Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 221056

Area Forecast Discussion
National Weather Service Grand Rapids MI
656 AM EDT FRI JUL 22 2016


Issued at 310 AM EDT Fri Jul 22 2016

An area of high pressure will control the weather today in
Southwest Lower Michigan. This feature will act to keep the
weather hot and humid. A thunderstorm or two could develop today
but most locations should remain dry. Not much change occurs as we
go through Saturday...but a wave of low pressure moves in for
Saturday night into Sunday night. Thus the risk for thunderstorms
will increase.


.SHORT TERM...(Today through Sunday)
Issued at 310 AM EDT Fri Jul 22 2016

Will maintain the heat advisory. As the convective complex in
Illinois shifts south...the clouds here in MI will diminish
supporting increasing sunshine. The low level thermal ridge is in
place. Thus...we are more likely to see temperatures climb into
the 90s today as compared to Thursday. This thermal ridge remains
in the area Saturday. As a result we may need to extend the
headline. However...surface dewpoints are forecasted to fall of on
Saturday...somewhat offsetting the heat.

Will hold onto a low chance for storms across southern parts of
the CWA for today. The atmosphere remains unstable...with new
storms developing around Detroit. There is not large scale lifting
mechanism around to trigger widespread storms. Thus only a
localized storm or two appears possible.

Its hard to say with a lot of confidence how much if any storms we
see for Saturday night into Sunday. A mid level shortwave does
push into the Great Lakes region...but its forcing may not arrive
til after Sunday. There is a low level jet shown to arrive
Saturday night into Sunday. So with building instability and some
lift...we could see an increase in the thunderstorm activity then.
Will hold onto the relatively high pops then.

.LONG TERM...(Sunday night through Thursday)
Issued at 310 AM EDT Fri Jul 22 2016

The long term portion of the forecast will feature chances of storms
at the beginning and end of the period, with a quiet period in
between. We expect that temperatures will remain rather warm through
the period.

We will see chances for showers and storms from the end of the short
term linger into the long term beginning on Sun night. A strong
enough short wave will beat the ridge down enough over the area that
a cold front will slip through by Mon morning. This front will sink
south of the area on Mon, and take with it the core of the heat and
instability. Until it moves through, a chance of storms will remain
Sun night.

Drier weather will then settle in from Mon through most of Wed
as high pressure at the sfc builds through the state. Temps will drop
down a notch or so, but will remain very warm with max temps
expected to be well into the 80s. Heights will have lowered some,
but the noticeably cooler air will stay north of the area.

We will see rain chances increase then as early as late Wed, but
more likely Wed night into Thu. A short wave embedded in the
somewhat more zonal flow is expected to approach the area on Thu.
This will draw better moisture back up into the area from the


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 652 AM EDT Fri Jul 22 2016

Only a small risk for a thunderstorm exists for the forecast
period. Southern Lower MI is the region where this could occur.
Not enough confidence at this time to add it to the TAFS. So it
looks like VFR weather into tonight...then some late night fog
could develop. A risk for IFR conditions exists so aviators should
monitor trends closely.


Issued at 310 AM EDT Fri Jul 22 2016

The storms overnight resulted in strong and variable wind
conditions. The waves responded...especially over the southern end
of the lake and briefly came up to 5 feet. With no additional
strong/severe convection forecasted today...the waves will likely
settle down through the day. At this time will hold off on a SCA
and Beach Hazards. Will take another look prior to 6 am...and may
issue headlines if the waves do not diminish.


Issued at 334 PM EDT Thu Jul 21 2016

Rainfall is not expected to be heavy enough to result in large
scale flooding of rivers or streams in the coming week. Even so,
locally heavy rain from thunderstorms tonight may cause some
localized flooding in areas with poor drainage and flashy streams.


.GRR Watches/Warnings/Advisories...
MI...Heat Advisory until 7 PM EDT this evening for MIZ044>046-050>052-



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