829
FXUS63 KGRR 052350
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
750 PM EDT Sat Sep 5 2026
.KEY MESSAGES...
- Fair Weather through Labor Day
- Chance for showers and Thunderstorms Tuesday and Wednesday
&&
.DISCUSSION...
Issued at 157 PM EDT Sat Sep 5 2026
- Fair Weather through Labor Day
An Omega block develops across the CONUS this weekend as the
central U.S. upper high is bookended by cut off lows across the
NE and NW CONUS. This lowers heights across the central Great
Lakes and allows surface high pressure ridge to build in from the
northeast with lower temperatures and dew points. Showers end this
afternoon and clearing pushed south this evening with it becoming
noticeably cooler overnight. Morning lows on Sunday and Monday
expected to be in the upper 40s to lower 50s across the northern
forecast area.
- Chance for showers and Thunderstorms Tuesday and Wednesday
The surface high retreats east eastward by Tuesday. The Omega
block breaks down as a low across the Pacific NW kicks east and
flattens the upper high, with surface low pressure tracking across
southern Canada. Return flow of moisture and a surface warm front
should kick off some showers and thunderstorms late Tuesday into
Wednesday. Another round of storms will be possible as a cold
front moves through late Wednesday and shear profiles suggest
strong storms are possible if instability is sufficient.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 750 PM EDT Sat Sep 5 2026
Skies are trending mostly clear tonight following a fairly cloudy
day with some rain showers in southwest Michigan. Dew points at
the surface are still fairly high compared to the expected low
temperatures tonight. Some of the high resolution models are
developing fog or LIFR ceilings for pre-sunrise Sunday. The one
thing that might keep fog in check is 15-20 knot winds at 500
feet. Seems reasonable to plan on the potential for IFR ceilings
or visibility between 07 and 13 Z, though it is medium confidence.
&&
.MARINE...
Issued at 157 PM EDT Sat Sep 5 2026
Light offshore winds, generally less than 15 knots, can be
expected through Monday. High pressure will move east on Tuesday
and winds will be on the increase, with a Small Craft Advisory
probably being needed for Tuesday and Wednesday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Ostuno
AVIATION...CAS
MARINE...Ostuno
NWS GRR Office Area Forecast Discussion
