Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
328 PM EST Wednesday Jan 28 2015
high pressure will move off to the southeast of the region
tonight...followed by an Alberta clipper which will cross the
area Thursday and Thursday night. High pressure will return for
late Friday into Saturday. A new storm may bring a round of wintry
weather for later Sunday into Monday...before another surge of
cold air works into the area early next week.
Near term /until 6 am Thursday morning/...
bright middle winter sun has helped temperatures rebound somewhat from the
very chilly early morning readings. Skies will remain basically
clear well into the evening before some increase in high
Have backed off the timing of precipitation into my northwestern zones by early
Thursday based on latest short range operational guidance. The
slow increase in high clouds should help make for another very
cold night with lows generally from 5 to 15 above zero.
Short term /6 am Thursday morning through 6 PM Thursday/...
clouds will thicken quickly Thursday with warm advection precipitation
overspreading the area by late morning or early afternoon. We have
opted for a low end advisory for our western higher elevation
counties for the potential of several inches of snow...with the
possibility of a brief period of freezing rain at the onset.
Models all agree in shoving a wedge of warm air aloft into the
area Thursday morning...but forecast soundings show the column
cooling quickly once precipitation starts so the threat for sig icing
will be pretty small. Thinking is that a general 2-4inch snowfall
is likely over the ridge counties...with a coating to perhaps as
much as 3 inches from central areas eastward before things wind
down Thursday night or Friday.
Highs Thursday will make to the upper 20s to around freezing in
the brisk SW flow ahead of the clipper/Arctic front.
Long term /Thursday night through Wednesday/...
a strong shot of warm air advection aloft and moderately strong upper level
divergence associated with the right entrance region of an
upper level jet maximum across southern Ontario will lead to periods of
light /to briefly MDT snow/ focused across the northwest half of the
state later Thursday after into Thursday night. Some freezing rain
could mix in early...but upward motion offsets the warming.
Forecast temperatures at buf cooler now than yesterday. Thus think most
of our area will stay mainly below 32 on Thursday. Source region
of the airmass is from the plains. It was in the 70s and lower
80s across the Southern Plains yesterday...warm there today too.
Snow will linger into early Friday...as the main cold front drops
southeast. It will be windy on Friday.
Friday night will be cold...as skies clear and winds die down.
A bright day on Sat...but not real warm.
Still have chance probability of precipitation on Sunday. A lot of spread in the model output
the last few days. 12z models backing off some now. Pattern
supports low pressure systems that are fast moving and weak. Would
still expect some light snow into Monday morning.
A cold night Monday night...as the next high builds into
Some hints at another fast moving low for middle week...for now
went with chance probability of precipitation.
Minor changes to the package made.
Aviation /20z Wednesday through Monday/...
high pressure will build in from the west today...bringing
widespread VFR conditions. Northwest winds will diminish this evening as
the high moves overhead and eventually off to our southeast.
Thursday will bring increasing cloudiness with conditions
deteriorating in snow starting around middle day over western
terminals...spreading rapidly east through middle afternoon.
Reduced conditions will continue into early Friday.
Friday...conditions improving during the day...but remaining MVFR
over the higher elevation terminals of the west and north.
Sun...restrictions developing with snow overspreading from the
Winter Weather Advisory from 11 am Thursday to 7 am EST Friday
near term...la corte
short term...la corte