textproduct: Duluth

KEY MESSAGES

- Heavy rainfall is possible tonight from the Brainerd Lakes to the Hayward Lakes this evening through early Wednesday morning. Localized flash flooding and minor flooding are possible.

- A Flood Watch in effect tonight through late Wednesday morning from the Brainerd Lakes east to Pine County where the risk of flooding is greatest.

- A brief cooldown on Wednesday with a break in the humidity until late this week.

- Minimal precipitation in the extended forecast with potentially impressive heat this weekend into next week.

- Hot and humid weather returns as early as Saturday and persists through next Wednesday. The risk of heat-related illness will increase.

DISCUSSION

Issued at 254 PM CDT Tue Jul 7 2026

Main stories for this forecast package involve the potential for heavy rain tonight and early Wednesday then the warm-up this weekend into next week which will raise the potential for heat- related illness.

Synopsis...

As of 19Z this afternoon a nearly stationary front stretched from near Watertown, SD to near St. Cloud, MN to near Bayfield, WI. Regional radar mosaic revealed an area of light rain over eastern North Dakota with showers over a portion of northwest Minnesota. A compact MCS was noted over west-central Minnesota while an MCV from early morning convection was centered over far northeast South Dakota within an area of stratiform rain. The latest SPC RAP analysis revealed MLCAPE values of 2000-3000 J/kg over east-central South Dakota into southwest Minnesota with a gradient northward along and just north of the front.

This afternoon through Wednesday morning...

Expect the MCS to propagate eastward along the instability gradient through late afternoon. It will likely strengthen as greater instability builds ahead and to the south of the complex. Meanwhile the trailing MCV will create a localized enhancement in convergence and lift in its wake. The showers over North Dakota and northwest Minnesota are forecast to spread eastward into northern Minnesota by this evening in response to a lobe of 500 mb vorticity over North Dakota this afternoon which will propagate eastward through tonight.

The main focus for heavy rainfall and a small risk of severe storms will be found along and north of the front. This evening, an 850 mb low-level jet is forecast to develop and create enhanced low-level convergence along and north of the front. Instability will become somewhat limited overnight with MUCAPE values of 500-2000 J/kg straddling the front. Thunderstorms are expected to develop in north-central South Dakota this afternoon and propagate eastward with time tonight. Meanwhile additional storms are forecast to develop over central Minnesota into northwest Wisconsin. The strongest moisture advection will be over the Brainerd Lakes by 08.06Z and will propagate farther eastward overnight.

A reservoir of PWAT values of 2 to 2.5 inches is forecast to build over central Minnesota in response to southerly theta-e advection through late evening. Freezing heights will be around 13kft which combined with limited instability and 0-6 km bulk shear of 30-40 knots should produce low-centroid storms and efficient precipitation production. Several CAMs reveal a training patter of storms tonight over central Minnesota which raises the potential for widespread 1-3 inch rainfall amounts. Isolated 2-4 inch amounts are certainly possible. With all these factors in mind along the the recent rainfall over the Northland, we decided to issue a Flood Watch from the Brainerd Lakes east into Pine County. That area is the most likely to see excessive rainfall. Flash flood guidance over the watch area ranges from 1.5 to 2.25 inches in 1 hour and 1.8-2.5 inches in 3 hours. Those precipitation rates are well within reach given this setup.

The severe weather risk is more limited. The modest instability and mid-level winds will limit the potential for large hail and damaging wind gusts. The greater potential for severe storms is to the southwest of my area.

The existence of the MCS/MCV combination has the potential to displace the strongest convergence south of the Northland for tonight, which would shift the area of heavy rain potential out of our area. These trends will need to be monitored through this evening.

Showers and storms will persist overnight and slowly taper off from west to east Wednesday morning. The risk of flash flooding decreases rapidly as storms weaken.

Wednesday afternoon and evening...

The front is expected to loiter over the southern third of Minnesota into central Wisconsin Wednesday. Another round of showers and storms is forecast to our south which may propagate eastward into the Hayward and Phillips areas during the late afternoon and evening hours. Depending on how far east the heavy rain tonight occurs, there may be a chance of flash flooding over those areas. Temperature will generally trend cooler for Wednesday due in part to lingering cloud cover. Northeast winds will allow a weak lake breeze to propagate well inland keeping temps cooler. Look for high temperatures in the low 80s north and south to the low to upper 70s from the Brainerd Lakes into NW WI and shoreline areas of the Arrowhead.

Thursday through early next week...

We will enter a period of quieter weather for the remainder of this week. Widespread rain chances dwindle as zonal flow develops over the northern Plains and Canadian Prairies. Upper- level ridging will build Sunday into early next week which will allow strong southwesterly theta-e advection to bring a return of upper 80s to low 90s temperatures. Dewpoints will increase as well. The risk of heat-related illness will trend higher starting as early as Saturday and persisting through Wednesday at least. Several rounds of heat headlines may be needed.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 118 PM CDT Tue Jul 7 2026

Expect mainly VFR conditions into tonight. Slight complicating factor is BRD and the storms over west-central MN. Diurnal cumulus developed over the past hour across NE MN and portions of NW WI and feature mainly VFR cloud bases. A brief period of MVFR cloud bases was noted at BRD between 1730Z and 1800Z. Think there is a potential for another brief period of MVFR clouds at BRD. Remainder of the terminals are showing VFR cloud bases, so less of a ceiling concern there for now. Showers and storms are forecast tonight and early Wednesday morning which will bring brief periods of IFR/LIFR conditions to the terminals in heavy rain. Opted to keep a period of IFR visibility and ceilings for now. INL has the best potential for radiational cooling. Opted for IFR mist and patchy fog for now at that location. If the rain moves out overnight at the remainder of the terminals, forecast models suggest a period of IFR/LIFR visibility with low ceilings. Conditions gradually improve after sunrise although showers and a few storms may persist into Wednesday afternoon.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 254 PM CDT Tue Jul 7 2026

Relatively light winds and waves of less than 2 feet are forecast for the remainder of the week. There is a 30-40% chance of thunderstorms tonight over western Lake Superior. A few storms may be strong with small hail and wind gusts to 30 knots. Persistent southwest winds are forecast Sunday through Tuesday which would build waves from Grand Marais to Grand Portage. Small Craft Advisories may eventually be needed.

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

FIRE WEATHER

Issued at 254 PM CDT Tue Jul 7 2026

Showers and storms are forecast to develop tonight mainly from the Brainerd Lakes eastward into northwest Wisconsin. Heavy rain is possible with these storms with 1-3 inches of rain possible and localized areas of 2-4 inches. A secondary area of rain and storms is possible farther north over northern Minnesota. It is possible that areas closer to the International Border receive little to no rain. Light northerly winds continue (outside of any thunderstorms) tonight and Wednesday. RH values will dry out into the 35-45 percent range north of a line from Northome to Ely to near Grand Portage. Clouds and showers will keep RHs higher south of US-2. After Wednesday morning the potential for widespread rain dwindles. A warm-up expected this weekend into next week.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Flood Watch from 10 PM CDT this evening through Wednesday morning for MNZ033-034-036-038. WI...None. MARINE...None.