Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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992
FXUS63 KGRR 251746
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
146 PM EDT MON JUL 25 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 214 AM EDT Mon Jul 25 2016

A high pressure system centered in Iowa will build slowly east
today and into Michigan on Tuesday. This fair weather system will
act to dry out the region and lower temperatures closer to
seasonable values. A low pressure system will approach the Great
Lakes region Wednesday into Thursday bringing with it an increased
potential for showers.

&&

.UPDATE...
Issued at 523 AM EDT Mon Jul 25 2016

The South Haven buoy was up close to 5 feet as of 5 am. Thus a
headline was needed for parts of the nearshore waters. The update
has been sent.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 214 AM EDT Mon Jul 25 2016

The main challenge deals with the precipitation chances this
morning. I did raise pops for southeast parts of the CWA to start
the morning.

There have been a few stronger thunderstorms in southern Jackson
county early this morning. The axis of stronger instability
associated with these storms will pivot east over the next couple
of hours. Thus the risk for thunderstorms will decrease through
daybreak. However...the mid level wave is still hanging back. The
radar does show returns over Lake MI...in an area where the DGZ is
forecasted to be moist. Bufkit profiles show a dry layer below the
moist DGZ...so it is not certain that what is over the lake is
reaching the ground. My though is that with a still very moist low
level airmass over southeast parts of the cwa...that I should
increase pops for a few hours to start the day until the mid level
wave tracks though.

With skies clearing out and diminishing winds tonight...there
should be some patchy fog developing especially up over northern
parts of the CWA.  A similar setup for Tuesday night as well.

I do see a small risk for a thunderstorm arriving...mainly Tuesday
night for northwest parts of the CWA. This would include
Ludington. Mid level cooling develops while warm and moist air
advection develops in the low levels. This will act to destabilize
the atmosphere somewhat...possibly leading to a storm or two. A
better chance for thunderstorms is on Wednesday. The mid level
cooling continues. Thus we may see a couple of storms developing.

.LONG TERM...(Wednesday night through Sunday)
Issued at 214 AM EDT Mon Jul 25 2016

The extended portion of the forecast features a return to more
seasonable temperatures and multiple chances for showers and
thunderstorms. A series of a couple shortwaves will dig out an upper
level trough over the Midwest and Great Lakes Thursday into Friday.
During this time, an upper level ridge that was previously over the
southern CONUS will amplify over the western coast of North America.

In general, expect a fair amount of cloudiness late in the work week
into the early part of the weekend. Showers are expected at times,
but models are not consistent on the handling of any single,
significant low-level feature. After highs in the low to mid 80s
Thursday, temps will hold in the lower 80s Friday through the
weekend. Lows will be in the upper 50s and 60s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 145 PM EDT Mon Jul 25 2016

VFR weather is expected over the next 24 hours with the exception
of the risk of some patchy radiation fog late tonight into early
Tue morning. Continued the theme of the previous TAFS, which
advertises 3-5 mile MVFR vsbys from 09z through about 13z. Some
IFR vsbys are possible too but dew pts have been falling today so
still not confident enough to go with any IFR in the TAFs.

&&

.MARINE...
Issued at 214 AM EDT Mon Jul 25 2016

The wind and waves will continue to diminish today and Tuesday as
the pressure gradient weakens. Waves will initially start out
today in the 2 to 3 foot range.


&&

.HYDROLOGY...
Issued at 1254 PM EDT Mon Jul 25 2016

No river flooding is expected through the week. Area wide rain of
around an inch with locally up to 3 inches (mainly near Lake
Michigan) fell this weekend. A small chance of rain is in the
forecast Wednesday through Friday. River levels have risen and are
at or above normal for this time of year. Even with the
precipitation, no rivers should approach flood level.

&&

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

$$

UPDATE...MJS
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...EBW
AVIATION...Meade
HYDROLOGY...63
MARINE...MJS



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