textproduct: Marquette

KEY MESSAGES

- Active weather continues through much of at least the week as several periods of showers and thunderstorms are poised to move through the region.

- A prolonged period of well above freezing temperatures and higher dewpoints will bring increased snowmelt. This, combined with periods of potential heavy rain and thunderstorms, will accelerate river rises and lead to ponding of water in areas with poor drainage. A Flood Watch remains in place for all of Upper Michigan through Wednesday morning.

- Some severe thunderstorms for hail and wind are possible Monday night.

DISCUSSION

Issued at 213 PM EDT Sun Apr 12 2026

Warming and moist conditions are being realized across Upper Michigan this afternoon thanks to a warm front bringing showers and thunderstorms across the area earlier this morning. In addition, training of storms has occurred over the south central along the US- 41/US-2 corridor between Iron Mountain and Escanaba, with the local radar predicting rainfall amounts up to 4 inches over this area. While a quick respite in the rainfall is now being seen for the area for the early-to-mid afternoon hours, one more round of showers and storms may make its way through the central and eastern U.P. during the mid-afternoon hours today. Thus, an additional 0.50 to 1.50 (potentially even 2) inches of rainfall could be seen over the south central today before things wind down with this first round of rainfall this week. Because of the abundant rainfall that fell this morning, decided to hoist up a Flood Warning for the US-2/US-41 corridor in the south central/northern Menominee County as Flash Flood guidance from the North Central RFC was being well-exceeded. With additional rainfall potentially moving in this afternoon, decided to reissue the Flood Warning and keep it going until 345 PM EDT/245 PM CDT; will reevaluate just before then to see if the warning needs to be extended or not. While the rainfall looks to be done by the late afternoon hours today, with the VERY moist soil conditions keeping the recently fallen/melted liquid from percolating into the ground efficiently, the Flood Warning may need to be extended much further in time than currently anticipated as ponding of water in the low-lying areas could keep roadways inundated.

With the weak cold front passing through the area tonight, we may see some light rain showers and maybe an occasional thunderstorm or two along the frontal boundary. However, with the frontogenesis/lift being weak, not too much rainfall (if any) is expected; maybe just up to 0.25 inches of liquid or so in a couple of isolated spots. Weak high pressure ridging dropping in from northern Ontario looks to give us a break from the convection on Monday. While this ridging is looking to lower temperatures along Lake Superior on Monday (generally 50s today in comparison to the 40s on Monday), highs in the south central look to increase from the lower 60s today to approaching 70 on Monday. In addition, while dewpoints are expected to lower back into the 40s and winds are expected to become pretty calm, snowmelt is still expected to make a dent on the remaining snowpack, especially since temperatures haven't gotten below freezing for most of the area since this past Saturday morning. This could keep river rises steady, as well as keep the soils exceptionally moist across Upper Michigan.

Our next round of precipitation looks to come in Monday night. A shortwave low passing through the Upper Midwest is expected to bring showers and thunderstorms back across the area, with some CAM reflectivities and model hodograph soundings hinting at some strong to potentially severe thunderstorms rolling through the region. While most of the CAMs do have reflectivities dwindling over us once convection reaches our neck-of-the-woods, other solutions like the NAMNEST show a potential line of strong to severe thunderstorms rolling across the west and central U.P. during the evening hours. While the convection is looking to move overhead during the overnight hours, with model soundings showing it to be almost completely elevated, and with 0-6 km bulk shears achieving/over- achieving 50 knots, we could see some hail above one inch (quarter- sized). In addition, although the chances are lower due to the convection being elevated, some severe winds could potentially punch down to the sfc as the inversion in the boundary layer is not that impressive. Besides the severe threat, flooding concerns are once again looking to flare up Monday night as rainfall could be heavy (think downpours) at times with some limited training possible for a few hours. In addition, with the extra rainfall on top of a melting snowpack, expect river rises and ponding of water in the low-lying areas, particularly where rainfall is heaviest. Thus the Flood Watch continues over Upper Michigan through early this week.

Above normal temperatures and above freezing dewpoints (save for potentially the Keweenaw) look to remain across the area the rest of this week as an additional round of precipitation via a shortwave low looks to move into the area on Thursday. Much of the same hazards being experienced now and potentially Monday night could be seen with this shortwave low's passage too. Behind this third round of rain, expect the warmest temperatures of the week as highs potentially get into the lower 70s over the interior west by Friday (the NBM shows up to around a 75% chance of high temperatures above 70 for the interior west). With winds also predicted to intensify from the south ahead of a robust cold front, we could see more significant snowmelt across the area where snowpack still remains. Heavy rain showers and thunderstorms could also be seen along the cold front as it passes through the U.P. from west to east too, potentially bringing elevated flooding concerns once more.

However, behind the cold front, expect a pattern shift as more normal to below normal temperatures become realized. In addition, we may see the return of light lake enhanced to lake effect snow showers across the northwest wind snow belts next weekend. Should this occur, the colder air from behind the stout cold front will limit snowmelt and help to reduce flooding concerns as we head into next week.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 842 PM EDT Sun Apr 12 2026

VLIFR visibility restrictions due to fog will persist into the night at SAW as warm, moist air moves over snowpack. The fog threat at CMX has diminished for now, but a wind shift to the northwest later tonight will likely bring a resurgence of fog to CMX in upslope flow. Fog at SAW, on the other hand, should begin to lift. Elsewhere, IWD can expect gradual deterioration in cigs to MVFR and eventually IFR through the night. Meanwhile, a period of LLWS will impact all TAF sites into tonight due to a strengthening LLJ.

