Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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284
FXUS63 KGRR 302027
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
325 PM EST Wed Nov 30 2016

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

.SYNOPSIS...
Issued at 325 PM EST Wed Nov 30 2016

An upper level trough of low pressure will bring cool and
unsettled weather tonight through late this week with extensive
cloud cover and intermittent rain showers. Some wet snow flakes
will mix in late tonight into Thursday morning as well but
there will be no snow accumulations. High pressure will briefly bring
dry weather for Saturday before another system moves in to bring
potential for mixed rain and snow showers for Sunday.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 325 PM EST Wed Nov 30 2016

Primary short term fcst challenges involve determining
probabliities for showers and to assess potential for pcpn type
issues mainly for late tonight into Thursday. The upper
level trough will bring cool and unsettled weather tonight
through Thursday.  Showers will develop this evening as deeper
moisture moves in and showers will increase in coverage overnight.

Brisk southwest flow caa tonight will cause pcpn to become mixed
with some wet snow very late tonight through the early to mid morning
hours Thursday as wbz heights and low level critical thickness values
lower and deeper moisture through the dgz moves in. However only a
couple tenths of an inch of snow will fall mainly east of US-131 and
there will be no snow accumulation overnight. Pcpn type will remain
mainly all liquid form west of 131 due to the modifying affect of
Lake MI.

Seasonably cool and unsettled wx will continue through the day
Thursday with scattered light rain showers. Pcpn type Thursday
will be predominantly liquid form although a few wet snow flakes
may mix in mainly early in the day.

Extensive cloud cover and scattered light rain showers will linger
Thursday night through Friday. The relatively best chc for a few
showers will continue to be near to west of US-131. 12z guidance
consensus time height rh/temp progs indicate an unsaturated dgz
Thursday night through Friday so light rain showers/drizzle will
be the predominant pcpn type.

.LONG TERM...(Saturday through Wednesday)
Issued at 325 PM EST Wed Nov 30 2016

Followed the GFS for guidance in the long term as it has had much
better consistency the last few days. The ECMWF has had issues
handling southern stream energy, namely the upper cut off low moving
across northern Mexico. Temperatures through the long term look to
undergo a slow moderating trend through the period and end up a bit
above normal as we head into next week.

The long term period begins on Saturday with some light lake
generated precipitation ongoing. The moisture depth decreases
quickly though, so precipitation should come to an end as we move
through the day. Expecting a dry Saturday night with ridging moving
through the area.

Sunday a northern stream shortwave will move through the area
bringing some rain and snow to the area. Surface temperatures as
well as 850mb temps would indicate a rain and snow mix with
potentially some light wet snow accumulations possible. Would not
expect more than an inch or so at best.

Ridging takes hold for Sunday night into Monday night with mainly
dry weather expected. The GFS then has a warm air advection event
for Tuesday into Tuesday night when rain will likely be the
predominant precip form.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 119 PM EST Wed Nov 30 2016

A variety of conditions are occurring across Southwest Lower
Michigan at 18z. An area of IFR ceilings has just lifted towards
KLAN and KJXN. Much of the area is seeing clouds fill back in, in
a dry slot with ceilings that are mainly in the 2000-3000ft layer.
This should continue to be the trend of more and more in the way
of MVFR clouds. A much more widespread overcast will then spread
in this evening between 21z and 01z.

The widespread overcast will be MVFR and is associated with colder
air filtering in from the west. The colder air will develop rain
showers off of Lake Michigan. These rain showers may mix with a
bit of snow late tonight into Thursday morning, but did not
include yet as the dominant precip type should be rain. The
outlook for Thursday is more MVFR ceilings with lake effect rain
showers continuing.

&&

.MARINE...
Issued at 325 PM EST Wed Nov 30 2016

A small craft advisory remains in effect from this evening through
early Friday morning. Southwest winds will ramp up to 15 to 25 kts
tonight and cause wave heights to build to 4 to 7 feet. West winds
of 15 to 25 kts will cause wave heights to remain up at around 4
to 7 feet through Thursday as well.

&&

.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 from 7 PM this evening to 4 AM EST Friday
     for LMZ844>849.

&&

$$

SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...Duke
AVIATION...Duke
HYDROLOGY...CAS
MARINE...Laurens



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