Area Forecast Discussion
Issued by NWS State College, PA

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453
FXUS61 KCTP 280641
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
141 AM EST Tue Feb 28 2017

.SYNOPSIS...
Return flow around high pressure off the mid-Atlantic coast
will bring milder air into the region through the middle of the
week. Low pressure will move across the Ohio Valley and track
north of Pennsylvania midweek, bringing a rainy period followed
by a potent cold front late Wednesday. Much colder air is in
store for late week, with sub-normal temperatures likely over
the weekend.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
Spinkles moving north of the arewa. Little to no wind around but
clouds abound. There is clearing right along the Mason-Dixon
Line and this might work north a few inches. But, clouds from
earlier upstream convection moving in now. They are higher
clouds, though, and not as likely to re-radiate a significant
portion of the terrestrial longwave radiation. Will therefore
hold forecast temps as is across most of the area, but nudge
them down a hair in the far south.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
Low pressure deepening over the upper midwest Tuesday will push
a warm front into the state bringing showers and perhaps a
thunderstorm or two late day or Tue night. Overall, precip will
be on the light side during this period. Temps on Tuesday will
be another 10F higher than today thanks to the warm advection
and morning sunshine - especially in the south. Readings climb
back into the 50s north/60s south. A very mild night in store
for Tue night as warmer air surges in from the SW ahead of a
potent low pressure system - keeping lows in the 50s most
locales.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Severe thunderstorm risk is the primary focus on Wednesday with
another strong cold front impinging on a convective environment
characterized by unseasonably warm temperatures, above normal
PW, relatively low instability and very strong low-to-mid
tropospheric winds. There is still some uncertainty in the
details such as timing and whether CAPE can be realized due to
preceding clouds/pcpn. Despite depicting clear potential for
strong to severe storms given high shear/low cape scenario,
there is still room for adjustments as models begin to converge
on a consensus solution. The key message is preparation for what
could evolve into another damaging thunderstorm wind event. The
threat and risk information have been communicated through the
HWO and social media/decision support channels with updates
coming tomorrow morning with the Day 2 SPC outlook.

It will turn noticeably colder Wednesday night into Thursday as
strong NWLY post-frontal flow directs colder air into the area.
Widespread 30-35 mph wind gusts are probable with 40+mph gusts
possible on the Laurel ridges. The surge of CAA will bring snow
showers downwind of Lake Erie into the NW Alleghenies/Laurels
with minor accumulations (<1 inch) forecast Wed. night into
Thursday morning.

A broad trough remaining over the Northeast U.S. on Friday will
push off the coast by the beginning of the weekend. A clipper
system associated with the final piece of shortwave energy
embedded in the trough may bring a mix of snow and rain Thursday
night into Friday with a light accumulation possible. The mean
500mb flow is fcst to flatten out a bit over the weekend with
temperatures moderating nicely to above average after bottoming
out on Friday. Overall, the pattern looks fairly quiet over the
weekend and into early next week with another strong frontal
system possible by March 7-8.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Mainly mid level clouds across the region as of midnight.
Some lower clouds at BFD.

06Z TAFS sent.

Earlier discussion below.

Weak shortwave has now weakened and slid off to the northeast.
Showers and patchy drizzle are pretty much over for the night,
as radar showing just minor returns in the northeast...likely
not producing any sensible weather at the surface. All locations
now back to VFR conditions.

As a warm front approaches Tuesday, expect lowering conditions,
with showers moving into the west during the later afternoon.
Some restrictions in ceilings and visibilities are expected
late (after 20z) in the western airfields.

Outlook...

Wed...Rain showers/Sub-VFR reductions. Breezy. LLWS likely.
Chance of thunderstorms.

Wed Night...Strong FROPA early with gusty winds/tstms.

Thu-Fri...Sub-VFR likely west in sct snow showers. NW winds. VFR
elsewhere.

Sat...No sig wx.

&&

.CLIMATE...
With only one more day left in meteorological winter
(Dec+Jan+Feb), it seems that we are currently running as the
4th-warmest winter at both Harrisburg (tie) and Williamsport.
Today should be another above-normal day, which may push
Harrisburg up to 3rd place, and Williamsport may get nudged up
to a tie for or even an outright 3rd place.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Dangelo/RXR
NEAR TERM...Dangelo
SHORT TERM...RXR
LONG TERM...Steinbugl
AVIATION...Jung/Martin
CLIMATE...Dangelo



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