947
FXUS63 KGRR 251047
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
647 AM EDT Sat Jul 25 2026

.KEY MESSAGES...

- Northwest flow regime continues with occasional chances for rain
  with low confidence convection forecast

&&

.DISCUSSION...
Issued at 230 AM EDT Sat Jul 25 2026

- Northwest flow regime continues with occasional chances for rain
  with low confidence convection forecast

The Great Lakes region remains in between an upper high across
the western CONUS and longwave troughing across the eastern CONUS
with occasional shortwave troughs passing through and bringing
the chance for some much-needed rain.

A weakening shortwave trough moves through tonight. Not much
moisture available and the best lift is off to the east, so
low/slight chance POPs and limited QPF in the current forecast
looks good.

There is inherent low confidence in the details of how things
play out Sunday night through Tuesday given the lack of strong
dynamic lifting mechanism, but instability and shear are
sufficient for a slow-moving front and weak midlevel vorticity max
to focus convection across Minnesota/Wisconsin Sunday afternoon
which eventually moves southeast into western Lower Michigan. The
failure of the last two similar synoptic scenarios to produce so
much as a lightning strike in our forecast area leads to
skepticism, but every drought has to end sometime.

The front moves through Tuesday with fair weather for mid to late
week before the longwave upper trough amplifies with a cold
front bringing another chance of rain by next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 647 AM EDT Sat Jul 25 2026

VFR conditions expected to continue through Sunday morning.
Southwest winds today AOB 10 knots diminishing to 5 knots or less
tonight.

&&

.MARINE...
Issued at 230 AM EDT Sat Jul 25 2026

Decided to hold off on a SCA/BHS for Saturday afternoon/evening
given tendency for observed winds and waves to be lower than
model forecasts during southwest flow warm advection set up. The
day shift will have to monitor trends, especially around Little
and Big Sable points.

Gusty winds in thunderstorms are possible Sunday evening into
Monday and a SCA/BHS is likely for late Monday and Tuesday as
high pressure builds in.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Ostuno
AVIATION...Ostuno
MARINE...Ostuno