008
FXUS63 KGRR 011035
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
635 AM EDT Sat Aug 1 2026
.KEY MESSAGES...
- Showers ending Sunday
- Dry early next week, then chances for rain.
&&
.DISCUSSION...
Issued at 312 AM EDT Sat Aug 1 2026
- Showers ending Sunday
Regional radar shows a large area of showers over the cwa
extending south to the Tennessee Valley. No big changes to the
forecast planned for today.
A slow moving low pressure system over central IL will continue
to produce light to occasionally moderate rain today, tonight and
ending from northwest to southeast Sunday. Instability isn`t high,
but there is enough SBCAPE to keep the mention of thunder in the
forecast. Precipitable water values remain somewhat high...around
1.75 inches, which suggests that a stronger shower or storm could
produce heavy rainfall; the far southern cwa remains in a slight
risk for excessive rainfall. Overall, basin QPF ranges from a
third to around an inch. Thus, while there may be localized
flooding, widespread river flooding isn`t expected. Heaviest
rainfall will occur this afternoon as deformation forcing
develops.
The upper trough axis will pass through the cwa Sunday morning,
which should push the precipitation east; much of the cwa will be
dry by Sunday afternoon.
- Dry early next week, then chances for rain.
High pressure will begin building into the region Sunday night and
continue through Tuesday; we`ll be dry through that time period.
Highs will be in the mid 80s and lows in the mid to upper 50s;
dewpoints will also be in the 50s. Thus, lower humidity is
expected early in the week.
Troughing then develops late in the week and we could see several
low chances for additional precipitation.
&&
.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 629 AM EDT Sat Aug 1 2026
Regional radar shows light rain showers over the region with
steadier rainfall near US-10. We`ll continue to see showers move
in from the south as low pressure moves across IL/IN today and
tonight. A rumble of thunder is not out of the question at the
I-94 terminals, but confidence wasn`t high enough to include in
the TAFs.
Ceilings will eventually fall to MVFR late this afternoon and then
IFR tonight as the upper trough approaches.
&&
.MARINE...
Issued at 312 AM EDT Sat Aug 1 2026
Northeast winds will increase to 15 to 20 knots today resulting in
highest waves near the 5 mile point offshore. Winds increase a bit
to 15 to 25 knots tonight and a small craft advisory may be
needed. Otherwise, chances for thunderstorms, while not zero, are
minimal given the best instability with this system remains south
of the lake.
Waves are likely to increase again Sunday afternoon as high
pressure builds over the Great Lakes and an advisory may be needed
then too.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...04
AVIATION...04
MARINE...04
NWS GRR Office Area Forecast Discussion
