645
FXUS63 KGRR 181803
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
203 PM EDT Thu Jun 18 2026
.KEY MESSAGES...
- Cooler Than Normal with Rain Possible Sunday into Monday
&&
.DISCUSSION...
Issued at 155 PM EDT Thu Jun 18 2026
- Cooler Than Normal with Rain Possible Sunday into Monday
The weather pattern continues to be dominated by zonal flow being
steered by a large quasi stationary upper level low situated over
central Canada. That low will continue to bring north westerly
flow through the region, along with anomalous cold air advection.
NAEFS mean temperature anomalies show -1 to -2 standard
deviations through the mid levels. That means while the region
will see a mix of sun and clouds, the temperatures will struggle
to get into the mid 70s. Max temperatures through the weekend and
into early next week will be 5 to 10 degrees below normal. Models
continue to be in good agreement on the passage of a few weak
shortwave traversing the previously mentioned upper level low as
it shifts to the south. Those shortwaves will trek through the
Great Lake Saturday. This will allow for a chance of precipitation
Saturday. Precipitation should be fairly light and will make its
way eastward as the day continues. Chances for precipitation of
over a tenth are best along the lakeshore Saturday morning. The
better chance for heavier precipitation continues to be as a upper
level low, currently over the Pacific, filters through the upper
level pattern, stamps down a ridge through the intermountain west,
and finally makes its way through the midwest. That wave and mid
level and surface low will advect good moisture with it. However
latest ensembles struggle with its position and track. The best
chance for heavy rain remains south of Michigan, though Southern
lower could see some rainfall late Sunday into Monday.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 116 PM EDT Thu Jun 18 2026
MVFR cigs are beginning to breakout to VFR and will continue to do
so over the next 1-2 hours. Given the observation trends of
intermittent breaks in restrictions have gone with a TEMPO until
ceilings should become VFR. VFR conditions are then expected
through the rest of the TAF period. Westerly gusts to around 25
knots continue through this evening before diminishing tonight.
Winds then increase from the west Friday with 20-25 knot gusts.
There are some signals for FEW to SCT Cu development around 5kft
late in the TAF period, especially at LAN and JXN.
&&
.MARINE...
Issued at 155 PM EDT Thu Jun 18 2026
The west to northwest winds continue as advertised. Waves of 3 to
6 feet continue along the lakeshore. The winds will slacken as the
day continues and with it the waves will slowly subside. This will
occur from the north to the south into Thursday evening. The SCA
and Beach hazards will then end accordingly. Winds tomorrow are
trending low but there could be a brief period of higher waves, 2
to 4 feet, early in the day.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 4 PM EDT this afternoon for MIZ037-
043.
Beach Hazards Statement until 6 PM EDT this evening for MIZ050-
056-064-071.
MARINE...Small Craft Advisory until 6 PM EDT this evening for LMZ844>847.
Small Craft Advisory until 4 PM EDT this afternoon for LMZ848-
849.
&&
$$
DISCUSSION...Ceru
AVIATION...Thomas
MARINE...Ceru
NWS GRR Office Area Forecast Discussion
