Area Forecast Discussion
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FXUS61 KPBZ 100048 AAB
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
748 PM EST Fri Dec 9 2016

.SYNOPSIS...
Cold northwest flow will continue a few bands of snow showers into
Saturday. Low pressure will bring accumulating snow Sunday, mixing
with and changing to rain later Sunday night and Monday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
745pm update...lake snow band continues to shift northward as the
flow in the lower levels has turned to the southwest. By the end
of the evening, expect much of the snow to be just touching the
northern most reaches of Mercer, Venango, and Forest counties.
This alignment of the band is expected through the overnight
period.

Previous discussion follows...
An approaching shortwave later tonight, will again turn the flow
more west to southwest, diminishing lake enhanced snow showers.
There will be a bit of an uptick in snow showers with the
shortwave overnight. Have only raised snow amounts about a half
inch across portions of Mercer and Venango counties mainly this
afternoon and evening. No changes to temperatures, and remainder
of forecast is unchanged.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
High pressure will begin to move east Saturday with flow becoming
westerly as weak shortwave exits. Temperatures will continue well
below average.

Complex low pressure will approach Sunday and move across the
Great Lakes Monday. Warm advection snow will develop across the
region Sunday and continue into Sunday evening, before mixing
briefly with freezing rain and then changing to plain rain except
for areas north of I-80 where cold air will hang in until mid
morning Monday. With surface low so far west, warm air should be
able to move north fairly quickly, keeping snow accumulations in
check for the most part. Best estimate for now is 4-6 inches north
of SR 422 in PA, with only an inch or two across Pittsburgh. Areas
south of Pittsburgh will have little in the way of accumulation.
Some light icing possible mainly in the ridges for a time Sunday
night. Warm advection will push temperatures into the upper 30s to
mid 40s Monday before a cold front drops temperatures back toward
normal in the afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Main feature will be an arctic cold front Tuesday night crossing
east of the ridges early Wednesday. Temperatures will be 15 to 20
degrees below average through late week. While snow showers will
be scattered mainly across the north, no significant snow is
expected.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Broad upper troughing maintain mainly MVFR conditions through
Saturday morning for most ports. Scattered snow showers are also
expected through the evening, though the best chance of local IFR
conditions should be N of I 80 where some lake enhancement should
occur. Gusty W winds should also persist this afternoon with a
tight pressure gradient, before diminishing this evening.
Conditions should improve to VFR by Saturday afternoon as high
pressure briefly builds in.

.OUTLOOK...
Widespread restrictions are likely Sunday and Monday, and again
Wednesday, with crossing areas of low pressure.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...Lake Effect Snow Advisory until midnight EST tonight FOR
     PAZ007.
WV...None.

&&

$$



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