Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 311927
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
327 PM EDT TUE MAY 31 2016

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

.SYNOPSIS...
Issued at 327 PM EDT Tue May 31 2016

A frontal system moving toward the area will begin to increase
shower and storm chances toward daybreak Wednesday along the
lakeshore. Showers and storms will then move through the area
Wednesday and Wednesday evening. A few of the storms could be
locally strong with some large hail and gusty winds.

Rain will end by Thursday morning, allowing the area to dry out.
Cooler and less humid air will also filter into the area. Rain
chances will increase again for the weekend as an unsettled weather
pattern settles in across the area.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 327 PM EDT Tue May 31 2016

Our main focus of the short term is convective potential mainly for
Wed and wed evening as the frontal system is expected to come
through at that time.

Showers and storms are not far from the CWFA this afternoon, as
close as far NW Indiana and just west of Chicago and Milwaukee. They
are moving more north than east, and are expected to focus back
across WI for tonight. This occurs since the llj closest to MI will
weaken, and will refocus a little further N and W with a lead short
wave staying NW of the area. We will also see SE winds strengthen a
bit and hold the dry air in a little longer.

We will see the shower and storm chances increase on Wed, with the
best chances coming from afternoon into the early evening hours. We
will see what is left over from the llj tonight slip across the CWFA
Wed afternoon. It will be weakening as it does so. The focus will
then shift to a pre-frontal trough that looks to enter the area
early in the afternoon and exit by 00z Thu.

The eastern areas have the best chance of seeing some of the
stronger storms on Wed. Areas further west will see more clouds and
some showers early, limiting the amount of diurnal instability that
can build. Further east, some early sun looks to build instability
for a later trough passage. The severe setup is not exciting as deep
layer shear is only on the order of around 25 to 30 knots. Some
thicker CAPE will allow for some decent updrafts that could produce
some larger hail and gusty winds.

The cold front will arrive overnight Wed night and should clear the
CWFA by 12z Thu. Ridging will build in and clear the area out
through Thu night. Cooler and less humid air will filter in with
h850 temps dropping to around 8-10c. This should yield highs in the
70s for Thu and Fri.

.LONG TERM...(Friday through Tuesday)
Issued at 327 PM EDT Tue May 31 2016

The long term begins with high pressure situated across the Great
Lakes region. Dry conditions are forecast on Friday with highs well
into the 70s. Showers creep in from the northwest Friday night in
advance of a low moving our direction from the northern plains.

The weekend looks like it will feature a decent amount of cloud
cover and chances for showers and thunderstorms. The threat for
storms looks to exist from Saturday into Sunday as an upper trough
pivots our direction from Wisconsin. Late in the weekend and into
early next week, the upper trough becomes more situated overhead
which should result in cooler weather and chances for showers.

So, the bottom line we are looking at a dry Friday with chances for
showers and storms Saturday into Sunday. Highs will remain in the
70s through Saturday. Sunday night through Tuesday looks more
showery with highs cooling back into the 60s.

Models are in fairly good agreement on the main forecast features so
confidence is on the higher side of normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 144 PM EDT Tue May 31 2016

VFR conditions are forecast through the 18z to 18z period. Some
cirrus with bases above 20000FT can be expected the remainder of
today, lowering to an altocumulus cloud base around 12000FT
tonight. We will be dry this afternoon and tonight.

The weather becomes more active into the day on Wednesday when a
cold front progressing from west to east touches off some showers
and thunderstorms. Still expecting VFR conditions for the most
part though through 18z on Wed. Showers and a few thunderstorms
will be progressing into Western Lower Michigan Wednesday morning,
but coverage is probably still too scattered to have anything more
than VCSH and VCTS through 18z. Coverage of showers and storms
will increase and peak during the 18z to 00z time frame tomorrow
afternoon, just beyond the TAF period.

&&

.MARINE...
Issued at 327 PM EDT Tue May 31 2016

Winds will increase a bit tonight as the frontal system makes a move
toward the area. Flow looks to remain offshore a bit and warmer air
over the cooler waters should limit winds from coming up too much.
It appears that winds should remain just below Small Craft Advisory
criteria. Waves should be limited also with the aforementioned
reasons listed above. Winds will remain up until Thu night into Fri
when they are expected to drop off.

&&

.HYDROLOGY...
Issued at 1203 PM EDT Tue May 31 2016

River levels are stable or slowly falling and near normal for this
time of year. Parts of the Kalamazoo basin are even slightly below
normal. We expect around half an inch or less of rain Wednesday
into Thursday, which should produce only minor rises. This period
of rain will be followed by dry weather through the end of the
work week. This should help to limit the magnitude of the rises.

&&

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

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...Duke
AVIATION...Duke
HYDROLOGY...TJT
MARINE...NJJ


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