Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
650 PM EST Wednesday Feb 10 2016
snow showers through tonight will gradually diminish Thursday.
Temperatures will continue to fall through the week with bitter
cold to start the weekend.
Near term /through Thursday/...
update early this evening to bump down snow accumulations south of
Pittsburgh and slightly increase amounts to the north where latest
forecasts suggest lake enhanced bands persist longest overnight.
Otherwise not much change needed to the ongoing forecast...or
current advisories. As drier and colder air moves in this
evening...the boundary layer will drop quickly and may be able to
pull advisories south of i80. Previous discussion follows..
Snow showers increasing in coverage across northeast Ohio into northwest
PA as shortwave and wind shift move east across the region. Still
expect better snow accumulation to be this evening with best cold
advection...and as a lake enhanced band attempts to shift south
across the region. Drier air will work in tomorrow but with a
window of mean northwest low level flow some lake bands will
continue north with upslope snow showers into the ridges.
Temperatures generally in line with newer models...and with winds
remaining elevated overnight wind chills in the southeast ridges will
fall to 10 to 15 below zero toward daybreak. Snow amounts are
likely on the high side but little changed from previous numbers.
Short term /Thursday night through Saturday/...
weak high pressure will end snow showers Thursday night with well
below average temperatures. Even colder air will surge south
later Friday as Arctic vortex drops south. Front will cross
region later Friday with a round of snow showers into Friday
night. Bigger story will be wind chills later Friday night through
Saturday 15 to possibly 25 below zero as winds remain up and
temperatures will be in the single digits. Headlines for wind
chills will likely be necessary.
Long term /Saturday night through Wednesday/...
skies should begin to clear out Saturday night as high pressure
builds into the region. Although it is early to sort out effects
of fresh snowpack and just how much radiational cooling will occur
due to clearing skies...models remain in good agreement that
Saturday night will be the coldest night of the winter with
temperatures in many locations below 0f.
Sunday should remain dry before the next system moves in between
Sunday night and Tuesday. Models are not in as good agreement with
this system today as they were yesterday...with some model
guidance now bringing in the system from the southwest instead of
the west-northwest...which would affect both coverage and timing
of any precipitation. Winds may be favorable for some lake effect
snow showers behind the system...with a weak system approaching by
Wednesday. While Sunday and Sunday night will also be
cold...temperatures should begin to approach normal values again
for the work week.
Aviation /00z Thursday through Monday/...
while most terminals are bouncing back and forth between MVFR and
IFR in occasional snow showers...primary focus in the first six
hours is on a heavier snow band currently across the Lake Erie
shoreline that is supposed to move across the region later this
afternoon and evening. The northeast to southwest oriented band
has been moving slower than anticipated by model forecasts...and
the timing in the tafs still could be an hour or two earlier
considering recent trends. Have generally gone with 1 mile
visibility for a few hour window...but potential is definitely
there for visibilities to drop to 1/2 mile or less. Confidence was
not high enough to include that specific mention in 18z tafs. The
band may stay far enough north as to not impact the zzv/mgw
After the band moves through...winds should shift a little more
west-northwest...allowing lake effect snow showers to develop.
Strongest snow showers will be at fkl/duj...with IFR/LIFR
conditions expected. Elsewhere...think that intensity of snow
showers will be light enough and ceilings high enough to keep MVFR
flight categories instead of IFR flight categories. Coverage of
showers should decrease by Thursday morning...although snow will
continue at fkl/duj.
Outlook.../Thursday through Monday/...
occasional restrictions are expected through the period under
cold upper-level troughing. While Thursday and Sunday should be
generally dry...scattered to widespread snow showers are expected
Maryland...Winter Weather Advisory until 7 PM EST Thursday for mdz001.
Ohio...Winter Weather Advisory until 7 am EST Thursday for ohz041.
PA...Winter Weather Advisory until 7 PM EST Thursday for paz007>009-
Winter Weather Advisory until 7 am EST Thursday for paz013-014-
WV...Winter Weather Advisory until 7 PM EST Thursday for wvz510>514.