542
FXUS63 KGRR 161944
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
344 PM EDT Tue Jun 16 2026
.KEY MESSAGES...
- Chance for Severe Storms this afternoon and evening
- Slight Risk for Severe Weather Tomorrow, Minor flooding possible
- Quieter Late Week with rain and storms possible Sunday
&&
.DISCUSSION...
Issued at 252 PM EDT Tue Jun 16 2026
- Chance for Severe Storms this afternoon and evening
Storms have begun throughout the southern Peninsula today. An
upper level trough is bringing a short wave with two LLJ`s
associated with it. The first LLJ is associated out ahead of the
trough and is driving the current storms moving through Central
and Eastern Lower MI. Two more lines will be moving through MI as
the day progresses. Those have the potential to be stronger as a
perpendicular 40kt LLJ will be driving those storms. Low topped
supercell thunderstorms will be the main mode of convection. While
there is not a lot of DCAPE over the region, there is around 1000
J/kg upstream. With MUCAPE around 1K J/KG and increasing bulk
shear there will be an increased risk for severe storms. The
strongest storms should be associated with the front as it moves
through between 6 PM and 9 PM. The main threat will be from
damaging winds and large hail. However, With PV anomalies and the
previously mentioned LLJ providing sufficient shear, there is a
chance for tornadoes, especially through far southwest Michigan.
- Slight Risk for Severe Weather Tomorrow, Minor flooding possible
Another round of storms remains likely tomorrow. A large upper
level low will move through WI, IL and into IN. The best forcing,
along with upwards of an 80kt LLJ, will be through those regions
with MI being in the warm sector. The boundary will remain
through far southern Michigan. So while storms are expected and
damaging winds will be possible, the biggest threat will be from
heavy rainfall. Anomalous 1.5 inch to 2 inch PWATS with strong
moisture transport vectors are indicative of the plethora of
moisture associated with the system. As the low moves overhead
there should be a long residence time, with 1 to 2 inch per hour
rates. Due to this there is expected a wide swath of 1 to 2 inches
along and south of the I-96 corridor with locally heavy amounts
upwards of 3 or more possible. The best threat for showers and
storms will be later in the day. Given those conditions, minor
flooding will be possible, especially along and south of the I 94
corridor.
- Quieter Late Week with rain and storms possible Sunday
Cooler, drier flow will move through in the wake of the system
with broad high pressure. The next chance for rain will be from a large
upper level low that drops from the north and coincides with a
mid level and sfc low propagating eastward. There is some
questions on timing and position but late in the weekend to early
next week should be a rainy and stormy period.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 141 PM EDT Tue Jun 16 2026
Showers and storms continue to develop over Wisconsin and Lower
MI. Some of those storms could be strong to severe this afternoon
and evening. An upper trough is responsible for the storm
development. Generally VFR conditions are expected through the
period. However, during storms, MVFR and potentially IFR
visibilities are possible.
&&
.MARINE...
Issued at 319 PM EDT Tue Jun 16 2026
Small craft advisory and beach hazards statement remains in place
through the rest of the evening. After the frontal system passes
the winds and waves will subside.
Showers and storms will move through tomorrow, though winds and
waves will be offshore. Another round of strong winds and waves
are expected tomorrow night into Thursday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through late tonight for MIZ037-043-050-
056-064-071.
MARINE...Small Craft Advisory until 4 AM EDT Wednesday for LMZ844>849.
&&
$$
DISCUSSION...Ceru
AVIATION...CAS
MARINE...Ceru
NWS GRR Office Area Forecast Discussion
