Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
927 am EST Tuesday Jan 27 2015
light snow and flurries will persist today before high pressure
builds and decreases clouds tonight. A cold Wednesday morning will follow.
Near term /through tonight/...
middle morning update featured further adjustments to probability of precipitation and weather as
light deformation zone snow persists. That zone is projected to
shift eastward as New England low lifts northeastward later today.
Otherwise...dry surface high pressure will build eastward undr north-northwesterly flow aloft
tonight. A clearing sky...light wind...and widespread snow cover will
spprt a temperature significant temperature drop with single digits and around
zero anticipated for much of the area.
Short term /Wednesday through Thursday night/...
continued cold but dry Wednesday into Wednesday night as surface
ridge axis shifts east. Next shortwave and associated low pressure
arrives later Thursday and exits Thursday night. Models track the
surface low along Lake Erie and this will enable warmer air at the
surface to surge north ahead of system. For now continued snow
mixing or changing to rain basically along or south of the
Turnpike with mainly snow north. Much colder air will quickly wrap
back in behind Thursday night to change precipitation to all snow as it
diminishes. No Gulf of Mexico connection for system and with
quick movement any snow accumulations look to be below headline
criteria. Highs Thursday will reach the lower 40s far south to
lower 30s far north in strong warm advection despite snow cover.
Possible there could be a wintry mix at the start of precipitation but
kept things simple for now. Arctic high pressure will begin to
work southeast Thursday night pulling temperatures down into the
upper teens and 20s.
Long term /Friday through Monday/...
cold Arctic high shifts east into Saturday with snow showers in
northwest flow Friday ending Friday night. With 850mb temperatures
prognosticated near -20c by 00z Saturday temperatures Friday will be
steady or fall. Clouds should begin to break as center of high
moves into region Friday night...with lows below zero north and
single digits south. If conditions go clear and calm Friday night
may go below zero across the entire region. Temperatures recover
to mainly the 20s Saturday. A significant storm looks possible for
Sunday into early Monday before Arctic air returns to start the
Aviation /14z Tuesday through Saturday/...
appears a general MVFR forecast is in order through the period.
Large stratocu deck will continue to rotate over the region on
back side of coastal low. Eastern ports could see a redevelopment of
snow showers later this morning and into the afternoon as
shortwave...swinging in from the west...will interact with
Outlook.../Tuesday through Friday/...
the next chance for widespread restrictions is expected on
Thursday and Friday with crossing low pressure.