305
FXUS63 KGRR 181914
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
314 PM EDT Sat Jul 18 2026
.KEY MESSAGES...
- Fleeting chances for Storms This afternoon
- Smoke Returns Sunday
- Cold front with showers and storms Late Monday into Tuesday
&&
.DISCUSSION...
Issued at 247 PM EDT Sat Jul 18 2026
- Fleeting chances for Storms this afternoon
The Southern most corner of the area is in a severe watch this
afternoon. This is due to the cold front that is swinging its way
through the region. The best CAPE and shear are further east,
however as the convection through Eastern Michigan moves southward
it could spark storms along the US 127 corridor. The atmosphere
remains moister today with CAPE values of 2700 J/KG and DCAPE`s
upwards of 1300. While there is very little shear, there is more
than enough CAPE. However, the smoke, the precipitation from this
morning, and a mid level conditionally stable layer will reduce
chances for storms to form. The best chance will be over the next
few hours. Best chance for severe will be through Indiana.
- Smoke Returns Sunday
The cold front will shift winds back to the north. This will bring
a return of smoke from the Canadian wildfires. From The Michigan
Department of Environment Great Lakes and Energy (EGLE)The
concentrations will filter into the regions tomorrow for a
statewide alert. The latest HRRR and RRFS smoke models show this
fairly well with a band of smoke moving southward through Southern
Lower tomorrow. This will create a period of air conditions that
will be Unhealthy for Sensitive Group period tomorrow morning and
afternoon. Latest model trends, along with a pattern shift shows
a reduction in smoke tomorrow evening.
- Cold front with showers and storms Late Monday into Tuesday
Another upper level low will trek through the upper Great Lakes
early next week. The upper level vort max will aid a large mid
level low that will bring another cold front through the region
late Monday into Tuesday. This system has decent QPF with
anomalous mid level moisture through the NAEFS. The best QPF
seems to be in WI and based on time of day there is a question how
much convection makes it across the lake Monday evening. However
with good dynamics any showers and storms should continue into
early Tuesday morning. QPF estimates at this point range from
three quarters to an inch of rain. Best QPF should be east of the
US 131 corridor.
The cold front will usher in below normal temperatures for the
upcoming week. Temps should drop into the 70s by Wednesday,
which would be 5 to 10 degrees below normal, before rebounding
through the latter half of the week.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 129 PM EDT Sat Jul 18 2026
VFR conditions expected through the afternoon although some 5-6
mile visbys are possible from smoke through Sunday. Thunderstorms
could be in the JXN vicinity until about 20Z then no significant
weather through Sunday morning. Northwest winds will gust over 20
knots this afternoon before going north this evening and
diminishing to 10 knots or less.
&&
.MARINE...
Issued at 255 PM EDT Sat Jul 18 2026
Winds and waves will remain high through the rest of the day. Thus
the Beach Hazards and small craft advisory will remain in effect
through tonight. Winds will shift to a more northeast direction
late tonight, going offshore allowing waves to subside. Winds and
waves are expected to be calmer through Sunday and most of Monday,
increasing as the next frontal pattern moves in late Monday.
Showers and storms will be possible late Monday into Tuesday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT Sunday night for MIZ037>040-
043>046-051-052.
Beach Hazards Statement through late tonight for MIZ037-043-050-
056-064-071.
Air Quality Alert from midnight tonight to midnight EDT Sunday
night for MIZ050-056>059-064>067-071>074.
MARINE...Small Craft Advisory until 4 AM EDT Sunday for LMZ844>849.
&&
$$
DISCUSSION...Ceru
AVIATION...Ostuno
MARINE...Ceru
NWS GRR Office Area Forecast Discussion
