627
FXUS63 KGRR 060713
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
313 AM EDT Thu Aug 6 2026
.KEY MESSAGES...
- Areas of Fog this Morning
- 20 to 30 Percent Chance for Showers and Thunderstorms Today
- Additional Rain and Thunderstorm Chances Friday into Next Week
&&
.DISCUSSION...
Issued at 313 AM EDT Thu Aug 6 2026
- Areas of Fog this Morning
Residual moisture from rain over the past 24 hours, clearing
behind the showers in eastern Michigan, along with fog that has
developed over the cooler waters of Lake Michigan will bring
reduced visibility to portions of western Michigan this morning.
Lowest visibilities of 0 to 1/2 mile are along Lake Michigan south
of Grand Haven. Expect these lower visibilities to continue into
Thursday morning before improving within a few hours of sunrise.
Fog is not expected to be as dense further inland but could see
some spots drop down to 1 mile. Make sure to give yourself extra
time for the morning commute and use your low-beam headlights.
- 20 to 30 Percent Chance for Showers and Thunderstorms Today
Overall Thursday morning could remain largely dry with a diurnal
trend for showers and thunderstorms today. There will also be
some support with upper level divergence and a 500mb shortwave
passing to the north during the afternoon. Showers and
thunderstorms will be isolated to scattered during the afternoon
and early evening before the inversion builds in. Instability
builds to around 1000 J/kg this afternoon and with marginal shear
around 25 knots. With these variables not expecting severe
storms, but the strongest storms could contain small hail and
gusty winds.
- Additional Rain and Thunderstorm Chances Friday into Next Week
Overall the large scale pattern remains stationary with the upper
level low anchored over the Hudson Bay. What that means for us is
troughing remains overhead with multiple shortwaves moving
through into next week. With each disturbance in our moist
environment, showers and thunderstorms will be possible. However,
there are differences with the timing and track of each of these
shortwaves. This brings higher uncertainty with when and where the
best chances will be.
At this time there is better agreement for Friday into Saturday.
Friday looks to be a rinse and repeat of today with some diurnal
showers and thunderstorms during the afternoon and early evening.
A quick moving front tracks through the area Friday night into
Saturday morning bringing another 20 to 30 percent chance for
showers and thunderstorms. Afterwards confidence quickly
decreases, but no one day looks like a washout as each shortwave
quickly moves through. Additionally between the different severe
weather outlook models, severe weather doesn`t look likely over
the next week. Confidence should increase as we get closer, but it
may be an pattern where we have to take it day by day.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 212 AM EDT Thu Aug 6 2026
Showers are exiting the area with IFR ceilings advecting in off
of Lake Michigan. Ceilings are expected to drop below 1000 feet
overnight into Thursday morning. Visibilities are also expected to
fall within the 1 to 3 SM range by 12Z with the potential for 1/2
SM visibility closer to Lake Michigan. Visibilities are expected
to improve by 14Z with ceilings lifting above 3000 feet during the
afternoon.
Today`s thunderstorm potential is lower. Showers and thunderstorms
this afternoon will be hit and miss. With confidence not high that
terminals will be impacted, kept the mention in a Prob30 group.
Heavy rain will be possible with any thunderstorm.
&&
.MARINE...
Issued at 313 AM EDT Thu Aug 6 2026
Dense fog has developed largely south of Grand Haven this morning.
A Marine Dense Fog Advisory is in effect until 10am. Fog may
expand further north before clearing.
Winds will remain light and variable through the day, but will
become more westerly as the lake breeze develops this afternoon.
Pop up showers and thunderstorms will be possible during the
afternoon and early evening, but the best chances (20 to 30
percent) will be over land. Friday winds will be more southerly
wind thunderstorms chances remaining over land until late Friday
night. Several chances for rain and storms are expected over the
weekend into next week, but confidence is low in when and where
chances are best. Winds may approach Small Craft Advisory levels
Monday, but overall winds and waves are expected to remain below
Small Craft Advisory and Beach Hazard Statement levels.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Dense Fog Advisory until 10 AM EDT this morning for LMZ844>846.
&&
$$
DISCUSSION...RAH
AVIATION...RAH
MARINE...RAH
NWS GRR Office Area Forecast Discussion
