Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 281856

Area Forecast Discussion
National Weather Service Grand Rapids MI
256 PM EDT SAT MAY 28 2016

Synopsis/Short Term/Long Term/Marine

Issued at 256 PM EDT Sat May 28 2016

Isolated severe thunderstorms are possible on Sunday as a cold
front works through the region. The main threats are large hail
and damaging winds. Until then, isolated to scattered
showers/storms will be possible this afternoon into tonight.

Memorial Day looks beautiful with a bit less humidity, plenty of
sunshine, and highs in the lower 80s. Rain chances increase
Wednesday and peak Wednesday night into Thursday.


.SHORT TERM...(This evening through Monday night)
Issued at 256 PM EDT Sat May 28 2016

Isolated strong to severe thunderstorms are possible on Sunday as a
cold front moves through Lower Michigan. The primary threats will be
hail and damaging winds.

The Plains upper trough will weaken as it swings into the Great
Lakes region through Sunday. The H500 vort will provide weak mid-
level support as a cold frontal passage coincides with peak heating.
Showers and thunderstorms are expected to develop along and ahead of
the cold front. Moderate destabilization is expected prior to the
frontal passage. The 12z NAM and GFS diverge a good deal on the
amount of MLCAPE available from late morning into the afternoon, but
it seems reasonable to expect 1000-1500 J/kg. Deep layer shear is
marginal at best around 25 kts. Wind fields in the mid and upper
levels are unimpressive.

However, the cold front will provide better forcing than we`ve had
in the past week in a buoyant atmosphere. A few strong to severe
thunderstorms are possible, with large hail and damaging winds as
the primary threats.

Low level flow goes westerly behind the front Sunday evening, and
mid level height rises begin Sunday night. Surface ridging then
builds into the southern Great Lakes. Memorial Day looks beautiful
with a bit less humidity, mostly sunny skies, and highs in the lower

.LONG TERM...(Tuesday through Saturday)
Issued at 256 PM EDT Sat May 28 2016

After a break break in the rain chances on Monday, the rain chances
will return at the beginning of the long term portion of the
forecast on Tuesday. These rain chances will not be very high, and
will be more diurnal in nature as increasing moisture will return
ahead of the next system.

The rain chances will increase then on Wednesday and will peak
Wednesday night into Thursday. Showers and thunderstorms will be
supported by the upper low system that is currently centered over
British Columbia. This will gradually drop southeast, and push a
frontal system into the area late Wed into Thu.

We will tend to dry out a bit then for the end of the week and the
beginning of the weekend, but keep a small chance of a few showers
in. The upper low will open up to a trough and move through by Fri
morning. We will see additional short waves coming in on the nw flow
and help to establish a long wave trough over the area. This should
allow for a few diurnal rain showers Fri and Sat afternoon with
cooler temperatures.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 140 PM EDT Sat May 28 2016

The few showers and isolated storms that were floating through
earlier have moved out for the time being. The mid cloud deck that
has been over the area this morning is now breaking up and
allowing more sun to break through. This heating will provide for
a bkn cumulus deck this afternoon with a few pop up showers and
isolated storms developing inland. These should diminish toward

The moist air mass in place and front coming in will bring a good
chance of some fog/stratus across the area later tonight. The
winds aloft holding up would favor a stratus deck. We have gone
with a sct002 and some haze for now with somewhat limited
confidence in the coverage of it. Any fog/stratus should dissipate
by mid morning.

Finally, the front will move through tomorrow afternoon. This will
potentially pop some showers/storms ahead of it. The favored area
will be South and East where the front will be during peak
heating. We have VCTS in for all sites except KGRR and KMKG
tomorrow afternoon.


Issued at 256 PM EDT Sat May 28 2016

Conditions on Lake Michigan will remain hazardous to smaller craft
and dangerous to swimmers north of Grand Haven through this
evening. Southerly winds will continue to gust to 30 mph this
afternoon and evening before diminishing late tonight. Waves will
subside to 2 to 4 feet tonight and 1 to 3 feet on Sunday.


Issued at 109 PM EDT Sat May 28 2016

River levels across the area are near to just above their expected
values for this time of year. Precipitation of up to an inch is
possible over the next week. Convection through the weekend will
produce mainly localized heavy rainfall. Rises will mainly be
confined to smaller creeks and streams and should not reach flood


.GRR Watches/Warnings/Advisories...
MI...Beach Hazards Statement until 10 PM EDT this evening for MIZ037-

LM...Small Craft Advisory until 10 PM EDT this evening for LMZ847>849.



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