textproduct: Marquette

KEY MESSAGES

- Another round of showers and thunderstorms lifts into the UP tonight through early Tuesday morning. There is a slight risk (level 2 of 5) for severe thunderstorms across the stateline border counties, although the chances seem to be decreasing as most convection is now predicted south of us in Wisconsin.

- Any heavy rainfall received will exacerbate ongoing flooding concerns. There is a marginal risk (level 1 of 4) for flash flooding with tonight into early Tuesday morning's rainfall event.

- A prolonged period of well above freezing temperatures and higher dewpoints will bring increased snowmelt. This, combined with periods of potentially heavy rainfall 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

DISCUSSION

Issued at 155 PM EDT Mon Apr 13 2026

Satellite imagery shows low-level cloud cover remaining across most of the U.P. early this afternoon as very weak high pressure ridging moves through the area. The low-level clouds are thanks to the warm temperatures and dewpoints moving over the remaining melting snowpack, which has caused some fog problems since yesterday afternoon. However, with sunshine now starting to show itself in southern Menominee County this afternoon, temperatures down that way are rising into the lower 60s. Thinking the 50s to lower 60s will be seen across the area by late this afternoon, with the warmest temperatures in the south central as the cloud cover slowly gives way to sunshine.

That being said, another round of rainfall is expected to move through the U.P. tonight through early Tuesday morning. Thankfully for flooding and severe weather purposes, it looks like most of the rainfall and severe weather potential has shifted south of the area into Wisconsin over the past 24 hours. Thus, lower rainfall amounts are generally expected in comparison to 24 hours, as well as the threat being lowered for severe weather. That being said, we could see some spots get to around half an inch of liquid, with maybe an isolated spot or two getting up to 1 inch if some heavier rainfall hangs out for a couple of hours; the heaviest rainfall is still expected in the south central where flooding was and still is being seen from yesterday to now. As of right now, the latest HREF still brings a 10 to 40% chance of greater than 1" of rainfall tonight into Tuesday morning in the interior west, south central, and east, with the highest chances in the south central and interior west. Should the rainier solutions play out, we may see flooding exacerbated over these areas as US-2 and US-41 continue to have water flowing over them in northern Menominee County. In the low (5% or less) chance that we see severe weather, expect damaging hail followed by severe winds. However, with CAMs bringing convection further south, thinking the un-worked airflow into convection going over the south central tonight will be limited, and thus so should the severe weather threat; the area where the chance for severe weather is greatest is Menominee County.

Behind the convection tonight into early Tuesday morning, expect a period of generally drier weather conditions as weak ridging builds in from northern Ontario Tuesday through Wednesday. Hopefully the slightly cooler air from northern Ontario and drier conditions will help to reduce the flooding risk across the area for the rest of this week. That being said, a weak shortwave low moving through the Upper Midwest could bring additional showers and thunderstorms to the U.P. late Tuesday into Tuesday night; whether this shortwave brings precipitation into the U.P. or not will depend on the strength of the ridging from northern Ontario. Another shortwave low moving through the Upper Midwest could bring additional rain showers and thunderstorms to the area around the Thursday time period, although with medium range guidance weakening the strength of this shortwave recently, it may only graze the south as it potentially moves through Lower Michigan; again, it will depend on the strength of the remnant high pressure ridging from northern Ontario.

The warmest conditions of the weak move in on Friday as a cold air from northern Canada causes a robust cold front to develop across the central CONUS late this week. With PWATs looking to rapidly increase to around 1 inch in the warm sector via Gulf air ahead of the cold front, the NBM brings up to a 90% chance for temperatures greater than 70 to the western half of the U.P. as dewpoints have a 20 to 50% chance of exceeding 50 degrees (highest chances in the south central and interior west). Combined with intensifying southerly winds, this becomes a recipe for accelerating snowmelt on the snowpack that we have left across the area. Now, where guidance diverges for this week is whether or not a shortwave low lifts through the area before and/or after the arrival of the cold front. Expect higher rain totals if a shortwave rolls through the area before the cold front moves through, as the cold front could bring additional showers and storms across the area into early this weekend. However, if a shortwave low rolls through the area immediately behind the cold front (like the latest deterministic Euro is suggesting), then the western half of the U.P. may be in for a significant wet snowfall event. Therefore, while the confidence is low at this time, we will keep an eye out to see if model guidance continues to converge on a solution. Regardless, there is fairly good agreement that colder temperatures and at the very least light snowfall will be seen over the northwest to west wind snow belts behind the cold front to end the weekend. Expect a transition to more normal temperatures early next week.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 804 PM EDT Mon Apr 13 2026

Widespread IFR/LIFR flight restrictions to persist tonight at all TAF sites as scattered showers and isolated thunderstorms move through the TAF sites. Simultaneously, fog will continue to reduce visibilities, and overnight cooling will help reinforce the IFR/LIFR conditions, possibly dropping as low as VLIFR at times near daybreak tomorrow. Do not expect conditions to improve above IFR at all through this TAF period.

