Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 231140
Area Forecast Discussion
National Weather Service State College PA
740 AM EDT SAT JUL 23 2016
Pennsylvania will be on the northern edge of the subtropical
ridge into next week. A series of weakening cold fronts will bring
the mention of mainly afternoon or evening showers or thunderstorms
in the forecast, but most of the time it will be fair, very warm
and generally dry.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Mainly clear skies and rather muggy conditions continue across
the region with a generally light westerly breeze, temps in the
l-m 70s, and dewpoints in the 60s. A few, dissipating brief
showers will drift southeast across the endless mtns region of
NEPA over the next hour or so.
lows around sunrise will average around 10 deg above normal for
A relatively weak, sfc cold front extending across Lake Ontario
and Lake Erie at 0730Z will drift SE to near the NY/PA border
by 12-14Z...then sag slowly south of Interstate 80 early this
afternoon...before nearing the Mason/Dixon line this evening.
The timing of this front and notably drier air/lower PWATs behind
it suggest very little or no threat for SHRA across northern
PA...while even locations along and south of it in the 18z Sat-00Z
Sun period will find it very difficult to pop up shows through the
warm mid-level temps (+8-9C at 700 mb) and deep dry air aloft.
The moderately gusty West to WNW flow (in the teens to around 20
kts during the midday and afternoon hours) just in advance and
behind the cfront this afternoon will allow temps to rise to hot
levels once again.
Mid to late afternoon high temps today will range from the mid to
upper 80s across the highest terrain of the north and west...to
the mid and upper 90s in the Lower Susquehanna Valley. Certainly
and unfortunately, no relief for agricultural interests badly in
need of rain.
The high dewpoints in the upper 60s across the Southern Valleys
will lead to Heat Indices in the upper 90s (just shy of Heat
Advisory criteria), while the decreasing dewpoints behind the
front will limit Heat Indices to below 90F across the Northern
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
A ridge of high pressure extending south into the state tonight
and Sunday will bring mainly clear skies and slightly cooler
temps tonight, with lows early Sunday near 60F across the north
and 65-70F over the southern half of the state.
Sunday should feature abundant Sunshine for most or all of the
day...along with very warm to hot temps. 850 mb temps will
actually rebound by 2-3C on Sunday...compared with those on
Saturday. Highs on Sunday will be very similar to Saturday`s.
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Big story in the extended fcst is the expected heat wave lasting
into early in the upcoming week, as the axis of the subtropical
ridge briefly shifts from the plains to the northeast conus.
Anomalous upper lvl ridging building over PA should bring hot and
mainly dry wx this weekend, as warm temps aloft suppress
convection. Next chance of shra/tsra for most of the area comes
Monday ahead of shortwave working across the Great Lakes. However,
any rainfall Monday is likely to do little to stem the dry pattern
we have been in. Latest GEFS mean qpf is up to a half an inch at
12Z ECENS/NAEFS mean 8h temps are near 22C Saturday through
Monday, indicating the potential of several days in a row with
highs in the 90s in the valleys. The hottest temps look to be on
Saturday as latest GEFS gives high temperature anomalies in the
+4 standard deviation and have slightly backed off on Sunday. Have
adjusted Max temperatures accordingly. Heat indices around 100F
appear possible by Mon across the Susq Valley, as higher dewpoints
are advected into the area ahead of potential convection.
Overnight lows are also a concern as the area doesn`t cool off at
night through the weekend with Southern PA lows in the 70s with
highest readings Monday morning. Some modest cooling appears
likely by Tue/Wed of next week behind weak cold front. However,
temps still likely to remain somewhat abv normal within a
generally zonal flow.
Midweek weather looks dry again, with just low pops for isolated
tstms. Fri looks to be the next higher chance for tstm impacts
areawide as another cool front progged to move through.
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Clouds are banking up against the Laurels this morning. This has
brought MVFR to even very briefly IFR conditions. The cigs/bases are
higher elsewhere. But, the residual moisture could linger for
another few hours. Expect VFR for the rest of the period. The wind
will pick up to a decent breeze this afternoon as we mix up to
fl050. There is the smallest chance for a shower or tsra to pop up
into KJST or KLNS this aftn/evening. Will not mention in the TAFs
quite yet. High pressure, subsidence and warm temps aloft will do
their best to quell the instability. Expect more of the same
tonight - fog forming in just a few locations and light wind.
Sunday also looks hot and dusty. Winds should be lighter with sfc
ridge axis right overhead.
MON...Scattered restrictions possible with a cold front bringing
scattered showers and thunderstorms.
TUE-WED...No sig wx.