Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 291151
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
751 AM EDT MON AUG 29 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 AM EDT Mon Aug 29 2016

Plenty of sunshine should be seen today as high pressure will be
situated across the Great Lakes region. Slightly less humid air will
be in place today making for more pleasant conditions. The high will
slide off to the southeast of the area tonight allowing a cold front
to approach from the north on Tuesday. The front will move through
Southwest Lower Michigan Tuesday night and off to the south on
Wednesday. Scattered showers and thunderstorms are in the forecast
Tuesday through Tuesday night. There will be some lingering showers
and storms Wednesday morning towards Interstate 94. Highs will
remain in the 80s Monday and Tuesday, cooling into the 70s for the
latter half of the work week.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 330 AM EDT Mon Aug 29 2016

Main focus in the short term is on the cold front forecast to
traverse the area Tuesday into Wednesday. Models are still showing
scattered showers and storms associated with the front. Maintained
the 30-40 pct chance wording in the forecast. The main shortwave
aloft stays well north of the area and the low level jet is forecast
to be weak on the order of 20 knots. Not expecting severe weather
given weaker wind fields and 0-6km bulk shear values on the order of
20 knots as well. CAPE values are forecast via the ECMWF to be in
the 1000-1500 j/kg range. Much of the precipitation may be confined
to Central Lower Tuesday afternoon, slowing moving south with the
front Tuesday night. Models have trended a bit slower with the front
which will likely linger some showers across the south Wednesday
morning.

Otherwise, quiet weather is expected Today through Tonight with the
high in place. Only cloud will be some cirrus debris from upstream
convection. Decreasing clouds are expected post front on Wednesday.

.LONG TERM...(Wednesday night through Sunday)
Issued at 330 AM EDT Mon Aug 29 2016

A comfortably cool air mass will continue to filter into MI Thursday
as a deepening troughing takes place over New England. This brings
northern upper flow and a Canadian high pressure over the region.
With H8 temps dropping to around +8C, highs will just be 70 to 75
both Thu and Fri, and a few upper 60s daytime highs will be possible.

Upper ridging begins to build into the region by Fri night and into
the weekend leading to a moderating trend, bringing temps back to
around normal.

Otherwise the extended period looks quiet with either surface or
upper ridging in place.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 751 AM EDT Mon Aug 29 2016

The main focus of the next 24 hours is on the fog and stratus that
is in place across portions of the area this morning. At 12z a surge
of VLIFR fog and stratus was pushing east and southeast out of the
thumb and Saginaw Bay area. It looks like it will make it into GRR
and LAN for a time this morning before lifting. The other TAF
sites look like they will escape the fog/stratus. Between 12z and
15z or so, the stratus/fog will likely impact GRR and LAN.

Otherwise VFR conditions are expected the remainder of the day and
tonight with light winds.


&&

.MARINE...
Issued at 330 AM EDT Mon Aug 29 2016

High pressure will provide very quiet conditions out on Lake
Michigan from today through tonight. Tuesday looks to be a low wind
and wave day as well, with winds 10 knots or less for the most part.

Tuesday night through Wednesday night looks to be a period when
waves will be up on Lake Michigan, potentially reaching small craft
advisory criteria. Winds will be northerly and of the cold air
advection variety. Highest waves will be at the south end of the
lake.


&&

.HYDROLOGY...
Issued at 1201 PM EDT Sun Aug 28 2016

Will extend the Flood Warning for the Portage River based on the
half-inch of rain that fell on Saturday. The warning will be
maintained until observations can verify it has fallen and will
stay below flood stage. There is a chance of rain Tue-Wed this
week but likely not enough to cause problems. No other significant
rainfall or hydrologic concerns are expected this week.

&&

.GRR Watches/Warnings/Advisories...
MI...None.
LM...None.
&&

$$

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



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