Ceresco, Michigan Weather Forecast Discussion

018
FXUS63 KGRR 200536
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
Issued by National Weather Service Detroit/Pontiac MI
136 AM EDT Sat Sep 20 2025
.KEY MESSAGES...
- Cooler and Showery Weather Pattern Begins Saturday
- Hints of a Drier and Sunnier Pattern for 2nd Half of Next Week
&&
.DISCUSSION...
Issued at 304 PM EDT Fri Sep 19 2025
- Cooler and Showery Weather Pattern Begins Saturday
We`ve been on the warm and dry side of an atmospheric blocking
pattern for the last week or so. The other side of this pattern has
featured a nearly stationary upper low bringing persistent showers
and storms to the High Plains. This weather pattern is currently
breaking down, and that upper low is now making slow but steady
progress into the western Great Lakes. The upper ridge axis is
passing over West Michigan currently, which is opening the door to
broad southwest flow at the mid and upper levels. Clouds and showers
currently over Illinois and Wisconsin will begin working their way
toward Lake Michigan and Lower Michigan tonight. This showery
weather pattern looks to stick around through at least the beginning
of next week.
While there will be low chances for rain showers at almost all times
of day over the next few days, we can now start to narrow down the
most likely times for more widespread rain/shower activity. The
first such period arrives Saturday evening and into the overnight
period as the main upper trough associated with the weakening upper
low brings a more coherent shot of cyclonic vorticity advection to
Lower Michigan. We can now start to see a 2nd period of increased
rain chances arriving about 24 hours later, on Sunday evening and
perhaps into the overnight period. Instability is limited throughout
all of the next few days evolution, so while we do think general
thunderstorms are a possibility, the risk for severe weather at the
present time looks like. Depending on timing, it`s possible that a
line of some more organized storms could develop Sunday afternoon,
but confidence in this is low at this point.
The more impactful result of this changed weather pattern will
likely be most places receiving some beneficial rain. Rain totals
over the next several days will probably mostly fall in the 0.25 to
0.75 inch range at most places, with some higher and lower
bullseyes. While this won`t be enough to be a drought buster, every
little bit helps.
- Hints of a Drier and Sunnier Pattern for 2nd Half of Next Week
There remains quite a bit of uncertainty with how the long-range
weather pattern shapes up for the middle and end of next week, but
there has been a bit of a trend toward the redevelopment of a
blocking pattern (this time more of a Rex Block with high pressure
to the north and low pressure to the south). Michigan looks to fall
in between these two features, thus the model uncertainty, but
ensemble guidance over the last 24 hours does show some movement
toward a drier solution that would keep the repeat rain shower
activity over Ohio and Indiana. The picture will certainly get
clearer as we go through the weekend, though. Regardless, we`re
heading back to a more seasonably normal temperature regime, with no
widespread major rain storms or severe outbreaks on the horizon.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 124 AM EDT Sat Sep 20 2025
Lingering upper level ridge over Lower Michigan with peristent
deep column dry air will result in prevailing VFR conditions
throughout tonight and early Saturday. Geopotential height falls
from upstream troughing and synoptic scale warm advection will
broaden into the state after 21z Saturday, yielding precipitation
chances between 30-70%. Introduced a TEMPO group for all taf sites
between 2z-6z.
&&
.MARINE...
Issued at 304 PM EDT Fri Sep 19 2025
Winds increase from the east tonight with a Small Craft Advisory in
effect near and north of Holland for 20-25 knot gusts. Isolated
gusts around 22 knots are possible from South Haven to Holland but
are not expected to be frequent or widespread enough to warrant
expanding the advisory. Winds decrease to 10-15 knots and veer to
southerly for Saturday and southwesterly for Monday. Isolated
showers and storms are possible during the day Saturday with more
widespread showers and storms Saturday Night into early next week.
Offshore flow tonight and weaker winds into the weekend will keep
waves two feet or less over the next several days.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ846>849.
&&
$$
DISCUSSION...AMD
AVIATION...DTX
MARINE...Thomas

NWS GRR Office Area Forecast Discussion