MARINE

Issued at 229 PM EDT Sun Apr 12 2026

Southerly winds of 20 to 30 knots over mainly the eastern half of Lake Superior this afternoon will slowly turn southwesterly this evening, before a cold front pushes through and generally brings light winds of 20 knots or less back to the area late tonight through Monday morning. In addition, satellite imagery is picking up on some low level clouds across much of the open waters and along the Keweenaw. As such, in collaboration with the WFO DLH office, hoisted up a Dense Fog Advisory for the rest of today through tonight, before drier conditions behind the cold front make dense marine fog less favorable by Monday morning.

Moving through the rest of the week, winds look to mostly stay 20 knots or less across the lake. However, a shortwave moving through on Monday evening could bring some thunderstorms to the lake, with some potentially bringing severe hail and winds to the water's sfc; much the same could happen on Thursday too as a shortwave passes through the Upper Great Lakes. Winds do look to intensify from the south once again by Friday ahead of a stout cold front pushing in from the west; expect southeast to southerly winds of 20 to 30 knots with a 20% chance of gales happening by late Friday as additional showers and storms push from west to east across the lake. Gale chances look best (up to 30% according to the NBM) early Saturday as strong cold air advection works into the Upper Great Lakes behind the front.

HYDROLOGY

Issued at 321 PM EDT Sun Apr 12 2026

Now with most of the first round of rainfall done for this week, we can see that most of the area last night/this morning received 0.25 to 1 inch of rainfall across the area. However, the interior west to south central all the way past Manistique received multiple inches of rainfall, with the highest amounts predicted by radar up to 4 inches. Having called the Menominee County EM and having been told of 20 to 30 roads already being inundated with water and Flash Flood Guidance being well exceeded, decided this past morning to hoist up a Flood Warning for the US-2/US-41 corridor. By the afternoon hours, decided to reissue the product as additional rainfall was expected. However, with the most recent radar scans showing the remaining showers and storms trending away from our area, thinking enhanced flood risks from heavy rainfall are done for today. Nevertheless, with the soils still being inundated with liquid, the Flood Warning may once again need to be reissued as water will have a very difficult time percolating into the well-saturated ground.

In response not only to the rainfall, but also to the above freezing temperatures and dewpoints today through the rest of the workweek, river rises are looking to increase across Upper Michigan as the remaining snowpack melts away. In addition, the heavy rainfall at times may accelerate the liquid entering into the streams, rivers, and waterways of the U.P. at times this week, with the next bout of heavy rainfall looking to come Monday night. River observations and forecasts have thus increased in measured and expected water level heights, with Moderate Flooding now expected for the Paint River in Crystal Falls and becoming possible for the Sturgeon River in Alston; the latest River Forecast for Crystal Falls has the Paint River getting up to a height of 8.2 feet, but with the river observations already exceeding the river forecast, I'm wondering if we will overachieve and get closer to the flood of record (9.8 feet). Elsewhere across Upper Michigan, other rivers have been put under a River Flood Advisory as they are expected to get to bankfull; however, uncertainty still remains on whether or not they will achieve flood stage as it will depend on the speed of snowpack melt and rainfall this week. The rivers are: the Black River near Bessemer, the Chocolay River at Harvey, and the Middle Branch of the Escanaba River at Humboldt. As of last evening, the Black River had over a 30% chance of getting into Minor Flood Stage. Meanwhile, the Chocolay at Harvey and the Middle Branch of the Escanaba River at Humboldt have over a 50% chance of reaching Minor Flood Stage later this week. Eastern Delta County has received so much rainfall today that the latest observations already show the Sturgeon River near Nahma Junction already at bankfull; thus a River Flood Advisory has been issued for it until further notice. Outside of these spots, others like the East Branch of the Escanaba River at Gwinn and the Michigamme River at Witch Lake could get to bankfull or more later this week. From the HEFS run last night, there is a 70% chance that the Escanaba River in Gwinn gets to Minor Flood Stage. Outside of these rivers, there may be additional spots where flooding and bankfull stages could be achieved. In addition, expect the saturated soils over the U.P. to potentially keep the poor drainage and low- lying areas inundated with water. Therefore, if you see any flooding please report it to the NWS and go around it; turn around, don't drown.

Besides the storms expected to roll through on Monday night, additional rain chances (with the rainfall potentially being heavy at time) look to move in on Thursday and again late Friday as a shortwave and robust cold front, respectively, move through the region. With snowmelt continuing until the cold front passes Friday night, flooding concerns look to continue across the area until colder air arrives by Saturday. With the warmest weather expected on Friday, expect snowmelt to accelerate as winds pick up from the southeast and south and dewpoints reach up to around 50 once again. Thus, we may see river rises intensify late this week as the rainfall along the cold front combined with the snowmelt could exacerbate river rises and flooding across the Upper Peninsula. However, after the cold front passes early Saturday, expect the snowmelt to become limited if not cease entirely as light lake enhance to lake effect snow moves over the northwest wind snow belts. With cooler and drier weather expected this upcoming weekend, we may see flood concerns start to alleviate by the end of the forecast period.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Flood Watch through Wednesday morning for MIZ001>007-009>014- 084-085.

Dense Fog Advisory until 2 AM EDT Monday for MIZ004>007-013- 014-085.

Lake Superior... Dense Fog Advisory until 11 AM EDT /10 AM CDT/ Monday for LSZ162-243>246-263>267.

Lake Michigan... Dense Fog Advisory until 8 AM EDT Monday for LMZ221-248-250.