textproduct: Duluth

KEY MESSAGES

- Warming trend continues Memorial Day Monday 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 Memorial Day Monday afternoon and evening northeast of a line from Crane Lake to Grand Rapids to Duluth to Ashland WI. This includes the Arrowhead, Twin Ports, and portions of the South Shore. 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 for the next several days.

UPDATE

Issued at 1143 PM CDT Sun May 24 2026

A vort max and associated shortwave trough was located along the ND/SD border near ABR as of 25.04Z 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 moving into the Brainerd Lakes over the next several hours. GOES-East Band 13 imagery revealed a persistent area of stratus from near the ND/SD/MN border east into central MN. Generally cloud tops were maintaining their thermal appearance with short periods of cooling/warming featured.

The latest (25.02Z) RAP indicates increasing 850 mb moisture convergence ahead of the shortwave/vort max combo by 25.07Z. A secondary LLJ supporting convection over southern MB ahead of a larger vort max and shortwave trough is forecast to move into northern Minnesota and northwest Ontario in the 25.07Z to 25.09Z timeframe. MUCAPE is forecast to trend toward 600-1200 J/kg by 25.09Z over central and north-central Minnesota although the axis of the strongest MUCAPE values is displaced slightly west of the strongest 850 mb moisture convergence. Steep mid-level lapse rates and dry air aloft will support hail growth. 0-6 km bulk shear around 30 knots limits storm-scale organization. Veering winds in the lowest 3 km of the profile yields favorable hodograph curvature with backing winds between 3 and 6 km and an elongated hodograph above 3 km. These factors suggest a low- to mid-level mesocyclone may be present with storms, though the additional ascent provided by pressure perturbations will be maximized below the freezing level. Small hail of pea to penny- size seems most likely for the strongest storms.

High-res model guidance shows modest convection percolating over central Minnesota by about 25.09Z and advancing eastward into northwest Wisconsin by around 12Z. A secondary area of convection may move into north-central Minnesota and northwest Ontario around that time. The showers and storms are expected to progress eastward through the morning and should be out of our forecast area by 11 am-12 pm today.

DISCUSSION

Issued at 153 PM CDT Sun May 24 2026

Current Conditions/Today:

Quite the summer time set up we are getting into for the Northland. This morning we had some weak clusters of storms moving across northern MN on the edge of a weak 925mb low level jet. These storms have lost a lot of strength as we've moved into the mid day point but their lingering outflow boundaries and interactions from other lake boundaries will have a lasting effect this afternoon. The overall scheme for today boasts an impressive warming trend with southerly winds streaming back into the Northland. Not a strong moisture feed at the moment but PWATs climb to 0.50-0.75" which is enough to kick off some showers and storms at times. Instability climbs to around 500 J/Kg MLCAPE in the afternoon with bulk shear on the order of 30 kts. We are lacking synoptic forcing as subsidence over the region remains abundant. Despite this, diurnally processes intermingling with remnant boundaries stand the chance of allowing a few storms to develop this afternoon. Mid level lapse rates remain steep so a few stronger storms can't be ruled out. Primary threat would be hail the size of pennies to nickels. Additionally, today marks the start of a warming trend with highs today in the 70s and low 80s with cooler temps by Lake Superior.

Tonight:

Another nocturnal low level jet ramps up across the Midwest with the nose of the jet nudging its way into our southern tier of counties. MUCAPE will be around 500 J/kg with the better instability south of our area. Bulk shear also remains on the fringe of ideal speeds clocking in around 30 kts. We will have a shortwave projected to move in from the Northern Plains that could provide a boost to synoptic forcing helping storms to grow stronger. At this time though the better dynamics remain to our south where SPC has a marginal risk outlined for primarily a hail threat with damaging winds as a secondary threat. A few of the latest high res runs are highlighting a few cells making it as far north as the Twin Ports, but they don't look to have quite the juice necessary to warrant an expansion of the severe weather outlook.

