Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
535 PM EST Friday Dec 26 2014
high pressure will keep fair weather over the region through
Saturday. A new frontal system will bring a chance of showers
Saturday night and Sunday. Colder and drier air will continue to
filter into the area next week with temperatures returning back to
seasonal normals...which will feel quite cold considering how warm
it has been recently.
Near term /until 6 am Saturday morning/...
once the thin low overcast started to evaporate and mix out...it
did so very quickly with bright sun being observed over the entire
region as of early afternoon.
With most areas seeing abundant sunshine...temperatures will be
well above average for this time of year as readings range from
the low 40s to low 50s from northwest to southeast.
Skies are expected to remain mainly clear overnight but for some
gradually increasing high clouds late. The only question is if some
fog or low clouds manage to form over the northwest late under the weak
warm advection pattern that will be developing. The NAM is wetter
in the boundary layer than the GFS so I haven't jumped on the
increasing clouds too aggressively.
The clear skies will allow for a good night of radiational
cooling...but even with the long nights and nearly calm
winds...lows will struggle to even fall much below freezing in
some areas of the forecast area.
Short term /6 am Saturday morning through 6 PM Saturday/...
a SW breeze will develop across the area Saturday as the high
recedes and the front approaches from the west. The operational
GFS/NAM both show light precipitation trying to sneak into my northwestern zones
before the day is over...but their ensembles remain dry as does
the European model (ecmwf)...so I opted for the dry forecast.
Skies will slowly cloud up in the afternoon...but it should still
be an overall very fine early winter day with highs ranging from
the middle 40s to middle 50s...some 10 degree or more above average.
Long term /Saturday night through Friday/...
a frontal system will move across the region Saturday night into
Sunday...before sinking south of the County Warning Area late Sunday/early Monday.
Increasing clouds and showers will accompany the frontal
passage...before colder air advects in behind the front.
Uncertainty increases Sun night as some guidance shows a weak S
stream wave riding along the front which could bring a short
period of precipitation to the southeast zones Sun night and early
Monday. With cooling 850 temperatures...a mix of r/S is possible if this
wave does indeed develop and track far enough north.
High pressure will build over the middle of the County by midweek
and slowly drift off the East Coast by the end of the
workweek...bringing an extended period of fair weather to the
forecast area. However...waves of colder air diving down from the
north will help temperatures will return to normal for the last week
Guidance is showing a more organized weather system developing by
next weekend...however there is much uncertainty in the
track given that this system is still over a week out.
Aviation /00z Saturday through Wednesday/...
clear skies rule the region for a change. We will remain VFR into
Saturday as high pressure moves off to our south. It's possible
some low clouds could form later tonight over the northwestern
mountains...but this is a low confidence outcome at this time so
it was left out of the Bradford taf.
The next chance for reduced conditions will be Saturday night
into Sunday as a new frontal system sags slowly south across the
Sat nite-sun...MVFR/IFR with scattered rain or snow showers.
near term...la corte
short term...la corte