837
FXUS63 KGRR 082331
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
731 PM EDT Wed Jul 8 2026
.KEY MESSAGES...
- Slow moving front brings rain tonight and Thursday
- Upper High builds in early next week
&&
.DISCUSSION...
Issued at 258 PM EDT Wed Jul 8 2026
- Slow moving front brings rain tonight and Thursday
Thunderstorms ahead of the cold front have shown a weakening trend
last couple hours as they move over Lake Michigan and we do not
expect significant rain or thunder until closer to midnight as
the front sags in from the northwest.
Severe and excessive rainfall threats are low overnight as the
front moves through with limited instability, shear and deep
moisture, but the southern zones could see some resurgent
convection on Thursday morning. With deeper moisture pooling south
of the front, any training of thunderstorms could bring minor
flooding.
Showers could linger through Friday afternoon across the southern
zones as the front becomes parallel to the upper flow and slows
down or stalls.
- Upper High builds in early next week
Large scale subsidence and drying begins over the weeknight as an
upper high builds across the Northern Plains and edges into Lower
Michigan. Expect a spell of hot and dry weather for early next
week before heights fall as an upper trough amplifies across
eastern Canada.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 731 PM EDT Wed Jul 8 2026
Main change this update was to add a bit more detail after 12Z
with prevailing groups of precipitation instead of PROB30s. Rain
showers seem increasingly likely during this time but there is
some question regarding thunder potential earlier in the day prior
to maximum diurnal destabilization. The most plausible scenario is
needing a brief mention of prevailing thunder at LAN/JXN...and
possibly BTL as well...towards afternoon. Given that this is too
far out to assign large probabilities to, have omitted that level
of detail for now.
&&
.MARINE...
Issued at 258 PM EDT Wed Jul 8 2026
Scattered thunderstorms with gusty winds and heavy downpours will
be moving southeast across Lake Michigan tonight into Thursday
morning. Otherwise, conditions will continue relatively tranquil
into the weekend. As high pressure builds in on Thursday into
Friday, north winds could gust to 20 knots, otherwise winds should
remain at 15 knots or less.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT tonight for MIZ050-056-057-
064-065-071.
MARINE...None.
&&
$$
DISCUSSION...Ostuno
AVIATION...TJT
MARINE...Ostuno
NWS GRR Office Area Forecast Discussion
