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Area forecast discussion 
National Weather Service State College PA
652 am EST Sat Feb 13 2016

Synopsis...
polar vortex over S Quebec will rapidly lift NE by late in the
weekend. A deepening upper level trough over the central Continental U.S. Will
spawn a low pressure system...which will likely track northward across
eastern PA on Tuesday.

&&

Near term /until 6 PM this evening/...
Arctic air mass pouring into the region early this morning...accompanied
by gusty northwest winds. Wchills already 10-15 blw across the north mountains at
11z and expect those readings to fall through middle am...as temperatures fall
and winds pick up. Wind Advisory remains in effect across the SC
mountains and susq valley today. However...00z model soundings suggest
gusts will likely fall a bit short of 40kts in most spots.

Today will be the coldest day since last winter. Gefs mean 800 mb
temperatures between -22f and -25f should support high temperatures only around
zero across the northwest mountains...to the middle teens in the southeast.

Radar at 11z showing scattered shsn accompanying arrival of Arctic air
mass across the central mountains arrival of low precipitable water air mass should
cause snow showers to dissipate over northern PA by around 12z...with
only minor additional accums expected the rest of the day across
Warren/McKean cos based on latest model output. Bone dry Arctic air
mass flowing over the lakes will limit snow potential outside of Lake
Huron plume and latest model quantitative precipitation forecast supports this scenario with only
very light additional accums indicated across Warren/McKean cos.
Latest Storm Prediction Center sseo indicates almost no chance of 3 inch amts across the
northwest mountains and ncar mean snowfall today only an inch or less.

Further south...expect snow showers associated with Lake Huron connection
to persist through the day across the Laurel Highlands. Consall quantitative precipitation forecast
and ncar ensemble mean quantitative precipitation forecast support additional accums over The
Laurels today of around an inch.

&&

Short term /6 PM this evening through 6 PM Sunday/...
falling inversion heights upon approach of surface high will cause lake
effect snow showers to dwindle to flurries over the West Mountains tonight.
Any additional accums should be less than an inch. An active northwest
breeze and neutral temperature advection should result in temperatures only
slowly falling tonight. Superblend and 00z ecme MOS indicate min
temperatures from 5-10f blw over the north mountains...to the lower single digits
in the southern valleys.

Dangerous wchills will finally relent by Sunday afternoon...as high
pressure builds over the state...accompanied by mostly sunny skies and light
wind. Still a very cold day with temperatures only reaching the teens.

&&

Long term /Sunday night through Friday/...
*impact weather highlights: potential winter storm early next
week.

Bulk of medium range guidance indicates the likelihood of some light
snow arriving Monday...as surface high drifts off the coast and milder
southerly flow overruns retreating Arctic air mass. However...the
bigger concern involves digging upper trough over the miss valley and
associated surface low pressure lifting up the Appalachians. Model spread
continues to narrow...with most runs tracking surface low across
eastern PA Tuesday. This track would certainly favor rain across
eastern PA and rain or snow across western PA. Given inherent model
uncertainties this far out...will maintain rain/snow in the forecast
for most of central PA Monday night-tues. Have raised probability of precipitation into the
likely category based on converging model solutions.

Will also have to watch for the possibility of flooding across
eastern PA...given rainfall and snowmelt potential. Latest model
ensemble river forecasts using naefs suggests minor flooding is a
possibility across the lower susq valley by Tuesday. Wpc also has
highlighted southeast PA for a slight risk of flooding Tuesday.

Near to above normal temperatures appear likely later next week...as
heights are forecast to rise and a possible low pressure system lifts
through the Great Lakes to the west of PA.

&&

Aviation /12z Saturday through Wednesday/...
Arctic air mass pouring into the region early this morning...
currently accompanied by gusty northwest winds of 15g25kts. Winds will
pick up further during the day...with gusts approaching
40-45kts...before gradually diminishing tonight.

Radar at 11z showing scattered shsn accompanying arrival of Arctic air
mass across western/central mountains arrival of low precipitable water air mass
should cause most of these snow showers to dissipate early in the
day. Snow showers will linger over Warren County /with possible
brief excursions toward kbfd/ with more persistent snow
showers/bands associated with Lake Huron connection to last through the day
across the Laurel Highlands /kjst/. Restrictions will persist over
western higher terrain. But with downslope flow kicking in for
central mountains and southeast...VFR will be the general rule - with just a
chance for some scattered snow bands to creep into portions of the
central mountains late day.

Outlook...

Sun...no sig weather expected.

Monday...widespread restrictions develop with snow developing.

Monday night and Tuesday...snow likely northwest half of Penn...with rain and/or
snow in the southeast. Widespread restrictions continue. Low level wind shear poss southeast.

Wednesday...another wave slides through keeping restrictions in
place along with potential for light snow...especially over the west.

&&

Ctp watches/warnings/advisories...
wind chill warning until 11 am EST Sunday for paz004>006-037-
041-042.
Wind Chill Advisory until 11 am EST Sunday for paz010>012-017-
018-024-033.
Wind Advisory until 5 PM EST this afternoon for paz019-025>028-
034>036-045-046-049>053-056>059-063>066.
Wind Chill Advisory from 5 PM this afternoon to 11 am EST
Sunday for paz019-025>028-034>036-045-046-049>053-056>059-
063>066.
Winter Weather Advisory until 7 PM EST this evening for paz024-
033.

&&

$$
Synopsis...Fitzgerald
near term...Fitzgerald
short term...Fitzgerald
long term...Fitzgerald/gartner
aviation...rxr

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