754
FXUS63 KGRR 010709
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
308 AM EDT Fri May 1 2026
.KEY MESSAGES...
- A few showers today; Freeze tonight
- Mostly dry Saturday through Monday
- Wet system Monday night-Tuesday; Unsettled and cool next week
&&
.DISCUSSION...
Issued at 227 AM EDT Fri May 1 2026
- A few showers today; Freeze tonight
We continue to see a lot of small features driving the forecast with
the upper low complex in charge, and weak waves rotating around it.
One of these waves is currently responsible for the band of light
rain along the I-94 corridor this morning. The wave itself is south
of the state line, with the deformation zone barely sneaking up over
our far southern area. This rain will move out by daybreak this
morning.
The upper flow remains cyclonic today with multiple weak short waves
moving through. The hi-res models indicate that a weak one coming
from Wisconsin will touch off a few light showers over the lake and
spread inland this morning. Then, diurnal heating combining with
another wave coming in will pop isolated to scattered showers inland
this afternoon. These will then dissipate mid evening and allow
skies to clear out quite a bit.
This clearing combined with dew points in the 20s are setting up the
night for a good freeze potential for most of the forecast area,
with the coldest across the interior portions of Central Lower. With
Frost/freezing conditions up north this morning, coordination with
neighboring offices supports holding on to the headlines as is right
now to limit confusion.
- Mostly dry Saturday through Monday
While most areas will stay dry Saturday, there remains about a 15
percent chance of a shower popping up along the lake breeze Saturday
afternoon. The cyclonic flow will slip east of the area later
Saturday. Hi-res models are indicating an isolated shower popping
along the lake breeze. Inversion heights coming down will help to
limit shower development, but not completely with some
forcing/convergence to assist.
Again most of the area should be dry on Sunday, but northern areas
have a chance of some light rain. We get out from under the cyclonic
flow, but a short wave will ride just close enough to us over the
U.P. to help fire a few light rain showers. The southern portions of
the area should remain dry.
High pressure at the sfc and weak broad ridging aloft should keep
most of the area dry on Monday. It may be close late Monday as the
cold front approaches, and moisture gets close coming in from the
Gulf.
- Wet system Monday night-Tuesday; Unsettled and cool next week
The system coming in on Monday night will be facilitated by the next
long wave upper trough diving SSE from Western Canada. As this
trough dives SE, it will be able to tap some better moisture that
will be in place already just south of the state. The better
moisture, somewhat warmer air ahead of the front could produce just
enough instability to allow for a rumble or two of fire.
The general theme of the weather from Tuesday through Thursday next
week will be once again cool and uncertain with regards to timing of
waves and any details with them. It does look like we end up back
under cyclonic flow, and periodic shower chances on and off through
the period with any embedded wave that moves around the upper low.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 145 AM EDT Fri May 1 2026
We are seeing light rain continuing across the I-94 terminals
early this morning. All of the sites are now VFR after a little
MVFR briefly. This rain should move out gradually from west to
east through 10z.
The other sites are currently VFR, but we are watching for some
MVFR possible at KMKG and KGRR as some stratocumulus and a few
showers come off of Lake Michigan around or just after daybreak.
Any MVFR should lift to VFR. All inland terminals will see a
chance of a few showers through the afternoon and early evening
hours as they pop up during peak heating with the cold pool aloft
overhead.
Everything should diminish after sunset, and skies will go mostly
clear with a light flow from the NW.
&&
.MARINE...
Issued at 227 AM EDT Fri May 1 2026
We continue to watch this afternoon for a possible marginal SCA
event with the building ridge coming in and squeezing against the
lower pressure over land due to heating. At this time, it looks too
marginal to issue the headline.
The first half of the weekend will see tranquil conditions with high
pressure nearby. We will see winds and waves build Saturday night
into Sunday as we start to see return flow on the backside of the
ridge. SCAs are likely going to be needed for Saturday night and
Sunday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Frost Advisory until 8 AM EDT this morning for MIZ037-043>046-
051-052.
Freeze Watch from late tonight through Saturday morning for
MIZ037>040-043>046-050>052-056>059-064>067-071>074.
Freeze Warning until 8 AM EDT this morning for MIZ038>040.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...NJJ
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