MARINE

Issued at 212 PM EDT Mon Apr 13 2026

Light winds of generally 20 knots or less continue through the rest of the workweek as shortwave lows move through the area and bring showers and storms to Lake Superior occasionally between tonight and Thursday. Weak high pressure ridging moving through Tuesday through Wednesday may keep the lake dry, but confidence is low at this point as the precipitation chances will be dependent on the strength of the ridging. Nevertheless, here are the time periods where thunderstorm activity is possible over Lake Superior: tonight/early Tuesday, and Thursday. That being said, the chance for rain showers and thunderstorms on Thursday remains low as the shortwave currently looks to lift too far to the south to impact Lake Superior. In addition to the winds and rain/storm chances, we may see fog form over Lake Superior a few times throughout the week; indeed, marine dense fog is looking increasingly likely tonight and may warrant a Marine Dense Fog Advisory in the near future.

The main pattern shift for the period looks to come late this week through this weekend as a cold front approaches from the central CONUS. Expect increasing airflow from the Gulf ahead of the cold front to intensify winds from the south and southeast Friday, with over a 30% chance (highest over the open waters of the east according to the NBM) of increasing to gales of at least 34 knots by Friday night before the cold front moves through the lake around the Saturday time period. Behind the cold front, as the strong cold air advection improves mixing of the higher winds aloft to the sfc, expect the winds to become northwesterly as gale chances increase up to 50% late in the day through Saturday night. In addition to the winds, some thunderstorms may be seen ahead of and along the cold front late Friday into Saturday.

HYDROLOGY

Issued at 304 PM EDT Mon Apr 13 2026

In response to the ongoing snowmelt and heavy rainfall that occurred yesterday, river rises and flooding of low-lying areas are expected/are occurring across Upper Michigan, particularly over the south central where rainfall up to 4 inches fell, causing inundation over several roadways (including US-2/US-41) even through today. While much of the area near Wisconsin lost the entirety of their snowpack yesterday through last night, several inches to over a foot(!) of SWE remains over the Keweenaw and higher elevations of the north central U.P., as well as portions of the eastern U.P. upslope from Lake Superior over the northwest wind belts. Thus, while flooding concerns look to start dwindling over the areas near Wisconsin after Tuesday, expect continued snowmelt over the remaining areas to continue river rises over those areas with or downbasin from an area with notable snowpack remaining.

Because of this and the rainfall chances expected through the rest of this week (including tonight, which I will touch on in the next paragraph), river flooding to bankfull conditions are being seen across several rivers across Upper Michigan. Starting with the Black River near Bessemer, the quick loss of snowpack with the rainfall yesterday has created Minor Flooding conditions which are forecasted to continue until Tuesday; bankfull conditions for the Black River look to continue until Tuesday night. Moving over to the Sturgeon River at Alston, Minor Flooding is currently being realized; with plenty of snowpack left to melt, expect the river levels to slowly rise the rest of this week into early this weekend. The high river levels at Alston and high flow at Prickett Dam may also bring elevated river levels to Chassell later this week; we will continue to monitor the local observations over there and issue products accordingly should bankfull and/or floodstage be achieved along the Sturgeon River at Chassell. Moving along to the Paint River at Crystal Falls, Moderate Flooding is expected starting late Tuesday as we move into Minor Flood Stage this evening. While not quite looking to get into Major Flood Stage, river heights are currently expected to get up to 8.5", which does start to approach the River Flood of Record. Moving into the Michigamme River basin, some bankfull conditions to Minor River Flooding looks possible at Bangston Bridge and Witch Lake late this week as the snowmelt in the basin progressively melts and increases flows with time. As for the Ford River, we are currently flirting with bankfull conditions this afternoon and could go over tonight given the chances for rainfall (some potentially heavy at times). Moving over to the Escanaba River, bankfull to Minor River Flood conditions are expected over the Middle Branch at Humboldt and the Eastern Branch at Gwinn. Given the recent call with one of the dam operators in Escanaba about the high flows, will continue to keep an eye on the snowmelt in the north central as rainfall moving through tonight could help to push- up cfs to hazardous levels. As for the Sturgeon River (Delta County) at Nahma Junction, the recent heavy rainfall and snowmelt has caused river levels to exceed bankfull; I'd be shocked if the river doesn't go into Minor Flood Stage shortly as even the HEFS shows the river at about 100% for getting into Minor Flood Stage. As for the Manistique River, the increasing snowmelt and heavy rainfall recently (and potentially tonight) could bring above bankfull river levels, potentially causing ponding of water and inundation in low- lying areas near the river Tuesday and beyond; a Flood Advisory may need to be issued for this river's area of influence in the future.

One more thing worth mentioning: while the flooding threat looks to progressively decrease in the areas near Wisconsin this week, with model guidance suggesting another round of rain showers and thunderstorms moving (mainly) through the south central tonight into early Tuesday morning, flooding concerns may be significantly increased as the area is still inundated from the previous rainfall and snowmelt. As of now, the south central has up to a 40% chance of receiving over an inch of liquid tonight. With the rainfall potentially being a torrential downpour at times, flooding along the US-2/US-41 corridor between Iron Mountain and Escanaba may worsen; additional roadways and areas may be inundated as the water within in the low-lying areas increases in height. Therefore, a Flood Warning may need to be re-issued for the southeastern Dickinson, northern Menominee, and western Delta county area once again this evening as the rain showers and thunderstorms begin to make there way into the U.P.

MQT WATCHES/WARNINGS/ADVISORIES

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

Lake Superior... None. Lake Michigan... Dense Fog Advisory until 8 AM EDT Tuesday for LMZ248-250.