Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 010828
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
328 AM EST Thu Dec 1 2016

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 329 AM EST Thu Dec 1 2016

The trend toward cooler temperatures continues today. Highs will
mostly be in the upper 30s to near 40. Lake enhanced rain
shower, mixed at times with snow inland of Lake Michigan will
continue through the day. Tonight colder air comes in and most
locations should see some snow overnight. Accumulations will be
less than an inch. The showers of mixed rain and snow will
continue into Saturday before finally coming to an end, if only
for a shore time. The next upstream system may bring some snow to
the area Sunday but another strong central plains storm will surge
in warm air early next week before we finally see the arctic air
that has been over Siberia for over a month reach Michigan in the
Thursday time frame.

&&

.SHORT TERM...(Today through Saturday)
Issued at 329 AM EST Thu Dec 1 2016

Little question about the forecast for the next 48 hours... cloudy
temperatures in the 30s and showers mixed at times with snow
likely becoming all snow (except alone the lake shore) Friday
evening before ending Saturday afternoon.

The deep moisture is in the area through late today, then that
moves out but we remain in surface through 850 mb cyclonic flow
continue into Saturday. The coldest air moves in Friday night into
Saturday. There are two periods of good lift, during the mid
morning of today and overnight as the upper level jet moves across
the area. During those times we will see the greatest
precipitation coverage and intensity. However most of the lift is
below the DGZ so I do not expect much in the way of snow.

All of this moves out by late Saturday afternoon. It will however
remain cloudy.



.LONG TERM...(Saturday night through Wednesday)
Issued at 329 AM EST Thu Dec 1 2016

Surface and upper ridging builds into the area Saturday night,
bringing an end to any lake effect snow showers.  However the break
will be short as another system will be close on it`s heels by mid
day Sunday.  The progressive pattern brings a northern stream short
wave into the Western Great lakes by Sunday with favorable warm
advection ahead of a cold front.  This should bring a period of pcpn
to all of SW MI Sunday afternoon and evening.  The forecast
soundings favor mostly snow, which may mix with rain at times.
Surface temps should be in 35 to 40 so it may be hard for the snow
to accumulate other then on grassy areas.  Seems like an inch or
less will be all we can expect.

Temps should warm further into Monday and Tuesday with another ridge
building over SW MI.  Monday appears dry, but then rain should
arrive on Tuesday.  The models are showing the same theme that the
ridge slides to the east and we develop deep SW flow which brings a
Western Gulf surface low into the Great lakes by Tuesday.  The
consensus shows the low staying to our west allowing us to remain all
rain for this event into Tuesday night.  We should be in between
systems on Wed.

Beyond the long term, into late next week, the next system appears
to bring an arctic surge across the Great Lakes with H8 temps
plunging to around -15C by Thursday night.


&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 112 AM EST Thu Dec 1 2016

A mix of VFR and MVFR ceilings covered the region attm. Expect
this to continue, but gradually becoming more MVFR with time
through the rest of the morning. There could be some patchy IFR
around daybreak, mostly over far Western Lower MI. A few snow
showers will also be scattered about, that may briefly bring
vsbys down to MVFR too.

Little overall change is expected in the ceilings into the
daylight hours, although they should diurnally lift a bit, but
MVFR is largely expected. The snow showers should diminish toward
mid day, although widely scattered showers may linger near the
lakeshore.

Brisk west southwest winds will remain around 10 knots, and
occasionally gust to around 20 knots in the afternoon.


&&

.MARINE...
Issued at 329 AM EST Thu Dec 1 2016

Cyclonic flow with colder air moving on mostly westerly to
northwest winds to keep our Small Craft Advisory going into early
Friday morning. It may have to be extended but at this time
marginal enough not to do (extend the end of the SCA).

&&

.HYDROLOGY...
Issued at 200 PM EST Wed Nov 30 2016

Sycamore Creek at Holt has crested a few inches above bankfull and
is now receding. Maple River at Maple Rapids continues its slow
rise toward bankfull. Only light lake enhanced precipitation is
expected this week, but it will not affect river levels. There
will be chances for more substantial precipitation next week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 4 AM EST Friday for LMZ844>849.

&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...JK
AVIATION...JK
HYDROLOGY...CAS
MARINE...WDM



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