158
FXUS63 KGRR 041737
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
137 PM EDT Sat Apr 4 2026
.KEY MESSAGES...
- Chance of storms this afternoon
- Colder Sunday-Tuesday with light snow possible
- Showers/storms late week
&&
.DISCUSSION...
Issued at 136 PM EDT Sat Apr 4 2026
- Chance of storms this afternoon
A cold front extends south over Lake MI across CHI and south along
the IL/IN border. Radar shows abundant showers moving northeast
across the cwa ahead of the front. The main concern this afternoon
is the thunderstorm potential. A warm front is lifting north
across the southern row of counties and this may result in the far
southeast cwa seeing some warmer more buoyant air for a few hours
late this afternoon. CAMs indicate we`ll see some convective
development, but stronger storms remaining south of the cwa.
Eastern Calhoun and Jackson counties have the highest likelihood
of seeing a stronger storm this afternoon where MUCAPE values are
closer to 800 j/kg. Once the cold front sweeps through late
afternoon, that`ll put an end to the thunder threat.
- Colder Sunday-Tuesday with light snow possible
Once the cold front moves through, temperatures will drop. H8
temperatures around 12c this afternoon will fall to -8c by Sunday
morning and -14c by Tuesday morning after a secondary cold front.
Lake effect rain/snow showers will develop and move inland Sunday.
Some wet snow will mix in with the showers. Highest chance to see
some snow is later Monday and Monday night after the secondary
cold front moves through. Minor accumulations are possible, mainly
over the northern portions of the cwa. Highs Sunday through
Tuesday will be in the lower to mid 40s.
- Showers/storms late week
Another cold front is progd to move across the state Thursday and
potentially stall out over the cwa. Similar to last week, we could
see a couple rounds of showers and thunderstorms as waves of low
pressure ride northeast along the frontal boundary and this could
exacerbate ongoing flooding across the region. Of course, if parts
of the cwa could remain in the warm sector, then chances for
strong to severe storms would also increase and it`s something
we`ll be watching.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 136 PM EDT Sat Apr 4 2026
Rain showers will gradually diminish from northwest to southeast
during the afternoon. A cold front moving across the region may
also generate a thunderstorm.
IFR conditions are expected through late afternoon before rising
to MVFR during the evening. Latest visible loop sows clearing
occurring behind the cold front over parts of Missouri and that
clearing may try to work its way north across the terminals for a
few hours around midnight, before lower MVFR cigs wrap back into
the region. Breezy west winds are expected through much of the
period.
&&
.MARINE...
Issued at 136 PM EDT Sat Apr 4 2026
Once the cold front moves across the lake around 6 pm, winds will
become westerly and gusty. Waves will increase accordingly to
around 7-8 feet by Sunday morning. Winds will diminish Sunday
afternoon and waves will decrease; the small craft advisory
remains in effect until 8 PM Sunday.
Another cold front will move across the lake Monday and waves will
increase again. Another small craft advisory may be needed then.
&&
.HYDROLOGY...
Issued at 136 PM EDT Sat Apr 4 2026
Rainfall of 1-3 inches across Southwest Michigan in the past 24
hours adds to the previous accumulations for a roughly 4-6 inch
rainfall total over the last week. Additional rainfall will
generally be 0.25" or less through mid afternoon, though up to 1" is
possible under any thunderstorms. This rainfall for the most part
should not significantly exacerbate the poor drainage flooding that
developed this morning.
With the heaviest rain across the Grand River basin, this will lead
to river flooding over the next several days. River Flood Warnings
have been issued for the Grand River and its tributaries in Lansing,
the Portage River at Vicksburg, the Muskegon River at Newaygo and
Bridgeton, the Grand River at Comstock park, and the Thornapple
River at Caledonia and Hastings. For the most part rivers will peak
at minor flood stage, with the exception of Comstock Park and
Robinson Township (the latter of which is in a watch) where moderate
flooding is forecast.
The high water will work its way through Grand River system over the
next several days, with flooding forecast along the Grand River from
Ionia to Grand Rapids, to Robinson Township. Given flooding is 48-96
hours away for these areas, river flood watches have been issued,
with the potential for warnings as we get closer to the event.
Numerous other rivers will reach Action Stage over the coming days,
some like the Muskegon River at Evart getting close to minor flood
stage. People near area rivers should monitor the latest National
Weather Service forecasts.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT Sunday for LMZ844>849.
&&
$$
DISCUSSION...04
AVIATION...04
MARINE...04
HYDROLOGY...Thomas
NWS GRR Office Area Forecast Discussion
