Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
726 PM EST sun Dec 8 2013
low pressure crossing the Great Lakes region will keep a wintry
mix in the region before changing to all rain late tonight.
Another disturbance will cross the area Tuesday.
Near term /through Monday night/...latest radar imagery shows
limited coverage at the moment across the forecast area...however
..expect to see this fill in over the next hour or so as latest
guidance shows just enough lift in the upper half of saturated low
levels to get precipitation started. The lift is weak and with 00z
sounding data confirming the height of saturated layer now below
temperatures cold enough for ice formation...supercooled droplets
will result in freezing drizzle to be the dominant precipitation
type. Freezing drizzle will transition to a very light rain over
the course of the night from south to north...with this transition
occurring in the Pittsburgh area around 1am to 2am and areas north
of Interstate 80 by middle morning. Even though precipitation amounts
will be light...even trace amounts of ice can result in a glaze of
ice on untreated surfaces. The warning for Preston...Tucker.. and
Garrett counties was also left as is. Although any significant
snowfall is over these locations...they have a higher likelihood
to see more significant icing overnight.
Most areas will see dry conditions by Monday afternoon...with the
exception of the ridges where a fair amount of orographic lift
under west southwest flow will keep chances up through Monday
Short term /Tuesday through Wednesday/...
any lingering freezing rain/fzdz should end Erly Monday morning as surface temperatures
climb above freezing. A cold front will cross the area in the morning through
Erly afternoon...with chances for showers decreasing from west-east through the day. Another
quick moving shortwave will move across the area Tuesday with chances for snow
showers rtng. Trended probability of precipitation up to high chance across especially from pit southward. Lack
of avail moisture will be the main limiting factor with this system. The
shortwave exits Tuesday Night. Lake effect snow showers should develop Tuesday night/Wednesday
but should stay mostly north of the area in wrly flow. After a brief warm
up Monday temperatures will remain well below average through the period.
Long term /Wednesday night through Sunday/...
much colder air will settle in for most of the long term with
temperatures about 10 degrees below average into late week. Only
low chance probability of precipitation included later Saturday into Sunday with an
uncertain storm system in the southern jet stream moving toward the
Aviation /00z Monday through Friday/...
MVFR conditions early this evening will deteriorate to IFR ceilings
and possible IFR visibility overnight. Additional low level moisture
will increase from the south causing very light freezing rain to
develop lasting several hours across the central terminals with
longer prevailing times at kduj before temperatures reach above
freezing and turn precipitation to all rain through early afternoon
Monday. Rising dew points above the freezing threshold and
increasing wind speeds will help cause snow melt...hence keeping
visibilities to around MVFR.
Conditions will gradually improve Monday afternoon as a cold front
crosses the region with MVFR ceilings.
Outlook.../Monday night through Thursday/...
an interruption in VFR conditions might occur Tuesday as a
disturbance moves across the forecast area. Otherwise general VFR
conditions are expected through Thursday.
Maryland...Winter Storm Warning until 6 am EST Monday for mdz001.
Ohio...Winter Weather Advisory until 1 am EST Monday for ohz039>041-
PA...Winter Weather Advisory until 1 am EST Monday for paz020-021-
Winter Weather Advisory until 7 am EST Monday for paz007>009-
Winter Weather Advisory until 6 am EST Monday for paz074-076.
WV...Winter Weather Advisory until 1 am EST Monday for wvz001>004-
Winter Storm Warning until 6 am EST Monday for wvz023-041.