FXUS63 KGRR 040003

Area Forecast Discussion
National Weather Service Grand Rapids MI
803 PM EDT Tue Oct 3 2023


.SHORT TERM...(This evening through Wednesday night)
Issued at 338 PM EDT Tue Oct 3 2023

Changes are on the way but for the time being we remain in a very
summerlike pattern with record/near record warmth. The first
change will be for increasing cloudiness tonight and tmrw with the
approach of the upper trough from the west as the upper ridge
axis slips east. High temps Wednesday will still be 15 degrees or
more above normal inland from the Lk MI shoreline though,
especially if the cloud cover isn`t particularly thick.

The showers associated with the incoming sfc cold front primarily
hold off until Wednesday night, although a few could arrive into
the Ludington area by late in the afternoon (after 4 pm or so).
Breezier conditions will develop Wednesday, most notably along
the lakeshore north of Holland where south winds could gust up to
30 MPH.

Fairly widespread coverage of showers is anticipated on Wednesday
night as PWATs surge to 1.5 inches along the cold front, but the
slow movement of the front (due to it being parallel to the upper
level flow) could delay rainfall arrival south and east of GRR
until very late at night or even toward morning, especially
around JXN.

.LONG TERM...(Thursday through Tuesday)
Issued at 338 PM EDT Tue Oct 3 2023

A dynamic and amplified evolution of the polar jet stream across
North America will dig an upper level trough into the Midwest and
Great Lakes in the latter half of this week, which will transition
to serve as the eastern foot of an omega block early next week. A
series of cold fronts will pass through our area Thursday-Friday,
and we will find ourselves in the trough of cold air (with 850 mb
temperatures near 0 C) over the weekend, on the west side of a
maturing cyclone.

Ensembles remain in strong support of progressively colder
temperatures Thursday through Sunday, followed by a tendency for
moderating temperatures early next week. Rain showers are likely
with a chance of thunder ahead of the first cold front from
Wednesday night to Thursday. Instability looks modest, though deep
moisture and a healthy amount of lift would support a chance of rain
amounts around 1 inch, particularly south/east of Grand Rapids and
lesser amounts northwest.

Much of Friday may be dry, then lake-enhanced rain showers are
likely from late Friday into at least Saturday. There are a few
members in the ensemble envelope which produce heavy rain (greater
than an inch) over the weekend if the wraparound mid-level moisture
on the west side of the cyclone nudges back toward our area rather
than staying farther east-northeast. Winds over the weekend may also
gust over 30 mph. Quite a dramatic seasonal change in the weather is
on the way.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 805 PM EDT Tue Oct 3 2023

Prevailing VFR will continue the next 24 hours with southerly
winds. While moisture is depleted, there is still a chance for
localized MVFR vsbys overnight. The warm air tomorrow should allow
for gusty winds to mix to the sfc late tomorrow morning and
through the afternoon.


Issued at 338 PM EDT Tue Oct 3 2023

Have issued a Small Craft Advisory north of Holland from 8 AM
Wednesday through Midnight for a period of south winds 15 to 25
kts ahead of an approaching cold front. Waves will build to 3-5
feet, largest near Big and Little Sable Points, before subsiding
overnight in baggier sfc pressure gradient as the cold front
nears. Other marine headlines are a near certainty from Friday
through the weekend as progressively colder air flows in on the
heels of brisk west/northwest winds.


Issued at 338 PM EDT Tue Oct 3 2023

Record highs through Wednesday:

                 Today                 Wed

Grand Rapids    85 - 1953,`19,`00    87 - 1951
Muskegon        83 - 2018            83 - 1951
Lansing         90 - 1898            86 - 1951,`00
Kalamazoo       88 - 1953            90 - 1951
Battle Creek    88 - 1953            87 - 1951
Jackson         89 - 1953            90 - 1951
Holland         86 - 1919            89 - 1951


LM...Small Craft Advisory from 8 AM Wednesday to midnight EDT
     Wednesday night for LMZ846>849.




NWS GRR Office Area Forecast Discussion