Area Forecast Discussion

FXUS63 KGRR 110828
Area Forecast Discussion
National Weather Service Grand Rapids MI
328 AM EST Mon Dec 11 2017
Synopsis/Short Term/Long Term/Marine
Issued at 328 AM EST Mon Dec 11 2017
A low pressure system will track south southeast from Northwest
Minnesota early this morning to near Chicago by late this 
afternoon. That will bring snow to the area today into this 
evening. Tonight and arctic front comes through bringing in the 
coldest air of the season with very strong winds. Heavy lake 
effect snow squalls are expected near the Lake Michigan shore 
tonight into Wednesday morning. Travel in that area will be 
challenging Tuesday. Outside of that expect snow showers and highs
only in the lower 20s. We get a break between systems Wednesday 
but by late Wednesday the next system will bring more snow to the 
area into Thursday. 
.SHORT TERM...(Today through Tuesday Night)
Issued at 328 AM EST Mon Dec 11 2017
I have decided (in coordination with our Gaylord and North Webster
offices) to issue a Winter Storm Warning for all of our lake shore
counties for tonight through Tuesday into Wednesday morning. This
is a dangerous situation as there will be heavy snow squalls from
with winds will be gusting to over 40 mph resulting in near zero 
visibilities in the heavier snow bands. 
We have a clipper type low tracking south southeast toward
Chicago for late this afternoon. That will keep all of our CWA in
the snow from the warm advection / isentropic lift part of the 
event. This will bring two periods of snow. The first one is the 
warm advection part of the event, which will last only about 3 
hours in any one place. It will for the most part occur from 
around 8 am near Muskegon end by Jackson by 1 pm. That should be a
1 to 2 inch snowfall event. The second part of this is the 
deformation zone snow band that from most of the high resolution 
models (for several runs in a row) to occur near I-94 from around 
4-5 pm till around 9 pm. This will have heavier snow with it, more
like 2 to 3 inches. I considered an advisory for this event but 
the event tonight into Wednesday morning seems to this forecast to
be a much more significant event so to keep the headlines simple 
I only have headlines for the Lake Effect event tonight into 
Wednesday morning. 
With the coldest air of the season crossing water that is still
over 40 degrees, and 850 temperature near zero, that is by far and
away a very unstable setup. Bufkit time sections show strong lift
in the DGZ from around midnight tonight till around early
Wednesday morning. The inversion heights are near 10000 ft. Given
there is 40 knots in the mixed layer for wind gusts, this seems
like an event that would need a warning. 
I put an advisory for the counties next to the warning area as
there will be some snow squalls that get into those counties. The
inland counties near route 10 will have a Lake Superior connection
and some upslope to help the cause.
Inland of all that it will just be windy and cold Tuesday into
Tuesday night.
.LONG TERM...(Wednesday through Sunday)
Issued at 328 AM EST Mon Dec 11 2017
More cold air and intervals of snow showers will continue through 
the end of the work week. We will then see a decent shot at a period 
of milder weather for next weekend, with a mix of pcpn types 
Snow showers will be trending down a bit by Wed after the decent 
lake effect event expected for Mon night into Tue night. The chance 
of snow will remain on Wed however, especially for Western and 
Southern areas. This is the result of the next short wave rounding 
the long wave trough. This wave is expected to dive mostly south of 
the area. It could clip the Western and Southern portion of the area 
with some light snow. The track of the low will produce an offshore 
flow, so the lake should not be much of a factor.
Lake effect will ramp up a bit on Thu in the wake of the Wed system. 
Colder air on the order of around -14- to -16C will pour in over the 
relatively warmer waters of Lake Michigan. The flow will be W/SW as 
another system will be approaching the area with the low north of 
the CWFA. A slight moderation in temps will occur on Fri with the 
low level SW flow.
A better moderation in temps is still expected next weekend with 
chcs of rain/snow. The long wave trough that has been sitting over 
the region over the last week will get pushed out with the strong 
wrn ridge getting beat down some by a strong Pacific Jet. The 
transition will bring more chcs of pcpn. These will gradually shift 
North as the jet flattens out a bit, and the systems are a bit 
further North. 
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1247 AM EST Mon Dec 11 2017
This forecast will be an unsettled period with a couple of periods
of impactful conditions with snow, lower conditions, and
eventually wind.
Conditions are relatively tranquil to start out the period. All
sites have seen cigs lift above 3k ft for VFR conditions. This
will continue likely through 12z.
A narrow band of snow will then approach from the West after 13z.
This will likely only impact each of the terminals for 2-3 hrs.
When it does come through, IFR will be likely for a short period
in vsbys and cigs. This will move East then, and a lull in the
activity can be expected with only light pcpn.
We then expect a band of convective snow to develop across the
area, especially along I-96 after about 20-21z from West to East.
The biggest impacts will be near the I-96 corridor where LIFR/ 
VLIFR will be likely under the band. The I-94 terminals will see 
some snow, but it will likely not be as intense as up North. This 
will last almost through the end of the period as the low moves 
by. When the snow lightens up, winds will increase with gusts over
20 knots toward the end of the period. 
Issued at 328 AM EST Mon Dec 11 2017
With 45 knots in the mixed layer it made sense to just go ahead
with the Gale Warning for tonight into Tuesday night. 
Issued at 1000 AM EST Sun Dec 10 2017
Rivers are running near normal levels to a little above normal. No 
flooding or significant rises in river levels are expected. Snow is 
forecast periodically through the week.
Temperatures have been near to below freezing since last Tuesday 
night and similar temperatures are expected to persist through the 
end of this week. This should allow ice to begin forming on area 
rivers, especially on the Muskegon River in Central Lower
MI...Winter Storm Warning from 10 PM this evening to 7 AM EST 
     Wednesday for MIZ037-043-050-056-064-071.
     Winter Weather Advisory from 10 PM this evening to 7 AM EST 
     Wednesday for MIZ038-039-044-057-065-072.
LM...Gale Warning from 7 PM this evening to 7 PM EST Tuesday for