457
FXUS63 KGRR 021857
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
257 PM EDT Sat Aug 2 2025

.KEY MESSAGES...

- Fair, Smokey and dry into mid next week.

- Chances for rain late Wednesday into Thursday

- Hot and humid weather could return into next weekend


&&

.DISCUSSION...
Issued at 246 PM EDT Sat Aug 2 2025

- Fair, Smokey and dry into mid next week.

 New guidance from Michigan EGLE came in this morning and the
Canadian wildfires will keep the Air Quality Alerts flying through
tomorrow. The short to mid term trends don`t look to afford any
relief through the first half of the week. Latest HRRR sfc and
vertically integrated smoke keeps it hazing up the skies.

    The driver, or lack there of, of the stagnation is a high
pressure system that will dominate the air mass over the Great Lakes
through the first half of next week. While this will keep fair
temperatures, in the mid 80s, it will also have light winds at the
surface and northwest flow overtop of the high. That northwest flow
continue to advect the wildfire smoke into Michigan.  What is needed
to change that will be a change in air flow. While there is a chance
of happening Wednesday, there are a lot of question and not
confident on that occuring.

- Chances for rain late Wednesday into Thursday

  The tale of next week will be that of two highs. One over the East
coast and and one over the desert southwest. Upper level flow
from the west will skirt through the northern US and along the
Canadian border. Moist southerly flow will be pulled up in between
these two highs as the low from the northwest moves into the
midwest. A negatively tilted trough will give the region a chance
for rain Wednesday into Tuesday. There are some questions as to
if there will be enough  moisture and the trough will be more
divergent given the eastern High.

  The mid to upper level trough will slowly advect into the Great
Lakes into Thursday. Given the warm and dry air overhead
precipitation should be limited if it occurs at all.

- Hot and humid weather could return into next weekend

The upper level trough from the west should flatten out and this
should allow for warm aid advection from the southwest through the
latter half of next week. Latest mid to long range models continue
to be in sync with the long range ensembles. There remains the
potential for max temps to get into the 90s end of next week.
This is consistent with the overall pattern. Hot, moist air into
next weekend could bring chances for showers. While it remains
questionable, and as such don`t have strong confidence. Stay
tuned.


&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 116 PM EDT Sat Aug 2 2025

Primary concern for aviation interests over the next 24 hours is
the presence of near-surface wildfire smoke. Wildfire smoke will
begin mixing down from aloft over the next few hours leading to
visbys falling to MVFR levels at most terminals. This is already
being seen at terminals across northern lower MI. MKG should be
slightly better due to being adjacent to the lake with lower
mixing. HRRR forecasts suggest these conditions will continue
through the night into Sunday, particularly at GRR and LAN, as
smoke becomes trapped under the nocturnal inversion. Northeasterly
winds are expected today except for MKG who will be westerly due
to the lake breeze. Light and variable winds overnight will
increase from the east Sunday. A lake breeze looks to once again
develop at MKG Sunday afternoon.

&&

.MARINE...
Issued at 116 PM EDT Sat Aug 2 2025

High pressure and weak gradient flow will keep winds and waves
below hazardous levels over the next several days. The two primary
marine concerns are smoke on the water and upwelling. First,
wildfire smoke mixing down from aloft may lead to intermittent
periods of reduced visibilities. Mixing will be notably less than
over land so impacts will be limited. Continued effects of
upwelling are also noted leading to cool temperatures along the
lake. Many observation sites are reporting water temperatures in
the upper fifties to lower 60s today.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT Sunday night for MIZ037>040-
     043>046-050>052-056>059-064>067-071>074.
MARINE...None.

&&

$$

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