Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 171924

Area Forecast Discussion
National Weather Service Grand Rapids MI
324 PM EDT Tue Oct 17 2017

Synopsis/Short Term/Long Term/Marine/Hydro

Issued at 305 PM EDT Tue Oct 17 2017

The rest of the week looks quiet with increasing temperatures
especially for Friday and Saturday, with low 70s expected. These
temperatures are 10 to 15 degrees above normal for mid to late
October. Plenty of sunshine is anticipated for much of the week.
The next chance for showers looks to hold off until later Saturday
into Sunday.


.SHORT TERM...(This evening through Thursday night)
Issued at 305 PM EDT Tue Oct 17 2017

Quiet conditions expected in the short term. Medium range model
guidance is indicating an H500 shortwave moving through on
Wednesday which will provide a subtle shift from the SW flow
pattern today and Wednesday to a more westerly flow and slightly
cooler temps advecting in at H850. This translates to a slight
drop in temps on Thursday by a few degrees, especially near and
north of I-96.

In terms of cloud cover, we are expecting a good amount of
sunshine with some intervals of high clouds possible, mainly on
Thursday morning, looking at the GFS H250 RH. Other than this, the
skies will be mostly sunny to completely clear.

Winds on Wednesday will not be as strong as today, at least for
inland locations. Expecting max gusts of 20 to 25 mph with the
highest wind gusts likely across west central Lower MI with H850
LLJ core moving overhead.


.LONG TERM...(Friday through Tuesday)
Issued at 305 PM EDT Tue Oct 17 2017

Three distinct time frames of similar weather in the long term. The
first is a warmer and mainly dry period from Friday through
Saturday. Saturday night through Sunday night should feature a band
of rain showers moving through the Great Lakes region along a cold
frontal passage. Finally Monday into Tuesday will feature cold air
advection and lake effect rain showers at times.

Friday through Saturday looks mainly dry in the southerly warm air
advection ahead of the front. There are some timing differences with
the front with the GFS and the Canadian being faster than the ECMWF.
The ECMWF is about 12 hours slower with the frontal passage. We look
to be 10-15 degrees above normal for highs which will be in the
lower 70s.

Saturday night through Sunday night the band of rain showers will be
working through the area with Saturday night and Sunday being the
periods with the best chances for rain. Sunday will be cooler with
highs in the 60s due to the clouds and precipitation.

Monday into Tuesday we should see lake effect rain showers develop
as Delta T`s over Lake Michigan increase into the upper teens C on
Tuesday. Monday night and Tuesday look to be the best chances for
lake precip as the upper trough will be overhead. Highs by next
Tuesday look to be below normal in the lower 50s.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 144 PM EDT Tue Oct 17 2017

The main weather feature in terms of aviation the next 24 hours
will be the wind. Southwest winds of 15-25 knots are expected
through about 23z, at which time it should diminish to about 5-10
knots. South winds will pick up again on Wednesday morning after
14z to 12-25 knots. Otherwise look for VFR conditions and mainly
clear skies the next 24 hours.


Issued at 305 PM EDT Tue Oct 17 2017

Decided to upgrade the SCA to a Gale Warning on Wednesday from
Whitehall north based on updated wind guidance from high res
models. The timing of the gales will likely hold off until mid to
late afternoon Wednesday for this region. Further south, gales are
not anticipated and will go ahead and extend the SCA through 08z
Thursday to match up the end time of the Gale Warning.
Nevertheless, a rough chop is expected on the lake with 5 to 8
foot waves common into Wednesday and early Thursday morning.


Issued at 305 PM EDT Tue Oct 17 2017

Most of the area rivers have reached their peak from the heavy
rainfall event over the weekend.  The exception is the Kalamazoo
River at New Richmond...which should reach its crest early
Wednesday before returning below bankfull stage early Thursday.

High pressure will continue to dominate the area weather through
Wednesday...with a dry frontal passage expected Thursday.  The next
significant rain event is not expected until later Saturday into
Sunday...when a stronger frontal system moves through the region.
The dry weather will allow area rivers to return to typical flows
for late October.


LM...Small Craft Advisory until 2 PM EDT Wednesday for LMZ848-849.

     Gale Warning from 2 PM Wednesday to 4 AM EDT Thursday for LMZ848-

     Small Craft Advisory until 4 AM EDT Thursday for LMZ844>847.



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