802
FXUS63 KGRR 261353
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
953 AM EDT Sun Jul 26 2026
.KEY MESSAGES...
- Northwest flow regime with occasional chances for rain but low
confidence in convective details
&&
.UPDATE...
Issued at 953 AM EDT Sun Jul 26 2026
Latest forecast trends suggest a low risk of showers and storms
this afternoon. However with the lack of a robust forcing source,
storm coverage looks to be isolated. With strong deep layer shear
and ample DCAPE could see strong to damaging winds, and maybe
large hail, if we can get robust thunderstorm development.
However, given limited forcing uncertainty remains as to if/where
any storms can develop.
Water Vapor satellite imagery also shows a mid-level wave across
the Northern Plains. Expectation is for this wave to initiate
storms across northern Minnesota/Wisconson this afternoon/evening,
which then track southeast along the advancing instability
gradient. Model solutions do vary with the eastward extent of this
instability plume, which could keep storms west of our area, or
see them reach areas mainly west of US-131 late this evening into
tonight. Expectation would be upscale growth into clusters with
damaging winds as the main concern and large hail as a secondary
concern. Mesoscale trends will continue to be monitored into the
evening to evaluate whether storms will reach West Michigan or
miss us to the west.
&&
.DISCUSSION...
Issued at 211 AM EDT Sun Jul 26 2026
- Northwest flow regime with occasional chances for rain but low
confidence in convective details
The Great Lakes region remains in between an upper high across
the western CONUS and longwave troughing across the eastern CONUS
with occasional shortwave troughs passing through and bringing
the chance for some much-needed rain.
A weakening shortwave trough moving through early this morning
has yet to initiate any showers, which is not surprising given
limited moisture and lift. Isolated showers are possible through
the afternoon.
Still low confidence in the details of how things play out tonight
through MOnday night in terms of organized convection, but
instability and shear are sufficient for a slow-moving front and
weak midlevel vorticity max to focus convection across Minnesota
and into Wisconsin this afternoon which eventually moves southeast
across Lake Michigan and perhaps western Lower Michigan.
The hi-res convective allowing models take the bulk of the storms
west of our forecast area, but there is a chance an MCS could
impinge on the western or southwest zones late tonight or early
Monday morning. Additional convection is possible across the rest
of the forecast area during Monday and Monday night as the front
pushes south.
The front moves through by Tuesday with fair weather for mid to
late week before the longwave upper trough amplifies with a cold
front bringing another chance of rain by next weekend.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 704 AM EDT Sun Jul 26 2026
Patchy IFR/MVFR conditions with low stratus this morning should go
over to VFR by 18Z. There could be some rain moving in tonight
across western Lower Michigan, with MKG having the best chance
late tonight. Winds will be from the southwest AOB 10 knots.
&&
.MARINE...
Issued at 211 AM EDT Sun Jul 26 2026
Today should see a continuation of southwest winds around 10 to 15
knots then thunderstorms could bring strong wind gusts over Lake
Michigan tonight. A cold front moves through Monday night and
north winds increase to near 30 knots with waves building over 4
feet on Tuesday and continuing into Wednesday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
UPDATE...Thomas
DISCUSSION...Ostuno
AVIATION...Ostuno
MARINE...Ostuno
NWS GRR Office Area Forecast Discussion
