


Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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145 FXUS63 KMQT 172325 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 725 PM EDT Fri Oct 17 2025 .KEY MESSAGES... - Rain chances return late today in the west, then rain becomes more widespread this evening and tonight across the east half. - Rain and breezy winds are expected across eastern Lake Superior and Upper Michigan Sunday. A Gale Watch has been hoisted for eastern Lake Superior. - Rain returns Monday night through the middle of next week. Expect breezy conditions on Tuesday. && .DISCUSSION... Issued at 258 PM EDT Fri Oct 17 2025 After this morning`s warm front and rain, Upper Michigan has been parked within the warm sector of a closed and near-vertically stacked low positioned near Lake Winnipeg. Within this region, southwesterly flow has warmed the region into the 60s so far. Upstream, a cold front is analyzed extending south of the system`s triple point into Minnesota and into the east-central Plains. Rain ahead of the front this morning was generally light and fast moving toward the northeast over western Lake Superior, the Arrowhead, and northwestern Wisconsin. As the rest of today progresses, the front will inch into Upper Michigan, likely resulting in additional shower development. Enough elevated instability will be in place to support some weak thunderstorm activity by evening. As the front pushes eastward this evening, rain will end in the west and then become more widespread in the east in part due to the elevated instability, but also because increasing synoptic forcing from an associated jet streak aloft. Rain will gradually end in the east Saturday morning, followed by a mostly dry day for the forecast area save for isolated or scattered passing rain showers in the east. Overnight lows tonight fall into the 40s west and low to mid 50s east, Keweenaw, and by the lakeshores. Daytime highs Saturday climb into the mid 60s to low 70s. Colder air will eventually pour into the area Saturday evening/night behind a secondary cold front. The front may support rain along the boundary while a shortwave aloft takes on a negative tilt in response to an amplifying jet streak at 300mb over the central Mississippi River Valley, resulting in a surface low developing near Chicago. There continues to be spatial differences in ensemble clustering, but the general idea is for the low to lift northeast through Lower Michigan to near or east of Drummond Island by Sunday afternoon while deepening to around 989mb, then to near James Bay by Sunday evening. The intensifying nature of the system and increasing cold air aloft will result in rain become widespread over eastern Upper Michigan and winds increasing through the day. Wind speeds of near 25-30 mph will be common across the east half near the lakeshores of Lake Superior per LREF/NBM 4.2. Inland areas should also expect gusty winds through the day to at least 20mph; should the surface low end up being further west though, winds closer to 30 mph may be widespread across the east half. QPF in the various deterministic solutions varies thanks to the spatial disparities, but the GEFS and ECS suggesting probabilities for >1 inch increasing above 30% in and east of Luce County looks realistic. Rainfall ends Sunday night as a ridge builds into the region. Daytime highs Sunday look to peak in the 50s and bottom out in the low 40s to low 30s, coolest interior west. Dry conditions prevail into at least Monday afternoon, potentially into the evening. An amplifying shortwave is expected to press east or eastsoutheast through south-central Canada/northern CONUS Sunday night while a surface low organizes in northeastern Wyoming. As Monday progresses, the surface low will lift into northeast North Dakota or Minnesota, eventually filing into the Upper Great Lakes Monday night through Tuesday evening/night. Considering its still a ways out, there is fairly good clustering in the various ensemble systems with this evolution, which gives me higher confidence in widespread rain across the forecast area. The pressure gradient forces and cold air advection suggested by all deterministic packages also suggests breezy to windy conditions as well, but confidence is lower in this given the more nebulous consensus in the depth of the system and magnitude of these parameters. Weak ridging returns Wednesday with another system on its heels in the Thursday/Friday time frame. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 725 PM EDT Fri Oct 17 2025 VFR conditions prevail at all terminals throughout the forecast period. However, with a passing cold front, a few showers will be possible at SAW over the next few hours. That said, impacts should be limited. Meanwhile, breezy southwesterly winds will persist into tonight at CMX, with gusts to around 20-25kts. Some 20kt gusts will also be possible through the first half of the night at SAW. Expect partly cloudy and quiet weather into Saturday before clouds spread in again late in the day. && .MARINE... Issued at 258 PM EDT Fri Oct 17 2025 Southerly winds of 15-30 kts have been observed across Lake Superior today, with the higher end reports coming from high platforms like STKM4. Winds may increase this afternoon and evening ahead of and behind a passing cold front, but generally remain 25kts or less tonight. By Saturday, light winds below 20kts are expected. A passing cold front Saturday night will help elevate winds back to near 25kts across the west half and be the focus for a developing low pressure near Chicago. This low will lift northeast along the front as it deepens through the day Sunday, resulting a tight pressure gradient developing around the low. There are still questions about the exact track, but the model consensus is that it should lift to near Drummond Island or just east of there by Sunday afternoon, then to James Bay Sunday evening/night. With the increasing cold air spilling into the region, at least low end gales look good for the east half of Lake Superior. This is further supported by deterministic guidance`s suggestions of 35-45kt 925- 850mb winds. Opted to go ahead and issue a Gale Watch with this forecast package for this potential. Winds are expected to lighten Sunday night back below 20kts. The next system begins moving into the region Monday/Tuesday. The signals are there for another gale, perhaps high end if the track is right. Given the uncertainty in the track and thus where all the key conditions would line up, I`m currently not confident in anything more than low end gales. Recommend those transiting Lake Superior Monday night/Tuesday to monitor future forecasts. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Watch from Sunday morning through Sunday evening for LSZ249>251-266-267. Lake Michigan... None. && $$ DISCUSSION...JTP AVIATION...LC MARINE...JTP