Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 160304
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1104 PM EDT Fri Mar 15 2024

.KEY MESSAGES...

- Increasing Clouds Saturday with Scattered Showers

- Chilly with Some Snow Showers Sunday into Monday

- No Big Warmth on the Horizon

&&

.UPDATE...
Issued at 1103 PM EDT Fri Mar 15 2024

High pressure will move off to the southeast of the Great Lakes tonight
which will allow a cold front to approach from the northwest late.
We will see an increase in mid and high clouds overnight. We will
remain dry through the night. Any light precipitation that tries
to develop will hold off until after daybreak on Saturday. Stronger
southwest winds aloft spreading in from Wisconsin will keep a lid
on low temperatures. Lows will bottom out in the lower to middle
30s. Normal lows are in the upper 20s.


&&

.DISCUSSION...
Issued at 257 PM EDT Fri Mar 15 2024

- Increasing Clouds Saturday with Scattered Showers

Upper troughing will really get underway this weekend over the Great
Lakes in response to anomalous upper ridging across the Pacific
Northwest, which will help send chilly air down from Canada into
Lower Michigan beginning Sunday. Before this occurs, increasing mid
and high level RH is shown by the models to increase Saturday
morning into the afternoon ahead of a surface cold front. Eventually
lower levels such as around 850mb will begin saturating with some
scattered light rain showers possible during the day. However, model
soundings show a rather dry sub-cloud layer (inverted V) so some
areas may just have virga and nothing making it to the ground. Most
of the day looks dry but just be aware of some spotty sprinkles and
light showers possible at times. Breezy conditions ahead of and
also behind the cold front look likely with 20-30 mph winds
expected.

- Chilly with Some Snow Showers Sunday into Monday

A rather unseasonable shot of -12C to -14C air at 850mb is heading
our way late Sunday into Monday. This will send surface temps
tumbling into below normal territory with highs Sunday in the mid to
upper 30s and for Monday, not much above freezing for most areas.
Coincidentally, it was March 18 of last year that we had highs below
freezing with accumulating lake effect snow. Not looking as bad as
that event, but nevertheless some snow showers will likely be around
mainly near and west of US 131 and wind chill values in the teens to
around 20F can be expected Monday, so bundle up.

In terms of snow shower potential, Sunday night into Monday morning
will be the main window, and is looking slightly more impactful than
earlier indications. The NAM12 1000-700mb RH is shown to increase to
90% or greater for our lakeshore region along with 925-850mb omegas
that would support snow shower development and sustenance. Based on
these two factors plus the mean 1000-700mb flow being NW, we expect
the best potential for snow showers and light accumulations to be
across the lakeshore counties (especially Mason, Oceana, Allegan,
and Van Buren) plus Lake County. Snowfall amounts generally around
an inch or less are likely, but a bullseye of 2"-3" is possible
in Allegan and Van Buren Counties as WPC QPF is now lasering in on
a higher potential for 0.15"-0.20" of liquid equivalent in that
area. Some impacts to the Monday morning commute are possible
along the lakeshore as road surfaces will likely cool off Sunday
night as air temperatures fall into the 20s. The threat for slick
roads would be greatest from Ludington to Baldwin and also in a
triangular region from Holland to South Haven and Kalamazoo. As
the day progresses on Monday, the March sun angle will begin
melting the snow, though some scattered snow showers may persist
before winding down midday.

- No Big Warmth on the Horizon

Temperatures will average somewhat below normal for the most part
after Monday. Normal highs are in the mid 40s this time of year.
Highs of 40-45 are expected Tuesday into Wednesday though a
moderation into the upper 40s to near 50 is possible by Thursday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 834 PM EDT Fri Mar 15 2024

Expect VFR to persist throughout the forecast period. Winds have
shifted to the northwest and will shift to the southwest Winds
become light overnight, then will increase and become gusty
Saturday mid to late morning.

&&

.MARINE...
Issued at 257 PM EDT Fri Mar 15 2024

A rough stretch ahead is expected on the lake as winds increase
overnight and into Saturday ahead of a cold front. Waves build
into the 3 to 6 foot range Saturday but increase even further
Sunday into Monday with 5 to 9 footers possible as cold air aloft
surges over the lake. A SCA will go into effect at midnight
tonight and last into Saturday evening, but realistically will
need to be extended right through the entire weekend.

&&

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

&&

$$

UPDATE...Duke
DISCUSSION...Hoving
AVIATION...Ceru
MARINE...Hoving


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