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Area forecast discussion 
National Weather Service Cleveland Ohio
920 PM EDT Sat Oct 22 2016

the northwest flow will become southwest overnight as high
pressure builds across the Ohio Valley. Low pressure will slide
quickly across the Great Lakes on Sunday dropping a cold front
across the area Sunday night. Chilly northwest flow will return on
Monday. High pressure will spread across the Great Lakes Tuesday.
The next low pressure system will approach by mid week.


Near term /until 6 am Sunday morning/...
lake effect shower activity has decreased since the last issuance.
A few showers remain over northwest PA. A short wave is evident on
satellite in lower Michigan and is forecast to move across the
forecast area overnight. Despite little shower activity
currently over Michigan, this system may generate More Lake
effect showers for the eastern areas. I will leave a low chance in
this region. A slight adjustment to clouds and probability of precipitation with this
update. Temperatures appear to be on track.

Previous discussion...
the lake effect showers have thinned as subsidence has increased
and not much radar returns remaining outside of the Huron band and
a couple of showers near ytown. A little synoptic upward motion
expected later tonight as warm advection begins. Often the upward
motion can invigorate the lake effect providing the thermodynamic
and wind conditions remain favorable. The NAM and gfs20 model
soundings indicate that that conditions become favorable again on
toward midnight although the surface winds begin to back quickly
early Sunday morning. Will keep a small chance for showers in the
snowbelt this evening and again overnight. Any radar returns
outside of the snowbelt will likely be just a little virga from
patches of mid clouds.

Low temperatures are tricky. With the clouds and breeze the
temperatures will not bottom out. There is a chance that areas south
of Route 30 could see the wind get light enough to decouple and it
may be colder there, perhaps upper 30s. All that being said, could
not really argue with the GFS/mav MOS guidance with most forecast
lows around 40/lower 40s.


Short term /6 am Sunday morning through Monday night/...
fast moving low pressure will slide southeast across the Great
Lakes Sunday and Sunday night. Ridging will dominate across the
Ohio Valley the first part of Sunday and warm advection and a
southwest breeze will pick up, especially across Northwest Ohio
and Lake Erie. Not sure how thick the mid and high clouds will be.
It could be the difference between a nice Sunday morning/early
afternoon versus a kind-of-cloudy day. Will be optimistic given
the lack of clouds upstream at the moment and the ridging. Enough
upward motion will develop across the far northern counties for
showers to develop toward evening, perhaps just as some virga at
first. The southern counties will just see an increase in clouds.
Eventually there will probably be some decent showers across
northeast Ohio and especially northwest PA Sunday evening as a 110
knot jet and short wave dive across the Great Lakes and
frontogenesis increases, all enhanced by the Warm Lake waters.

It will be cold enough for lingering lake effect showers on
Monday in the snowbelt. Not expecting anything significant with
ridging and subsidence increasing. Partly to mostly sunny Northwest
Ohio. Highs Monday in the 50s except upper 40s northwest PA.


Long term /Tuesday through Saturday/...
Tuesday will be cool as winds remain out of the northwest with lake
effect clouds. Highs will range from the upper 40s in northwest
Pennsylvania to mid 50s in Northwest Ohio where mid clouds will be
on the increase.

A series of shortwaves moving through the flow upstream will
consolidate into a fairly potent trough over the Great Lakes region
by Thursday. Southerly flow will ramp up ahead of the system on
Wednesday night and raised mins across the area. Showers are
expected to arrive from the west late Wednesday night and affect
much of the area on Thursday. The 12z European model (ecmwf)/12z Gem are in pretty
good agreement with this system and are a little slower than the 12z
GFS as another piece of energy moves south out of Canada into the
back side of the trough. Leaned the forecast in this direction but
will have to monitor trends heading into next weekend.


Aviation /00z Sunday through Thursday/...
lake effect clouds will continue in the east into early tomorrow
afternoon when 850mb ridge finally builds in from the west.

Outlook...NE Ohio/northwest PA will have non-VFR ceilings Sunday night
into Monday...possibly lingering into Tuesday in scattered rain
showers. Non- VFR possible again on Thursday.


high pressure will slowly expand north and east into the Ohio Valley
tonight. Winds on Lake Erie will decrease on the western basin into
the 15 to 20 knot range and back to westerly. This should allow wave
heights to start to come down and have changed the expiration time
on the Small Craft Advisory west of Vermilion to end at 10 PM. The
Small Craft Advisory will remain in effect through 4 PM Sunday for
the remainder of the lake where winds and waves will be slower to
come down. The advisory on the eastern half of the Lake May have to
be extended all the way through Monday as a clipper slides east
across the lake and pulls another cold front south across the area.
North to northwest winds of 15 to 25 knots will lead to building
waves again late Sunday night into Monday with slow improvement on
Monday night.

High pressure will move across the lake on Tuesday with better
marine conditions. We will be monitoring the track of the next low
pressure system that will move through the central Great Lakes mid-
week and bring another period of strong winds.


Cle watches/warnings/advisories...
Marine...Small Craft Advisory until 4 PM EDT Sunday for lez145>149.


near term...Garnet
short term...kosarik
long term...kec

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