textproduct: Grand Rapids

KEY MESSAGES

- Excessive rainfall/severe threat this week

DISCUSSION

Issued at 233 AM EDT Mon Apr 13 2026

- Excessive rainfall/severe threat this week

The threat of excessive rain continues through the end of the week, along with severe storms in the vicinity of a stalled front across central Lower Michigan.

There will be a short lull today between the rain moving through early this morning and an expected flare up of convection this evening as another wave of low pressure moves along the baroclinic zone. The CAMs show convection across southern WI/northern IL this afternoon moving east as multicell clusters or bowing lines when they reach southwest Lower Michigan in the evening. Hail and downburst winds are the main threat, along with localized flooding as very moist airmass yields heavy rain rates falling on saturated ground.

The process repeats several successive times Tuesday through Saturday as shortwave energy ejects from with western CONUS longwave trough persistent baroclinic zone and southwest flow keeping deep moisture in place. A break in the action may finally come later this weekend as sfc high builds in followed by shortwave upper ridging early next week.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 647 AM EDT Mon Apr 13 2026

Low ceilings will bring areas of IFR through the morning, followed by a gradual improvement to MVFR then VFR in the afternoon. LLWS continues this morning with some gusts over 25 knots reaching the surface at times through the afternoon.

MARINE

Issued at 233 AM EDT Mon Apr 13 2026

No changes to the SCA. There will be a brief lull this afternoon and evening before winds and waves pick up again tonight so another SCA will probably be needed for tonight and Tuesday when the current SCA expires.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Flood Watch through Wednesday morning for MIZ037>040-043>045. MARINE...Small Craft Advisory until 4 PM EDT this afternoon for LMZ844>849.