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FXUS61 KCTP 191124
Area Forecast Discussion
National Weather Service State College PA
724 AM EDT Sat Aug 19 2017
A weak cold front will move across the region Saturday
afternoon and evening. Temperatures will stay above normal but
rise even higher each day through Tuesday as a ridge builds
aloft. Another cold front should trigger showers around mid-week
and the week should end on a cooler note.
Skies are mainly clear to partly cloudy and the night time
Microphysics imagery is starting to show some valley fog
forming over middle and upper Susq Valley.
An anomalously vigorous (for mid August) shortwave and
secondary cold front can be seen moving through the lower lakes
tracking eastward. After a sunny start to the day, clouds will
be on the increase with the approach of the shortwave.
Guidance is in good agreement with developing some modest
instability coupled with moderate shear as the trough swings
through this afternoon. Forecast soundings show an inverted V
signature and the RAP displays downdraft CAPEs in the 800-1500J
range over much of the Central and Northern Mountains by early
to mid afternoon. Scattered showers and thunderstorms are
expected to become most numerous in the 18-00Z timeframe and
some of the stronger updrafts could cause locally damaging winds
and perhaps some marginally severe hail. The best chance for
rain will be over the central and northern areas. The latest
HRRR runs are not as aggressive with shower development so I
lowered POPs a bit into the high chance range.
SPC has highlighted the region with a Marginal Risk to cover the
severe storm potential.
Expect convection to diminish in intensity/coverage as it
pushes into eastern Pa during the cooling hours of Saturday
evening. Any lingering showers early will turn into a dry and
much less humid overnight, compared to the last few. While
overnight lows will be near to even a bit above normal, it will
feel much more comfortable with lows in the mid 50s to lower
The quick exit off to the east of the sharp shortwave will lead
to a bright day Sunday with a light breeze and comfortable
The medium range models are all in good agreement on bringing a
renewed surge of heat and humidity into the area to start the
new work week. Highs Monday and Tuesday will be well up into the
80s with some southern locations possibly touching 90 Tuesday.
There`s decent agreement in having a vigorous cold front pass
through the region Tuesday night into early Wednesday. That will
be the best chance for organized precipitation coming up next
week with widespread showers and thunderstorms likely starting
late Tuesday, lasting into the overnight before tapering off as
scattered showers Wednesday.
The remainder of the week into the weekend looks to be cool and
mainly dry as a sprawling high moves slowly eastward out of
southern Canada.
A west wind of about 5 knots at LNS all night, but
fog and low CIGS in and out all night there.
Main change to 12Z package was to add a VCSH group
to the eastern sites late today, given trend of wet
summer and models showing band of showers and storms
holding together this evening.
Still should a decent mid summer day for much of the
time today.
Again, looking at perhaps a shower or storm later this
afternoon into the early evening hours, as a secondary cold
front moves across the region. Potential for some strong
storms, but one will need to keep low level moisture
A nice day on Sunday, with almost no chance of a shower for
a change.
Sun-Mon...Mainly VFR, but restrictions in morning fog.
Tue-Wed...SHRA/TSRA poss.
NEAR TERM...La Corte
LONG TERM...La Corte

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