textproduct: Duluth

KEY MESSAGES

- Patchy fog, dense in isolated pockets, is expected to dissipate after sunrise. Mostly sunny to sunny skies are expected today with dry relative humidity.

- Showers and thunderstorms arrive on Thursday, with isolated severe storms possible in portions of east-central MN and northwest WI on Thursday afternoon and evening. The primary hazard is large hail up to 1 inch in diameter.

- Scattered showers on Friday afternoon and evening in the Arrowhead are expected to give way to pleasant conditions this weekend as high pressure returns. Additional rain chances arrive early next week.

UPDATE

Issued at 349 AM CDT Wed Aug 19 2026

Patchy fog is occurring early this morning, with localized dense fog being observed around the Iron Range. This fog is expected to dissipate shortly after sunrise as diurnal heating begins and mixing occurs. Moderately deep mixing in excess of 8,000 feet occurring over northwest WI will allow for dry min RH this afternoon as low as 25%. While min RH will be very dry this afternoon for portions of NW WI, relatively light northwest winds around 5 mph keep fire weather concerns minimal. Relative humidity is forecast to be slightly higher in the Borderlands in the 30-40% range, where mixing won't be as robust as northwest WI.

The forecast for showers and thunderstorms remains on track on Thursday as a shortwave and attendant warm front move into the area. One change to note since the previous discussion is an increased potential for isolated severe thunderstorms Thursday afternoon and evening in portions of east-central Minnesota and northwest Wisconsin. The Storm Prediction Center has included these portions of the CWA in a Marginal Risk (Level 1 of 5) for severe thunderstorms on Thursday. Thermodynamics will certainly be on the marginal side, with dewpoint temps in the low to mid 60s and mid- level lapse rates only around 6 degC/km. This will allow for modest instability up to 1000 J/kg of CAPE by the afternoon and evening, which could produce severe hail to 1" in diameter. Damaging winds are a secondary concern due to the timing being around when a nocturnal inversion will be developing. Peak DCAPE values are only forecast to be around 400-600 J/kg.

No major changes to the extended forecast on Friday into next week. Still looking at the potential for post-frontal showers/storms on Friday and pleasant conditions this weekend. This will be followed by additional chances for precipitation on Monday into Tuesday and an active pattern next week providing additional chances for precip.

DISCUSSION

Issued at 1155 AM CDT Tue Aug 18 2026

Quiet and dry conditions continue through Wednesday with seasonal high temperatures in the upper 70s. The next shortwave moves through the area on Thursday and brings a 45 to 70 percent chance of showers and non-severe thunderstorms. A warm front sets up and brings instability that is forecast to build to around 1000 J/kg of CAPE, PWATs approaching 1.5 inches, bulk shear of 45-50 knots and mesoscale forcing associated with the shortwave system. A few strong thunderstorms are possible for the Brainerd Lakes to east-central Minnesota and into far western Wisconsin Thursday late afternoon to early evening.

A cold frontal passage on Friday keeps widely scattered post-frontal showers in play for Friday daytime, along with non-severe thunderstorms into the Arrowhead to the Twin Ports and across northwest Wisconsin. Following the front, a mild and very nice weather weekend is coming up for our region. Temperatures will remain pleasant in the 70s with mostly sunny skies.

The next weather system after the Thursday and Friday one brings rain shower and thunderstorm chances back to the area early Monday morning into Tuesday. This progressive pattern will continue to provide periodic precipitation chances.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1228 AM CDT Wed Aug 19 2026

With the exception of patchy fog early this morning, VFR conditions are expected through the period. Confidence in patchy fog is highest for KHIB, with the potential for brief periods of LIFR visibility just before sunrise. Calm winds will become west to northwest for the afternoon with speeds generally being light.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 349 AM CDT Wed Aug 19 2026

Expect generally light winds today as high pressure occurs. Our next system brings rain and thunderstorm chances to western Lake Superior on Thursday into Thursday night. A few storms on Thursday afternoon and evening may become strong, capable of producing small hail. These potentially strong storms are most likely near the Twin Ports and along the South Shore, with the potential greatly decreasing for waters farther north.

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

FIRE WEATHER

Issued at 349 AM CDT Wed Aug 19 2026

High pressure will result in dry conditions today, especially across northwest Wisconsin where min RH as low as 25% is forecast this afternoon. Calm winds early this morning become northwest later this morning, with light speeds around 5-10 mph and gusts of 15 mph or less this afternoon. The next chance for precipitation arrives late tonight into Thursday, as a warm front and associated low pressure move into the area. This will likely to be followed by post cold front scattered showers on Friday afternoon. At least some measurable rainfall is expected across the region, although wetting rains of 0.25" or greater will be more hit or miss on Thursday through Thursday night. A few storms may be strong to severe in east- central MN into northwest WI, with large hail to 1" being the primary hazard. High pressure returns this weekend, with additional chances for rain early next week.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...None.