Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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554
FXUS63 KGRR 290522
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
122 AM EDT Mon May 29 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Sun May 28 2017

A few showers or storms will be possible over the next couple of
days, but the main time frames will be Monday and then again Tuesday
afternoon and evening.  Another rain chance will come Thursday night
and Friday.

Temperatures will stay rather uniform, with highs in the mid 60s to
mid 70s.

&&

.UPDATE...
Issued at 935 PM EDT Sun May 28 2017

Just enough leftover instability around for an isolated shower or
thunderstorm to exist over Lake MI this evening. As the
instability decreases...the risk for precipitation will decrease
as well. The main change with the forecast was to show a small
chance for a shower or thunderstorm over the nearshore waters and
lakeshore counties.

UPDATE Issued at 734 PM EDT Sun May 28 2017

The main change to the forecast was to reflect less in the way of
cloud cover. I also added some fog to the nearshore forecast.
Satellite trends show less clouds over the region than currently
forecasted. Also some fog was seen on the visible imagery...along
with the webcams supporting it for parts of the nearshore waters.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 330 PM EDT Sun May 28 2017

Storms will exit the area this evening, leaving behind impacts from
an upper low into Tuesday night.

Once the showers and storms exit we will be dry for the remainder of
the night.  Slightly cooler with lows of 50 to 55.

Memorial Day will see scattered showers around as we get into the
impacts of the upper low over the Northern Lakes.  Troughs will be
passing through from time to time, and along with some diurnal
instability, we should see a peak in the showers in the afternoon on
Monday.

Same goes for Tuesday with showers increasing in coverage through
the afternoon.  Looks like a trough goes through later in the day,
so these showers/storms should linger into the evening.

Despite the showers most areas will only see a tenth of an inch or
less through Tuesday evening.  Temps will slowly slip back, from 70
to 75 on Monday, to the 60s on Tuesday.

.LONG TERM...(Wednesday through Sunday)
Issued at 330 PM EDT Sun May 28 2017

Some gradual improvement will occur in the extended period as an
upper low slowly moves east. After a few diurnally enhanced showers
on Wednesday, there should be a dry period as sfc high builds in and
heights rise Wednesday night into early Thursday, before area of
isentropic ascent in warm advection pattern brings the chance of
some showers late Thursday.

There is low confidence in the forecast by end of the week and into
the weekend as ensemble spread increases. Canadian sfc high may hold
on for Friday and Saturday or there could be an area of warm
advection and isentropic ascent bringing scattered showers as a sfc
low tracks across southern Canada.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 115 AM EDT Mon May 29 2017

VFR expected through the period. Chances for a few showers are not
zero however due to the presence of an upper low spinning over the
Great Lakes, but are low enough to not include in the tafs.

&&

.MARINE...
Issued at 330 PM EDT Sun May 28 2017

Still expecting some higher winds and waves into Monday afternoon.
With the cold advection these conditions should linger into Tuesday
afternoon before diminishing.


&&

.HYDROLOGY...
Issued at 1236 PM EDT Sun May 28 2017

Not expecting any significant impacts from thunderstorm activity
today or showers on Memorial Day. While some rivers in the
Kalamazoo River basin may be running above normal this week, many
rivers will likely run near normal. Any rises should be well
within banks. No flooding is anticipated.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

UPDATE...MJS
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...Ostuno
AVIATION...04
HYDROLOGY...Hoving
MARINE...JK



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