textproduct: Grand Rapids

KEY MESSAGES

- Numerous strong storms likely through daybreak this morning

- Small chances of mainly diurnal showers/storms into Thursday

- Better chances of rain return next weekend

DISCUSSION

Issued at 336 AM EDT Mon Aug 10 2026

- Numerous strong storms likely through daybreak this morning

We are seeing the effects of the secondary low level jet over the area early this morning in the form of numerous showers and storms over the southern 2/3rds of the forecast area. Some of the storms have had some good updrafts/cores associated with them. Forecast soundings show that there is an inversion from around 925mb and lower, which will limit the ability for stronger winds to reach the ground. Some wind was present in storms a couple of hours ago, so they will be possible.

The bigger threat looks to be the heavy rain potential. Precipitable water values just short of 2.0 inches are leading to some very heavy downpours. Some of the storms earlier sat over one area, and produced over 2 inches in just over an hour in SW Kent County.

The expectation is that the storms over the area this morning will push out toward 12z or so. This lines up nicely with the low level jet pushing east by that time, with no additional forcing moving in. The front is expected to push far enough south then behind this morning's storms, that as the next low level jet ramps up this evening, everything should stay south of the forecast area. We can't rule out a pop up shower/storm this afternoon with plenty of moisture remaining. The coverage looks to be quite low (<20%) due to a lack of any big feature to force it.

- Small chances of mainly diurnal showers/storms into Thursday

We get into a pattern for Tuesday through Thursday now where we will be looking at some small diurnal chances for a few showers and storms each afternoon and evening. Generally speaking, we should see MU CAPEs build to 1000-2000 J/kg each afternoon and evening with dew points remaining in the 60s, and temps in the 80s. Weak short waves in the upper flow from the WNW will help the cause also. There may be a little bit better chance across the far south where instability will be a little higher due to higher dew points and warmer temps.

This includes Thursday now, where a few runs ago, it looked like Thursday may be dry. This is due to a delay in the backdoor front dropping down, and clearing out the higher dew points and temperatures. Now it looks like it will take until Friday before we can go with a dry forecast.

- Better chances of rain return next weekend

The break in the rain chances will be small for Friday, as we see a pattern change take shape by Saturday to bring rain chances back in.

The front and the heat will be locked up to our south much of this week. However, a long wave trough emerges over the Western U.S. and shifts the upper flow to the SW for our area. This will allow energy to eject from the Western trough, and lift up toward the area. The models have been hinting at this quite consistently, just with some fluctuations in track and timing.

The stronger system will tend to draw better moisture northward, and this will be possible as early as early as Friday night into Saturday at the leading edge of the moisture advection. The system will eventually move through, and push a front through that will sweep out the moisture and warmer temperatures.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 737 AM EDT Mon Aug 10 2026

The widespread showers and storms from earlier this morning have just about all exited the area as expected by now. In their wake, we have many terminals with MVFR ceilings and some IFR with lingering low level moisture in place. We will see these clouds lift and break up a bit to VFR by late this afternoon. Can't rule out a pop up shower this afternoon, but most sites will stay dry.

Mid cloud cover will hold on tonight, and winds will go light. This will set sites up for some possible fog late in the period. We are expecting some low end MVFR to IFR at most sites.

MARINE

Issued at 336 AM EDT Mon Aug 10 2026

It continues to look like that we will remain headline free for marine interests for most of this upcoming week. The gradient remains relatively weak for the area with no major systems expected through Friday. A bit of a gradient will move in from the NE behind a weak cold front that drops down through late Thursday, but it does not look strong enough at this time to need a headline.

A better chance for wind and possible headlines will come next weekend as we see a bit better organized system come out from the Western U.S. This could occur as early as Friday night and more likely into Saturday.

GRR WATCHES/WARNINGS/ADVISORIES

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