textproduct: Grand Rapids

KEY MESSAGES

- Fall Storm System to bring Wind, Rain and Lightning to the area

- Rather benign weather expected this weekend into early next week

DISCUSSION

Issued at 245 PM EDT Thu Oct 15 2026

- Fall Storm System to bring Wind, Rain and Lightning to the area

Low pressure is centered just east of Des Moines Iowa at 18Z with widespread rain located to the north of the low over Minnesota and Wisconsin. Two upper shortwaves from both the northern stream and southern stream are phasing off to the west over the upper midwest at this time. As such, the low will deepen as it moves east through the Lower Peninsula. Widespread/deep lift will sweep through Southwest Lower Michigan between roughly 400pm this afternoon and 400am tonight. The bulk of the rain will fall during this period. The lift is driven by the right entrance region of an upper jet that will be located overhead which will drive a low level response of strong isentropic lift and significant moisture transport.

Sounding climatology for DTX shows the max PWATs for today being 1.55 inches. We will be north of 1.75 inches this evening. Given abnormal moisture in the depth of the column tonight we expect efficient rainfall production. Most areas will see 0.50 to 1.00 amounts. Amounts may exceed an inch up towards Ludington. Given low river levels and amounts that are not overly concerning not expecting flooding issues.

Thunderstorms are a possibility this evening, especially along I-94 between 800pm and 200am. The instability is not strong, several hundred j/kg, but given the dynamics, thunder is a distinct possibility.

Wind is the next concern and we have Gale Warnings out on the big lake. As for the land, we feel we will stay just below wind advisory criteria with most gusts in the 30-40 mph range. It will very much feel like fall with a wet, windy and rainy system working through the state.

The second portion of the event will come on Friday as a strong cold front sweeps south around daybreak. Showers will accompany the front and usher in cold enough air for lake effect rain. Midday into the afternoon CAPE over the lake is maximized, pushing towards 1,000 j/kg. We are likely looking at thunderstorms off the lake given the significant moisture boost this time of the year via the warmer water. Some diurnally driven showers and storms will be possible inland as well given the cold air aloft. The most concentrated rain will be working down the length of the lake though in northerly flow.

- Rather benign weather expected this weekend into early next week

Quiet weather conditions will persist over the weekend into early next week as high pressure dominates the scene both at the surface and aloft.

The main item of note is that frost and freezing temperatures are possible both Friday night and Saturday night.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 153 PM EDT Fri Oct 16 2026

The first batch of rain has moved through the area ahead of a front that is located near KLAN to KJXN at 0530z. A noticeable wind switch is occurring with the front, and a brief increase in wind gusts to about 35 knots. IFR remains dominate across the area with pockets of MVFR. IFR will continue for a few more hours with showers continuing with the next part of this system moving in. Conditions will improve to MVFR this morning, but we could see some IFR with another front moving through mid-morning to early afternoon. This front could actually cause some storms at KMKG with the instability over the lake.

Once the secondary front moves through this afternoon, winds will shift to become from the NNW and gust to 30-35 knots. Conditions will improve slowly to high end MVFR, and eventually VFR late this afternoon and evening. Showers will tend to migrate closer to the Lake Michigan shoreline. More cloud cover may hold at KLAN and KJXN this evening with some clouds coming in from Lake Huron.

MARINE

Issued at 245 PM EDT Thu Oct 15 2026

A deepening fall storm system is still expected to pass through the Great Lakes in the next 24-36 hours. The low will reach 995mb to 999mb Friday morning and early afternoon as it passes east from Ontario into Quebec. To the west a stout high pressure will be sliding south through the plains at a magnitude of 1040+ mb. Even though the distance between these two features is fairly wide, a tightening pressure gradient will reach its peak on Friday. The strongest winds will likely occur from midday into the evening hours with Gales likely along with the possibility of some Storm Force gusts. 40-45 knot gales look very reasonable over the water. Given the flow is north or even just east of north, the largest waves will be out over the open waters. That said, we are looking at 8 to 13 footers in the nearshore waters. Given along shore flow and water levels (near 579ft) that are 2.5 feet below advisory (582.5ft) we are not expecting any lakeshore flood issues in our area.

Small Craft Advisory begins this evening and lasts into Friday morning. A Gale Warning is in place from Friday morning into Friday night. Two items we will be watching are... 1) do we need to jump into the Gale earlier as some models are showing gales in the 06Z-12Z time frame tonight and 2) how much will the wind touch storm force tomorrow. Do not see either as a high probability at this point and will leave the headlines unchanged.

Waterspouts will be possible over the lake late tonight and Friday morning before the wind truly ramps up. The stronger winds tends to shear apart waterspouts. Much of this activity will remain over the lake given northerly flow.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory until 11 AM EDT this morning for LMZ844>849. Gale Warning from 11 AM this morning to 2 AM EDT Saturday for LMZ844>849.