Severe Thunderstorm Warning 87, NWS Grand Rapids, MI

Area Forecast Discussion
National Weather Service Grand Rapids MI
721 PM EDT Mon Jun 15 2026

.KEY MESSAGES...

- Showers and storms with a chance for severe Tuesday

- More organized convection Wednesday with heavy rainfall possible

- Unsettled weather pattern continues

&&

.DISCUSSION...
Issued at 259 PM EDT Mon Jun 15 2026

- Showers and storms with a chance for severe Tuesday

 The forecast remains fairly consistent. An upper level node will
swing through the Great Lakes tomorrow. Corresponding mid level
trough will aid in instability. The strong gradient will allow
for strong southerly flow throughout the day. While temperatures
remain cooler than normal, with dewpoints only in the 60s, any
sunshine will aid the 1K J/kg of CAPE. Latest ensembles chances
for several lines to move through. First one will be fairly weak
and if the atmosphere remains unstable there is a better chance
for strong to severe storms early Tuesday evening. Shear remains
nominal but there is some signal for better shear as the mid level
trough moves overhead after 22Z.

- More organized convection Wednesday with heavy rainfall possible

 The upper level low situated over central Canada is the weather
system that is driving the weather pattern this week. It is the
system that the above mentioned node is moving off of.
 Another short wave will move through the Midwest and then the
Great Lakes on Wednesday. The difference from Tuesday's system is
that it has better moisture and a closed low in the mid levels and
at the surface. With this better organization it has stronger
winds and shear and thus a better chance at producing severe
weather. However, there remains some questions on timing and
position. The negatively tilted trough off the 850mb low will
bring a frontal system through late Wednesday. Out ahead of that
frontal system is approx. 1 to 2 inches of QPF. Given that amount
of weather, along withe the instability warrants the slight risk
that SPC has along and south of the I 94 corridor for Michigan.
Will need to hone in on timing but damaging winds will be possible
late Wednesday. As heavy rainfall is likely, localized flooding
Wednesday evening will be possible.

- Unsettled weather pattern continues

 The upper level low over Canada will slowly move eastward but
will continue to cycle cooler and wetter weather through the area
through the rest of the week. This will keep temperatures below
normal and keep chances for rain this week, especially the
upcoming weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 720 PM EDT Mon Jun 15 2026

A broken cirrus deck is moving across the terminals this evening.
VFR expected overnight. An approaching cold front may generate
showers/storms after 20z Tuesday and a prob30 group was included
in the TAFs to address this.

&&

.MARINE...
Issued at 259 PM EDT Mon Jun 15 2026

The strong westerly flow from last evening is slowly subsiding
this afternoon. That flow had caused 2 to 5 foot waves to the
lakeshore between Saugatuck and Pentwater.
 Waves at Grand Haven and Holland continues to have near 5 footers
this afternoon. Waves will continue to slacken as the afternoon
continues and into the early evening.
 Strong southerly flow will move in tonight bringing strong
southerly winds. Those winds and waves will bring another round of
SCA conditions with widespread beach hazards through Tuesday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 8 PM EDT this evening for MIZ050-
     056-064.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ845>847.

&&

DISCUSSION...Ceru
AVIATION...04
MARINE...Ceru