textproduct: Grand Rapids

KEY MESSAGES

- Showers and Thunderstorms Tonight into Saturday

- Turning Colder from Sunday to Tuesday

- Rainy Pattern Returns Latter Half of Next Week

DISCUSSION

Issued at 204 PM EDT Fri Apr 3 2026

- Showers and Thunderstorms Tonight into Saturday

Clusters of thunderstorms are expected to develop around/after midnight and persist into part of Saturday morning. These storms will be developing with increasing moisture and convergence on the nose of an 850 mb jet along an elevated warm frontal surface. Several hundred J/kg of MUCAPE is expected but up to 1000 is possible. Can't rule out some storm cells producing hail given instability extending through -10 to -20 C air. Shear above 1 km (the effective inflow layer tonight) is a little junky but there is some, perhaps can also aid some cells in the production of hail. Also have to add that a little freezing rain is possible in the highest elevations of northern Osceola and Clare counties prior to daybreak Saturday.

The storms tonight do appear to be good rainmakers as well. Deep moisture will be present through much of the lower and middle troposphere. A majority of the CAMs produce a broad swath of around an inch of rain through Saturday, with embedded narrower streaks around 3 inches possible. Most CAMs place the highest rain potential along and south of I-96. See the Hydrology section for additional details given the recent rainy conditions.

Toward midday and afternoon Saturday, it will remain showery for many areas, but diminishing instability will be a limiting factor for thunderstorm potential. Some of the CAMs including the HRRR and WRF-ARW depict a narrow cold frontal rainband developing with 25-35 mph gusts in its vicinity.

- Turning Colder from Sunday to Tuesday

A temporary change in the pattern as synoptic troughing over the Great Lakes brings -5 to -10 C air at 850 mb. This will support highs only the 40s Sunday through Tuesday, and lows are favored to dip into the 20s Monday night. Some snow flurries are possible Sunday morning, and snow showers are also possible Monday as Clipper-style shortwave troughs move through the mean flow pattern.

- Rainy Pattern Returns Latter Half of Next Week

An active spring pattern is favored to return later next week and into the early week following, with western CONUS troughing and a Bermuda High setting up to provide a flow of warmer air and moisture from the Gulf as early as Thursday. Yesterday's CPC outlook highlighted Lower Michigan in a moderate chance for heavy precipitation during this upcoming pattern.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 651 PM EDT Fri Apr 3 2026

--- Key Changes With This Forecast ---

- TEMPO TSRA added for initial warm frontal surge

- Added detail for improving conditions after 18z

- Added LLWS for all terminals

--------------------------------------

Ongoing conditions are VFR with scattered clouds in the 2-4kft range under a cirrus deck. Increasing low-level moisture with a warm front, and associated showers and thunderstorms, will cause conditions to deteriorate to MVFR then IFR, and possibly LIFR cigs overnight. Have added a TEMPO group to highlight the higher confidence TSRA potential on the warm frontal surge, with PROB30s covering the more scattered activity behind the front.

Widespread showers will keep cigs and visbys reduced until the last 6 hours of the TAF window as a cold front moves through and scours out the low-level moisture. The other concern is wind, as gusts to 25 knots are likely beginning with the warm frontal surge late this evening through the end of the TAF period. Winds will be shifting through the period from easterly with the approach of the front, to southerly, to southwesterly behind the front. This change in winds will result in a period of LLWS late tonight into Saturday morning.

MARINE

Issued at 204 PM EDT Fri Apr 3 2026

Scattered thunderstorms are expected to develop over Lake Michigan late this evening and continue overnight. A new Small Craft Advisory will be needed late tonight for strengthening east winds, becoming southwest during the day Saturday, with west winds persisting into much of Sunday. Waves will build on Saturday and diminish late Sunday. Another period of hazardous conditions on the lake is likely Monday into Tuesday.

HYDROLOGY

Issued at 204 PM EDT Fri Apr 3 2026

2 to 4 inches of rain has fallen across a large portion of Lower Michigan over the last week. Rivers are now rising, and soils are saturated. A final round of rain from this storm cycle is expected to impact our area late Friday night and continue through the day Saturday. Most areas will receive an additional 0.5 to 1.0 inches of rain, with some indications that a few counties could end up with a streak of more like 1.5 to 2.5 inches of rain or more. If this heavier rain tracks over an urban area like Kalamazoo, Grand Rapids, or Lansing, localized urban flooding issues are likely.

Meanwhile, as all this water continues to find its way into our river systems, minor flooding is becoming likely on parts of the Muskegon River, and is also a possibility on some of the typical flood-prone trouble spots in the Grand River watershed, including in Comstock Park and Maple River. Much will depend on exactly where the heaviest swath of the upcoming rain falls, but the bottom line is that some minor river flooding is becoming more likely across parts of Southwest and West-Central Michigan as all this rain continues to add up.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory from 2 AM Saturday to 8 PM EDT Sunday for LMZ844>849.