817
FXUS63 KGRR 260443
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1143 PM EST Sat Jan 25 2025

.KEY MESSAGES...

- Quick Moving Snow Showers This Evening

- Windy and Snow Chances Monday

- Additional Chances for Snow Tuesday into Wednesday

&&

.UPDATE...
Issued at 1000 PM EST Sat Jan 25 2025

The steeper lapse rates in the 0 to 3 km layer along with a cold
front pushing through continues to support snow shower growth,
even for areas south of I-96. We went ahead and increased the
potential into southern parts of the CWA. Based off of SPC`s snow
squall parameter on their Meso Analysis page, some of the snow
showers could be locally heavy. We have been issuing SPS`s along
the path of these snow showers.

&&

.DISCUSSION...
Issued at 308 PM EST Sat Jan 25 2025

- Quick Moving Snow Showers This Evening

The shortwave trough and associated positive vorticity advection
over northern Wisconsin will gradually move east this afternoon
and evening bringing with it our next chance for snow. There is
some uncertainty on how this system will evolve as it moves into
and through our area. HIRES guidance varies on how far south snow
showers will reach with HRRR and FV3 being the farther south
toward the I-94 corridor while others keep snow chances mainly
north of I-96. We`ll have to monitor and adjust the forecast based
on observations in Wisconsin and as it moves across Lake Michigan.
With the quick moving nature of the snow, not expecting much in
the way of accumulations. Amounts for those who do see snow are
expected to be around a quarter to an inch of snow through
tonight. Additionally there is the potential to mix down some
stronger gusts as seen from observations in Minnesota and in the
RAP and HRRR soundings. Probability of gusts of 40 mph with these
snow showers is 20 to 40 percent looking at HREF probabilities.
With the combination of snow and winds areas could see quick
reductions in visibility, blowing and drifting snow, and light
accumulations before ending late tonight.

- Windy and Snow Chances Monday

Ensembles focus in on Monday for higher than usual winds for
Monday. Looking at 850mb and 925mb southwest winds are around 40
to 50 knots. With this bumped up wind gusts from the NBM with with
some areas seeing wind gusts around 40 mph. There is also a chance
for light snow (20 to 40 percent) Monday. Moisture is deeper and a
week area of positive vorticty advection moves through but the
main vorticity maximum remains north of the area. Any snow looks
to be brief with dry conditions returning Monday night resulting
in only light amounts.

- Additional Chances for Snow Tuesday into Wednesday

A deeper trough and associated positive vorticity advection
gradually work their way into the area later Tuesday into
Wednesday bringing with it colder temperatures and better chances
for lake effect snow within the northwest flow. This could cause
impacts for the Wednesday evening commute.

On the horizon upper level ridging and high pressure move in
behind Wednesday`s snow. Saturday`s wintry mix is still in play as
we move from a cold pattern to a warmer one. Still too early for
exact details, but something to watch as we get closer.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 1117 PM EST Sat Jan 25 2025

The last of the snow showers associated with cold front pushing
through the region were located near KJXN. They will track east of
that site by 07z. Then VFR clouds will give way to a period of
MVFR as the cold air advection strengthens overnight. Those lower
clouds are forecast to linger into Sunday however in the
afternoon, a warm air advection patterns develops. That will
allow for some increase in cloud bases, rising to VFR.

&&

.MARINE...
Issued at 308 PM EST Sat Jan 25 2025

Winds and waves remain hazardous to small craft through the
weekend with a brief period of gales possible this evening.
Looking toward Monday gusty southwest winds are expected with the
potential for gales for most of the day. A Gale Watch has been
issued for Sunday night through Monday night. High waves may cause
ice along the lakeshore to break up.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 7 PM EST Sunday for LMZ844>849.
     Gale Watch from Sunday evening through late Monday night for
     LMZ844>849.

&&

$$

UPDATE...MJS
DISCUSSION...RAH
AVIATION...MJS/Thomas
MARINE...RAH

NWS GRR Office Area Forecast Discussion