677
FXUS63 KGRR 120417
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
1117 PM EST Thu Dec 11 2025
.KEY MESSAGES...
- Lake Effect Snow Friday and Saturday
- Arctic Air into Early Next Week
&&
.DISCUSSION...
Issued at 315 PM EST Thu Dec 11 2025
- Lake Effect Snow Friday into Saturday
Inversion heights lower tonight as surface ridging with
subsidence and drying builds in, ending the snow showers except in
the far NW zones. Some clearing is possible inland which would
allow temperatures to drop below 10F and possibly below zero if
skies remain clear for several hours.
An a shortwave trough arrives Friday afternoon and raises
inversion heights to around 10 kft. We expect lake effect snow to
perk up in southwest to west flow during the afternoon. There
could be a brief burst of heavier snow as an arctic front moves
though Friday evening with strong low level convergence with lake
effect continuing in west-norrthwest flow behind the front. Given
onshore flow and strong lake instability, we expect some localized
amounts of 3 to 5 inches of snow before inversion heights fall and
snow showers decrease on Saturday.
- Arctic Air into Early Next Week
A vast area of arctic air pooling across northwest Canada surges
southeast by the weekend, with a lobe of the polar vortex reaching
Lower Michigan by Sunday. 850 MB temperatures plunge below
minus 20C and should result in high temperatures being confined
to the teens on Saturday and Sunday with wind chills approaching
minus 10F, especially Saturday night when the core of the coldest
air aloft comes through.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1111 PM EST Thu Dec 11 2025
Skies are overcast across the terminal with ceilings ranging from
MVFR to VFR. Forecast soundings overnight show a pronounced
inversion overnight across the region. That will trap low level
moisture in place and not allow ceilings to fluctuate much. The
exception to that might be at LAN/JXN where some clearing skies
across the Thumb and northeast Lower are trying to move southwest
a bit. The higher likelihood is that skies will remain overcast
and that is the direction that the TAFs lean.
An Arctic cold front will move across the terminals Friday evening
and light snow will accompany the front. Ceilings/visibilities
will fall to MVFR after 00z as the front moves through.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Ostuno
AVIATION...04
NWS GRR Office Area Forecast Discussion
