383
FXUS63 KGRR 180500
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
1200 AM EST Thu Dec 18 2025
.KEY MESSAGES...
- Rain develops Thursday, warmer
- Light snow Thursday night/Friday
- Light snow north Saturday night
&&
.DISCUSSION...
Issued at 306 PM EST Wed Dec 17 2025
- Rain develops Thursday, warmer
Warmer air will continue to advect northward into the cwa tonight
and Thursday. The snowpack will continue melting; we`ve lost 2
inches since last night at the WFO. Rain will develop late tonight
ahead of a strong cold front as strong isentropic lift quickly
saturates the column. Models have been consistent for a few days
in depicting around 0.4 inches of rainfall before the cold air
quickly pours in late Thursday. We`ll lose a decent amount of the
snowpack, but probably not all of it. At this point we don`t see
many river issues with the rain. The largest impact may be ponding
on roads near clogged storm drains. Highs Thursday will be in the
mid 40s.
- Light snow Thursday night/Friday
H8 temperatures quickly fall from +6c to -14c Thursday night.
There`s roughly 15 hours from 03z-18z Friday where conditions will
be favorable for lake effect snow; highest amounts will be west of
US-131 and generally north of I-96. However, strong boundary layer
winds will push some of the snow showers inland. Accumulations
east of US-131 should be a half inch or less.
- Light snow north Saturday night
Lake effect snow showers will end by late afternoon/early evening
Friday and high pressure will quickly build into the region.
Another cold front will push across the cwa Saturday afternoon.
Given the low north of Lake Superior, there won`t be a lot of
moisture to work with; a 30 percent chance of light snow with the
front Saturday north of I-96.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1158 PM EST Wed Dec 17 2025
VFR conditions will lower to MVFR overnight then decrease to IFR
on Thursday morning as rain and low clouds move in. South winds
will gust over 20 knots along with 50 knots of LLWS. There could
be gusts over 40 knots in the afternoon as a narrow line of
showers brings strong winds to the surface from AZO to LAN and JXN
during the afternoon.
&&
.MARINE...
Issued at 306 PM EST Wed Dec 17 2025
The approach of a deep low pressure system tonight will cause
southwest to increase to gales which will continue through
Thursday. Thus, no change to the gale warning currently set to
begin tonight. We`ll likely need a small craft advisory Friday
through Saturday once the gales subside but waves remain high.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Gale Warning until 7 AM EST Friday for LMZ844>849.
&&
$$
DISCUSSION...04
AVIATION...Ostuno
MARINE...04
NWS GRR Office Area Forecast Discussion
