617
FXUS63 KGRR 041048
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
648 AM EDT Tue Aug 4 2026
.KEY MESSAGES...
- Periods of Rain and Thunderstorms Tonight into Next Week
&&
.DISCUSSION...
Issued at 205 AM EDT Tue Aug 4 2026
- Periods of Rain and Thunderstorms Tonight into Next Week
Dry conditions are expected today with areas to the southeast
staying dry into Wednesday afternoon. Our next chance for rain
moves in late tonight with a slow moving front. Instability will
be limited with the front around 500 J/kg as seen in the HREF and
other ensembles. Paired with shear around 20 to 30 knots, not
expecting any severe weather into Wednesday. However with the slow
moving boundary, synoptic support with the upper level jet
divergence and positive vorticity advection, along with
precipitable water values increasing to 1.5 to 2 inches there will
be a potential for localized spots of 1-3 inches of rain. Areas
that see showers and storms repeatedly train over have the best
chance of seeing these higher end amounts. The front will slowly
shift east of the area Thursday with dry conditions returning
Thursday night.
Overall in the upper level flow we`ll remain under a broad trough.
Within this regime, multiple shortwaves are expected to track
through the region bringing additional chances for showers and
thunderstorms. `Long range ensembles are in decent agreement with
most if not all members showing rainfall accumulations over the
weekend into next week. Most members highlight 24 hour amounts
under an inch, there are a small number of members that show
higher amounts up to 2 inches. Not any one day looks to be a
complete washout with periods of dry time.
&&
.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 648 AM EDT Tue Aug 4 2026
VFR conditions are expected with mostly clear skies and southwest
winds developing this morning. Some gusts to 20 knots are possible
this afternoon at MKG and GRR. Showers and a thunderstorms may
move into MKG toward the end of the TAF forecast, better chances
hold off until after 12Z Wednesday.
&&
.MARINE...
Issued at 205 AM EDT Tue Aug 4 2026
South to southwest winds with gusts to 25 knots are possible
north of Whitehall. A Small Craft Advisory has been issued for
late this morning into this evening. Waves will largely be 2 to 3
feet, but 4 foot waves will be possible around 5NM offshore. With
these waves a Moderate Swim Risk is expected at beaches between
Whitehall and Manistee. South side of piers and breakwalls with be
the most susceptible to higher waves and currents.
Lighter winds move in for Wednesday into the weekend. Southwest
winds pick up again Sunday and may result in Small Craft Advisory
and High Swim Risk conditions.
Thunderstorms will be possible at times late tonight into Thursday
and then this weekend into next week. Severe thunderstorms are not
expected at this time.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 11 AM this morning to 10 PM EDT this
evening for LMZ848-849.
&&
$$
DISCUSSION...RAH
AVIATION...RAH
MARINE...RAH
NWS GRR Office Area Forecast Discussion
