Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 260730

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 AM EDT FRI AUG 26 2016

Synopsis/Short Term/Long Term/Marine

Issued at 330 AM EDT Fri Aug 26 2016

Comfortable temperatures and humidity are expected today in the wake
of a cold front that dropped south through the region on Thursday.
Highs today will range from the upper 70s to lower 80s in most
areas. Chances for showers and storms return to the forecast
quickly, on Saturday. Moisture will stream back into the area
Saturday on southerly winds on the back side of the departing high.
The best chances for showers and storms this weekend will come
Saturday and Saturday night. A decrease in precipitation should be
noted as we head through the day on Sunday. Highs Saturday and
Sunday will be in the upper 70s to lower 80s as well.


.SHORT TERM...(Today through Sunday)
Issued at 330 AM EDT Fri Aug 26 2016

Some high clouds are expected today, but otherwise pleasant
conditions should prevail. An increase in mid and high clouds
tonight will trend skies towards mostly cloudy by Saturday morning.
Moisture transport begins to increase late tonight at 850mb`s which
may creep a shower or storm into the west towards daybreak Saturday.

Moisture transport increases to moderate levels quickly on Saturday
which should result in an increase in showers and storms as we head
through the day. PWAT values are forecast to increase to near 2
inches. With the type of increase in PWAT values through the day it
is rare that we do not see a decent amount of showers/storms. Have
likely chances for showers/storms in the afternoon and evening. CAPE
values are forecast to reach the 1000-2000 j/kg range via most
models on Saturday afternoon. Bulk shear values are on the order of
30-40 knots so storm organization is likely. The key to any chance
for severe weather will be the amount of destabilization we see
given the amount of precip and clouds that will be around. Best
chances for severe will be Saturday afternoon and evening across
Central Lower where the stronger low level jet will be located.

Saturday night into Sunday a cold front will sag back south across
the area. Feel precipitation will begin to move towards southern
Lower Michigan overnight and may even exit the south on Sunday.
Prospects for drier weather are much better on Sunday as compared to

.LONG TERM...(Sunday night through Thursday)
Issued at 330 AM EDT Fri Aug 26 2016

The long term portion of the forecast looks fairly quiet and
seasonable for much of next week. We are looking at a chance of a
few storms centered around Tuesday. Otherwise chances of rain will
be fairly low.

We expect that any rain from the weekend will be long gone by the
beginning of the long term Sunday night. The frontal system
supporting the rain earlier in the weekend is expected to be south
of the state by Sunday night with high pressure building in behind
it. This ridge will hold over the area through Monday, keeping the
area dry with highs in the lower 80s.

The best chance of rain in the long term will come Mon night into
Tuesday. This results from a short wave moving just south of Hudson
Bay. This will push a front down into the area. The latest trends in
the models are for less moisture to be drawn into the system. There
will still be sufficient moisture for a decent shot at some rain.

We will dry out then for Wed and Thu. The Tue front will sink south
and weaken as it becomes detached from it`s upper support in Canada.
The upper pattern will buckle a bit, with Michigan expected to be
just downstream of the long wave ridge across the plains.
Temps will be a slight bit cooler with some lower heights in place
and NW flow aloft expected.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 139 AM EDT Fri Aug 26 2016

VFR conditions are expected during the entire forecast period
through 06z Saturday. A few high clouds are floating overhead
tonight, but that should be the extent of cloud cover. Fog
potential is not zero, but is too low to mention at this time with
a drier air mass coming in.

High clouds will remain during the daylight hours on Friday.
Cumulus potential looks low at this time. Winds will come up to
around 10 knots from the W/SW. Cigs will start to lower toward the
end of the forecast period as rain with the next system
approaches. Any significant impacts to aviation interests should
hold off until after 06z Sat.


Issued at 330 AM EDT Fri Aug 26 2016

Winds and waves on Lake Michigan look fairly tame today and tonight
as high pressure drifts from west to east across the Great Lakes.
Southerly flow will return on the back side of the high for
Saturday. It appears that winds on Saturday will reach the 10 to 20
knot range. Waves will likely remain below advisory criteria based
on overnight wave model output. Saturday and even Saturday
night though will be the two forecast periods we will need to keep
an eye on as winds will be around the 15-20 knot range. A slight
increase in wind speed could nudge waves/currents into advisory


Issued at 148 PM EDT Thu Aug 25 2016

Showers and a few thunderstorms will bring patchy MVFR and isolated
IFR conditions this afternoon, but VFR should prevail most of the
time. Some light fog overnight could bring MVFR to AZO and JXN but
conditions should be VFR elsewhere. West winds around 10 knots
through evening.


.GRR Watches/Warnings/Advisories...


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