Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 280730
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 AM EDT SUN AUG 28 2016

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

.SYNOPSIS...
Issued at 330 AM EDT Sun Aug 28 2016

An isolated shower or thunderstorm will remain possible through
early afternoon along and south of Interstate 96 ahead of a cold
front. Most areas will remain dry though. The front will slowly slip
south of the State of Michigan this afternoon and evening. Much less
humid air will filter in from the north tonight with dry conditions
expected. High pressure will be in control of the area weather
Monday and Monday night with fair weather expected. On Tuesday, a
cold front will move into Central Lower Michigan bringing scattered
showers and storms. Rain chances will continue into Tuesday night
before the cold front pushes south of the area by Wednesday morning.
High temperatures will be near normal in the lower 80s through
Tuesday, but cooler weather is expected behind the mid week front.
Highs later in the upcoming work week will top out in the 70s.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 330 AM EDT Sun Aug 28 2016

Short term focus is on chances for isolated showers and storms this
morning ahead of the front again on Tuesday ahead of the next cold
front.

Cold front still remains northwest of the bulk of the forecast area
at 07z, as it is just pushing into Ludington from the northwest. Dew
points remain up around 70 in all areas with Most Unstable CAPE
values in excess of 1000 j/kg across the south. An isolated shower
was noted off shore of Saugatuck. Bottom line, the precipitation may
not be over with an unstable air mass in place ahead of an advancing
cold front. Kept the mention of an isolated (20 pct chance) shower
or storm in the forecast in the southern half of the CWA through
midday. Could see the chance of a stray shower or storm continuing
after 18z near Jackson, but ended the chance at 18z.

Dry and fair weather will be in place from tonight through Tuesday
morning as high pressure only slowly slips southeast. A cold front
is forecast to be pushing into Northern Lower Michigan at 12z
Tuesday. Moisture return is not great ahead of this next front and
for that reason only expecting scattered showers and storms on
Tuesday. Best chance (30-40 pct) for precipitation will be across
Central Lower Michigan Tuesday as this is where the front will be
located at peak heating.

Not expecting severe weather today ahead of the front or on Tuesday
either with generally weak 0-6km shear values on the order of 20
knots or so.

.LONG TERM...(Tuesday night through Saturday)
Issued at 330 AM EDT Sun Aug 28 2016

A cold front will continue to drop south across the CWA Tuesday
night.  Widely scattered showers and storms should end from north to
south with it`s passage.

The models continue to show a fall-like cool down behind the front
for the latter half of the work week.. Northwest flow brings in a
cool and dry air mass into the area. A secondary upper trough passes
through Wednesday evening, supplying a reinforcing shot of cooler
air.  H8 temps trend down to around +7C by Thu.  This could bring
some lake clouds into the picture and if this happens we will only
see highs in the 60s. But at this point it appears too dry for much
cloud cover, so will remain optimistic and have low to mid 70s for
Thu.

Weak upper ridging is indicated by Friday night/Saturday.  This
should bring temps back to near normal.

Bottom line, after the frontal passage on Tuesday night, we will be
heading into a much drier period with below normal temps, trending
toward normal as we approach the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 126 AM EDT Sun Aug 28 2016

I reduced the expected impacts from the overnight fog. It appears
there will be enough wind in the boundary layer that the fog
should not get too dense. Some patchy IFR is still possible, but
overall, believe vsbys will largely just dip down into the MVFR
category. Some MVFR ceilings will be around too.

Any MVFR vsbys and ceilings will improve shortly after sunrise.
The reminder of the day will remain VFR along with light winds.

Fog may begin to redevelop toward 06Z Sunday night, but have left
this out of the TAFs for now.

&&

.MARINE...
Issued at 330 AM EDT Sun Aug 28 2016

Winds and waves will remain well below Small Craft Advisory criteria
through Tuesday. High pressure will be in place the bulk of the
time. Bufkit overview data via the NAM at MKG shows winds at 10
knots or less below 5000ft from this morning into Monday night.
Southwest flow will increase a bit on Tuesday ahead of a cold front,
but likely won`t go higher then 10-15 knots.

&&

.HYDROLOGY...
Issued at 207 PM EDT Sat Aug 27 2016

The Portage River at Vicksburg fell to just below flood stage this
morning. However with locally over an inch of rain possible through
tonight, the river level is expected to rebound to just above flood
stage this weekend and then slowly fall. No other locations are
currently near flood stage.

&&

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

$$

SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...JK
AVIATION...JK
HYDROLOGY...63
MARINE...Duke



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