Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 272355

Area Forecast Discussion
National Weather Service State College PA
755 PM EDT Mon Mar 27 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.


Early evening GOES-16 visible loop shows the last vestiges of
stratus have been scoured out of the Susq Valley as the surface
warm front lifts north of the region. Partly to mostly sunny
skies in the warm sector have push temperatures into the 60s
over most of the area at 21Z, with low 70s noted over the
south central valleys.

Clouds will return with a renewed chance of showers once again
tonight, as the next wave of low pressure moves into Ohio. Near
term models suggest an arrival time of around midnight across
the southwest counties and after midnight elsewhere. Lows will
be very mild in the 40s to lower 50s.


Latest NAM/GFS show the surface wave taking a track over or just
south of the PA-MD border during the day Tuesday bringing
occasional showers that will taper off from NW to SE during the
afternoon. The guidance once again shows the development of
some instability over southern areas so a thunderstorm cannot
be ruled out. It will likely be subject more to the amount of
sunshine that can develop than dynamic forcing.

It will be another mild day in the 60s in most locations.


The long term period will start with a frontal system and
associated precipitation exiting the region and heights building
aloft. Building high pressure will push the warm moist air off
to our south Tuesday night into Wednesday. Wednesday should be
a relatively nice day (though with some mdt northerly wind gusts
at times, as high pressure builds in from the northwest. The
dry air and high pressure are in all of the most recent
guidance, implying Wednesday and Thursday should be relatively
nice days.

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.


VFR conditions this evening will deteriorate with lowering
ceilings and dropping visibilities as lower atmosphere moistens
rather rapidly tonight on light southeast flow. Approaching
system will bring showers into most areas overnight, with damp
rain/shower activity lasting through Tuesday. This will bring
significant restrictions to flying conditions, with widespread
MVFR to IFR expected.

Cooler, drier air filters in behind the system late Tuesday
night into Wednesday with a slow improvement in conditions.

VFR conditions Thursday, before a large rain-making system
affects the area Thursday Night through Saturday.


Tue...IFR/MVFR across the region in showers/light rain.

Wed...Morning restrictions, gradually improving to VFR most

Thu...VFR/No sig wx.

Thurs Night-Sat...Sub-VFR restrictions/rain likely.




NEAR TERM...Fitzgerald/La Corte
LONG TERM...Lambert/Gartner
AVIATION...Jung/La Corte is the U.S. government's official web portal to all federal, state and local government web resources and services.