Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service State College PA
1038 am EDT Wed Oct 26 2016

a dry and chilly day will be followed by a dose of cold rain
later tonight into Thursday with a wet snow accumulation possible
from the northern alleghenies into the Poconos. Chilly air will
hold its ground through the end of the week with some moderation
in temperatures expected over the weekend and into next week.


Near term /through tonight/...
radar active well to our west with satellite showing thicker
clouds moving into cwa this morning. Cloud cover will continue to
lower and thicken today. Hrrr runs show warm front band of showers
moving into northern half of area close to sunset. Timing not real
favorable for sleet/snow initially but wet bulbs suggest
temperatures will drop fast closest to NY border. This band of
precipitation will exit cwa before midnight with main band of
precipitation arriving after early morning hours. Marginal low level
temperatures near freezing and relatively warm surfaces given
time of year/first snow make for a difficult winter wx fcst with
snowfall somewhat dependent on elevation, rate and type of surface
(grass vs. Pavement) with northern valleys likely having little to
no accumulation. The time of day (overnight- predawn) is most
favorable for early season accums and also most problematic in
terms of impact to the am commute. Secondary roads over the
highest terrain could be slushy for a time with some slick spots.
Therefore, will highlight potential winter wx threats/risk in the
severe weather potential statement for now and allow dayshift to assess possibility of an advy
given the early season aspect and timing impact. The 26/00z ncar
ensemble and Storm Prediction Center sseo both add confidence to winter ptypes with
the ncar more in line with conceptual snow- mix-rain dominant
ptype progression while sseo seems to favor more fzra/ice.


Short term /Thursday through Friday night/...
lingering wintry ptypes should transition to plain rain by later
Thursday morning in the northern tier. Elsewhere, a chilly rain
will expand south/east and continue through the afternoon before
tapering to showers from west to east into Thursday night.
Downstream blocking should allow northern stream energy to phase
with the lead trough and eventually result in a negatively tilted
trough over the northeast U.S. By Friday morning. Models show the
formation of a triple point low deepening along the coast into the
Canadian Maritimes by Saturday morning.

A brisk northwest flow may afford some lake enhancement to shower
activity Thursday night and temps are cold enough to mention
rain/snow showers especially in the orographically favored areas
downwind of Lake Erie. Overall the trend should be toward drier
conditions into Friday. The wind gusts may end up being a little
stronger than forecast on the backside of the intensifying low.

High pressure briefly returns later Friday afternoon/evening
before shifting southeast Friday night into Saturday morning as
low pressure tracks across the upper Great Lakes.


Long term /Saturday through Tuesday/...
models and ensembles generally agree in bringing a weakening cold
front through the area on Saturday and stalling it out near the
PA/Maryland border. Pops are in the chance range mainly over the northwest 1/2
with little in the way of moisture/qpf. The ec/GFS seem to be
trending toward the idea of a wave of low pressure developing to
the west along the wavy boundary and possibly bringing a better
chance for appreciable rainfall /0.25-0.50 inch/ to southern PA on
Sunday. Beyond Sunday, high pressure dominates the pattern
favoring dry weather.

A noticeable rebound in temperatures appears likely on Saturday
with an ensemble blend yielding highs 10-15 degrees warmer than
Friday. Temperatures may fall back on Sunday before moderating
again into early next week as southerly flow develops ahead of low
pressure in the upper Midwest.


Aviation /14z Wednesday through Sunday/...
today will be VFR ahead of a storm system that will be moving
into the lower Great Lakes late in the day. A warm front will lift
north into the area tonight into and Thursday bringing widespread
reduced conditions. The precipitation shouldn't begin until after
06z and begin from the northwest before enveloping the rest of the
state. So expect reduced conditions at bfd to begin around 06z
Thursday and then ipt around 09z, unv, jst and aoo around 12z.
MDT and lns are still questionable if the precipitation gets that
far south, however give the moisture and the flow expecting at
least vicinity showers between 12z to 15z Thursday morning.
Precipitation should continue along the boundary through tomorrow
into Friday. So expect intermittent periods of MVFR to IFR cigs
and visibility possible Thursday.

Outlook... shrasn/low cigs possible west mtns.

Sat...rain showers W/IFR cigs possible north PM. Otherwise no sig wx.

Sun...rain showers W/MVFR cigs north and west. Breezy northwest wind.


Ctp watches/warnings/advisories...


near term...Ross
short term...steinbugl
long term...steinbugl

National Weather Service Glossary of Abbreviations