Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 240102

Area Forecast Discussion
National Weather Service Grand Rapids MI
902 PM EDT Mon Apr 23 2018


Issued at 307 PM EDT Mon Apr 23 2018

The dry weather that has been in place since last week will come to
an end tonight. Light rain showers will move in from south to north
tonight, and will remain possible into Wednesday. Cooler weather can
also be expected after this afternoon.

A brief break in the rain chances will occur Thursday, as we will be
in between systems. Another system will move in by Friday, bringing
rain chances to the area for Friday and Saturday. Quieter weather
will return late in the weekend and early next week.


Issued at 901 PM EDT Mon Apr 23 2018

Curiously a meso-low has developed over Allegan County late this
afternoon and has drifting north northeast toward Southwest Kent
County by 8 pm. The GRR 88d shows a fine-line moving northward
toward I-96 from I-94. As this fine-line crossed I-94 KAZO and
KBTL had winds go from southeast around 5 mph to southwest at
15mph gust 25 mph. This has been well picked up but the HRRRX so I
have done a short term update to the grids with shows this area
of 15 to 25 mph winds moving north to near I-96 by 10 pm then
dissipating. Anyone in northern Allegan, southern Ottawa and
southern Kent Count will see these wind gusts by 10 pm. I would
think the northern sections of Ottawa and Kent county should not
see this sort of thing as the sun has sent and this meso-low
should dissipate. No precipitation is assoicated with this wind
shift line.

It still looks like most of the showers will be more toward
sunrise Tuesday morning as there is a lot of dry air to overcome.
I have not significantly changed that part of the current


.SHORT TERM...(This evening through Wednesday)
Issued at 307 PM EDT Mon Apr 23 2018

Our main focus of the forecast is on the rain chances coming in
tonight, and how long they stick around. We have added some rain
chances in for Wednesday as the 00z ECMWF trends for rain to stick
around longer have continued for the new 12z run.

Very dry air mass in place this afternoon (RHs 15 to 30%) will keep
the area dry into this evening. Upper low across TN this afternoon
will slowly rotate to the NE through Tue. Broad deformation with the
upper low and moisture being advected to the NW ahead of the low
will bring some rain showers in overnight tonight.

The heavier rain showers with the upper low will stay SE of the
state. However, the moisture wrapping back into our area will be
acted upon by another upper trough that will dive in over the area
from the NW. This interaction will keep the showers in over the area
on Tue, and now into Wed.

The reason the showers are lingering over the area longer is the
upper trough diving in from the NW is showing signs of closing off
over the area. This will then slow the progression of the system
down. The system should not get stuck over the area too long as yet
another upper trough pushes in, and keeps the pattern somewhat
progressive. This should allow for the rain showers to end
gradually through the day on Wed.

.LONG TERM...(Wednesday night through Monday)
Issued at 307 PM EDT Mon Apr 23 2018

A low pressure system will swing south from Canada and then east
over the Great Lakes Region Thursday night and Friday. This will
bring a chance of rain showers, possibly with some wet snow flakes
over Central Lower Michigan and points north. No impacts are
expected due to precipitation, and no other weather should occur in
the long term.

Cooler than normal conditions are expected behind the low over the
weekend with temperatures returning to near normal early next week.
Normal highs are in the lower 60s with lows around 40 degrees.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 713 PM EDT Mon Apr 23 2018

The solid VFR conditions of the past few days is about to come to
an end as the system to our south heads slowly north. I expect the
MVFR cigs to reach our I-94 TAF sites in the 04z to 07z time frame
the the I-96 sites in the 09z to 12z. Some light rain or drizzle
is expected lowering visibilities to MVFR possibly even IFR at
times. These conditions will continue past 00z Wednesday. Surface
winds should mostly stay under 12 knots and from an easterly


Issued at 307 PM EDT Mon Apr 23 2018

Quiet conditions into Tuesday with lake breezes expected for the
remainder of this afternoon and Tue afternoon. Next possible
headline needed will be Tue night into Wed with a tightening
pressure gradient expected. This bout of windier conditions will
likely be mostly an offshore component, so waves will be limited a


Issued at 307 PM EDT Mon Apr 23 2018

Warm and dry conditions will persist into the evening tonight,
before some relief will arrive by Tue. The relief will arrive in the
form of higher dew points and some rain for most of the area. This
should limit fire danger some for a few days with cooler weather


Issued at 307 PM EDT Mon Apr 23 2018

Five Flood Advisories remain on the area rivers as of this morning.
River levels are cresting up north where snow melt from Northern and
Central Lower has allowed for some runoff. The snow has pretty much
entirely melted in the Muskegon basin, so river levels will start
coming down.

For all areas, rain is expected tonight into Wed. Basin averages
should be mostly under quarter of an inch, with everybody expected
to stay under half an inch. This over a period of time should not
cause any rises on the rivers this week.




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