344
FXUS63 KGRR 140844
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
344 AM EST Sun Dec 14 2025
.KEY MESSAGES...
- Travel impacts ongoing with current lake effect event
- A period of quiet weather Monday through Wednesday
- Quick rain event on Thursday
&&
.DISCUSSION...
Issued at 344 AM EST Sun Dec 14 2025
- Travel impacts ongoing with current lake effect event
The lake effect event and ongoing Winter Weather Advisory are
going down as planned. As we thought, fairly widespread travel
impacts have occurred as seen by the midrive website the past 12
hrs. Accidents in the lakeshore counties and even more notable
the slowed (sometimes significantly) travel speeds indicate
conditions are poor. Temperatures towards the Lake Michigan
shoreline are in the upper single digits and lower teens and with
a consistent snowfall icy road conditions developed and are
occurring. At this point feel we are looking at the possibility of
another 1-2 inches of new snow this morning before it tapers off
considerably this afternoon. Bottom line, we are not making any
headline changes this morning and will let things play out. We
will continue to highlight the icy roads/slowed travel in the
WSWGRR. The upper cyclonic shear axis will move east of the lake
this afternoon and that will mark the end of the stronger snow
shower activity due to large scale subsidence.
- A period of quiet weather Monday through Wednesday
A period of quieter weather is expected from Monday through
Wednesday as the pattern shifts from one of deep upper troughing
(currently over the Great Lakes) to that of a zonal flow. The
quick west to east upper flow that develops this week will bring
shortwave troughs through our area about every other day. The
first will zip through the northern Great Lakes and may bring
Central Lower Michigan some light snow Monday morning. Any
accumulations up there will be on the order of a trace to possible
around an inch near U.S. 10. The next wave moves through Tuesday
night into Wednesday and we look to stay dry with that system.
We will see a fairly significant change in temperatures in the
next handful of days with -20C air at 850mb overhead now rising to
+8C in in the Euro by Tuesday evening. Highs around 20 today will
rise into the 30s on Tuesday and to around 40 on Wednesday.
- Quick rain event on Thursday
The next wave in line swings through the region Wednesday night
into Thursday with a good surge of air out of the south. The low
that moves through the region is deep (980s mb) with strong 850mb
winds in excess of 50 knots. Surface dew points are forecast to
rise into the lower 40s F and PWAT values increase to around 0.90
inches ahead of the front. Both of these values are high for this
time of year. Rainfall amounts look to be between 0.30 and 0.70
inches based on the current operational GFS and ECWMF. We will
certainly see a ripening of the snowpack with the increase in
temp/dew point as well as raining directly onto it. Given the
quick hitting nature of the warm air, it sweeps east fairly quick,
we are not anticipating significant hydro issues at this time.
Our hydro ensemble forecast system is showing within bank rises at
this point for Thur/Fri. We will continue to monitor trends of
both the rainfall/warmth and river level forecasts. What can be
expect is some local ponding of water given many drains are
currently covered in snow and ice and at least some of this will
remain.
Another surge of cold air and lake effect snow sets up for Friday
behind the Thursday low.
&&
.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1151 PM EST Sat Dec 13 2025
Lake effect snow showers have expanded in coverage and intensified
as expected, especially toward the lakeshore. Some of these
heavier snow showers are making it inland, and causing some
temporary lower conditions into the upper end of IFR. The snow
showers are starting to migrate closer to the lakeshore as the
flow becomes more from the NNW. This is expected to bring some
gradual partial clearing to all of the sites from NE to SW.
The snow showers will move back inland on Sunday as the flow backs
a bit back to the WNW. This will bring at least MVFR back in, with
some IFR possible once again, mainly closer to the lakeshore.
Inland locations could see a brief drop in vsbys under some
isolated heavier snow showers. Winds will pick up after sunrise
with gusts of 18 to 25 knots likely. Those winds will then
diminish toward sunset Sunday.
&&
.MARINE...
Issued at 256 AM EST Sun Dec 14 2025
We are in a period of stronger winds on Lake Michigan with
northwest winds of 20 to 30 knots currently. These winds are being
aided by a tight pressure gradient aided by strong polar high
pressure in the plains states of near 1042mb. There will be a
brief lull in the wind this afternoon and evening as the mean
ridge positions sinks southeast through the Great Lakes. Quickly
on the backside of the high however winds ramp up once again,
likely to gale force.
So, we have a long duration Small Craft Advisory in place now
which we have extended to 400am in the morning (Monday). We will
also be issuing a Gale Warning for a period of stronger winds late
tonight and on Monday. It appears we will tap into gales to 35-40
knots for a time centered Monday morning into midday.
Waves will likely peak this morning around 10 feet towards South
Haven and even at this hour the South Haven webcam looks rough. In
the gales on Monday morning the WaveWatch3 has waves peaking
around Muskegon near 12 feet (10am).
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 11 AM EST this morning for MIZ037-
038-043-050-056-064-071-072.
MARINE...Small Craft Advisory until 4 AM EST Monday for LMZ844>849.
Gale Warning from 4 AM to 3 PM EST Monday for LMZ844>849.
&&
$$
DISCUSSION...Duke
AVIATION...NJJ
MARINE...Duke
NWS GRR Office Area Forecast Discussion
