Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
137 am EDT Sat Mar 28 2015
a deep upper level trough will swing east across Pennsylvania
this weekend...bringing unseasonably cold weather. The upper level
flow will become more zonal next week leading to a slow moderation
Near term /until 6 am this morning/...
anomalously cold upper trough delivering deepening cold air this
evening over Ohio Valley and western PA. Increasing low level
cold advection and upslope flow will continue to favor scattered-
numerous snow showers overnight...with an inch or two so falling
across the northwest part of Warren County...and a coating to an
inch elsewhere across the northern and western mountains
Partly-mostly cloudy skies will prevail southeast of the alleghenies with
some flurries and isolated light snow showers. The approach of a
shortwave embedded in the larger scale trough will bring an area
of steeper low-middle level lapse rates and a better chance for snow
showers /even across the central mountains and susq valley/ heading
through the midnight and hour and into Saturday morning.
Lows in the teens and 20s early Saturday will average some 5 to
15 degree below normal.
Short term /6 am this morning through 6 PM Sunday/...
the coldest 850 air will slide through the area for the first
part of Saturday...accompanied by a few-several hour period of snow
showers that will bring an additional light coating /even to some
lower elevations throughout the Central Ridge and valley region/.
Afterward...high pressure building in from the Ohio Valley
bringing brightening skies for the afternoon.
Saturday will be the coldest day we/ll see until later this coming
fall...with highs from only around 20f in the kbfd area...to
between 35-40f in the susq valley. These high temperatures will be 15-18
degrees below normal.
The unseasonably cold temperatures and gusty northwest wind in the late
morning/afternoon hours will feel more like middle winter than early
Spring with wind chills only around 10f across the northwest mountains...and
20s throughout much of the susq River Valley.
Long term /Sunday night through Friday/...
the return of the large scale upper trough will punctuate the
beginning of the extended forecast. Temperatures will begin the
period about 10 to 15 degrees below normal with a few record lows
possible Sunday morning.
As we move toward the end of March...general upper level
troughiness will continue over the eastern Continental U.S. But the axis will
move offshore. This will allow for a relaxation of the low heights
for a time. Although...only enough to bring US back to normal
temperatures by midweek. But this will feel relatively mild.
Because we are still in the effects of the upper
trough...scattered bouts of precipitation are likely through late
week. As temperatures fall near or below freezing over northern
Pennsylvania each night...a diurnal flucuation between daytime
rain to night time rain/snow or snow showers is possible through
Aviation /06z Saturday through Wednesday/...
deep upper level low resulting in deformation snow developing
between unv and ipt as of 1 am.
Made some changes to the tafs based on this...hard to see much
change in conditions until late afternoon today.
As the coastal low pulls away Saturday night...breezy
conditions will prevail.
More less than great weather will work back into the area
by early Monday morning.
Sun...no sig wx/VFR.
Monday...chance of light rain /light snow early/ across the
western half with MVFR reductions. VFR southeast.
Tuesday...chance of light rain across northwest half with MVFR reductions.
Wednesday...mainly VFR...as high pressure builds into the area.
long term...la corte/tyburski