Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 280922
Area Forecast Discussion
National Weather Service State College PA
522 AM EDT Tue Mar 28 2017
An area of low pressure will move along or just south of the
Mason-Dixon line late tonight and Tuesday. High pressure will
build down out of southern Canada and bring cooler and drier
weather for Wednesday and Thursday.
A new storm system will approach for the end of this week with
the potential for more inclement weather.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Isolated to scattered showers extend from the Northwest
Mountains eastward to the Pocono Plateau early this morning,
with the most persistent showers located over the Northwest
Mountains in the vicinity of 850-700 frgn forcing. Farther
south...isolated showers and thunderstorms are tracking along
the PA/MD border and more numerous showers upstream will push
into the Laurel Highlands by dawn.
Showers will increase from southwest to northeast today as
wave of low pressure tracks first into southwest PA then
propogates ESE to the Chesapeake Bay region by tonight. A cool,
rainy day appears likely across the Northwest Mountains where
frgn forcing is most persistent throughout the day. This will
keep highs in the mid to upper 50s. Farther south sct to nmrs
showers are expected across the central and south central
portions of the commonwealth. Thin breaks in the overcast will
allow temps to range generally in the lower 60s. Along the
southern tier, readings will range from the upper 60s to perhaps
the low 70s if warm sector manages to lift north of the PA/MD
The guidance still continues to show the development of some
instability over southern areas by afternoon, and have
maintained slgt chc thunder there.
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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Showers will be on the decrease this evening as the low exits
off of the mid Atlantic coast. Slightly cooler and drier air
will overspread the region overnight...but there may be areas of
fog due to the widespread daytime rainfall. Mins will range from
the lower 30s north to the mid 40s south.
Wednesday should be a relatively nice day (though with some mdt
northerly wind gusts at times, as high pressure builds in from
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
The dry air and high pressure are in all of the most recent
guidance, implying Wed ngt and Thursday will remain dry and
High pressure, dry air, and normal to slightly below normal 850
hPa and 925 hPa temperatures imply near normal daytime highs.
Most of the 26/00-06Z U.S. and int`l model guidance (and EFS)
indicates more of southern...shearing storm track for late in
the week...thanks to a stronger and more wwd position of a deep
nrn stream vortex across the Canadian Maritimes.
The trend of the big model discrepancy for late this week and
this weekend (between the GFS and EC over the past several days)
has trended toward the GFS and its ENS members with southern
stream energy and its moisture being prevented from amplifying
with an associated storm track to our west.
Rather, what we see is a shift of the primary southern stream
sfc low track to our south as the potent midweek southern stream
sfc/upper low (that will be trying to take the turn northeast
across the Mid Miss Valley twd the Great Lakes) encounters great
resistance from the notably stronger WNW upper jet core
defining the northern stream that will be situated from the
Upper Glakes to the Mid Atl Coast.
With this type of consensus storm track, pops will be somewhat
less for Friday and Saturday (compared to a heavily weighted
EC/ECENS solution) and limited to mainly the southern half of PA
where some rain (or even an elevation-dependent rain/wet snow
mix) with expansive cooler and drier air north of PA.
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
28/06Z TAFs maintained continuity with lowering cig/vis trend
this morning. Expect coverage of rain showers to increase
through the first half of the period before tapering off from NW
to SE into tonight.
Wed...A.M. restrictions; becoming VFR.
Thu...VFR/No sig wx.
Thu Night-Fri...Sub-VFR restrictions/rain likely.
Sat...Gradually improving conditions.