Area Forecast Discussion
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411
FXUS61 KPBZ 052309
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
609 PM EST Mon Dec 5 2016

.SYNOPSIS...
Low pressure is expected to spread precipitation across the
region Tuesday. A Thursday cold front will return snow shower
chances and much colder temperatures for the end of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
The erosion of low clouds from the south has been evident on
satellite imagery late in the afternoon into the early portion of
the evening hours. This has been coincident with subsidence and a
loss of the northerly component of the low level flow. As the
evening goes on, low clouds will likely further erode all the
while high clouds ahead of the next system to impact the area on
Tuesday arrive from the south. The net result will still be mostly
cloudy skies for many areas through the night, except from
Pittsburgh northward where the slow encroachment of high clouds
may take a tad longer than the erosion of the low clouds later
tonight. Fries

Previous discussion follows for the system that arrives on
Tuesday...As the high exits late tonight, a shortwave and
associated weak surface low is progged to track from the
Mississippi Valley region, reaching the Upper Ohio Valley region
Tuesday. Deep layer moisture, ascent and low level jet support
should result in widespread rain across much of the region.

With southeast upslope flow, cold air is expected to remain
across the higher terrain SE of PIT, where a winter weather
advisory has been issued to highlight a freezing rain threat. With
the low level jet, gusty winds are also expected in the higher
terrain. The cold temperatures should persist until the flow
veers to the southwest Tuesday evening, and precipitation exits.
Areas toward DUJ could also see a wintry mix with some light snow
or ice accumulation possible, though confidence in advisory level
precip in this area is lower. Included an HWO mention for this
potential.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
The shortwave and precip are progged to exit Tuesday night as the
surface low weakens, and coastal development occurs. Ridging
should return dry weather for Wednesday. A cold front is progged
for a Thursday passage, with subsequent upper troughing progged
across much of the eastern CONUS. Maintained high chance to likely
snow shower pops for this scenario. The boundary layer flow should
remain WSW preventing any lake enhancement. Temperatures are
expected to be a few degrees below average Wednesday, with
readings 10 to 15 degrees below average for Thursday.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Upper troughing and cold W-WSW flow should persist across the
eastern CONUS through Friday maintaining snow shower chances. A
less amplified pattern is progged from the weekend through early
next week, with several crossing shortwaves progged. Maintained a
mention of chance pops from Saturday night through early next
week. Much below average temperatures are expected to moderate
with the less amplified pattern by early next week.

&&

.AVIATION /23Z MONDAY THROUGH SATURDAY/...
Building high pressure is expected to alleviate MVFR cigs this
evening and maintain VFR for the night. Condition deterioration
will be quickly Tuesday morning, as low pressure spreads precip
over the region.

.OUTLOOK...
A strong cold front will bring more restrictions by Thursday.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Winter Weather Advisory from 4 AM to 10 PM EST Tuesday FOR
     MDZ001.
OH...None.
PA...Winter Weather Advisory from 4 AM to 10 PM EST Tuesday FOR
     PAZ074-076.
WV...Winter Weather Advisory from 4 AM to 10 PM EST Tuesday FOR
     WVZ512>514.

&&

$$



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