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Area forecast discussion 
National Weather Service Grand Rapids Michigan
922 PM EST Friday Feb 12 2016

Latest update...

issued at 300 PM EST Friday Feb 12 2016

The passage of an Arctic front this evening will bring southwest
Michigan the coldest weekend of the winter. The snow showers over
areas east of US-131 will come to an end this evening but lake
effect snow showers with considerable blowing and drifting snow
ill continue along Lake Shore tonight. Saturday polar high pressure
heads to the southern Great Lakes. That will end the blowing and
drifting snow along the Lake Shore but snow showers will continue
into the evening. The center of the surface high will pass south
of Michigan Saturday night. Even so skies will clear and that will
bring US the coldest night of the winter. Most locations should
see low below zero.

A storm system moves through the Great Lakes Sunday night into
Monday bringing light snow and milder temperatures to the area.
Yet another system may bring more light snow Tuesday night and
that will be followed by more cold air with lake effect snow
showers. A Big Warm up follows that for following weekend.


issued at 916 PM EST Friday Feb 12 2016

Radar shows moderate to heavy lake effect snow showers falling
west of US-131 along the Lake Shore. Heaviest snow is over
Allegan and Van Buren counties...right where the warning is. The
Winter Weather Advisory for Barry, Kent, Newaygo counties expired
earlier leaving headlings aling the Lake Shore plus Kalamazoo and
lake counties. We/ll leave the rest of the headlines as is. Winds
will continue to decrease a bit overnight which will keep wind
chills out of advisory criteria.


Short term...(this evening through Sunday night)
issued at 300 PM EST Friday Feb 12 2016

I have made no changes to any of our headlines as our going
forecast looks great. We will see the line of snow showers/snow
squalls with the Arctic front cross the area this evening and it
is for that reason I will continue the Winter Weather Advisory for
The Row of counties inland from Lake Michigan. Nearly every
reporting station that has been hit by the line of snow showers
ahead of the Arctic front has seen 1/4sm +sn with gusty winds. The
high resolution models continue to bring this band of snow
showers cross I-96/I-196 around 6 PM and I-94 around 8 PM. Once
this passes the snow showers will end near and east of US-131.

Meanwhile along the Lake Shore...they two will have these snow
shower but for those near US-31 to the Lake Shore... it is only
after the Arctic front that heavy lake effect snow begins.
Inversion height rise to nearly 10000 feet between 00z and 06z and
the dgz is still in the clouds with considerable lift. Also
Theta-E decreases with height to 8000 feet and there is nearly 300
j/kg of most unstable cape along the Lake Shore behind the Arctic
front. All the high resolution models show over a 1/4 inch of quantitative precipitation forecast
from South Haven south tonight. Given all of this I have to
believe we will see a good 4 to 8 inches overnight in the warning
counties near and west of US-31. Those close to US-131 will see
very little after 10 PM. The advisory counties near the Lake
Shore will likely see 2 to 5 inches overnight.

Saturday this all slowly quiets down as surface high pressure
moves toward the area decreasing the pressure gradient and hence
the surface wind. Since the sun is getting stronger now as it is
middle February... we will see surface heating cause the snow
showers to spread inland during the day time hours of Saturday.
Accumulations will be mostly less than a half inch east of US-31.

Saturday night with the high moving across the area we will see a
land breeze set up and that will clear the sky nearly to the Lake
Shore. That will set the stage for the coldest night of winter.
Winds will go near calm and even the winds in the boundary layer
will be less than 10 knots after midnight. A great set-up for
very cold temperatures. I went 5 degrees below MOS across the County Warning Area
for low temperatures.

The next system comes in from the northern stream... it is a warm
advection lift event so we should see light snow across the area
Sunday night. I put likely probability of precipitation across the area after midnight.
This will be a light snow with most areas one to two inches by
sunrise Monday.

Long term...(monday through friday)
issued at 300 PM EST Friday Feb 12 2016

A weak low pressure system will bring a chance of light snow
Monday and a few light snow showers and flurries may linger Tuesday.
Temperatures will average near to slightly above normal Monday and Tuesday
before some colder air moves in for Wednesday and Thursday as a surface
high pressure ridge builds in.

It is noted that a consensus of latest medium range guidance
suggests the Gulf Coast system Monday will strengthen significantly
and track northeast into the middle Atlantic region Tuesday. Precipitation
with this system should stay well southeast of our area across Ohio and
further east.

Temperatures should moderate to above normal by late next week as southerly
flow warm air advection develops on the back side of the departing ridge. There is
potential for a mix of precipitation Friday due to isentropic upglide
north of a warm front that will likely be draped across the Ohio
Valley region by then.


Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 655 PM EST Friday Feb 12 2016

Snow showers will bring isolated IFR and LIFR to all of Southern
Lower Michigan early this evening...then the mostly VFR and MVFR
inland and IFR near the lake for the rest of tonight and into
Saturday afternoon. Northwest winds will be around 15 knots with
gusts over 25 knots at times into Saturday afternoon.


issued at 300 PM EST Friday Feb 12 2016

No changes in the marine headlines. Gales look good behind the
Arctic front into early tonight. With little in the way of ice in
the near shore... freezing spray is assured... and with those sort
of winds and tempters the heavy freezing spray idea looks great.
Again... all of this should slowly improve Saturday afternoon into
Saturday evening as the surface high moves toward the area.


issued at 301 PM EST Friday Feb 12 2016

River gauges through southwest lower Michigan continue to show signs
of being affected by ice build up. It is also evident that the Grand
River at Robinson TWP has a bit more ice flowing downstream than was
the case yesterday. This trend will continue through the weekend up
through at least Tuesday...when we finally see high temperatures
rise slightly above freezing. Long term forecasts suggest we may
even see warmer temperatures for the following weekend.

Fluctuations are still a possibility to make note of through the
short term. Rivers will need to be monitored closely in the event
that thicker ice begins to develop.


GRR watches/warnings/advisories...
Michigan...Winter Storm Warning until 4 PM EST Saturday for miz064-071.

Winter Weather Advisory until 4 PM EST Saturday for miz037-038-

Lm...heavy freezing spray warning until 7 am EST Saturday for

Gale Warning until 7 am EST Saturday for lmz844>849.



short term...wdm
long term...Laurens

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