931
FXUS63 KGRR 242302
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
702 PM EDT Fri Apr 24 2026
.KEY MESSAGES...
- Storms lingering into this evening
- Severe weather potential increasing for the Monday night time frame
- Cooler and mostly dry from Tuesday through Friday
&&
.DISCUSSION...
Issued at 245 PM EDT Fri Apr 24 2026
- Storms lingering into this evening
The radar across Southern Lower Michigan has been lighting up a bit
over the past 1-2 hours as expected ahead of the incoming cold
front. The cold front appears to be caught by radar and verified by
sfc obs to be located just east of Holland to near Big Rapids and of
210 pm this afternoon.
Ahead of this front, MU CAPEs have increases to over 1,000 J/kg with
some sunshine and advection of moisture in the lower levels. The
storms that have developed have been behaving as expected with weak
deep layer shear values as we have been advertising for days. Small
hail and winds gusts of 40 mph are the most likely threats from
these storms. The threat is likely to be exiting the area to the
east toward 00z/8 pm EDT this evening as the front exits the area at
that time.
We will see cooler air behind this front as 850 mb temps drop from
around 13C today to around 7-9C Saturday afternoon, and then
slightly warmer on Sunday as the thermal trough moves by and we
start to see return flow. Upper ridging building in behind the front
will bring dry conditions with a good deal of sunshine during our
longer April days.
- Severe weather potential increasing for the Monday night time frame
As we see this current system exit the area in the next few hours,
our next focus becomes the system that is forecast to approach the
area on Monday, and move through around Monday night. This system is
looking more and more ominous as more details become visible as we
get closer to that time frame. That said, there are some slight
timing differences and strength of parameters. Definitely something
to watch.
The overall pattern remains the same with a cutoff upper low over
Saskatchewan driving the pattern over much of the country. This low
will help to steer a wave currently offshore of CA and lift it to
the NE toward later Monday. There is some broad agreement that
showers and storms ahead of the front will arrive as early as Monday
evening, and as late as the pre-dawn areas Tuesday morning. Most of
the Model ensemble means are showing some healthy MU CAPE advecting
in ahead of the sfc front, and the supporting upper wave. Some of
this could even be sfc based even coming in overnight. Deep layer
shear values are likely to be fairly favorable given the stronger
upper level winds expected to be in place, as will be the low level
shear as 850 mb winds are expected to be upwards of 40 knots. To
help this cause, the upper wave is expected to be nearby to help
force convection.
Again, being 4 days out, still a lot could change. But this is
something that could cause some trouble.
- Cooler and mostly dry from Tuesday through Friday
As we see the system Monday night move out on Tuesday, we are
looking at an even cooler air mass move in, with mostly dry
conditions. This will take place as we see somewhat of a return to
the pattern of the upper flow from the NW like much of this past
winter saw.
There do look to be some ripples in the flow that might keep the
precipitation chances from being zero. However, there will be quite
dry air in place, so it will be tough for rain to make it to the
ground. 850 mb temperatures will drop below 0C by Wednesday evening
and remain there through Friday. These types of 850 mb temperatures
will support highs in the 50s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 702 PM EDT Fri Apr 24 2026
VFR conditions are present across West Michigan with VFR rain
showers likely for the next hour or two, mainly at JXN. Low clouds
begin developing late tonight with the lowesr cigs for LAN/JXN
where more widespread rain occured with this afternoon`s showers
and storms. Most sites will reach IFR overnight with the exception
of MKG where MVFR is favored. The cloud deck will lift over the
course of the late morning and into the afternoon on Saturday.
However, it is not clear at this time whether LAN/JXN will be able
to break into VFR conditions by the end of the TAF window. Winds
will go from westerly at present to northeasterly by Saturday
afternoon, with gusts to around 20 knots possible Saturday
afternoon and LAN/JXN.
&&
.MARINE...
Issued at 245 PM EDT Fri Apr 24 2026
We will be flirting with SCA conditions for a brief period this
evening across the northern marine zones, and across much of the
marine area on Saturday. We have determined in collaborating with
neighboring offices to hold of on headlines for now. This evening`s
winds will be barely hitting criteria, and for only 2-4 hours.
Saturday`s pattern is the ridge building in, and a mesoscale
stronger gradient right along the shore. This may still possibly
need a headline, and future shifts can monitor that need to hoist.
The next period of concern will be starting Sunday night and lasting
through much of Tuesday. We will see the gradient strengthen out
ahead of the late Monday system, and continue through Tuesday when
we will see the cooler air arrive behind the front.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...Thomas
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
