textproduct: Duluth

KEY MESSAGES

- Warming trend continues today with Tuesday expected to be the hottest day of the work week. Highs will be in the 80s with a few 90s possible.

- There is a Marginal Risk (threat level 1 out of 5) for severe storms this afternoon and evening over a portion of the Minnesota Arrowhead. Hail up to half-dollar size (1.25 inch) and wind gusts to 65 mph are the main threats from severe storms.

- Off and on chances for showers and storms persist for the next several days.

DISCUSSION

Issued at 355 AM CDT Mon May 25 2026

Early this morning through tonight:

A vort max and associated shortwave trough was located near ND/SD/MN border 08Z per GOES-East water vapor imagery. The associated shortwave trough appeared to be digging ahead of the vort max with increasing cyclonic curvature over western MN. That feature should lead to enhanced ascent over central Minnesota into the I-35 corridor through 12Z. At 0830Z regional radar and GOES-East Band 13 temperatures revealed a broken line of showers and weak thunderstorms ahead of the vort max over Brainerd to near Isle to near Bethel MN. Expect this weak cluster of storms to persist through this morning and advance slowly eastward with time. The southwesterly low-level jet ahead of these storms seems to have limited moisture available due to the convection over northern Iowa intercepting the feed.

Another shortwave trough and associated vort max was featured over southern Manitoba with an area of showers and storms just north of the Northwest Angle. Additional weak showers/sprinkles developed on the nose of a secondary low-level jet over far north-central Minnesota early this morning. Limited instability and moisture convergence in that area will allow the precipitation to persist while slowly becoming less intense with time. Those showers and storms will move eastward along the Canadian border through late this morning.

The latest (25.07Z) RAP indicates increasing 850 mb moisture convergence ahead of the shortwave/vort max combo over central Minnesota. It seems the available moisture associated with the LLJ is more limited than the RAP suggests. Thus modest MUCAPE of 500-1000 J/kg will be sufficient to sustain the existing storms. It's unlikely we will see stronger convection with these features through late morning. Small hail up to half-inch diameter and wind gusts to 40 mph appear to be the greatest threats this morning.

Mostly sunny to partly cloudy skies are forecast today with high temperatures forecast to reach the low to upper 80s, except over the Arrowhead where southerly winds off of Lake Superior will keep temperatures in the upper 60s to low 80s. "Moderate" heat risk values are forecast today from the Brainerd Lakes north to the Canadian border. Those values are being driving primarily by the above average high temperatures for today. Modest dewpoints will limit heat indices to the middle 80s. Thus as of this time, Heat Advisories do not appear necessary. That could change if temperatures soar above current forecast values.

In combination with the very warm temperatures, deep mixing is forecast which will allow afternoon RH values to drop into the 20 to 30 percent range for most of Minnesota. Those low RH values are dependent on good mixing. If clouds from morning showers and storms persist, the RH values will be buoyed higher. For now it appears near-critical fire weather conditions are most likely over portions of the Brainerd Lakes.

A cold front emanating from surface low pressure centered over southern Manitoba will propagate eastward into north-central Minnesota by late afternoon and will stall out overnight over the Northland. Daytime heating will support MLCAPE of 1500-2000 J/kg over northern Minnesota. Modest 0-6 km bulk shear of 30 to 35 knots will support marginal storm-scale organization for any storms which develop ahead of the front. Hodographs feature favorable curvature in the lowest 6 km for right-moving supercells to develop. Mid-level lapse rates won't be the most supportive of strong storms with values of -6.5 to -7 C/km. Given the thermodynamic and kinematic parameters, it seems the strongest storms will be capable of hail up to half-dollar (1.25 inch) diameter and perhaps a few wind gusts of 45 to 65 mph.

Storms will propagate southeasterly through the afternoon and evening and will move into northwest Wisconsin in the 6-8 PM timeframe. Storms will gradually weaken with time as they move out of the Northland by midnight-2 AM.

Tuesday:

A convectively-reinforced quasi-stationary front will be draped west to east across the Northland Tuesday morning. This boundary won't move much during the day. A 300 mb jet streak will move across northern Ontario Tuesday with the right entrance region over northwest Ontario and northern Minnesota. A mid-level ridge will continue to build over the northern Plains and upper Midwest which will generate broad modest subsidence. Ample daytime heating is forecast with high temps in the low 70s along the North Shore to the upper 80s and low 90s over much of central Minnesota into northwest Wisconsin. By late afternoon MLCAPE values of 1000-2000 J/kg will develop near and south of the front amidst 0-6 km bulk shear of around 30 knots. Showers and storms may develop during the afternoon along and south of the front. The weak shear suggests storms will be relatively short-lived and should produce numerous outflow boundaries which will then trigger additional convection. The area where storms are possible becomes larger in the evening due to the diffuse nature of the forcing by that time.

