textproduct: Grand Rapids

KEY MESSAGES

- Rain and thunder chances have increased for today

- Small chances for Rain Monday through Wednesday

- Dry and mild Thursday and beyond

DISCUSSION

Issued at 249 AM EDT Sun May 24 2026

- Rain and thunder chances have increased for today

We are currently in a lull in rain activity in the wake of the system that came through yesterday, and the next system to our west poised to move through today. A cold front can be seem in the sfc observations just east of the Mississippi River over the WI/IL/IA region. This is a sfc reflection of the long wave trough that stretches from Manitoba to near Kansas City as of 2 pm/06z Sunday.

A few light showers are currently found along the front, and this activity is expected to expand in coverage and intensify a bit as it approaches the area. There is some moisture pooling ahead of the front with dew points in the 60s. We will not see those, but we will see some of the moisture move north over the area ahead of the front. In addition, the system as a whole is slightly delayed, so some diurnal heating will help boost instability slightly.

Forecast soundings show that updrafts will have just enough CAPE (couple hundred J/kg) to generate some ice, helping with thunder chances some. The lack of instability will keep the threat of anything strong quite limited here. The showers and storms should move out by 20-22z, and allow for some clearing by tonight. That will allow for some fog generation with light winds and a moist boundary layer.

- Small chances for Rain Monday through Wednesday

We expect that most of the area will stay dry on Monday. There will be a weak short wave moving through Central and Northern Lower on Monday. The general consensus of the models is showing rain chances over the higher elevations of interior portions of Central and Northern Lower during peak heating. All other areas should remain dry on Monday.

Tuesday probably has the lowest chance of rain for these three days, which is not saying much. There is not really a short wave shown to move through, and the upper ridge axis is building a bit toward the area. Wednesday probably has the highest chance over the largest portion of the area of the three day period. That is still not a lot with a back door cold front dropping through the area with really no upper support. There is little to no moisture with it. Model ensemble members vary a bit with their solutions with almost half showing nothing, and other ensemble members a few hundredths of an inch. With this in mind, we will keep rain chances on the lower side.

- Dry and mild Thursday and beyond

The back door cold front will have moved south of the area on Thursday, bringing in a cooler and drier air mass. The flow around the sfc ridge will be from the NE, which will bring cooler and drier air in from Eastern Canada. The air behind it is not that cold with 850 mb temps around +15C Wed morning, dropping to around +8 to +9C Thursday morning. This will support highs in the 80s Tuesday and Wednesday, then the 70s on Thursday. The upper ridge axis and sfc ridge building over the area will help to squash any cloud cover trying to develop.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1224 PM EDT Sun May 24 2026

Several challenges for the aviation forecast this afternoon into tonight. The confidence in timing the thunderstorm arrival into LAN and JXN is good, with occasional lightning and temporary IFR heavy rain being reported in Southwest Michigan. There is little to no lightning in the few hours of rain that will follow the up- front thunderstorm, so expecting to hold on to MVFR to tempo IFR cig/vis in the rain and remove the TS after it spends about an hour passing through the remaining aerodromes.

The back edge of low clouds is crossing Lake Michigan, and mostly clear skies are present in Wisconsin and Illinois. Latest models lend less confidence in VFR late this afternoon and evening, as there may be scattered to broken cumulus on either side of 2,000 feet hanging on through sunset. Then a brief clearing is possible from sunset which should give way to fog development overnight. The timing of fog onset will be difficult to pin down as it depends on how much each location can dry out prior to sunset, but this nonetheless is a good setup for fog tonight with lingering lower atmospheric moisture, light winds, and clearing skies late in the evening.

MARINE

Issued at 249 AM EDT Sun May 24 2026

We are anticipating not needing any marine headlines for potentially the next week. We have no major systems expected to approach or move through the area over the next week. There are a couple of periods (Monday night and Wednesday night) that winds 2-3k ft above the sfc of the lake will come up, but these scenarios are during strong warm air advection over the cool lake and winds should not make it to the sfc.

GRR WATCHES/WARNINGS/ADVISORIES

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