Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
1118 PM EDT sun Aug 2 2015
fair weather will continue into the overnight as high pressure
slides off to our south. A cold front is expected to pass through
on Monday...followed by mainly dry conditions for Tuesday into middle
week. The second half of the week looks wetter as the front to
our south lifts back into Pennsylvania.
Near term /until 6 am Monday morning/...
we have a few thin cirrus bleeding off into northern PA from an mesoscale convective system
dropping through the lower gr lakes. Most of the area will still
enjoy a mainly clear sky as the convection will tend to diminish
as it moves toward the region.
Strengthening pressure gradient ahead of an approaching cfront
will help to keep blyr from completely decoupling and should help
to increase SW winds to around 10-15 miles per hour for the last half of the
The wind will keep temperatures milder tonight...generally in the low-middle
A few showers and perhaps a rumble of thunder could sneak into our
far northwest zones toward daybreak Monday.
Short term /6 am Monday morning through 6 PM Monday/...
Storm Prediction Center day two outlook places all but the extreme southeast part of our County Warning Area
in a slight risk for severe Monday. The afternoon/evening timing
of the cfrontal passage will combine with modest convective available potential energy in the
1000-2000 j/kg range per the latest sref...but more importantly
will have fairly strong...and well-aligned -06 km bulk shear
increasing from 25-35 kts during the midday hours...to 40-50 kts
in vicinity of of the best moisture convergence and mesoscale uvvel close
to the front.
Expect to see one or more broken thunderstorms and rain lines containing enhanced bows
with potential for localized straight-line wind damage as dcapes
should be fairly high and local/S at or above 1km above ground level in most places.
Temperatures will reach near normal values in the u70s to l80s across the
high terrain of the north and west...and in the middle to upper 80s
throughout the Central Ridge and valley region. Readings could
touch 90f in the southeastern half of the area before the storms move
down from the northwest in the latter part of the day.
Long term /Monday night through Sunday/...
a well developed low pressure system will continue to move
through the upper Great Lakes/lower Canada and into the North
East Monday night into Tuesday. This low will drag the before
mentioned cold front through Monday evening into early Tuesday
morning. Expect convection to continue through the first half of
the evening and overnight hours through central and eastern
Pennsylvania. The cold front is currently prognosticated to stall along
the New York border...which could not only allow for cooler
temperatures through the middle and latter half of the week but
the boundary could allow for showers and storms Tuesday afternoon.
The low should continue to drift to the northeast and zonal flow
is expected to follow as a quasi- stationary boundary forms
through Pennsylvania. Current runs of the GFS/ec have moved the
boundary further north so the question remains if it will form
here or will continue to move northward as the event moves closer.
However the low sitting over northeastern Canada will keep
tumultuous weather in the region through the latter half of the
week and into the weekend. The upper level low will finally move
off next weekend which will be a Herald for quieter weather.
Temperatures should average near normal in the first part of the week
before trending cooler later in the week.
Aviation /03z Monday through Friday/...
03/03z update...no significant changes to 00z tafs.
03/00z...VFR conditions are expected overnight and into Monday.
Low confidence in localized fog/br visibility restrictions over the
southeast airspace where the blyr may decouple toward daybreak.
Low level wind shear at bfd 06-12z Monday as 40-50kt southwesterly low level jet precedes cold front
pushing southeast from the Great Lakes. Thunderstorm complex moving southeastward across
central lower Michigan will bring some layered middle-to-high clouds into the
For Monday...the aforementioned cold front will continue to
advance east-southeast downwind of the lower lakes and move through
the airspace during the afternoon/evening hours. Scattered thunderstorms are
expected with the cfropa and a few storms may be strong to
severe...with brief IFR visibility in +ra and highly-localized westerly
surface wind gusts at or above 40kts. Will use -shra with thunderstorms in the vicinity between 18-22z to
show thunderstorm impact risk at all terminals.
Tuesday...VFR. Very isolated p.M. Rain showers possible xtrme northern airspace.
Wednesday...VFR. No sig weather.
Thu-Fri...VFR/MVFR with rain possible as low pressure tracks south of
near term...la corte