853
FXUS63 KGRR 161206
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
806 AM EDT Thu Apr 16 2026
.KEY MESSAGES...
- Lingering Showers and Storm Into Afternoon, Continued Flooding
- Dry Friday, Rain and Thunderstorms Friday Night into Saturday
- Colder and Windy Sunday
- Dry Early Next Week
&&
.DISCUSSION...
Issued at 229 AM EDT Thu Apr 16 2026
- Lingering Showers and Storm Into Afternoon, Continued Flooding
Thunderstorms have exited the area, leaving areas of rain. Additional
storms are noted upstream across southern WI. Although the vast
majority of expected precipitation has fallen already, there is a
signal in some of the convection allowing models that localized
bands of a quick additional half inch or so are possible in some
spots before the rain fully exits this afternoon.
- Dry Friday, Rain and Thunderstorms Friday Night into Saturday
After a dry and warm Friday with highs in the 70s, we will experience
deep southwesterly lower tropospheric flow in response to an approaching
sharp upper trough. SPC does advertise a Day4 (12Z Sat to 12Z Sun)
risk for severe weather that reaches into SE Lower MI, and this is
corroborated by several of the medium range AI models. This will
depend in large part on frontal timing. Predictability for this
might actually be relatively good due to the highly phased and
especially prominent nature of the upper trough and associated low
level baroclinic zone.
- Colder and Windy Sunday
Colder air moves in behind the low Saturday with low temperatures
Saturday night into Sunday dropping into the upper 20s to 30s. Breezy
west to northwest winds will cause wind chills to be in the 20s
Sunday morning. Highs are expected to make it into the 40s, but
this will still feel quite brisk with the winds and coming off a
prolonged period of unseasonable warmth.
- Dry Early Next Week
Northwesterly flow aloft in the wake of the exiting upper low will
yield dry conditions with a gradual warmup. Some of the deterministic
model solutions show an upper PV max brushing the northern Great
Lakes, but precipitation chances remain in question due to scarcity
of low level moisture. The odds currently favor a dry forecast into
and including Wednesday, but this could change. The good news is
that any precipitation that occurs should be far less impactful
than what has been experienced this week.
&&
.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 800 AM EDT Thu Apr 16 2026
Showers and isolated thunderstorms will impact much of West
Michigan through early-mid afternoon, as weak low pressure crosses
the Great Lakes. This will result in MVFR ceilings/vsbys. Best
chances for thunder between roughly 14Z-21Z will most likely be
over southern areas... including AZO/BTL/JXN. Winds turn WNW late
this afternoon as disturbance passes east and ridge of high
pressure builds into the western Great Lakes. Widespread VFR
conditions will return by late afternoon and early this evening.
Fog development will need to be monitored later tonight. Have
introduced IFR vsbys /2-3 SM/ after 05-06Z at all TAF sites, given
clear to partly cloudy skies, moist boundary layer, light winds,
and good radiational cooling. Given set up and upstream conditions
this morning, vsbys could ultimately be much lower.
&&
.MARINE...
Issued at 229 AM EDT Thu Apr 16 2026
In coordination with MKX, have extended the Marine Dense Fog
Advisory until Friday morning. As noted previously, we expect
increasing winds and waves to become hazardous to small craft
beginning Friday night.
&&
.HYDROLOGY...
Issued at 250 PM EDT Wed Apr 15 2026
Bottom line: The most significant flood in recent years continues
to develop along the Muskegon River. Meanwhile, heavy rains last
night are also likely now going to create another round of
primarily minor flooding along the Grand River and associated
tributaries.
Another 1.5 to 2.5 inches of rain fell last night across a large
portion of the area, with the exception of the headwaters areas of
the Grand, Muskegon, and Kalamazoo watersheds (where closer to 1
inch of rain fell). Unfortunately, another 0.5 inches is expected
tonight and tomorrow across a large area, with localized streaks
of 1 to 3 inches.
Along with the river flooding, urban and low lying areas will be
prone to flooding due to any additional thunderstorms rains in the
next day or so.
Further south, the Kalamazoo River has been a bit drier lately,
so no flooding is expected to develop there, though urban and
poor- drainage area flooding will definitely be possible into
Thursday as additional rounds of thunderstorms move through.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Flood Watch through late tonight for MIZ037>040-043>046-050>052-
056>059-064>067-071>074.
MARINE...Dense Fog Advisory until 8 AM EDT Friday for LMZ845>849.
&&
$$
DISCUSSION...TJT
AVIATION...Smith
MARINE...TJT
HYDROLOGY...AMD
NWS GRR Office Area Forecast Discussion
