textproduct: Duluth

KEY MESSAGES

- Rain showers increase in coverage through the afternoon, with fog developing tonight as warm air advection occurs over snow.

- Snow pack temperature across Northwest Wisconsin is right at freezing, so it should efficiently melt with any rainfall and elevate the flood threat.

- We have trended downward with QPF, but flooding threat remains possible along the South Shore and Arrowhead regions.

- Isolated strong to severe thunderstorms are possible through Monday, bringing a large hail risk to northwest Wisconsin.

DISCUSSION

Issued at 117 PM CDT Sat Apr 11 2026

For the rest of the day, rain showers increase in coverage through the afternoon as a prominent tongue of moisture pushes northward. Trended downward with QPF from prior forecasts, but above NBM for this initial round. Expect scattered showers to transition to widespread rain with embedded thunderstorms overnight. Added fog tonight in areas with cold snow and warm air advection moving over the region, which will lead to reduced visibility across the northern portion of the Northland, especially along the North Shore where onshore flow will help cool and saturate the air mass.

Heading into Sunday, a second warm front will surge into the area, setting the stage for a very warm spring day with highs reaching into the upper 60s and 70s for many inland locations, but not Cook County where onshore flow will keep it cool and in the 40s. Another round of showers and thunderstorms is expected by the afternoon and evening hours. The environment will be conditionally supportive of isolated strong to severe thunderstorms, particularly across northwest Wisconsin, where large hail and damaging winds are the primary hazards if storms can breach the capping inversion.

A critical hydrology component to monitor is that the snow pack temperature across NW WI is right at freezing, so it should efficiently melt with rainfall. Despite the fact that we have trended downward with QPF, this efficient melting combined with multiple rounds of rain will maintain a threat for minor flooding across the South Shore and potentially the Minnesota Arrowhead where deeper snowpack remains as it ripens more quickly with these warm temperatures. Feel like the current Flood Watch covers the area of most concern unless things change as the QPF axes become more apparent with radar trends.

Heading into Monday and Tuesday, the active pattern persists as a surface boundary lifts back north as a warm front. High temperatures will again soar into the 70s on Monday with dew points in the 50s. This will fuel another severe weather threat Monday afternoon and evening, with all hazards possible depending on storm mode. Tuesday will see another surface low track through the Upper Midwest, bringing renewed chances for widespread rain, isolated storms, and gusty winds, though severe chances look slightly lower.

By Wednesday, precipitation will gradually taper off from west to east as a cold front sweeps through the region. This will usher in a pattern change for the late week period. Expect Thursday to be mainly dry and breezy with temperatures returning to near normal. By Friday, a much colder air mass will drop out of Canada, bringing daytime highs back down into the 40s and 50s and reintroducing chances for rain and possibly some snow showers across the northern tier.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 117 PM CDT Sat Apr 11 2026

VFR conditions this afternoon will rapidly deteriorate to MVFR and IFR this evening across the terminals as rain showers and isolated thunderstorms spread northward. We added patchy dense fog tonight, which will lower ceilings to LIFR at times. Southeast winds gusting 20 to 25 knots will continue, alongside low level wind shear concerns tonight.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 117 PM CDT Sat Apr 11 2026

High pressure exiting to the east will give way to a developing low pressure system to our west. Easterly winds will increase tonight, channeling down the southwestern arm of Lake Superior with gusts approaching 20 knots. Waves will build to 2 to 4 feet after midnight. Winds become southerly on Sunday and Monday ahead of the next frontal boundary, keeping wave action choppy along the North Shore while patchy fog limits visibility. Stronger northeast winds to 25 knots are possible on Tuesday.

For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.

FIRE WEATHER

Issued at 117 PM CDT Sat Apr 11 2026

Minimum relative humidity values will drop to around 30 to 40 percent this afternoon across northwest Wisconsin and the I-35 corridor. Southeast winds will gust to 15 to 25 mph. Repeated rounds of rain starting this evening will keep fire weather concerns minimal through early next week. We may see a dry and breezy day on Thursday before more precipitation arrives.

See the Fire Weather Forecast product for a more thorough breakdown of fire weather conditions.

HYDROLOGY

Issued at 503 AM CDT Sat Apr 11 2026

No changes to the Flood Watch for Bayfield, Ashland, and Iron counties in Wisconsin for this evening through early Wednesday morning. The watch remains medium confidence as it will be less the traditional sense for flash flooding potential and more into the potential for around 1-2" of rain over several days combined with the potential for 1-5 inches of snow water to melt out of the remaining snowpack. There has been a trend with the latest forecast for a slight decrease in rainfall amounts for the North Shore and northwest Wisconsin both for the Saturday afternoon - Sunday morning timeframe and for the total accumulations throughout the several rounds of showers and storms as a whole. Given the convective nature of the precipitation, some pockets of locally higher and lower rainfall totals will be possible. The precipitation from this afternoon through Sunday morning will set the stage for subsequent rounds of flooding potential. Should this first round continue trending down regarding precipitation amounts, then flooding concerns through early next week would also decrease.

We will still need to monitor for river rise/flood concerns along the North Shore as well given the deeper snowpack to 12-24"+ of snow depth and snow water equivalents of 5-7"+ there. However, the trend has been for the heaviest rain to remain south of the North Shore. Additionally, despite temperatures forecast to be above freezing for several days in a row, Lake Superior will keep the North Shore high temperatures about 10-20F colder and low temperatures 5-15F colder than areas farther inland. This should slow the snowmelt process there relative to the South Shore. Should precipitation forecasts and/or temperature forecasts increase for the North Shore for tonight through Wednesday, then flood headlines may be needed.

As for river and stream concerns, the highest potential for minor flooding remains with the Tyler Forks near Mellen, which could see minor flooding by late Monday or early Tuesday depending on how heavy the first couple rounds of rain are. The Bad River and Nemadji Rivers also have some potential to rise into action stage in the Monday to Tuesday timeframe depending on heavy rain locations and amounts.

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...Flood Watch from 7 PM CDT this evening through Wednesday morning for WIZ002>004. MARINE...None.