Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
853 am EDT Tuesday Oct 13 2015
a cold front will bring a brief...1 hour period of light rain
showers to the Susquehanna valley and remainder of eastern PA late
this morning. Behind the cold front...an amplified upper level
trough developing over eastern Canada will dominate the weather
pattern with temperatures averaging below normal through the
Near term /through tonight/...
lead...and fairly weak surface cfront will move across the susq valley
late this morning...accompanied by an approximate 1 hour period
of light-briefly MDT rain showers. Total rainfl should be less
than 0.10 in most places.
Morning clouds should give way to some sun around midday into the
early afternoon as dry slot pushes eastward behind the cold front. This
along with a downsloping/gusty west wind should push maximum temperatures
into the 65-75f range east of the alleghenies. Meanwhile in the
northwest mountains...arrival of Post frontal stratocu will lead to a nearly
steady or flat diurnal curve with highs peaking around 60f.
Tonight should be dominated by a cooler west-northwest flow behind secondary
frontal passage with broken to overcast stratocu continuing to overspread the western
alleghenies into the central mountains lake effect rain showers are
likely across northwest PA although quantitative precipitation forecast amts look to be very light.
Short term /Wednesday through Thursday Night/...
Lake effect rain showers on day 2/Wednesday should dissipate on day
3/Thursday as surface ridging arrives from the Ohio/Tennessee Valley. Temperatures should also
rebound a few degrees on day 3 as the low level flow backs to the west-southwest
ahead of the next shortwave diving southeastward from the upper Midwest.
Timing of this feature remains a forecast issue with some spread in
the model guidance...however it looks like any precipitation would hold off
until after 00z Friday.
Long term /Friday through Monday/...
the late week shortwave trough digs southeastward through the Great Lakes and
Ohio Valley...helping to deepen the upper level trough over the
northeast Continental U.S.. ensemble mean 850 mb temperatures drop between -1 to -2sd
below normal which strongly favors below normal temperatures Friday-
sun...with a good opportunity for potential frost/freeze scenario.
A progressive frontal system with low pressure passing to the north
should move through the area on Friday accompanied by scattered to numerous
rain showers. The Post frontal northwest flow/cold air advection will be stronger and
colder in the wake of this system...with More Lake effect rain
showers impacting the northwest alleghenies...which could mix with snow
based on low level thermal profiles/forecast soundings. Cool Canadian high
pressure builds in from the Midwest later Sunday into Monday which
should result in improving weather conds and gradually moderating
Aviation /13z Tuesday through Saturday/...
showers associated with cold front moving west to east across
the susq valley airfield through 15z. A 2-3 hour period of
lower...mainly MVFR ceilings will accompany the pre-frontal band of
showers...along with brief MVFR visibilities.
Latest model data tracks cold front vicinity kmdt/klns around 17-18z. In
the wake of front...improving conds expected as westerly flow
draws drier air into the region. Model soundings and sref output
support a high confidence forecast of widespread VFR conds between 18z-
Secondary cfront followed by extensive MVFR stratocu and moisture
flowing off Lake Erie could potentially produce will impact the northern
and western mountains of Penn this afternoon right through Wednesday night.
Periods of IFR also possible in showers...in vicinity of kbfd and kjst
beginning tonight as low level winds become west to northwest and
orthoginal to the higher terrain.
Wednesday...periods of low ceilings possible kbfd/kjst...especially early...and
again Wednesday night. Broken-overcast VFR-MVFR ceilings in the central mountains
Thursday...morning IFR-MVFR ceilings possible across the northern and western
mountains...otherwise no sig weather expected.
Friday...cold frontal passage with morning restrictions possible.
Sat...no sig weather expected.