Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
728 PM EDT Tuesday Sep 1 2015
hot and humid weather will continue the recent Summer encore in
central Pennsylvania as the calendar flips to September 2015. The
precipitation pattern should be a mainly dry one with very
isolated showers and thunderstorms possible through the end of the
Near term /until 6 am Wednesday morning/...
cumulus already showing signs of thinning as we mix deeper and
incorporate drier air aloft under the suppressive upper ridging.
See no reason to add to probability of precipitation for the near term...as very mesoscale guidance
shows total loss of instability and almost all clouds before
Short term /6 am Wednesday morning through 6 PM Wednesday/...
ridging stays in place overnight and Wednesday. Mins tonight
will incorporate a healthy dose of persistence. Expect them to be
within a degree or two of Tuesday am mins. The fog will also be present
in the valleys...but the widespread stratus in the north is not as
likely to recur. There is a tiny depression in the otherwise
massive upper level ridge. The depression is currently associated
with a cluster of storms over central in. This depression should
move eastward through the upper Ohio Valley and into the middle Atlantic.
But that feature makes only a small dip in middle-level temperatures and tiny
decrease in stability on Wednesday. This may be enough to allow scattered
rain showers/thunderstorms and rain to develop in the afternoon over the higher terrain...mainly
The Laurels and northern mountains the 30-40 probability of precipitation in the mountains will probably
be the highest probability of precipitation we draw for quite a few days.
Long term /Wednesday night through Tuesday/...
an anomalous upper level ridge is forecast to dominate the large
scale pattern over the northeastern Continental U.S. Into early next
week...with high pressure taking control at the surface. This pattern
will continue to support above-normal temperatures and very
limited to no rainfall across central PA through the Labor Day
The GFS remains more bullish vs. The European model (ecmwf) with convection on
Friday. High pressure initially centered over Quebec will drop southward
over the weekend and bring slightly cooler and drier/less humid air
into the region. No risk of rain again until probably next
Tuesday as a cold front approaches from the Great Lakes/Ohio Valley.
Aviation /00z Wednesday through Sunday/...
A hazy warm and humid late Summer evening is under way over the
flying area. VFR conditions will give way to developing
restrictions from late evening through the early morning hours of
Wednesday as patchy valley fog forms once again.
More clear nights with am valley fog and mostly sunny days are
expected for the next several days.
Thu-sun...patchy am fog poss...mainly kipt/kbfd. Otherwise VFR.
preliminary data indicates Harrisburg and Williamsport recorded
near-normal temperatures and precipitation for the month of
August. More details can be found in the monthly climate
summaries. Seasonal summaries will be available this evening.