Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 211448

Area Forecast Discussion
National Weather Service State College PA
1048 AM EDT Thu Sep 21 2017

A ridge of high pressure at the surface and aloft will stay
anchored across the Lower Great Lakes, Ohio Valley and
Northeastern States through at least Tuesday. This will
continue of dry and unseasonably warm weather to Pennsylvania.


Fog almost gone except for the very deepest valleys of the
north and SWrn Somerset Co. Low clouds are trying to slide in
from BGM`s CWA, but these should get eaten up by the sun and
daytime mixing. Otherwise, the most cu will be found across the
far southern tier near MD. The mixing won`t be very deep as the
subsidence inversion continues to lower. Will keep POPs at

Latest GOES 16 10.3-3.9 UM fog channel shows dendritic valley
fog pattern expanding throughout the NW mtns and Laurel
Highlands attm, while most of the Central Ridge and Valley
Region and Susq Valley is still holding onto a deg F or two
T/Td spread with just some patchy lighter fog. Valley fog in
these latter noted areas will thicken-up throughout the valleys
containing larger rivers and streams between 09-10Z.

The fog will once again be locally dense through 13Z then
dissipate quickly.

Low temperatures around sunrise will vary from the lower-mid 50s
across the northern and western mtns, to the lower-mid 60s in
the southeast metro areas.

07Z run of the RAP shows nil sfc based cape across much of the
CWA later this morning and this afternoon, suggesting that any
cur will be vary flat and sparse at best. Otherwise, expect just
some patches of cirrus/cirrostratus (on the western periphery of
what was once Hurricane Jose) to occur across the eastern half
of the state.

Max temps this afternoon were nudged toward the slightly warmer
NBM and will range from the upper 70s to around 80F across the
Laurel Highlands and Northern Mtns, to the Lower-Mid 80s across
the Middle and Lower Susq Valley.


Ridge holding strong for tonight. Look for areas of fog to form
again in the early morning hours on Friday, followed by almost a
repeat of today (Thursday) cloud, temp, and wind-wise here in
Central PA and surrounding locations.


For this weekend and early next week, the pattern remains
stable as a building ridge continues to stifle any convection.
Weak flow at night should allow for valley fog to form nightly
and to greet morning commuters. The overall consensus in the
models through the weekend is for the 590 dam closed 500 hPa
high will drift slowly out of the midwest states, and become
centered over western PA by late this weekend through early next

Ensemble temperatures are in general consensus and high temps
through the weekend will be 10-15F above normal with little or
no chance of rain until Monday at the very earliest. There are
hints that what was left of Jose could bring moisture and thus
some rainfall through Monday into Tuesday. However there
continues to be model variability so have only chance POPS.

Lows early each morning will be consistently in the mid and
upper 50s across the northern and western mtns, to lower 60s in
the larger SE metro areas.

Min temps may cool off slightly for this weekend thanks to deep
dry air and a light N to NW llvl flow of drier dewpoint air at
the sfc.


VFR has returned to all terminals. Valley fog will redevelop
each overnight for the next 5+ days lingering through 13-14Z
each morning. Some morning fog may briefly impact the higher
elevation terminals (BFD/JST) in the west. Otherwise, VFR should
rule most of the area as high pressure remains stuck overhead.


Sat-Mon...AM valley fog. Otherwise VFR.


Astronomical Fall/Autumnal Equinox begins at 4:02 PM Friday
September 22, 2017.




NEAR TERM...Dangelo/Lambert
SHORT TERM...Ross/Lambert
LONG TERM...Lambert/Gartner
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