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563
FXUS63 KGRR 281432
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1032 AM EDT WED SEP 28 2016

LATEST UPDATE...
Update

.SYNOPSIS...
Issued at 330 AM EDT Wed Sep 28 2016

An expansive area of low pressure moving south through the Great
Lakes Region this morning will stall south of Michigan Thursday and
Friday then lift back north through the state over the weekend.
While it won`t be raining all the time, clouds and scattered
showers associated with this low will impact the area for the next
several days.

&&

.UPDATE...
Issued at 1032 AM EDT Wed Sep 28 2016

The on going forecast looks good. The rotation around the upper
low is apparent as the radar echos are now moving toward the west.
The next area of rain and showers is over the Detroit area and
will be also moving westward this afternoon so expect an increase
in rainfall across most of Southwest Michigan by early this
afternoon. With all the clouds temperatures will not rise a lot
today so highs in the mid 60s still seems good.

&&

.SHORT TERM...(Today through Friday)
Issued at 330 AM EDT Wed Sep 28 2016

Shortwave currently over srn Lk MI, rotating through the base of the
upper trough, will bring a bring a brief increase in showers and
isolated tstms to areas west of Hwy 131 early this morning. However
as the upper low settles south into Indiana, that shortwave heads
back to the west toward WI, which should lead to a decrease/lull in
showers for a time during the mid to late morning. Also the low
level flow goes offshore so any lake component will shift away from
the coast and toward the Milwaukee/Chicago areas.

Primary feature of interest later today is another shortwave
pivoting around the south side of the upper low which takes aim on
southeast and south central lower Michigan this afternoon. Guidance
is similar in showing numerous showers/isolated tstms developing
south and east of GRR as a trowal-like feature curls in from the
southeast and wraps around the north side of the low.

Highest pops tonight and Thursday will continue to be south of I-96,
particularly along I-94, within persistent trowal/deformation zone
on the north side of the upper low. Meanwhile, as the upr low
reaches it`s southern-most position, the potential exists for some
sunshine on Thursday northwest of GRR per RH progs. Downsloping low
level northeast flow with sun could lead to high temps in the lower
70s for the Muskegon/Ludington areas.

Thursday night/Friday sees clouds/pops lift back north/northwest
through the area as the upr low bounces back northward again. A
heavy rain threat may eventually develop as easterly flow around
north side of the low pulls in Atlantic moisture, with PWATs near
1.5 possible within the trowal area by Friday.

.LONG TERM...(Friday night through Tuesday)
Issued at 330 AM EDT Wed Sep 28 2016

The upper low is still progged to be somewhere near CVG into
Saturday before finally lifting NE toward Toronto by Sunday.
Scattered to numerous showers should continue through Saturday, then
gradually diminish into Saturday night/Sunday.

The pattern finally becomes more progressive with an upper ridge
sliding across the region on Monday bringing a period of fair
weather.  Despite the building ridge there is not much indication we
will see a warming trend, with H8 temps holding 8-10C.  So daytime
temps should largely stay in the mid 60s to lower 70s through much
of the long term, which is near normal for this time of year.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 750 AM EDT Wed Sep 28 2016

Predominately VFR cigs are expected today. Despite the scattered
showers rotating around the upper low, the low level northeast
winds are driving in dry air below 4000 ft. That may change later
today and tonight south of I-96, with MVFR cigs/vsbys probably
developing at JXN/BTL/AZO as a more persistent area of showers
rotates in from the southeast. Can`t rule out an isolated tstm
with small hail as well.


&&

.MARINE...
Issued at 330 AM EDT Wed Sep 28 2016

Will be cancelling the small craft advisory early as winds and waves
have subsided below criteria. However will keep a mention of
waterspouts over the lake through the day. Strengthening northeast
flow could necessitate new small craft advisories for the
southernmost zones later tonight into Thursday.


&&

.HYDROLOGY...
Issued at 140 PM EDT Tue Sep 27 2016

River levels are around normal for this time of year. Lake enhanced
rain showers are possible through Wednesday. Rain showers continue
to be possible into Sunday. Rainfall totals into the weekend will
range from a half inch up to an inch and a half. Rivers and streams
should remain below bankfull through the weekend.

&&

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

$$

UPDATE...WDM
SYNOPSIS...Meade
SHORT TERM...Meade
LONG TERM...JK
AVIATION...Meade
HYDROLOGY...63
MARINE...Meade