Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 171847
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
247 PM EDT Sun Mar 17 2024

.KEY MESSAGES...

- Lake Effect Snow Tonight Into Monday Morning

- Winter Isn`t Over Yet

&&

.DISCUSSION...
Issued at 247 PM EDT Sun Mar 17 2024

- Lake Effect Snow Tonight Into Monday Morning

The ongoing scattered snow showers will continue over the next few
hours as the 500mb positive vorticity advection and trough axis
move through. There is some surface based instability allowing for
stronger winds to mix down with the more intense snow showers.
Brief visibility reductions down to a quarter mile and quick
accumulations of a tenth or two are possible within these showers.

As the trough axis passes we transition more into northerly flow
along with some colder 850mb temperatures working their way over
the lake. This will transition the scattered showers into more
focused bands along the lakeshore. With water and 850mb
temperature differences around 17 Celsius and the fetch across
the lake around 100 miles expect to see some additional
accumulations of 1 to 3 inches along the lakeshore through Monday
morning. Some isolated spots could get up to 4 inches with the
best potential in southwest Michigan. This will likely result in
some slick conditions for the Monday morning commute so make sure
to give yourself extra time and take it slow!

Light snow will gradually taper off through the day as 850mb
temperatures warm and we lose our low level moisture.

- Winter Isn`t Over Yet

A couple of opportunities exist next week for some snow...but likely
not until the end of the week.

A clipper will move across Lake Superior Tuesday. Precipitation
associated with the warm air pattern ahead of it will likely remain
just north of the cwa. However, we`ll see cold air move south behind
the clipper Tuesday night and Wednesday. That will help to keep
temperatures much of the week below normal.

Ensembles are congealing around the possibility of light snow
thursday night and Friday as low pressure rides east along the
aforementioned cold front. At this point, ensemble mean accums are
around an inch. However, ensemble probabilities of greater than 3
inches are 15-20 percent and considerably higher north of the cwa.
So this system will bear watching.

An even more impressive system may be lurking toward the end of the
weekend. A southern stream system is showing up in the models that
would tap into Gulf moisture and move north toward the Great Lakes.
The track trend has been farther west in recent runs which would
eventually put us in the warm sector. However, ensembles still
produce some snow and/or freezing rain, then rain. Thunderstorms
could be a player at some point in this evolution too.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 1254 PM EDT Sun Mar 17 2024

Radar shows scatted to numerous snow showers moving across Lower
MI from the northwest. We`ll continue to see MVFR and occasionally
IFR conditions this afternoon. After 00z, winds will become more
NNWly which will push the snow showers toward the lake shore and
improve conditions. Drier air will move over the lake Monday
morning and further diminish the shsn.

&&

.MARINE...
Issued at 247 PM EDT Sun Mar 17 2024

Gusty northwest winds continue hazardous conditions for small
craft through Monday. Winds turn a little more west to southwest
Monday night into Tuesday. Another extension of the Small Craft
Advisory is likely as we continue in this windy pattern until
Thursday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT Tuesday for LMZ844>849.

&&

$$

DISCUSSION...04/RAH
AVIATION...04
MARINE...RAH


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