FXUS61 KCTP 161548

Area Forecast Discussion
National Weather Service State College PA
1148 AM EDT Thu Aug 16 2018


A ridge of high pressure will slide east across Pennsylvania
today. A weak cold front will approach the region later today
and tonight, before pushing through the region on Friday. A
secondary cold front will move across the state Saturday
followed by slightly cooler air with more comfortable humidity
for the second half of the upcoming weekend.



Satellite is showing a gradual increase in mid and high
cloudiness out ahead of a shearing shortwave moving out of the
OH Valley.

The latest HRRR shows showers and scattered showers and
thunderstorms spreading across the NW portion of the CWA
between 21Z-01Z Friday. WPC has a marginal risk for Excessive
Rain late today/tonight across about the NW half of the CWA, but
most of this area has not seen the kind of flooding rains ERN
and SERN areas have seen over recent weeks so as of now we are
not too concerned about flood headlines.

All Hi-Res CAMS and other regional scale models keep the SE
third to half of our CWA dry through most or all of this
afternoon and tonight.

Highs will climb well into the 80s to around 90 in the Susq
Valley, and top out in the mid 80s throughout the Central Ridge
and Valley region.


The axis of high PWAT air and +3 Sigma 850 Moisture Flux slides
across the NW MTNS of PA and the Laurel Highlands during the
early to mid morning hours Friday. The close proximity of this
feature and approach of one or more weak mid/upper short waves
embedded in the SW flow aloft will maintain the occurrence of
rather frequent showers and a some scattered TSRA overnight
tonight, while most of the SE half of PA stays mostly cloudy to
cloudy, but rainfree and muggy.

Expect an uptick in thunderstorm activity Friday afternoon and
evening as a cold front moves eastward from the Great Lakes/Ohio
Valley. With many areas experiencing near record or record
summer rainfall totals, more heavy downpours will pose an
isolated risk of localized flooding. A few storms with locally
strong to damaging wind gusts are also possible especially
along/east of the Susquehanna River, where SPC now has a
Marginal Risk outlook. Saturated ground will make it easier for
gusty storms to topple trees and cause power outages. The text
HWO was updated to account for the isolated flash flood/severe
storm risk.


A trailing frontal wave of low pressure at the surface and aloft
will continue the threat of showers/storms across at least the
southern 1/2 to 1/3 of central PA on Saturday. GEFS and SREF are
display rather light 6-12 hour QPF amounts, while the latest,
00Z EC latches on to a mesoscale feature lifting NE out of the
Lower Ohio River Valley that brings a cluster of heavier
convection to the Western Mtns of PA during the late
morning/early afternoon hours Sat, then over the Central Mtns
and Lower Susq Valley later Sat/Sat evening. Plan to raise pops
to the scattered/low likely category across Central and
Southern PA for now.

Sunday into Monday continues to look mainly dry under the
influence of high pressure and near- below normal precipitable
water airmass. A spotty P.M. shower or t-storm is possible on
Monday over the southern Alleghenies, as return flow brings
increasing moisture back into the area.

Models and ensemble continue to track a mature cyclone through
the Great Lakes early next week. The well-defined trailing cold
front will trigger T-storms as it crosses the Appalachians on
Tuesday. A severe storm and heavy rain/flash flooding risk will
likely accompany the frontal passage before a push of drier air
delivers a possible stretch of rain-free days later next week.



Widespread VFR prevails as of late morning and will continue
into the evening hours. Developing showers and thunderstorms
will begin to enter the airspace after 5PM/21Z with localized
brief reductions at terminals that take a hit from the

Mainly VFR conditions will prevail overnight with the
possibility of patchy fog, especially where it rains.


Fri...Cold front will bring more numerous showers/tstms areawide
with local restrictions.

Sat...Still a chance of showers and storms, mainly across the
south early on.

Sun-Mon...Mainly VFR.



With yesterday's rain, the State College COOP weather station
at PSU has 20.35", which makes it the wettest summer on record.
The old record was 19.83" in 2003.

Williamsport so far has 22.11" of rain making it the 2nd
wettest summer. The wettest was 1972 with 22.33".

Harrisburg so far has 19.43" of rain making it the 3rd wettest
summer. The wettest was 1972 with 23.33".

Altoona so far has 14.99" of rain making it the 7th wettest
summer. The wettest was 1972 with 17.77".

For ease of record keeping, the meteorological summer runs from
June 1st through August 31st.




SYNOPSIS...La Corte/Lambert
NEAR TERM...La Corte/Lambert
SHORT TERM...Fitzgerald/Lambert
LONG TERM...Lambert/Steinbugl
AVIATION...La Corte/Tyburski
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