Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
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FXUS61 KCTP 300351
Area Forecast Discussion
National Weather Service State College PA
1151 PM EDT FRI JUL 29 2016
An upper level trough will influence the region through early
next week...bringing daily chances of scattered showers and
thunderstorms. Most of the time will be dry in any one location
however. high pressure will build over the northeastern united
states by mid to late next week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Dying cold front pushing into central Pa this evening, producing
enough lift to support isold showers across the central and
southern counties late this evening. Latest CAMS indicate focus
for dwindling convection will shift into the southern counties
late this evening, then die out as blyr cools/stabilizes. Focus
will then shift toward shortwave approaching from the Grt Lks.
Latest guidance supports an increasing chc of showers assoc with
this feature ovr the western counties arnd dawn.
Low tonight mainly in the 60s some warmer spots in southeast and
cooler in northwest.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Most guidance continues to show the plume of high PW air coming
into PA Saturday ahead of approaching shortwave. This favors
an increasing chance of showers and thunderstorms as the day wears
on. The GEFS 0.5 degree data implies the chance of rain increases
rapidly after 11 AM Saturday and keeps climbing. It of course has
a big wet bias in convective cases. The GEFS and all the blends
imply lowest PoPs in northwest and west and higher central to
eastern areas. GEFS is basically showing rain over all of eastern
and central PA by 21Z.
Expect showers and thunderstorms with areas affected by intense
cores to see some better rainfall amounts by late in the day.
Both 12Z SSEO and earlier 00Z NCAR ensemble output supports fairly
widespread rainfall amts of arnd 0.5 inches by 00Z Sunday, with
localized amts ovr 1 inch.
The rainfall peaks in the SREF/GEFS shortly after the CAPE peaks.
This implies mostly convective and CPS is biasing forecasts.
The most intense rainfall is forecast mainly after 21Z and early
overnight Saturday which is mainly in the next forecast period.
Mainly cloudy skies and widespread convection should hold temps
down Saturday to the u70s and l80s. However, humidity will be high
with dwpts likely close to 70F.
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Shortwave moves across PA Saturday night triggering showers and
possibly a thunderstorm. As that passes to the east, there should
be a break and then the main trough moves through with some
scattered convection likely late Sunday and Sunday night. Do not
believe it will be as wet as earlier advertised by models. Diminishing
POPs into Monday as the upper level trough and cyclonic flow
slowly exits off the coast. Big ridge builds over the central US
and moves east to Ohio by Friday. This puts us into a drier
pattern with NW flow. May see something move over the ridge but
then drop to the west and south of PA. Can`t rule out some
afternoon clouds popping and maybe an isolated convective cell
over the higher terrain but that should be it. Temperatures will
start out in the normal range and warm to above normal toward the
end of the week.
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --VFR conditions exist at all airfields, yet there may be some local
restrictions in the widely scattered shower activity that still
lingers over the Lower Susquehanna Valley.
Expect convection to continue to trend downward in coverage
during the overnight...pretty much contained to the same area.
Expecting widespread MVFR conditions to develop overnight in fog,
with some patchy IFR conditions especially where any of the spotty rain
Showers and thunderstorms increase across the region tomorrow.
Model guidance implies restrictions in visibilities for much of
the area during the afteroon tomorrow. Have kept with this
thinking, with visibilities 5 or 6 miles in most areas, and
prevailing SHRA in all TAFs. Included VCTS as will in all TAF
locations beginning between 19z and 21z.
Rain and thunderstorms taper off Saturday overnight, but should
be plenty of fog around with widespread restrictions. Scattered
showers and thunderstorms remain through Monday, then generally
VFR from Tuesday onward, except for patchy fog.
SAT...Morning fog, then SHRA/TSRA with more restrictions during
SUN-MON...Morning fog restrictions, then scattered showers and
TUE-WED...Mainly VFR, but with morning fog restrictions.
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