Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 221429

Area Forecast Discussion
National Weather Service State College PA
1029 AM EDT Sat Jul 22 2017

A quasi-stationary frontal boundary will remain in the vicinity
of Pennsylvania through Monday. High pressure will build
southeast into the region for the middle of next week.


MCS approaching CWA. Strongest core will move south of CWA
though will see a quick hitting line of storms for southern
zones in next couple hours. Behind this expect more storms to
develop across the area. Where the strongest storms develop is
uncertain and each run of the HRRR shifts the location of the
storms to different spots across the central and southern CWA.
Further north thunderstorms are also possible though likely not
severe. Current forecast has this well covered and will make
only minor changes. FFG numbers indicates some pockets of wetter
ground across central Pa, which could be susceptible to
flooding today. NCAR ensemble indicates the possibility of
localized amounts in excess of 3 inches possible across the
central and south central mountains by this evening. At this
point, while a flash flooding is possible in the strongest
storms, will not issue a FF watch.


A second round of strong to severe convection is possible across
the southern half of the forecast area this evening, as strong
low level jet and plume of anomalous PWATs works through the
area. Bulk of model data then indicates a dwindling chance of
showers/storms from north to south overnight.

Favorable scenario for additional severe weather across central
Pa Sunday afternoon, as the region will be within warm sector
south of anomalous surface low tracking eastward along the PA/NY
border. Moderate CAPES and moderate westerly flow aloft,
combined with large scale forcing ahead of approaching upper
trough, should support widespread convection by afternoon.


Some uncertainty continues with regards to timing of upper
trough passage early next week, but additional showers/storms
appear likely Monday, especially over northern Pa. A period of
dry and cooler weather appears very likely by midweek, as upper
trough axis finally passes east of Pa and surface high builds
into the area.


Approaching warm frontal boundary which will be the catalyst
for shower and thunderstorm development around midday in the
west spreading eastward in the afternoon. Thunderstorm activity
will be most numerous south of I-80 with intermittent
restrictions expected into early evening

Thunderstorm coverage will diminish but convection will linger
over the SE into the overnight. In addition, restrictions will
develop over NW half of area.

Another round of convection driven by an upper trough will
begin to move into western areas around sunrise Sun, which will
spread across central PA during the day bringing another period
of intermittent restrictions.


Sun...AM restrictions likely NW half. TSRA/SHRA likely with
intermittent impacts.

Sun night...Cig restrictions likely. Scattered TSRA/SHRA.

Mon...AM restrictions likely. Scattered TSRA.

Tue-Wed...Patchy AM fog. Otherwise no sig wx.




NEAR TERM...Ross/Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Fitzgerald/Gartner
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