Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 281504
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1104 AM EDT Tue Mar 28 2017

.SYNOPSIS...
An area of low pressure will move along the Mason-Dixon line
through tonight...bringing showers to central PA and isolated
thunderstorms to southeastern sections today. 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/...
Overcast morning with the deepest moisture and most convective
looking rainfall over southeastern PA. Temperatures are mainly
around 50F. Similar to the GOES-16 data, the radar shows a more
light stratiform rainfall over north-central PA and convective
elements in the York-Harrisburg-Lancaster areas. We kept
thunder potential down there.

The HRRR is optimistic the rainfall lifts to our north and east
this afternoon. The low-level (7.3micron) WV shows deep drying
in southwestern PA moving slowly northeast.

So the rain should diminish and temperatures could raise well
into the 50s with some areas topping 60.

Things improve this evening into the next period.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Residual showers in eastern areas 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
the northwest.

&&

.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
pleasant.

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 /15Z TUESDAY THROUGH SATURDAY/...
Considerable areas of MVFR and IFR this morning in rain, mist
and fog. There could be the rumble of thunder in southeastern
areas this morning and early afternoon.

Conditions improve later today after 18Z but slow improvement.
Overnight the trend continues with better weather Wednesday.

Outlook...

Wed...A.M. restrictions; becoming VFR.

Thu...VFR/No sig wx.

Thu Night-Fri...Sub-VFR restrictions/rain likely.

Sat...Gradually improving conditions.

&&

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

&&

$$
SYNOPSIS...DeVoir/Fitzgerald
NEAR TERM...Grumm
SHORT TERM...Grumm/DeVoir
LONG TERM...Lambert/Gartner
AVIATION...Grumm/Steinbugl



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