336
FXUS63 KGRR 231800
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
200 PM EDT Tue Jun 23 2026
.KEY MESSAGES...
- Showers/storms Wednesday, then clearing Thursday
- 70s through Friday, then heat
&&
.DISCUSSION...
Issued at 200 PM EDT Tue Jun 23 2026
- Showers/storms Wednesday, then clearing Thursday
HIgh pressure and sunny skies this afternoon will soon be replaced
by an Alberta Clipper Wednesday; This type of system is usually
more indicative of winter through mid spring, but this has been a
relatively cool stretch of weather and we`ve have one more clipper
to go before the heat develops.
The clipper is currently nearing the Canada/Montana border and
will move across the northern Great Lakes tonight and Lower MI
Wednesday. Clouds will advect over the region late tonight and
showers and storms will move in either late tonight or early
Wednesday. The northwest cwa should see precipitation first.
Despite meager mid level lapse rates...5-5.5C/Km...this system
will also arrive with a push of moisture. A 35kt llj will move
over the cwa Wednesday coincident with a plume of 1.5 inch
precipitable water. More importantly, models show 40-45kts of bulk
shear Wednesday afternoon. These dynamics should be enough to
generate storms and a few could be strong to perhaps severe.
High pressure will build in from the north Thursday and last
through much of the weekend before we under a pattern change.
- 70s through Friday, then heat
A deepening upper trough over the northern Rockies will result in
a building upper ridge over the Great Lakes late in the weekend
and early next week. The increasing heights will result in highs
moving through the 80s to perhaps 90; it`ll feel more like summer.
Dewpoints will also climb into the mid to upper 60s to make it
very humid. Apparent temperatures by Monday and Tuesday are
likely to be in the upper 90s to lower 100s.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 117 PM EDT Tue Jun 23 2026
Diurnal Cu are developing mainly north and east of the terminals
this afternoon as high pressure tracks over the terminals.
Generally FEW to SCT coverage is favored with periods of BKN
possible at JXN given latest satellite trends. Cloud bases will be
in the 4-5kft range. Winds around 10 knots this afternoon will
become light and variable overnight. Beginning late Wednesday
morning, a batch of showers will approach from the west.
Conditions are forecast to remain VFR at this time with MKG seeing
the best chance of showers through 18z, though there is some
disagreement on timing in short range model guidance.
&&
.MARINE...
Issued at 200 PM EDT Tue Jun 23 2026
Wind will become southerly late tonight and Wednesday and this
will result in higher waves over the northern nearshore zones.
It`s possible we may need a small craft advisory Wednesday
afternoon for the northern 2-3 zones. Additionally, thunderstorms
will likely develop Wednesday which will pose a threat to boaters
and beach goers.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...04
AVIATION...Thomas
MARINE...04
NWS GRR Office Area Forecast Discussion
