615
FXUS63 KGRR 241038
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
638 AM EDT Sun May 24 2026
.KEY MESSAGES...
- Rain and thunder chances have increased for today
- Small chances for Rain Monday through Wednesday
- Dry and mild Thursday and beyond
&&
.DISCUSSION...
Issued at 249 AM EDT Sun May 24 2026
- Rain and thunder chances have increased for today
We are currently in a lull in rain activity in the wake of the
system that came through yesterday, and the next system to our west
poised to move through today. A cold front can be seem in the sfc
observations just east of the Mississippi River over the WI/IL/IA
region. This is a sfc reflection of the long wave trough that
stretches from Manitoba to near Kansas City as of 2 pm/06z Sunday.
A few light showers are currently found along the front, and this
activity is expected to expand in coverage and intensify a bit as it
approaches the area. There is some moisture pooling ahead of the
front with dew points in the 60s. We will not see those, but we will
see some of the moisture move north over the area ahead of the
front. In addition, the system as a whole is slightly delayed, so
some diurnal heating will help boost instability slightly.
Forecast soundings show that updrafts will have just enough CAPE
(couple hundred J/kg) to generate some ice, helping with thunder
chances some. The lack of instability will keep the threat of
anything strong quite limited here. The showers and storms should
move out by 20-22z, and allow for some clearing by tonight. That
will allow for some fog generation with light winds and a moist
boundary layer.
- Small chances for Rain Monday through Wednesday
We expect that most of the area will stay dry on Monday. There will
be a weak short wave moving through Central and Northern Lower on
Monday. The general consensus of the models is showing rain chances
over the higher elevations of interior portions of Central and
Northern Lower during peak heating. All other areas should remain
dry on Monday.
Tuesday probably has the lowest chance of rain for these three days,
which is not saying much. There is not really a short wave shown to
move through, and the upper ridge axis is building a bit toward the
area. Wednesday probably has the highest chance over the largest
portion of the area of the three day period. That is still not a lot
with a back door cold front dropping through the area with really no
upper support. There is little to no moisture with it. Model
ensemble members vary a bit with their solutions with almost half
showing nothing, and other ensemble members a few hundredths of an
inch. With this in mind, we will keep rain chances on the lower
side.
- Dry and mild Thursday and beyond
The back door cold front will have moved south of the area on
Thursday, bringing in a cooler and drier air mass. The flow around
the sfc ridge will be from the NE, which will bring cooler and drier
air in from Eastern Canada. The air behind it is not that cold with
850 mb temps around +15C Wed morning, dropping to around +8 to +9C
Thursday morning. This will support highs in the 80s Tuesday and
Wednesday, then the 70s on Thursday. The upper ridge axis and sfc
ridge building over the area will help to squash any cloud cover
trying to develop.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 638 AM EDT Sun May 24 2026
Fog and stratus has not been as bad as previously thought with
KGRR and KMKG losing their lower ceilings and visibilities. The
other terminals have seen that hold in some shape or form, and
continue to do so even at this hour.
Our focus then turns to showers and storms developing as far east
as Western Lake Michigan and more so over Wisconsin and Illinois.
We do expect now that storms should affect all of the terminals at
some point through this afternoon. We have handled this with a
tempo of 3-4 hours at each site with IFR.
Once the showers/storms move out early to mid afternoon, we should
see clouds and fog clear out through the evening. Winds go light
after dark, and this should help fog development overnight, so
have hit this fairly hard.
&&
.MARINE...
Issued at 249 AM EDT Sun May 24 2026
We are anticipating not needing any marine headlines for potentially
the next week. We have no major systems expected to approach or move
through the area over the next week. There are a couple of periods
(Monday night and Wednesday night) that winds 2-3k ft above the sfc
of the lake will come up, but these scenarios are during strong warm
air advection over the cool lake and winds should not make it to
the sfc.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...NJJ
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
