enough, the central valleys may also 
get fog, but the dryness of the air will likely balance that 
factor. The fog will be most likely between 08Z and 13Z. Poor
llvl mixing/light wind at first could mean it'll take a little 
longer than expected to burn the fog away. But, IPT is really 
the only site to worry about for tonight. BFD may fog at first, 
then go VFR again well before sunrise. 


Sat-Sun...AM fog possible. 
Mon...AM fog possible. SE low level flow, low clouds poss. 
Tue...SHRA poss, mainly W.
Wed...CFROPA. SHRA/TSRA likely.




NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Evanego