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265
FXUS63 KGRR 251145
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
745 AM EDT Sun Jun 25 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 AM EDT Sun Jun 25 2017

Cool weather is expected today through Tuesday. Temperatures will
likely stay in the 60s for highs both today and especially on
Monday. We will warm slightly into the lower 70s for Tuesday.
Normal high temperatures for this time of year are in the lower
80s, so we will be well below normal. Scattered showers are
expected today through Monday with an isolated thunderstorm
possible as well. Any storms should mainly occur during the
afternoon hours.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 330 AM EDT Sun Jun 25 2017

Fall like pattern is expected through the short term with
northwest upper flow. A shortwave is affecting the area at present
and will touch off scattered showers and possibly an isolated
storm through the morning hours. Another shortwave will dive
through the northwest flow on Monday. Given the cold airmass
aloft, there will likely be a diurnal flare to the precipitation
both today and on Monday. Monday may tend to overperform in regard
to precipitation as the upper shortwave will be coincident with
max heating and the thermal trough over Lake Michigan. Delta T`s
on Monday will be near 13 degrees C, so we may see lake generated
showers as well.

We should dry out for later Monday night into Tuesday as ridging
begins to build in both at the surface and aloft. Bottom line, its
going to be a cool period with some showers around through Monday
evening.

.LONG TERM...(Tuesday night through Saturday)
Issued at 330 AM EDT Sun Jun 25 2017

Surface high pressure moving by to the South of Michigan Tuesday
night into Wednesday should result in dry weather for the area. A
Low pressure system is then expected to pass over Michigan and drape
a front across the region, bringing showers and thunderstorms Monday
night into Tuesday. Another low pressure system will then move from
southwest to northeast along the front, accompanied by more rain and
thunderstorms Friday and Friday night. If the focus of the heavy
rain stretches across Lower Michigan, we could see areal and river
flooding by the end of the week.

Temperatures will be warming through the long term. They will be
below normal into mid week and near normal for the second half of
the week. Normal highs are around 80 degrees and normal lows are in
the upper 50s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 744 AM EDT Sun Jun 25 2017

Clouds will fill in fairly quick once again this morning. At the
onset, between 12z and 15z or so, some MVFR ceilings are possible.
Scattered showers are possible throughout the TAF period,
therefore we have VCSH wording in place. An isolated thunderstorm
cannot be ruled out, but given very low chances did not include
in the TAFs. It will be breezy again today with westerly winds of
10-25 knots between 14z and 23z. Tonight some MVFR ceilings will
likely fill back in after 06z.

&&

.MARINE...
Issued at 330 AM EDT Sun Jun 25 2017

Small Craft Advisory and Beach Hazards Statement look marginal
today, but will leave them in effect and see how things play out.
Waves have come up overnight in a burst of westerly winds behind
the mid level shortwave. Port Sheldon for instance has 5 footers
as of 300am. The day will likely at least start with higher waves.

There may be a bit of a lull in the waves late this afternoon and
evening, but winds and waves should increase tonight into Monday.
In fact, waves on Monday look to be the highest we have seen in
the last couple of days. Solid 5 footers with some 6`s look
possible in a cold air advection regime. Extended the marine
headlines through Monday evening.


&&

.HYDROLOGY...
Issued at 1231 PM EDT Sat Jun 24 2017

The Chippewa River at Mount Pleasant crested at 14.77 feet Friday
night, about 10 inches below the record flooding of 15.58 feet in
September 1986. All river forecast points in our area have crested
as the water is being routed down through the Muskegon and Saginaw
river systems. Scattered showers Saturday through Monday should
have little effect on the rivers. Heavy rain potential may return
during the latter part of the upcoming week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Monday evening for MIZ043-050-
     056-064-071.

LM...Small Craft Advisory until midnight EDT Monday night for
     LMZ844>848.

&&

$$

SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...63
AVIATION...Duke
HYDROLOGY...CAS
MARINE...Duke