Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
127 am EDT Tuesday Jul 29 2014
an unseasonably strong...mid-Summer storm system will move
northeast across New England tonight. Cooler and less humid air
will move in behind the departing storm...with much of the
upcoming week remaining cooler than normal.
Near term /until 8 am this morning/...
skies should stay mostly cloudy to cloudy for the overnight in the
north central mts. Breaks in the deck are already evident in the
11-3.9micron images. Expect the best clearing over the southeast with
downslope flow and also in the SW with considerable drying seen in
the dewpoints and clearing upstream in western PA.
It will feel quite chilly with much of the region expected to
bottom out around 50f or lower for an early morning low temperature. Southeastern
areas will remain in the middle 50s...but it will still be well below
Short term /8 am this morning through 6 PM Wednesday/...
Tuesday will begin a period of minor shortwaves rotating down in
the flow under the anomalously deep/cold upper trough that will
become established over the eastern US. This will mean that we
could see some mainly diurnally driven convection but no
organized precipitation for the most part. Best shortwave of the series
is timed in for Wednesday during the day and Storm Prediction Center see text in new day two
is already highlighting small hail from the showers/storms which
are expected and very slim chance of 1 inch hail from a stronger
cell or two. The 800 mb temperatures do not change considerably between now
and Wednesday aftn/eve...but the strength of the short wave will drive
the stronger showers and better coverage than what should occur on
Tuesday/today. It will remain cooler than normal but should get
slightly warmer each day.
Long term /Wednesday night through Monday/...
the deep trough will linger through the week with individual
impulses moving through the Great Lakes. A weak secondary cold
front is displayed in the guidance for Wednesday which should
help bring about the best chance for overall shower
activity...otherwise daytime heating/instability will likely
represent to most favored times for a few showers through
Then the models show good agreement in retrograding the upper
trough...in the Friday through Sunday timeframe. This allows for a
slight rebound in the western Atlantic ridge and for an increase
in moisture moving up the eastern Seaboard. It will also allow for
a moderation in temperatures with humidity returning to something
more recognizable for the height of Summer.
Aviation /05z Tuesday through Saturday/...
main aviation concern tonight will be the potential of low ceilings
at kbfd and jst...the result of low level moisture ascending the
high terrain of the Allegheny Mountains advection of drier air has
temporarily improved conds at kbfd/kjst with both locations
reporting only a scattered layer around 800ft at 03z. However...modest
radiational cooling and associated moistening of blyr may result in a
return to IFR ceilings later tonight. Latest model soundings suggest the
best chance of low ceilings will occur between 09z-12z. Further
east...downsloping northwest flow should yield better flying conds in the
Ridge/Valley region with occasional MVFR likely at kaoo and kunv. The
lower elevation airfields across the susq valley should remain VFR
Any early low ceilings should mix out shortly after dawn Tuesday. For
the rest of the day...there is a high confidence of VFR conds and
light wind...as high pressure and associated dry air mass builds over the
state. Cold air aloft will produce plenty of afternoon cumulus with ceilings
Wednesday...scattered PM thunderstorms and rain impacts possible...mainly West Mountains
Thursday...am fog possible northwest mountains
Fri-Sat...scattered PM thunderstorms and rain impacts possible.
long term...la corte/steinbugl