Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 120452

Area Forecast Discussion
National Weather Service Grand Rapids MI
1252 AM EDT Wed May 12 2021


Issued at 327 PM EDT Tue May 11 2021

-Two more frosty nights

-Dry through the weekend; warmer

-Chance for some rain next week


.DISCUSSION...(This evening through next Tuesday)
Issued at 327 PM EDT Tue May 11 2021

--Two more frosty nights--

Large surface high building in from the west and dry air mass
with clear skies will bring ideal radiational cooling conditions
conducive to frost the next couple nights. The current diurnal
cumulus and isolated showers, related to the cold air aloft and
strong May sun angle, will fade with sunset. Diurnal clouds likely
reforming on Wednesday afternoon inland from Lk MI, but not as
extensive as today (and no showers expected) due to subsidence.

Tonight will be the coldest of the next two and with many
locations expected to dip below freezing again have issued a
Freeze Warning areawide. Temps on Wednesday night should be a few
degrees warmer but still cold enough for frost, although a freeze
is possible again near and north of U.S. 10.

--Dry through the weekend; warmer--

The surface high becomes anchored over the Great Lakes Region,
moving little through Saturday. Result will be mostly
sunny/pleasant days from Thursday through Saturday with low
humidity and highs in the mid to upper 60s. Chilly nighttime lows
will still occur however as the dry air remains in place and
wouldn`t rule out more frost over northern sections of the CWFA.
As the high slips away on Sunday and the return flow develops, we
should warm to the lower 70s for highs along with more in the way
of mid and high level cloudiness in developing WAA pattern.

--Chance for some rain next week--

Large QPF spread exists next week in ensemble guidance, but a
better chance of receiving much needed rain does develop.
Southerly flow off the gulf and northward moving warm front with
PWATs rising to over one inch looks to provide a good opportunity
for showers and perhaps some storms. Currently the best risk
appears to be on Monday and Tuesday, after which time the
position of the frontal boundary becomes more uncertain.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1252 AM EDT Wed May 12 2021

For the next three days expect nearly clear skies and light winds.
There will be a few cumulus clouds with bases from 4000 ft to 5000
ft during the late morning into the early afternoon each day too.

Surface high pressure will be slow to move east. The center of the
surface high will be near or over Michigan today into Friday. This
is why the winds will light and skies nearly clear through the


Issued at 327 PM EDT Tue May 11 2021

Cold north-northwest winds have really cranked up this afternoon
along the lakeshore and are sustained around 20 kts between
roughly Holland and Whitehall. This is flirting with advisory
criteria but since it will be diminishing soon late this
afternoon and early evening will not issue a headline. However
conditions will remain choppy through sunset with wave heights
around 3 ft.

Big surface high will settle over the Great Lakes Region from
Wednesday into the weekend, leading to a lengthy period of
relatively tranquil conditions on Lake Michigan. That said,
typical springtime diurnal lake breeze development will result in
periods of stronger onshore flow during the afternoon and early
evening hours.


MI...Freeze Warning until 8 AM EDT this morning for MIZ037>040-



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