Scientific Forecaster Discussion
fxus61 kpbz 180545 aac
Area forecast discussion...updated
National Weather Service Pittsburgh PA
1245 am EST sun Feb 18 2018
snow will taper off early this morning and temperatures will
moderate during the day. The start of the work week will be
warm and wet.
Near term /through today/...
for the overnight. First, will cancel the advisory near the
Mason-Dixon line, but only in the low lands. Accumulating snow
is over there and temperatures have risen above freezing at most
locations. Next, will have to deal with rather impressive
shortwave trough which will quickly swing through late tonight,
swinging east of the area around 5am. This will keep in the
chance for snow showers across the northern half of the area
through the period. There are some indications that a weak lake
band could develop behind the exiting shortwave as winds swing
around to the northwest. However, inversion levels drop quickly
behind the wave, well below the snow growth zone, and
temperatures aloft are not impressively cold. Will indicate the
threat of the band in the late night pops.
Shortwave will quickly exit the East Coast this morning and
zonal flow aloft will setup behind it. The colder air aloft over
my area will slowly erode this morning, lingering over the
higher elevations until late morning. Will need to keep in pops
in the highest elevation through a portion of the morning
hours, as the risk for orographic snow showers continues.
Clouds will stubbornly hang on over the eastern half of the
area with the slowly exiting cold pool aloft and its
accompanying northwest flow. Clouds will erode from west to
east, but it may take until late in the afternoon for all of the
cloud cover to dissipate over the eastern half of the region.
Temperatures will moderate today.
Short term /tonight through Tuesday/...
continued the idea of slowing the onset of precipitation late
tonight and Monday morning, as the intrusion of upper level lift
is slowed and weakened by some minor ridging aloft. Rain will
overspread the entire area Monday morning, moving northward
along the surface warm front and rising upper level heights.
By Monday evening, most of the area should be well into the warm
sector and upper level heights will continue to slowly increase
Monday night. This will require ME to remove pops for much of
the region Monday evening, with the exception of the far north,
which will lie in close enough proximity to the surface
boundary that a passing shower cannot be ruled out.
By late Monday night, the warm sector will have spread across
the entire region and the upper level ridge will have settled
in, allowing for a dry forecast.
Mainly dry forecast will continue through most of Tuesday with
ridging aloft taking hold. A passing shower is possible across
the north Tuesday morning, as a weak shortwave rides over top
of the ridge, but only chance pops were indicated for this
Temperatures will push well above normal both Monday and
Long term /Tuesday night through Saturday/...
while the GFS and European model (ecmwf) have wavered on the timing for the cold
front passage over the last few days, there is general consensus
that this will happen late Wednesday into Thursday morning.
This will bring the best chance for rain, but also an end to
the very warm temperatures. The front will linger to the
southeast, keeping a chance of showers in the forecast. Even
after the cold front passes, temperatures should still remain
Aviation /06z Sunday through Thursday/...
IFR/MVFR restrictions through most of the morning hours. Snow
and patchy fog will provide visibility restrictions through
dawn. Snow will be mainly from pit and ports northward. By
midday, surface flow backing to the south will push drier air in
and scatter out the cloud deck from south to north. VFR is
expected for the latter part of the current taf period.
Outlook...VFR prevails until Monday afternoon when precip with a
lifting warm front clips the region.
flooding continues on the upper Monongahela, Ohio, and at
Stillwater creek. Precipitation tonight should not pose much of
an issue beyond slowing the fall today. All points are forecast
to be below flood stage tonight.
Maryland...Winter Storm Warning until 4 am EST early this morning for
PA...Winter Weather Advisory until 4 am EST early this morning for
Winter Storm Warning until 4 am EST early this morning for
WV...Winter Storm Warning until 4 am EST early this morning for