textproduct: Grand Rapids

KEY MESSAGES

- Periodic rain chances late Friday through Sunday

- Mainly dry early next week with warming temperatures

DISCUSSION

Issued at 304 AM EDT Thu May 21 2026

- Periodic rain chances late Friday through Sunday

Upper ridging and high pressure at the surface are dominating the weather for the forecast area this morning. We do have high clouds based around 15k ft agl floating overhead preventing a mostly clear sky from being experience this morning. Some low clouds are also floating from east to west. The low and mid/high clouds are separated way too much for any precipitation to occur in the cloud and make it to the sfc.

The mid clouds will hold through Friday also, before we see deeper moisture move in over the area ahead of the next system approaching the area. This will eventually lead to more widespread rain moving in by Friday night. This will be the result of a short wave that moves toward the area from the SW. The short wave itself is not that strong. However with it moving ahead of a stronger low to the NW, it will strengthen a bit. This will strengthen the sfc low, and strengthen the flow ahead of the low from the Gulf up into the area.

This looks like a more widespread rain Friday night and Saturday morning, before it tapers off from SW to NE Saturday afternoon. Instability is quite weak, with not enough present to include a chance of storms at this time. The system will then move away from the area Saturday afternoon, allowing the rain to taper off temporarily.

Showers and a few storms will move in for Sunday. These will be the result of the upper low over the Upper Midwest that will get dislodged, and will move through Sunday afternoon. Instability is once again not impressive, but may just barely be unstable enough to trigger a rumble of thunder during peak heating.

- Mainly dry early next week with warming temperatures

We will see a nearly zonal upper flow then set up for a couple of days in the wake of the Saturday system and Sunday short wave that moves through. This flow will not be conducive to good chances of rain, but it will not allow for completely dry conditions either. Monday and Tuesday will see some potential weak short waves embedded in the flow. These combined with peak heating and lake breeze boundaries could pop a shower off.

The small chances of rain Monday and Tuesday afternoons should diminish for Wednesday and Thursday. This is because we see the strong ridge over the Western states get pushed east by a strong upper low over the Eastern Pacific. The rising heights from the ridge building will squash any convection that would try to develop, and also warm temperatures through the period.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 115 AM EDT Thu May 21 2026

The majority of the time during this 24 hour forecast period, the area will be mainly under the influence of mid/high clouds based around 12-15k ft agl. The exception to this is an area of low clouds that has formed east of KLAN and KJXN early this morning. The hi-res models have caught on to this for a few runs now. We have brought this low cloud cover in the MVFR category to the I-94 corridor for 2-4 hours this morning. The I-96 terminals may see some of this low cloud cover, but will keep them VFR with sct lower clouds. These lower clouds should move west of the area and dissipate as they move into drier air by 11z or so. Winds from the NE will dominate through this entire period.

MARINE

Issued at 304 AM EDT Thu May 21 2026

We are not expecting to need any marine headlines for the next few days. High pressure situated just north of the area has brought in offshore flow. This is expected to hold through at least Saturday. Winds will not be enough to justify a SCA for our area, and waves surely won't with the offshore flow.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Frost Advisory until 9 AM EDT this morning for MIZ037>040- 043>046. MARINE...None.