Kalamazoo, Michigan Weather Forecast Discussion

093
FXUS63 KGRR 231730
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
130 PM EDT Tue Sep 23 2025
.KEY MESSAGES...
- Unsettled Weather into Thursday
- Drying Out Friday Through the Weekend
- Near Normal Temperatures Trending to Above Normal
&&
.DISCUSSION...
Issued at 404 AM EDT Tue Sep 23 2025
- Unsettled Weather into Thursday
Unsettled weather will continue today through Thursday as an upper
trough digging into the Great Lakes today closes off overhead for
Wednesday into Thursday. At the surface, a front off to our north
this morning will sag southward through the forecast area as we
head through tonight. Wednesday into Thursday we will be in a
northerly flow regime and dew points will correspondingly drop.
SPC has us in a general thunder outlook for both today and
Wednesday, but the better chance for storms will be today. The
reasoning is that we will have the front for forcing and our
highest dew points/instability will be today. Given weak
flow/shear we are not expecting severe weather which is in line
with SPC. Any storms on Wednesday will be more isolated. PWAT
values today into tonight will peak in the 1.25 to 1.50 inch range
so where storms persist some locally heavy rain is possible. Per
the HREF we expect the highest concentration of thunderstorms to
occur between 1pm and 9pm.
We will need to keep an eye on model trends to see if other models
come in line with a deeper low Wed/Thurs. The ECMWF is deeper as
it brings a low into the southern Great Lakes and therefore puts
down a heavier swath of rain into our area. 1-2 inches of rain
would fall in our southeast CWA towards Jackson in this scenario.
- Drying Out Friday Through the Weekend
Models have been consistent in showing a dry period of weather
Friday through the weekend as high pressure becomes dominant both
at the surface and aloft. CAPE values become non existent in the
ECMWF ensembles and PWAT values dip towards 0.60 inches. So a
change in airmass occurs as we get behind the mid week low.
- Near Normal Temperatures Trending to Above Normal
Near normal temperatures are expected today through Thursday with
normals and forecast highs in the lower 70s. Moving forward,
normal lows trail off into the middle 60s by early next week while
temperatures will be rebounding. With mid level ridging building
in we should see temperatures rise into the middle to upper 70s
late in the weekend.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 129 PM EDT Tue Sep 23 2025
A broken line of showers with embedded thunderstorms continues to
cross West Michigan this afternoon, with the line moving east of
JXN near 18z. Isolated showers and thunderstorms are possible
behind this line into the evening, with widely scattered activity
supportive of maintaining PROB30s with amendments as needed. Any
remaining MVFR sites will become VFR shortly as cigs climb to near
5kft. MVFR and lower conditions are possible in any showers and
storms. Tonight, widespread fog and low stratus are expected with
widespread MVFR/IFR conditions and a 20-40 percent chance of LIFR.
Have trended the TAFs accordingly with this package. While
visibilities will improve after sunrise, it may be well into the
morning/early afternoon before ceilings improve.
&&
.MARINE...
Issued at 404 AM EDT Tue Sep 23 2025
Marine concerns remain on the low side this week. Waves of 2 feet
or less are expected today and tonight with a weaker pressure
gradient in place. Wednesday into Thursday northerly flow
increases as low pressure slides northward through the Eastern
Great Lakes. At this point we are expecting 10-20 knot winds and
waves of 1-3 feet. That said, we will be keeping an eye on model
trends as the ECWMF has a fairly strong low (999mb) over Southwest
Ontario at 12z Thursday. If the ECWMF verifies winds and waves
will need to be increased from current forecast values.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Duke
AVIATION...Thomas
MARINE...Duke

NWS GRR Office Area Forecast Discussion