Portage, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

679
FXUS63 KGRR 161047
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
647 AM EDT Thu Jul 16 2026

.KEY MESSAGES...

- Poor Air Quality and Reduced Visibilities From Smoke Thursday

- Several Chances of Showers and Storms Through Early Next Week

- Temperatures Cooling Through Early Next Week

&&

.DISCUSSION...
Issued at 230 AM EDT Thu Jul 16 2026

- Poor Air Quality and Reduced Visibilities From Smoke Thursday

Primary forecast concern over the next day is impacts from near-
surface and aloft wildfire smoke across the area. ASOS
observations show widespread visibilities in the 1-3SM range as a
result of smoke. Some areas across Lower Michigan have fallen as
low as 1/2SM at times in the last 24 hours, and cannot rule out
similar conditons here as another pocket of near-surface smoke
arrives near daybreak. HRRR/Canadian smoke guidance shows near-
surface smoke persisting through the day today. Air quality
observations show unhealthy to locally hazardous conditions, and
an Air Quality Alert remains in effect areawide from Michigan`s
Department of Environment, Great Lakes, and Energy.

- Several Chances of Showers and Storms Through Early Next Week

A series of fronts and shortwaves drive several shower and
thunderstorm chances through early next week. First is Friday with
a warm front crossing the area. However, low-level moisture
quality is poor limiting precipitation potential. A cold front
Saturday brings greater potential for showers and storms, along
with ample CAPE and decent kinematics. However, ample MLCIN will
help put a check on storm development, with the best chance east
of US-127 into southeast Michigan. Given the ample CAPE/Shear, any
storms that develop could be strong to severe, so forecast trends
will need to be monitored. Another cold front Monday Night into
Tuesday brings a third round of shower/storm chances to the area.

- Temperatures Cooling Through Early Next Week

850mb temps will fall from near 20C over the next day or two to
the low to mid teens by mid next week. This will cause highs to
fall from the low 90s Thursday/Friday to the low 80s by early
next week. With lower post-frontal dewpoints expected after the
front bringing smoke to the area tonight, heat indices will be
limited to the 90s, cooler than previous days.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 628 AM EDT Thu Jul 16 2026

According to ASOS observations, widespread IFR conditions
continue across the terminals this morning due to near-surface
smoke with periods of LIFR at some terminals. This is likely to
continue through late morning until daytime mixing allows for
improvement to MVFR with intermittent IFR possible through much of
the rest of the TAF period. Smoke has also led to the development
of an effectively MVFR ceiling, dipping below 2kft at times.
Overall, wildfire smoke will lead to significant impacts to
aviation over the next 24 hours.

&&

.MARINE...
Issued at 645 AM EDT Thu Jul 16 2026

Webcams show widespread dense smoke north of Holland with smoke
starting to become dense south of Holland. In collaboration with
other Lake Michigan offices, have issued a Dense Smoke Advisory
through early afternoon. Will let day shift reassess to see if an
extension is needed as daytime mixing develops.

--- Previous Discussion Issued 230 AM EDT Thu Jul 16 2026---

Widespread smoke is expected across the waters with visibilities
below one mile possible at times. If confidence increases in lower
visibilities a Marine Dense Smoke advisory may be needed. Between
Friday morning and Saturday, a series of fronts bring the
potential for isolated thunderstorms over the waters. In addition,
strengthening northwest flow is expected to develop Saturday,
causing waves to build to at least 3-5 ft. This makes it likely
conditions will be hazardous to small craft and boaters.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT tonight for MIZ037>040-
     043>046-050>052-056>059-064>067-071>074.
MARINE...Dense Smoke Advisory until 2 PM EDT this afternoon for
     LMZ844>849.

&&

$$

DISCUSSION...Thomas
AVIATION...Thomas
MARINE...Thomas