Wednesday and beyond:

Mid-level ridging will persist over the northern Plains and upper Midwest Wednesday. Surface high pressure is forecast to drift from northern Manitoba and far northern Ontario into the Great Lakes. This will create strong northeast winds over western Lake Superior and allow a lake breeze to push well inland during the day. Temperatures for Wednesday will be in the 60s and 70s for areas closer to Lake Superior and low to upper 80s farther inland. A few showers/storms may develop, particularly away from the lake breeze. A few storms may develop during the late afternoon along and south of MN/WI Highway 70 (essentially Pine City to Winter to Phillips).

Mid-level ridge persists into the weekend. Thursday will see similar conditions to Wednesday with a prominent lake breeze forecast. An upper-level low pressure system is forecast to move southward toward the eastern Great Lakes and New England Friday and Saturday. That system will pull a cold front southward through the Northland and may touch of widespread showers and a few thunderstorms. Temperatures will trend closer to seasonal norms Saturday into early next week.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 636 AM CDT Mon May 25 2026

Showers and storms from earlier this morning have all but dissipated as of 1130Z. There may be a sprinkle at INL and HYR before noon. VFR conditions will be the norm for today. A cold front will move into the region from the northwest this afternoon and evening. Showers and storms are forecast to redevelop along and ahead of the front and will progress southeastward with time. Kept PROB30 mentions for the thunder chances. Fog may develop early Tuesday morning.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 355 AM CDT Mon May 25 2026

Light southerly and southwesterly winds are forecast today and tonight over western Lake Superior. There is a 10-20% chance of a few isolated storms developing over northern Minnesota this afternoon and moving across the waters through this evening. A few storms may be strong with hail up to quarter size (1 inch in diameter), occasional cloud-to-water lightning, and wind gusts to around 35 knots. Winds turn northeasterly and remain fairly light on Tuesday. By Wednesday high pressure will move from the northern Canadian Prairie provinces into northwest Ontario tightening the pressure gradient over Lake Superior. Expect gusty northeast winds and building waves. Those conditions will pose a risk to smaller vessels. Another round of strong northeast winds is forecast Saturday.

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

FIRE WEATHER

Issued at 355 AM CDT Mon May 25 2026

Warmer temperatures continue today with highs in the low to upper 80s away from Lake Superior and middle 60s to low 80s in the Arrowhead. Tuesday expected to be the hottest day of the week. Min RHs will prove to be a challenge over the next several days as southerly flow will help promote increased dewpoints and diurnally driven cumulus in the afternoon hours. There is also a 10-20% chance of isolated thunderstorms. Clouds from storms will limit mixing. Near-critical fire weather conditions with RH less than 25% is forecast over portions of the Brainerd Lakes today. If clouds and storms are more sparse than forecast, the area of sub-25% RH will be larger. If there are more clouds than forecast, RHs may not drop to 25%. Wind gusts of 15 to 20 mph will develop this afternoon and taper off this evening. Near-critical RH values are forecast over north-central Minnesota into the northern portions of the Arrowhead. These low RH values will be contingent on limited clouds and storm chances. Highs will climb into the 80s with a few spots in the low 90s for Tuesday. Wednesday will see winds turn northeasterly, particularly near and downwind of Lake Superior. A prominent lake breeze will move well inland from Lake Superior during the afternoon limiting temperatures to the 60s to middle 70s near Lake Superior with 80s farther inland. Dry RH values are possible though there is uncertainty regarding shower and storm chances.

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

CLIMATE

Issued at 355 AM CDT Mon May 25 2026

Hot, summer-like temperatures today and Tuesday could produce high temperatures nearing daily record highs at several climate sites. Below are the sites where forecast high temperatures are within 3 degrees of their record values.

Record High Temperatures:

Monday, May 25: Forecast Record KINL: 86 ........ 88 in 1919 KBRD: 88 ........ 90 in 2018 KHIB: 84 ........ 87 in 2010

Tuesday, May 26: Forecast Record KINL: 82 ........ 88 in 1919 KBRD: 90 ........ 92 in 2018 KHIB: 86 ........ 88 in 1978

DLH WATCHES/WARNINGS/ADVISORIES

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