845
FXUS63 KGRR 171810
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
210 PM EDT Tue Mar 17 2026
.KEY MESSAGES...
- Light snow accumulations likely Wed
- Rain chances Thu/Fri, potentially significant warmup Saturday
- Rain to snow Sat night/Sun with cooler temperatures early next week
&&
.DISCUSSION...
Issued at 1153 AM EDT Tue Mar 17 2026
- Light snow accumulations likely Wed
The last vestiges of the major storm system that affected the region
over the weekend are diminishing over the area this afternoon as the
upper low pulls away. Even though snow showers are expanding across
most of the area on the radar with a diurnal boost, the intensity of
the snow showers has noticeably trended down over the last few
hours. This jives well with the upper jet/shear zone pushing east of
the area, and the upper flow becoming anti-cyclonic this afternoon.
We will see only a brief break in the snow shower activity tonight
as a weak ridge moves through. The next short wave currently near
Minnesota is poised to move at the area very late tonight and on
Wednesday. This system looks quite weak with limited impacts
expected. A major reason for this is that we do not see a deeply
saturated column with this system About the time the lower levels
saturate sufficiently to allow snow to reach the ground, the
mid/upper level moisture is already peeling away.
This system is expected to produce less than an inch of snow for
most of the area. Areas along the lakeshore with a low level flow
from the SW could bump those totals up a bit due to some lake
enhancement. Forecast soundings and synoptic level views indicate
that inversion heights are low, resulting from a lack of deep cold
air with this system. This will keep the highest snow amounts from
being much higher than 2-3 inches.
One small concern with this system is we could see a brief period of
freezing drizzle on the backside of the system. This results from
losing the mid and upper level moisture, and the dgz becoming
unsaturated. This would be brief, if it happens at all. That said,
it doesn`t take much freezing drizzle to cause some minor impacts.
- Rain chances Thu/Fri, potentially significant warmup Saturday
Yet another weak system in the flow will arrive as early as pre-dawn
Thursday morning, and more likely during the day. This system once
again will not have a significant amount of moisture associated with
it as the low level flow will be coming from the Southern Plains.
A difference with this system from Wed`s system is upper heights
will be a bit higher, thus implying a little warmer. The column
generally looks like one where mainly rain is expected for most of
our forecast area. The exceptions to this would be across the higher
terrain of Central Lower Michigan where some of it may be snow
early. In addition, if the system comes in early enough before
sunrise, sfc temps may be around freezing, allowing for a little bit
of freezing rain being possible. Temperatures are expected to warm
above freezing by late Thursday morning.
Another system in the flow could clip the area on Friday. This
system will be further north as upper heights will continue to rise
a bit. Much of the area will likely stay dry, with the northern
portion of the forecast area seeing the best chance of some light
rain.
The Friday system being far enough north will allow the low level
flow from the SW to become established over the area. This will be
advecting warmer air up and over the area. This flow will increase
Friday night into Saturday. We will be looking at some potentially
warm weather, depending on the timing of a front passing through the
area sometime from early Saturday through late Saturday. The later
this front moves through, the better the chance we see warmer
temperatures on Saturday. The timing is uncertain at this time, with
temps on Saturday being as low as the upper 40s and 50s, to
potentially in the 60s to near 70F.
- Rain to snow Sat night/Sun with cooler temperatures early next week
Whatever the timing of the front is on Saturday, it will become
active Saturday night into Sunday with precipitation. It is likely
to be warm enough initially to be rain, but will transition over the
snow as colder air pushes in through Sunday. Still a lot of details
to be worked out with this over the next few days.
We will then see a fairly strong Canadian sfc ridge move over the
area Sunday night and linger through Tuesday. This will bring dry
and cool conditions to the area.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 209 PM EDT Tue Mar 17 2026
Have adjusted TAFs for timing of snow bands. We continue to see
occasional IFR visibility restrictions this afternoon, Mainly at
AZO and MKG. Restrictions will continue to lessen over the next
few hours with all ending around 22Z.
The next round of snow showers will come Wednesday morning. There
are some questions on timing but MVFR cigs and vsbys are expected
between 10Z to 16Z with period of IFR between 12Z to 15Z. Winds
will become gusty by 14Z. Expect improving conditions after 16Z.
&&
.MARINE...
Issued at 1153 AM EDT Tue Mar 17 2026
Small Craft Advisory will be left to continue with this afternoon`s
forecast package. Winds are coming down steadily at the limited
coastal sites. This will continue, with waves to follow suit in
their typical lag time after winds diminish. We will see a break for
tonight and most of tomorrow, before winds will come up again in
association with the next wave of low pressure moving by. These
winds and waves are likely to require another Small Craft Advisory
for Tuesday night through Wednesday.
&&
.HYDROLOGY...
Issued at 1153 AM EDT Tue Mar 17 2026
Water from the heavy rain over the weekend continues to move toward
and through the river systems. We have 3 river flood warnings -
Maple River at Maple Rapids, Grand River at Comstock Park, and
Muskegon River at Newaygo in effect currently. The minor flooding on
the Muskegon should begin to diminish overnight tonight. Meanwhile,
the Grand River and Maple River minor flooding will take another day
or two to drop below flood levels. With no additional heavy rain
threats in the next week or so, all of the rivers should have a
chance to recover back closer to more typical levels. However, this
time of year it takes a while for the saturated ground to dry out,
so we will remain vulnerable to renewed flooding for at least
several weeks.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ844>849.
&&
HYDROLOGY...AMD
$$
DISCUSSION...NJJ
AVIATION...Ceru
MARINE...NJJ
HYDROLOGY...AMD
NWS GRR Office Area Forecast Discussion
