407
FXUS63 KGRR 031859
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
259 PM EDT Mon Aug 3 2026
.KEY MESSAGES...
- Dry weather tonight and Tuesday
- Multiple chances for showers/storms Tues. night through Sat.
- Seasonable temperatures through the 7 day forecast
&&
.DISCUSSION...
Issued at 259 PM EDT Mon Aug 3 2026
- Dry weather tonight and Tuesday
High pressure will bring fair weather tonight through Tuesday as
high pressure slips away to the southeast of the Great Lakes
region. A cooler night than normal for this time of year is
expected tonight with lows in the 50s. Highs on Tuesday will reach
the middle 80s in most locations.
- Multiple chances for showers/storms Tues. night through Sat.
A surface cold front will push into the area Tuesday night and
wash out over Lower Michigan on Tuesday. The weak surface boundary
will be a impetus for showers and thunderstorms at times from
Tuesday night into Thursday. The pattern will be evolving into a
trough over the Great Lakes during this time. Embedded shortwaves
within the flow will aid in precipitation production as well.
Wednesday through Thursday are the forecast periods where the best
chances for rain look to occur. Highest chances for precipitation
occur during this time frame 60-70 pct.
Dew points pool along the front rebounding back into the 60s. Most
unstable CAPE values push into the 1000-2000 j/kg range. The
precipitation looks to be diurnally driven as is usually the case
with mid summer upper troughs. Cannot rule out some stronger
storms Wednesday afternoon into Wednesday night as the main
shortwave moves through combined with 50+ knots in the mid levels
at 500mb. At this point we are just in a general thunder outlook
from the SPC.
The next time frame of concern is out Saturday night into Sunday
with the passage of another upper shortwave. Showers and storms
are possible during this time as well. Surface dew points surge
into the 70s with the passage for a surface front. Only 20-30 pct
pops in the forecast at this point but this will be increased when
model continuity increases.
- Seasonable temperatures through the 7 day forecast
850mb temperatures are in the middle to upper teens C which is
typical for mid summer. Mid to upper 80s highs are expected for
the most part through the period. Low temperatures will be
seasonable as well in the mid to upper 60s.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 143 PM EDT Mon Aug 3 2026
Overall VFR conditions will dominate the next 24 hours. Winds
remain overall light and variable to calm. There remains the
likelihood of a lake breeze developing late today with light to
calm winds overnight. Winds are expected to shift to the
southwest tomorrow. MVFR vsbys from shallow fog are expected.
Brief periods of IFR remain possible between 08Z to 12Z. No
precipitation expected in the next 24 hours.
&&
.MARINE...
Issued at 259 PM EDT Mon Aug 3 2026
Quiet conditions are expected out on the big lake through Tuesday
morning. High pressure will slide away to the east tonight which
will allow southwest return flow to develop on Tuesday. Light
winds are expected tonight with waves 2 feet or less. With the
increase in winds on Tuesday, 10-20 knot winds with a few higher
gusts are possible up towards Big Sable Point. 4 foot waves only
look to impact the far northern marine zone up towards Big Sable
for a few hours and only a portion of the zone. So, given marginal
conditions will hold off on a Beach Hazards Statement and Small
Craft Advisory for now. We will be watching this closely.
Southwest winds persist Tuesday night into Wednesday, but
conditions will remain below advisory levels.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Duke
AVIATION...Ceru
MARINE...Duke
NWS GRR Office Area Forecast Discussion
