textproduct: Grand Rapids

KEY MESSAGES

- Showers and Storms Saturday into Sunday

- Cool and Dry through beginning of the week

- Showers and storms possible mid next week

DISCUSSION

Issued at 306 PM EDT Fri Aug 14 2026

- Showers and Storms Saturday into Sunday

There have been some shifts in the trends for tomorrow's incoming system. Today, the showers and storms continue to stream through Illinois and Indiana. This trend was expected to shift northward but there is some question to what extent.

An upper level vort max is still shown to move through Lower Michigan tomorrow, This would create some afternoon into early evening convection along and southward of the I 94 corridor. This is highlighted in the SPC Day 2 convective outlook. Latest Model soundings through the Kalamazoo region so lapse rates only 5 to 6 C/km with a mid level inversion tomorrow that could stifle any convection. Some of the ensembles do show some weak shear Saturday evening that shifts to the north and could allow some showers and storms along the I 96 corridor Saturday evening. So scattered showers and storms are possible, there is the possibility any convection remains to the south. The overall trend continues to show a shift of stronger convection southward. There remains a chance for increased precipitation through the south and given the moisture aloft, any showers could by heavy, with QPF of over an inch of rain possible.

There is a deeper upper level trough with mid level support moving through early Sunday. While there is less moisture with that system and it comes in overnight into early Sunday, it currently has the better CAPE and shear. While not huge, there is 1500 J/kg of MU cape and Lapse rates towards 7 C/km. This is with the frontal boundary and propagates through between 15Z to 21Z Sunday. So there remains a multitude of questions with the systems this weekend, there remains several chances for showers and storms across lower Michigan until Sunday evening but the trend shows a lower potential.

- Cool and Dry through beginning of the week

There is good consistency that this front moves through Sunday night with drier, cooler northwesterly flow into Monday. A large upper level low over Canada will dominate the pattern through the next week. It should form into a closed low over Hudson Bay through mid week. This will keep temps at to below normal with the region dry.

- Showers and storms possible mid next week

The previously mentioned upper level low will drive a short wave trough through the region and a corresponding low through the Great Lakes midweek. Currently there should be an elongating front associated with with warm air advection out ahead of it. There remains some position and timing questions. It could remain further north and/or come in later. But Wednesday into Thursday could see some decent convection.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 115 PM EDT Fri Aug 14 2026

Visible satellite shows some cu over the southern terminals and mainly high clouds along the I-96 terminals. Clouds will lower overnight as low pressure moves toward the state. Included some light rain at AZO late in the period, but don't think it will reach BTL nor JXN by 18z. A better chance of light rain will arrive across the southern terminals after 18z. Look for MVFR cigs to develop late in the period.

MARINE

Issued at 303 PM EDT Fri Aug 14 2026

The only marine concern is the potential for showers and storms Saturday through Sunday. Flow should remain offshore with a wind shift into Sunday. There is an increase in winds/waves Saturday night into Sunday. However, the gradient doesn't seem to support any winds/waves that would reach criteria.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...None.