Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 162355
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
755 PM EDT Mon Jul 16 2018

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Mon Jul 16 2018

A cold front will continue to progress south through the Lower
Peninsula this afternoon exiting the state towards midnight. A
noticeably cooler and less humid air mass will push into the state on
north winds. Dew points in the 50s on Tuesday and in some cases the
40s on Wednesday will feel very comfortable by mid summer standards.
A few showers and storms this evening will come to an end as the
front exits the area. Dry weather is then forecast from overnight
into Thursday night. High pressure will be centered right over the
state on Wednesday. A more widespread rain is forecast for Friday
through Sunday as an upper low moves through the Great Lakes.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 330 PM EDT Mon Jul 16 2018

The main weather in the short term occurs this evening and is
associated with the passage of a cold front. The front is situated
from near Saginaw Bay to near Holland at 300pm. Showers and storms
are occurring both in the warm sector ahead of the front and along
the front itself. A surge of stabilizing air off Lake Michigan has
ended the precipitation threat for areas west of U.S. Highway 131.
The surge off the lake is also weakening convergence along the
boundary. The bottom line is we will see scattered showers and
storms in the eastern half of the forecast area for another 2-4
hours with the precipitation ending after that time frame. Cooler
and drier air will surge in from the north overnight.

The remainder of the short term looks dry from Tuesday through
Wednesday night as high pressure settles in from the northwest.
Skies are expected to be mainly clear for Tuesday into Wednesday.

.LONG TERM...(Thursday through Monday)
Issued at 330 PM EDT Mon Jul 16 2018

The long term continues to look more active as an upper low drifts
into the Great Lakes from the Northern Plains. Chances for showers
and thunderstorms will develop Thursday night with the best chances
on Friday and Saturday. There are still differences in temps of
depth and position of the low between the operational ECMWF and GFS.
Will not try to differentiate between the two at this point and
stick with the message of a more widespread rain occurring in the
low term. Short wave ridging tries to push in for Monday which
should bring drier weather. Highs in the long term look to be near
to slightly below normal.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 755 PM EDT Mon Jul 16 2018

Confidence is high that VFR weather will prevail tonight and
Tuesday as a drier air mass settles into the region. Northwest
sfc winds of 10 to 20 kts early this evening will diminish to
less than 10 kts after sunset but increase again to 10 to 20 kts
by Noon Tuesday.

&&

.MARINE...
Issued at 330 PM EDT Mon Jul 16 2018

Winds will begin to increase tonight in a north flow behind the cold
front. Winds are expected to increase to 15-25 knots tonight which
will build waves into the 3 to 5 foot range south of Grand Haven.
There is a lull expected in the winds/waves Tuesday morning before
increasing once again Tuesday afternoon and evening. We have opted
to issue a Small Craft Advisory and Beach Hazards Statement from 06z
tonight through 06z Tuesday night. Waves on Tuesday afternoon and
evening will work there way down the shore as the stronger north
winds funnel down the coast. Given winds at 1000ft of 22-24 knots in
the South Haven Bufkit data, there may be some waves that reach the
6 foot mark at the buoys. The NAMnest is the model that usually
depicts the wind fields in these events the best. Fairly flat
conditions are expected on Lake Michigan for Wednesday as Thursday
with high pressure situated across the area.


&&

.FIRE WEATHER...
Issued at 330 PM EDT Mon Jul 16 2018

Scattered heavy rain occurred yesterday, with a few locations
receiving 3+ inch amounts. That type of rain was very localized
though. Today, much of the same is occurring with some areas having
seen zero rainfall. Locations along the lakeshore north of Saugatuck
and many areas along Interstate 96 have seen little to no rain. Fire
danger remains high in most areas. The cold front and showers and
storms associated with it will move southeast out of the area this
evening. Dry weather is forecast from tonight into Thursday night
behind the front as high pressure settles into the area. So, areas
that have remained dry will continue to see a high fire danger into
the end of the work week as dry weather and warm temperatures are
expected.

&&

.HYDROLOGY...
Issued at 139 PM EDT Mon Jul 16 2018

River levels showed little to no response to spotty rainfall
received last evening through early Monday afternoon, even near
Kalamazoo and near Rockford where the heaviest rain fell.

Scattered showers and thunderstorms Monday afternoon and evening
will be most numerous east of Grand Rapids. Storms will be capable
of torrential rain, with rainfall rates of 1-3 inches per hour,
possibly higher. Storm motion to the east at 20 mph is faster than
yesterday, but still supports the threat for localized flooding.
Mainstem river flooding (Grand, Muskegon, Kalamazoo) is not
expected, but rapid rises will be possible on smaller creeks and
streams if heavy rain persists long enough over the smaller river
basins.

Dry weather is expected Monday night through Thursday. A wetter
pattern will develop over the area Friday through Sunday as a large
area of low pressure slowly moves through the area.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from 2 AM EDT Tuesday through late
     Tuesday night for MIZ056-064-071.

LM...Small Craft Advisory from 2 AM Tuesday to 2 AM EDT Wednesday for
     LMZ844>846.

&&

$$

SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...Duke
AVIATION...Meade
FIRE WEATHER...Duke
HYDROLOGY...HLO
MARINE...Duke


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