Scientific Forecaster Discussion
fxus61 kpbz 051402
Area forecast discussion
National Weather Service Pittsburgh PA
902 am EST Thu Dec 5 2019
snow showers should gradually taper off later this morning as high
pressure builds in the Ohio River valley. A cold front will return
precipitation chances Friday.
Near term /through tonight/...
9am update: regional radar suggests diminishing snow showers in the
ridges this morning in conjunction with an exiting shortwave trough.
Thus, the Winter Weather Advisory has expired.
with an upper-level shortwave exiting into the New England region
and drier air advancing from the southwest, snow showers should
gradually taper off late this morning. Low-level clouds will
gradually mix out this afternoon as northwest flow shifts from the
west. However, mid to high level clouds are expected to filter into
the region as a new disturbance crosses the Great Lakes.
Short term /Friday through Saturday night/...
westerly flow will shift to the southwest early Friday morning, and warm
air will advance into the region ahead of a cold front. With low-
level temperatures near freezing, expected a rain/snow mix with the
frontal passage; areas near I-80 may see snow showers due to residing
cold air. Precipitation accumulation should be light across the Ohio
River valley due to the lack of moisture embedded in this system.
Dry conditions should return Saturday under building high pressure.
Near-neutral temperature advection will maintain below average
temperature given quasi-zonal flow aloft.
Long term /Sunday through Wednesday/...
a new surface low should quickly pass through the Hudson Bay region
Sunday, with high pressure focused over the East Coast. Our region
is synoptically set up for strong warm advection from the southwest.
The temperature is expected to be 10 degrees above the
climatological average Sunday and Monday.
Rain chances should return Monday as shortwave activity increases on
the Van of a deepening Central Plains trough. Much colder conditions
are possible with a strong cold front Tuesday, with widespread rain
ending as snow behind the frontal passage as the upper trough
Aviation /14z Thursday through Monday/...
snow showers will continue to decrease in coverage and intensity
as a shortwave pulls away, but northwest flow will keep some activity going
in the ridges through 14z or so. VFR/MVFR ceilings will dominate,
with brief drops to MVFR visibility still possible near duj and along
the ridges through mid-morning. Wind gusts have subsided in some
cases, but with daytime mixing, gusts of 15 to 25 knots will
High pressure and increasing subsidence will end snow showers by
midday. Ceiling improvements are expected through Thursday
afternoon, and wind gusts will diminish with sunset. VFR conditions
are expected through the night, but low level wind shear may appear
before 12z Friday as southwest wind off the surface increases in a
warm advection pattern.
more restrictions are likely with a Friday disturbance.
Maryland...Winter Weather Advisory until 9 am EST this morning for mdz001.
PA...Winter Weather Advisory until 9 am EST this morning for paz074-076.
WV...Winter Weather Advisory until 9 am EST this morning for wvz510>514.