Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 242341

Area Forecast Discussion
National Weather Service State College PA
741 PM EDT Wed May 24 2017

A storm over the TN valley will deepen and slide over PA on
Thursday and up the New England coast Friday. Rain tonight and
Thursday morning will be followed by scattered showers through
Friday night. Saturday may be the best day of the weekend. The
second half of the Memorial Day weekend looks wet with another
storm system moving through the Great Lakes.


Aside from a few small binovc over the North Central and
Northwest Mountains, skies are solid overcast over central PA
early this evening. Rain is advancing into the Laurel Highlands
on the eastern periphery of a 30 to 35 kt 850 mb jet. The rest
of central PA remains rain free at the moment. Between 00z and
06z...all but the Middle to Upper Susq River Valley should see
rain...with some moderate rates over the Laurel Highlands and
the Lower Susq River Valley in the pre dawn hours.

Will leave out the mention of thunder for tonight, as llvl
remains stable. Forecast precip amounts still on track with the
0.75-1 inch numbers still in the ballpark. The steadiest rain
will be crossing the Mason-Dixon line around sunrise.


The rain will lift up northward through the morning. However,
it looks to stay cloudy for another few hours. The southerly
flow is not all that strong and may not help to scour out the
low clouds very efficiently. Showers may again develop - esp if
there will be breaks develop in the south. These would then
rotate north in the aftn. But, for most folks there will be a
brief break of just cloudy during the morning in the south and
midday central and elsewhere. Again, if the low clouds hang
around too long, the arrival of the upper energy will not line
up with sun/instability. May be able to make some points on
MOS by keeping temps down a notch or two in the south. The sky
cover forecast for Thurs is pretty bleak, so we will hold maxes
below guidance a bit.


The strong upper trough will consolidate low pressure at the
surface over PA producing a rainy Thursday night before lifting
it up the New England coast Friday. Broad cyclonic/northwest
flow with additional shortwaves rotating around the departing
upper low will keep showers in the fcst on Friday before precip
winds down Friday night/AM Saturday.

A lower-amplitude mid level flow pattern in the wake of the
departing closed upper low will feature rising heights/weak
ridging aloft into the weekend. The pattern will evolve into a
broadly cyclonic flow regime by early next week with upper low
spinning between the Great Lakes and Hudson Bay into midweek.

There is still some uncertainty regarding the location and
timing of shortwave impulses that could be a factor for
convection on Saturday. Model and ensemble guidance still
favoring locations to the south/west of Central PA so a dry
start to the holiday weekend may be in store for the area.

Model blend maintains the highest POPs on Sunday with a risk for
thunderstorms as well as a frontal system slides through. Another
round of showers (storms SE) possible for Memorial Day, with sct
showers poss lingering Tue into Wed as the parade of shortwaves
around the trough continues into midweek.



MVFR ceilings have advected into my SWRN terminals in the
strengthening SE flow.

Regional radar shows a growing area of rain racing north out of
the Virginias already affecting my SWRN areas and about to move
into JST. Continuity and the HRRR show the rain continuing to
overspread the region during the evening and into the wee hours
of Thursday. Expect widespread MVFR/IFR to spread northward
with the rain with all terminals seeing conditions lower between
about 03-06Z.

MVFR/IFR conditions will continue into the morning in the south
and perhaps well into the afternoon in the north. Breaks
associated with the dry slot will develop in the south in the
morning as the steady rain pulls away. This will set the stage
for some modest instability to develop leading to the chance
for a thunderstorm in the afternoon.


Fri...Scattered showers with MVFR ceilings, mainly over western

Sat...Mainly VFR with scattered rain showers.

Sun...Reduced conditions with scattered showers/thunderstorms
associated with a cold front.

Mon...Mainly VFR with scattered showers/thunderstorms.




NEAR TERM...Dangelo/DeVoir
SHORT TERM...Dangelo
LONG TERM...RXR/Steinbugl
AVIATION...La Corte is the U.S. government's official web portal to all federal, state and local government web resources and services.