Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 091904

Area Forecast Discussion
National Weather Service Grand Rapids MI
204 PM EST Fri Dec 9 2016


Issued at 320 AM EST Fri Dec 9 2016

Snow is in the forecast every day through next week. Lake effect
snow will continue today mostly west of a Baldwin to Jackson line.
Additional accumulations are expected from Holland southeast through
Battle Creek.

Low pressure moving northeast toward Michigan will bring several
more inches of snow from Saturday night through Sunday night. Behind
the low, a blast of arctic air will move across the state inducing
more lake effect snow. Highs will mainly be in the teens next
Wednesday and Thursday.


Issued at 1100 AM EST Fri Dec 9 2016

Will maintain the headlines as is until expiration at 4 PM today.
All the warning counties continue to get steady, and sometimes
heavy snows. Some areas will see an additional 3 inches of snow
between now and 4 PM.  But portions of the advisory will see very
little snow. For example, Kent County will only see steady snows
in the SW corner, still worthy of maintaining the advisory there.
So will refine the remaining threat areas in the updated WSW.

Otherwise expect a slow diminishing trend to the intensity of the
snow after 18z, however the light snow will continue even beyond
the end of the headline period. But additional accums will stay
less than 2 inches from this evening into early Saturday.


.SHORT TERM...(Today through Sunday)
Issued at 320 AM EST Fri Dec 9 2016

We`re in a snowy pattern for at least another week. Latest radar
loop shows a dominant band extending from Muskegon county southeast
to near Battle Creek. Likely getting inch/hr snow out of this band
which was well forecasted by the 850 mb omega prog showing strong
lift from Allegan county southeast through Calhoun county. This area
of the cwa remains primed for more snow through 18z or so before the
lift begins to diminish. Strong instability over the lake will
continue today with h8 temps near -15c and lake temps in the 40s.
Although the boundary layer moisture decreases a bit, there is
enough that remains in place that the lake effect snow will not end.
Thus we decided to hang onto the headlines.

Moisture ramps up again Saturday as an approaching low moves
northeast toward Lower Michigan. This low will likely provide
another 5-8 inches of snow from Saturday night through Sunday night
over the southern cwa. Impacts over the weekend are typically a bit
less than during the week. After the current headlines end, we`ll
consider new ones based on the latest guidance.

.LONG TERM...(Sunday night through Thursday)
Issued at 320 AM EST Fri Dec 9 2016

Snow will be ongoing Sunday evening, and additional widespread
accumulations are expected Sunday night. The Monday morning commute
will likely be impacted and slower than normal. An arctic front will
bring very cold air to Lower Michigan Tuesday night through the rest
of the long term.

A potent mid-level wave will swing into the Great Lakes Sunday
night, with the 500 mb vort max forecast to track from Minnesota to
Northern Lower MI. The primary surface low is forecast to track
right over the CWA, from the vicinity of southern Lake MI to
southern Lake Huron, 06-12z Monday. The GFS is about 5 mb deeper
with the surface low during this period. But good lift and deep
moisture, including a saturated DGZ, will promote widespread snow.
An additional 2-4 inches of snow is possible from 7 pm Sunday
through Noon Monday.

Midday Monday through late Monday night looks fairly quiet with NVA
in place. Highs on Monday will warm to around 32 F. Light snow
chances increase early Tuesday. Modest moisture depth will exist
with the passage of an arctic front. Frigid air then pours into
Michigan Tuesday night into Wednesday as Canadian high pressure
takes control over the Central U.S. Continuous light lake-effect
snow will be the theme with the arctic air mass in place and the DGZ
in the ground. Expect highs Wednesday and Thursday in the mid teens
to lower 20s. Wednesday morning lows will likely be in the teens,
with single digits to low teens on Thursday morning.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1256 PM EST Fri Dec 9 2016

IFR conditions in lake effect snow band will be from GRR to AZO
this afternoon and periodically affect BTL and JXN. Conditions
will improve this evening to VFR as snow diminishes. Northwest
winds will gust to near 20 knots at times this afternoon.


Issued at 320 AM EST Fri Dec 9 2016

No changes to the marine headlines. The small craft advisory
continues through Friday night.


Issued at 203 PM EST Fri Dec 9 2016

The primary focus will be on river ice development into next week.
At this point it appears conditions will be very conducive to
frazil ice development, and it could occur quickly after the
Arctic front passes through. You need mean daily temperatures to
be 20 degrees or colder to promote an increase in thickness of
river ice. This will occur starting mid week. So, river ice could
form once temperatures plunge and the threat is there for rapid
growth after it initially forms. Near to above normal river flows
are favorable for increased frazil ice development coupled with
Arctic air.


MI...Winter Storm Warning until 4 PM EST this afternoon for MIZ037-

     Winter Weather Advisory until 4 PM EST this afternoon for MIZ039-

LM...Small Craft Advisory until 7 AM EST Saturday for LMZ844>849.



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