Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 220039

Area Forecast Discussion
National Weather Service Grand Rapids MI
839 PM EDT Fri Oct 21 2016


Issued at 330 PM EDT Fri Oct 21 2016

A frosty night is expect across much of Southwest Michigan tonight.
Only some areas near the lake shore will escape the frost.  The cool
fall weather will continue into the weekend, but then we will have a
brief warmup on Sunday.

The lake effect rain showers that have occurred along the lake shore
will slowly diminish overnight, with dry weather by daybreak
Saturday.  A weak system will cross the Great Lakes Sunday and areas
north of I-96 may see a few light rain showers in the afternoon,
otherwise it will be a dry weekend.  The next good chance of rain
should hold off until Tuesday night, lingering through Wednesday

After daytime highs of 60 to 65 on Sunday, much of next week should
feature highs in the 50s.


.SHORT TERM...(This evening through Sunday night)
Issued at 330 PM EDT Fri Oct 21 2016

Frost is likely tonight, with some concern about the impacts of the
cloud cover.  The lake effect will continue along the lake shore,
but end or diminish to sprinkles by daybreak Saturday.  Then a short
will move through Sunday evening with a few showers possible ahead
of it.

Frost is of most concern tonight and whether the clouds will allow
for temps in the 30s.  Feel we will see a diurnal min in the cloud
cover shortly after midnight making the chances high to see low to
mid 30s across a large portion of the CWA.  Winds also decouple to
less than 5 mph at this time to allow for frost formation.  It does
appear some of the lake effect clouds will move farther inland just
prior to daybreak, along with a bit more mixing.  So many areas near
and west of U.S. 131 will probably see a min temp around 5 AM, with
a slow temp rise thereafter.  Will word these location as areas of
frost.  Better likelihood of a widespread frost east of U.S. 131 and
north of I-96.

As for the lake effect tonight.  The short wave was passing through
late this afternoon, with slowly falling inversion heights
thereafter.  However it looks like the showers do not completely
diminish until close to daybreak when inversion heights drop below
5K feet.  Can not rule out a wet snow flake will mix in toward
Highway 10.  Flow remains north to north northwest, so POPs only hug
the shore.

Quiet weather for Saturday and Saturday night with surface high
pressure moving across to our south.  The flow will go more westerly
so we will see the band of lake effect clouds move inland and erode
in the morning.  Otherwise expect partly cloudy skies.  A turn in
the winds to the southwest will prevent the region from getting as
cold Saturday night, and other than some patchy frost near Highway
10, there should be no risk.

Added POPs to areas north of I-96 for Sunday afternoon as a short
passes through.  This feature also has a surface low that tracks
near I-96 with light pcpn to it`s north.  Skies clear out late
Sunday night, so again the risk of frost looks to be low.

.LONG TERM...(Monday through Friday)
Issued at 330 PM EDT Fri Oct 21 2016

To start the period...mid level heights will be on the rise as a
ridge approaches from the west.  Overall the flow will be confluent
which should act to result in dry weather.

Models show a shortwave topping the mid level ridge to our west on
Tuesday before digging and dropping into the Great Lakes region on
Wednesday. This system is looking rather dynamic. The GFS is a
little faster with this feature than the High Res Euro...but the
differences are not substantial. Based on the stronger height falls
and deep saturation...rain is forecasted to be on the increase.  It
looks like the instability remains south of the region so no
thunder...although will need to monitor trends here closely.

For now the models height rises trying to move in for the end of the
week...although upstream considerable differences exist across the
upper plains for Friday.  The High Res Euro has a broad mid level
trough dropping out of the Canadian Prairies while the GFS feature a
large ridge over the same region.  As a result...considerable
uncertainty exists toward the end of the forecast period.

Without a deeper and stronger southwest flow...the temperatures will
struggle to go much higher than climatology.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 839 PM EDT Fri Oct 21 2016

Much of the next 24 hours will feature VFR ceilings in the
3500-6000ft range. Lake stratocumulus continues to develop off of
the Great Lakes with a northerly wind tonight that will turn to
the west on Saturday. Some of the clouds today however were
enhanced by heating from the sun, so we do expect clearing away
from Lake Michigan tonight. On Saturday however with the winds
turning west, the lake clouds will overspread the TAF sites once
again. Heating of the day on Saturday will also aid cloud
development. So, the bottom line SCT-BKN ceilings of 3500-6000ft
the next 24 hours. Winds will be under 10 knots tonight into
Saturday morning, but will increase to around 10 knots (from the
West) during Saturday afternoon.


Issued at 330 PM EDT Fri Oct 21 2016

Will keep the headlines going for areas south of Holland tonight.
Waves should finally subside after midnight.  Much of the weekend
looks quieter on the lake with wind speeds mainly 15 knots or less.
We may need a small craft advisory into Sunday night as north winds
increase behind the passing low pressure.


Issued at 1133 AM EDT Fri Oct 21 2016

Recent rainfall did over perform near Jackson on Thursday.
However, it was not by much and hydro response were fairly brief.
All sites remained well within banks and most locations affected
by rainfall are now stabilizing or falling.

The next 5 days includes very little precipitation. It is not
until the middle of next week that Lower Michigan gets into a
wetter pattern. The current forecast plots the heaviest rain well
west of Lake Michigan, which will continue to be reassessed for
any potential changes in coming days.

There are no flooding concerns at this time.


MI...Frost Advisory from 2 AM to 9 AM EDT Saturday for MIZ037-043-050-

     Frost Advisory until 10 AM EDT Saturday for MIZ038>040-044>046-

LM...Small Craft Advisory until 4 AM EDT Saturday for LMZ844-845.



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