317
FXUS63 KGRR 161852
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
252 PM EDT Thu Apr 16 2026
.KEY MESSAGES...
- Scattered Showers and Storms This Afternoon, Flooding Continues
- Chance of Severe Storms Friday Night
- Cooling and Breezy Sunday
- Dry Early Next Week
&&
.DISCUSSION...
Issued at 251 PM EDT Thu Apr 16 2026
- Scattered Showers and Storms This Afternoon, Flooding Continues
Scattered showers and storms have begun to develop across Lake
Michigan and southern Michigan. Storms are possible through roughly
00z when the stationary front assisting potential development is
shifted east by approaching ridging. Marginal instability is
developing with SBCAPE on the order of 500-1000 J/kg will develop.
Strong kinematics will put in excess of 40 knots of deep layer shear
across our southeast CWA (towards Lansing and Jackson). As such,
cannot completely rule out strong to marginally severe winds and
hail across this region through early evening. Partial clearing
overnight then will support fog development overnight with some
guidance suggesting it may be potentially dense.
Areal flooding has ended with the widespread heavy rain shifting
east. We could see isolated pockets of 0.25-0.5" of rain under any
thunderstorms but this activity will be scattered. Widespread river
flooding will continue to be a concern, see the hydro section for
more details.
- Chance of Severe Storms Friday Night
Conditions will be dry during the daylight hours on Friday as
surface and upper-level ridging drive a dry profile and large scale
subsidence.
Attention then turns to late Friday evening into Friday night as
storms from the west congeal into a line as they cross into lower
Michigan. Given the trend in the latest CAMs for earlier storms, the
marginal risk has expanded east with a slight risk for our southern
lakeshore counties. Advection of moisture ahead of the line will
result in MUCAPE on the order of 1000-2000 J/kg with 40-50 knots of
deep layer shear. This brings concerns for severe weather across
west Michigan, highest close to the lakeshore. Primary concern is
for damaging winds in any bowing segments, with a very low chance of
a tornado given ample low-level instability and shear. Storms will
clear the area by early Saturday morning.
- Cooling and Breezy Sunday
Large scale troughing moves overhead Sunday leading to a notable
pattern shift across the area. Highs fall into the 40s Sunday with
lows Sunday Night potentially into the 20s. Winds gusting to around
30 knots Sunday afternoon may bring wind chills Sunday down into the
20s as well, which will feel downright bitter compared to recent
weeks.
- Dry Early Next Week
We move into a relatively drier pattern into early next week as we
are forecast to shift into predominantly northwest flow. Ridging
should keep things dry for the most part, however weak signals have
developed for showers Tuesday with a cold frontal passage. Highs
warm into the 60s by mid next week.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 139 PM EDT Thu Apr 16 2026
Ongoing scattered showers continue with isolated to scattered
thunderstorms developing in the next hour. Storms will be hit and
miss, but best chances for thunderstorms at the terminals will be
AZO, BTL, JXN, and LAN. The threat for thunderstorms ends around
00Z this evening. Winds will 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 is becoming more likely tonight. Visibilities of a
mile or less are expected to develop after 6Z with conditions
slowly improving Friday morning.
&&
.MARINE...
Issued at 251 PM EDT Thu Apr 16 2026
Benign marine conditions are expected through much of the day Friday
before winds and waves increase later Friday into the weekend. A
small craft advisory is likely to be needed. Marine Dense Fog is
likely overnight into Friday morning and the current advisory
remains unchanged. A line of thunderstorms then crosses the lake
Friday night with the potential for winds in excess of 34 knots.
&&
.HYDROLOGY...
Issued at 251 PM EDT Thu Apr 16 2026
Bottom Line Up Front: Significant flooding continues on the Muskegon
River with minor to moderate flooding expected in the Grand River
Basin through the coming days.
Overnight last night, 1 to 3 inches of rain fell across the lower
Muskegon River basin, with isolated pockets in the Grand River basin
as well. This will make its way into the river system resulting in
flooding. Major flooding is expected along the Muskegon River at all
forecast points, with minor to moderate flooding forecast for the
Grand River and its tributaries.
The Kalamazoo River basin seeing less rain of late, no river
flooding is expected. Our Saginaw River basin points at the Chippewa
River at Mt. Pleasant, and the Pine River at Alma are also forecast
to reach minor flood stage.
Little additional rainfall, outside of thunderstorms, is expected
through the daytime hours Friday. Thunderstorms then bring
widespread totals of 0.25-0.75" Friday Night into Saturday, highest
near I-94. Given the saturated antecedent conditions, urban and
small stream flooding is possible with thunderstorms, particularly
Friday Night.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Flood Watch until 2 AM EDT Friday 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...Thomas
AVIATION...RAH
MARINE...Thomas
HYDROLOGY...Thomas
NWS GRR Office Area Forecast Discussion
