850
FXUS63 KGRR 290505
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
1205 AM EST Sat Nov 29 2025
.KEY MESSAGES...
- Widespread Heavy Snow Expected Saturday into Sunday
- Near to Below Normal Temperatures with chances for snow next
week
&&
.DISCUSSION...
Issued at 339 PM EST Fri Nov 28 2025
- Widespread Heavy Snow Expected Saturday into Sunday
There are 2 upper shortwaves that will drive our heavy snow this
weekend. One shortwave is currently dropping south across Alberta
and Saskatchewan and another is driving east from Idaho into
Wyoming. These two shortwave will phase over the Plains states of
the U.S. on Saturday and lift east-northeast into the Great Lakes
Saturday evening. As the phased upper wave moves through our area
tomorrow evening it will be negative tilt. The upper wave will be
pivoting right over our area tomorrow evening which prolongs the
lift a bit. Down at the surface, lee side cyclogenesis is ongoing
this afternoon as the lead shortwave surges east over the Rockies.
Tonight the low emerges into the Plains and will be centered over
the central KS/OK border region by 12z Saturday. During the day on
Saturday the low will deepen as it moves towards the Great Lakes
due to the phasing occurring aloft. The deepening low will bring a
surge of moisture into Southwest Lower Michigan in the lower
levels of the atmosphere which will aid in heavy snow production.
The surface low will move through our Southern CWA late Saturday
night into Sunday morning which will transition the snow from
synoptic snow to lake effect.
As for the details, Colorado Lows are prolific snow producers for
Southwest Lower Michigan and this is one of them. A low coming
right over the top of the CWA is not normally the best
location/track for us to see heavy snow, but we have cold air
entrenched in already and we do not expect a change over to mixed
precipitation. The low moving over the southern CWA in this case
looks to actually increase snow totals directly under the low
track. So, we are expecting the heaviest snow over the I-96 and
I-94 corridors. The item of note that we have mentioned for over a
day now is the prolonged nature of the isentropic lift/warm air
advection snow. The 290k surface shows 12-18 hours of lift via
that mechanism which usually produces our heaviest snow. That snow
will be followed by the trowal/deformation zone snow at the tail
end of the event late Saturday night into Sunday morning which
will produce the higher snowfall totals across Southern Lower
Michigan. This will be a widespread plowable/shovel worthy snow.
Snow totals over much of the area will reach the 7-11 inch range. after
Totals of that magnitude are on the more rare side occurring less
than once a year at GRR. Some years we go without seeing that
magnitude of snow at all. So, folks will need to be prepared for a
longer duration, heavy snow that will produce significant travel
impacts at the very least. When we get towards double digits
snows, which this system has the potential to produce, the ability
to get out of driveways and secondary roads like cul de sacs
ramps up significantly. So, while this is not a wind driven snow
and blowing and drifting will not be a significant issue the heavy
nature of the snow in terms of totals will create impacts for
sure.
There will be a period of lake effect snow the backside of the low
on Sunday which will add to the totals in the far southwest corner
of the CWA towards Saugatuck, South Haven, Allegan, Bangor and
Hartford. These locations will likely see the heaviest totals near
a foot by the end of the day on Sunday.
WSW has already been sent and a Winter Storm Warning is in place
for the bulk of the forecast area, everywhere but the U.S. 10 row.
The U.S. 10 row is in a Winter Weather Advisory for 5-7 inches of
snow given its location away from the better moisture and track of
the low.
- Near to Below Normal Temperatures with chances for snow next
week
Colder air looks to remain entrenched over the Great Lakes region
into next week with highs in the upper 20s to lower 30s most
days. We have a couple different chances for light snow and lake
effect centered on Monday night and again Wednesday night. Both
will bring some light snow to all of the area, but lake enhanced
snows are possible towards the lakeshore. The ground will remain
white through next week!
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1204 AM EST Sat Nov 29 2025
VFR conditions overnight will drop to MVFR around 12Z then go to
IFR by 16Z at most places as snow moves in. IFR will continue
though Saturday evening. Winds will be southeast around 10 knots
on Saturday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory from 7 AM this morning to 10 AM EST
Sunday for MIZ037>040.
Winter Storm Warning from 7 AM this morning to 10 AM EST Sunday
for MIZ043>046-050>052-056>059-064>067-071>074.
MARINE...None.
&&
$$
DISCUSSION...Duke
AVIATION...Ostuno
NWS GRR Office Area Forecast Discussion
