Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 310249
Area Forecast Discussion
National Weather Service State College PA
1049 PM EDT SAT JUL 30 2016
A plume of deep moisture on the west side of the subtropical ridge
will produce showers and thunderstorms over the region into early
Sunday. A weak trough will push the deep moisture to our east
Sunday. Behind this system it will slowly dry out. A ridge
building to our west early next week will work its way eastward
producing some hot weather later in the week. This surge of warm
air appears to be just ahead of what could be a real cold front
and a real break from the warm weather we have had for the past
.NEAR TERM /UNTIL 8 AM SUNDAY MORNING/...
a broken line of weakening showers and isolated storms is
propogating south of the Laurel Highlands late this evening. the
northern portion of this line will brush the Laurels over the next
few hours. Scattered showers with isolated thunder will lift to
the upper Susquehanna through midnight. Expect only isolated
additional shra/tsra overnight...with the exception of the
northwest where greater coverage should break out in the pre dawn
hours as another shortwave lifts towards the GLAKS from the Ohio
Valley. Current cells over far northwest Pa are backbuilding...and
that could be the case overnight as well.
Areas of fog should be widespread overnight...with many areas
seeing vsbys below one mile thanks to plentiful residual llvl
moisture from afternoon/evening rainfall.
.SHORT TERM /8 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Sunday will feature more of the same...with a bit less coverage
the diminished deep layer moisture as the 2" PW plume will have
been displaced off of the eastern seaboard. This will allow temps
to warm several degrees higher than today`s...which will spark
another round of afternoon and evening shra and tsra.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Short-waves sweeps to the coast but broad upper level trough
lingering across PA. The main trough axis lies through Central PA
by 12z Monday and slowly progresses east through the day. With
the trough and cyclonic flow aloft scattered showers/isolated
thunderstorms are possible with best chances over the eastern
counties in the afternoon. High pressure builds in Monday night
and everything begins drying out. For Tuesday into Wednesday a sharp
upper level ridge is to our west over the Great Lake region with
the trough now off the coast, dry NW flow and surface high
pressure across the region.
Short-wave weakens the ridge into Thursday. ECMWF takes this south
across Ohio into VA leaving PA dry. GFS is weaker and further
north with some convection over the PA mountains which it moves
east across PA through Thursday night. Stayed closer to the ECMWF
solution with no POPs at this point. Both models agree on a more
rigorous cold front dropping southeast toward PA on Friday. This
will help surge the temperatures and humidity up ahead of it over
central PA Friday. Right now the timing is such that late day
convective storms will feed off the days heat and humidity and
roll through late in the day into the overnight. Models bring the
cold front southeast across PA overnight and then stall it near
the Mason-Dixon Line for Saturday.
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Rain tapering off to sct showers late this evening as upper lvl
disturbance shifts east of the area. Partial clearing, combined
with wet ground and light wind, will promote areas of fog/low cigs
overnight. Blend of latest mdl guidance supports the idea of
fairly widespread IFR/LIFR conds overnight with onset btwn 02Z-06Z
based on latest LAMP guidance and NCAR ensemble.
Mdl soundings indicate fog/low cigs will lift by late am, with widespread
VFR likely by aftn. Sct shra/tsra are likely form during the aftn,
which could produce a brief vis reduction in spots thru early
MON...Am fog possible, then isold pm tsra impacts possible.
TUE...Am fog possible.
WED...No sig wx expected.
THU...Isold pm tsra impacts possible western Pa.