Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
750 PM EDT Sat Mar 28 2015
upper level low pressure will move east of the area tonight. A
ridge of high pressure will slide east across the state Sunday
morning. A cold front and potent upper level disturbance will move
east from the Ohio Valley Sunday night and early
Monday...accompanied by a period of snow and light accumulation
across the northwest half of the state with scattered snow showers
across the southeast. Another disturbance embedded in the
northwest flow aloft...will bring the chance for some more light
snow across the north Tuesday...with a mix of rain and snow
elsewhere. The upper level flow will become more zonal during the
second half of the upcoming week...leading to a slow moderation in
Near term /until 6 am Sunday morning/...
steep boundary layer lapse rates are relaxing this evening with
loss of surface heating. Only scattered flurries left over from
the snow showers that were prevalent across central and eastern PA
Brisk northwest winds persist early this evening...making already cold
air feel much colder...more in line with January than the last
days of March.
Skies clouds will decrease this evening in most areas...but there
could be a few lingering flurries over the northern mountains
extending towards the Pocono plateau. Clearing skies later on
will allow temperatures to plunge into the single numbers over the north
to around 20 over the south. If winds drop off to near
calm...some readings near zero could happen over the far north.
Will have to keep an eye on the potential for some more clouds to
spread into the northwest mountains and laurels tonight as another weak short
wave /over lower mich at this time/ drifts to the east. This would lead to
an upward adjustment to temperatures by several degree f across the western
Short term /6 am Sunday morning through 6 PM Sunday/...
Sunday will be bright and sunny with just some increasing middle and
high clouds later in the day. This sun will help temperatures
rebound after the very cold start to the day. However highs from
the middle 30s to middle 40s...although noticeably milder than
today...will still be several degree below normal.
Long term /Sunday night through Saturday/...
the upper trough will be tough to breakdown this upcoming week as
reinforcing shots of cooler air broing the threat for snow showers
or a rain/snow mix through the first half of the week.
The first system is a cold front that will bring some light rain
or snow showers Sunday night into Monday...followed by a bout of
the all too familiar chilly Post frontal stratocu and mountain
rain or snow showers during the day Monday.
This is followed in quick succession by another shortwave for
Tuesday. The operational GFS/European model (ecmwf) both have an interesting
looking surface low that they take southeast through central or southern
PA along a tight thermal ribbon. The 850 0c line will bisect the
state but expect snow showers during the night time hours with a
rain snow mix or all rain during the day as a result of the April
By midweek...we should see upper heights rebound as the main
trough at least temporarily shifts into the Canadian Maritimes.
However the parent upper low remains over hudson's Bay and even
drops south in time...reinforcing the troughing over the northern US by
Aviation /00z Sunday through Thursday/...
VFR to occasional MVFR conditions across central and eastern Penn taf sites
through the rest of the daylight hours with brief IFR possible in
localized heavier snow showers between through 21z.
More persistent MVFR ceilings and IFR visibilities in frequent snow showers will
continue through late afternoon across the Laurel Highlands in vicinity of
Gradually improving conditions developing from west to east
during the late afternoon/evening hours as high pressure over the
Ohio Valley builds east.
Northwest winds averaging 10-15 kts will continue to gust between 20-25
kts through sunset...before gradually diminishing to under 10 kts
After a more tranquil and noticeably milder day Sunday with
plenty of sunshine...a fast moving clipper and preceding...few-
hour shot of moderately strong warm air advection from the southwest will bring clouds
and a few periods of snow/snow showers for Sunday night. Light
accums of a coating to 1 inch will be focused primarily across the
northern and western mountains...and a few spots across northwestern Penn could see
up to 2 inches by 12z Monday.
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 snow/rain...mainly across the northwest half with
MVFR reductions. VFR southeast.
Wednesday-Thursday morning...mainly VFR...as high pressure builds across the
Thursday afternoon night...a gradually decrease to MVFR with scattered
long term...la corte/tyburski