282
FXUS63 KGRR 151037
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
637 AM EDT Wed Jul 15 2026
.KEY MESSAGES...
- 20 Percent Chance for Pop-Up Thunderstorms Today
- Heat Continues with Wildfire Smoke Moving in Today into Tomorrow
- Several Chances for Showers and Thunderstorms Friday into Next
Week
&&
.DISCUSSION...
Issued at 240 AM EDT Wed Jul 15 2026
- 20 Percent Chance for Pop-Up Thunderstorms Today
Most if not all stay dry today, but and isolated thunderstorm is
possible between 5PM to 11PM. A weak boundary moving through may
be enough lift with SBCAPE values around 2000 to 2500 J/kg and
precipitable water values around 1.5 inches to spark off
thunderstorms in southeast and south central Michigan. If storms
occur, they`ll develop quickly and possibly contain gusty winds.
- Heat Continues with Wildfire Smoke Moving in Today into Tomorrow
Highs are expected to be in the 90s once more with heat index
values in the upper 90s to low 100s. The smoke from wildfires in
Canada will slowly move in from the north throughout the day. The
RAP and HRRR bring this smoke down to the surface reducing
visibilities and air quality. An Air Quality Alert is in place
into Thursday. Limit time outdoors, make sure to keep windows
closed, and if possible run central air conditioning with higher
rated filters.
Thursday temperatures will be a little cooler with highs in the
upper 80s to low 90s and heat index values right around air
temperatures.
- Several Chances for Showers and Thunderstorms Friday into Next
Week
Within the northwest flow we`ll see heights lower slowly Thursday
into Friday. Positive vorticty advection will gradually sink
south with moisture increasing. Instability will also be on the
rise allowing for scattered showers and thunderstorms to develop.
Heading into Saturday a deeper shortwave trough is expected to
swing through the region. The low level jet is trending stronger
with this system along with average MUCAPE values around 2000 to
3000 J/kg. As mentioned in the prior discussion, there is a
potential for strong to severe storms. With this deeper shortwave,
dry air moves in for Sunday resulting in a nice summer day with
highs in the 80s.
Another shortwave trough swings through Monday into Tuesday
bringing additional chances for rain and thunderstorms.
Temperatures on the backside will be colder with highs only
forecast to be in the 70s to low 80s Tuesday and Wednesday.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 637 AM EDT Wed Jul 15 2026
No changes from the previous discussion. VFR conditions are
expected initially today with westerly winds around 5 to 15 knots.
Wildfire smoke will slowly move in from north to south today
reaching MKG, GRR, LAN around 22Z and JXN, BTL, and AZO around 3Z.
Smoke is expected to reduce visibilities into the 3 to 5 SM
range, but there is a potential that visibilities could drop down
to 1 to 2 SM at times. Pop-up thunderstorms are also possible
today toward LAN and JXN, therefore kept the PROB 30 group from
the previous forecasts. If storms develop they could produce
isolated higher wind gusts.
&&
.MARINE...
Issued at 240 AM EDT Wed Jul 15 2026
Winds and waves are expected to remain below Small Craft Advisory
and Beach Hazard Statement levels through Friday. Northerly winds
are expected around 5 to 15 knots peaking during the afternoon and
early evening. Wave heights are expected to be 2 feet or less.
Thunderstorms are possible Friday but better chances exist for
Saturday. Saturday winds and waves could reach Small Craft
Advisory and Beach Hazard statement levels with an approaching low
pressure system. Lighter winds return Sunday resulting in a nice
summer day to wrap up the weekend.
&&
.CLIMATE...
Issued at 240 AM EDT Wed Jul 15 2026
Here are the high temperature records for July 14 and 15.
Location July 15
Grand Rapids 95 (2013)
Lansing 99 (1977)
Muskegon 93 (1995)
Kalamazoo 103 (1936)
Battle Creek 100 (1977)
Holland 98 (1932)
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Heat Advisory until 8 PM EDT this evening for MIZ037>040-043>046-
050>052-056>059-064>067-071>074.
Air Quality Alert until midnight EDT tonight for MIZ037>040-
043>046-050>052-056>059-064>067-071>074.
MARINE...None.
&&
$$
DISCUSSION...RAH
AVIATION...RAH
MARINE...RAH
CLIMATE...RAH
NWS GRR Office Area Forecast Discussion
