River Flood Warning 9, NWS Grand Rapids, MI

Area Forecast Discussion
National Weather Service Grand Rapids MI
742 AM EDT Sat Apr 4 2026

.KEY MESSAGES...

- Showers and Storms Today

- Colder with some Lake Effect Snow Sun-Tues

- Some Precipitation Thu-Sat

&&

.DISCUSSION...
Issued at 351 AM EDT Sat Apr 4 2026

- Showers and Storms Today

Showers and thunderstorms are ongoing at this time (330am) and
will continue through the morning. In fact we expect an increase
in coverage early this morning as a strong low level jet moves in.
Instability is not strong and not forecast to become strong this
morning, holding on the order of 500 j/kg or so. This should not
be enough instability to result in severe weather. A cold front
will move through and clear the better rain chances to the east
later this afternoon. Not out of the realm of possibilities to see
a stronger storm towards Jackson in the mid to late morning ahead
of cold front, but again severe weather is unlikely. See the hydro
section below for details.

- Colder with some Lake Effect Snow Sun-Tues

The cold front will usher in a much colder airmass over time.
Highs Sunday through Tuesday will be in the 40s. We will be cold
enough for some lake effect snow from Sunday night through Monday
night. Some locations downwind of the big lake will see the ground
turn white again with accumulations ranging from trace amounts to
around 1 inch.

- Some Precipitation Thu-Sat

A cold front will move into the region Wednesday night and stall
out on Thursday. Rain showers are expected during this time frame.
Beyond Thursday there is some disparity in the models but it
appears wet weather may continue, especially when looking at the
GFS. Temperatures warm back into the 60s for highs during this
time frame. Very much a spring like pattern as temperatures whip
back and forth both above and below normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 743 AM EDT Sat Apr 4 2026

Widespread showers are now over the area just before 12z, with
isolated lightning also being observed. Just about all of the area
is IFR with regards to ceilings. We expect that the thunder potential
will have ended at KMKG by 12z, and will quickly diminish by 15z
at all of the terminals. This will leave showers through much of
the rest of the day. IFR to LIFR conditions will rule mainly due
to the ceilings.

Rain showers should start to diminish from west to east this
afternoon and through the evening hours. Conditions will improve a
bit as somewhat drier air moves in and lifts ceilings to MVFR.
Then late tonight, a few rain and snow showers will rotate through
the area, bringing additional MVFR conditions.

&&

.MARINE...
Issued at 351 AM EDT Sat Apr 4 2026

A cold front will sweep through the area today and west winds
will increase behind it. West winds to 30 knots looks very likely,
but gales to 35 knots is plausible as well. We will be monitoring
closely from late this afternoon into tonight to see if gale
force winds become common. Waves of 6 to 9 feet look likely on
Sunday in strong cold air advection.

&&

.HYDROLOGY...
Issued at 351 AM EDT Sat Apr 4 2026

2 to 4 inches of rain has fallen over the past 5 days in Southwest
Lower Michigan. The ground is saturated and water is routing
through the river systems. Another round of showers and
thunderstorms is underway as of 300am early this Saturday morning.
A classic setup for heavy rain presents itself this morning with
a strong low level jet at 850mb of 45-55 knots surging PWAT values
of 1.5 inches into the region. Periods of showers and
thunderstorms are expected from 300am through roughly 300pm.
Another 0.50 to 1.00 inch of new rainfall is expected today.

We currently have River Flood Warnings (that were issued
overnight) for Maple Rapids on the Maple River as well as
Vicksburg on the Portage River in effect. River Flood Watches
remain at Newaygo and Bridgeton on the Muskegon.

The added forecast rainfall should send many area rivers higher.
We are expecting a few more River Flood Warnings as we move
through the next few days.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT Sunday for LMZ844>849.

&&

DISCUSSION...Duke
AVIATION...NJJ
MARINE...Duke
HYDROLOGY...Duke

Hazardous Weather Outlook
National Weather Service Grand Rapids MI
420 AM EDT Sat Apr 4 2026

MIZ037>040-043>046-050>052-056>059-064>067-071>074-050830-
Mason-Lake-Osceola-Clare-Oceana-Newaygo-Mecosta-Isabella-Muskegon-
Montcalm-Gratiot-Ottawa-Kent-Ionia-Clinton-Allegan-Barry-Eaton-
Ingham-Van Buren-Kalamazoo-Calhoun-Jackson-
420 AM EDT Sat Apr 4 2026

This hazardous weather outlook is for portions of southwest Lower
Michigan.

.DAY ONE...Today and Tonight

Thunderstorms are expected from early this morning through the
afternoon across Southwest Lower Michigan. At this time severe
thunderstorms are not expected. The main threats will be locally
heavy rain and flooding along with cloud to ground lightning
strikes.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Minor river flooding will persist into early and mid week as
water routes through the river systems.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

LMZ844>849-050830-
St Joseph to South Haven MI-South Haven to Holland MI-
Holland to Grand Haven MI-Grand Haven to Whitehall MI-
Whitehall to Pentwater MI-Pentwater to Manistee MI-
420 AM EDT Sat Apr 4 2026

This hazardous weather outlook is for the nearshore waters from
St Joseph to Manistee.

.DAY ONE...Today and Tonight

Conditions will be hazardous to Smaller Craft out on Lake Michigan
both today and tonight as winds increase out of the west.
Thunderstorms will remain possible into early afternoon. Cloud to
water lightning strikes will be the main threat from storms today.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Conditions will remain hazardous to smaller craft through the day
on Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.