Monday:

Monday morning may see some isolated showers across NW WI as the nocturnal jet settles down. The day will once again see a noticeable increase in temperatures as southwest flow increases and high temperatures climb into the 80s. We will also see a deeper pool of moisture moving back into the region as dewpoints start to climb into the upper 50s and 60s. This added fuel will boost our MLCAPE to over 1000 J/kg by the afternoon hours. A cold front is also expected to drop southeast out of Ontario in the afternoon and evening hours providing a boost to lift that may overcome any capping that will be in play from the warming temperatures. Mid level lapse rates remain steep with large hail being the primary threat and damaging wind being a secondary threat. Timing will largely depend on the frontal boundary but early estimates would light up northern MN after 3PM with the window for severe closing after 10PM. To account for this, SPC has introduced a marginal risk for the Arrowhead and into the South Shore.

Tuesday:

Not much relief in the wake of the cold front as it stalls out Monday night and we reverse the tides with a warm front advancing back north. Tuesday in particular looks to be our hottest day with highs in the upper 80s and some low 90s on tap. Decent southerly flow will also prevent the Lake breeze from penetrating too far inland. This warm moist environment will sport some very impressive CAPE values in excess of 2500 J/kg and mid level lapse rates remain favorable for rapid ascent. There may also be some ridge runners able to boost some synoptic forcing as a 500mb ridge sees a few impulses rotate through. Placement of the frontal boundary and the runners remain in high variance between the 12Z suite of deterministic guidance. Additionally, the best bulk shear may be displaced to the north of the better instability corridor. For now, we do not have a severe weather outlook and are carrying 20-40% for showers and storms in the afternoon and evening.

Mid week - End of the work week:

On Wednesday the surface boundary looks to retreat to the edges of our CWA as the upper level ridge sinks into the Midwest. In the absence of strong southerly flow Lake Superior should be able to flex its muscles and spread cooler temperatures across most of the region via its lake breeze. Depending on how far this stable air manages to permeate across the region we may have some very limited coverage for showers and storms to develop in the afternoon and evening.

Surface high pressure continues to linger across the Great Lakes region for Thursday and the early parts of Friday leading to a similar set up as Wednesday. Return flow from the exiting high pressure doesn't look to impact the region until late Friday. At which point we may see a return of showers and thunderstorms pending on the placement of the high pressure.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1253 AM CDT Mon May 25 2026

Outside of shower and thunderstorm activity, VFR conditions should prevail through the 06Z TAF period. Some scattered shower/storm activity expected during the current 06-08Z period near BRD with elevated convection developing on the nose of the low-level jet. This activity may also develop as far north as HIB/DLH, but potential there is only 30% or less. This activity should also shift eastward to HYR overnight into early this morning before diminishing with the weakening low- level jet towards 15Z. Any storms moving directly over a terminal could briefly produce MVFR visibility and erratic wind gusts. This afternoon, a low pressure system sliding through northwest Ontario will bring a cold front into northeastern Minnesota, with scattered shower and thunderstorm activity likely developing along it and moving southeast into the Lake Superior South Shore in the evening before diminishing. Storm initiation will likely be near or just southeast of INL, so the window of storm potential there will be limited. Expect more scattered coverage at HIB, with less confidence in storm potential towards DLH with later arrival timing towards the evening. Can't rule out some erratic outflow winds, hail, and brief MVFR conditions if any afternoon storms move directly over a terminal.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 153 PM CDT Sun May 24 2026

Southwest winds of 10-15 knots have helped to erode the widespread fog that ruled the Lake last night and this morning. These winds are expected to subside later this evening which may allow for widespread fog to envelope the Lake once again. Tomorrow afternoon and evening a line of storms may enter from the Arrowhead as a cold front sags south. Some of these storms may be strong to severe.

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

FIRE WEATHER

Issued at 153 PM CDT Sun May 24 2026

Today marks the start of a warming trend for the Northland with Tuesday expected to be the hottest day of the week. Highs will climb into the 80s and some 90s for Tuesday. 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. Won't be expecting bone dry conditions but areas of 25% can't be ruled out. Most likely across the Brainerd Lakes area. Winds will follow the typical summer pattern of increased gusts in the afternoon that taper off in the evening. At this time we are not forecasting overly strong wind gusts that would prompt critical fire weather conditions.

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

CLIMATE

Issued at 153 PM CDT Sun May 24 2026

Record High Temperatures:

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

Tuesday, May 26: Record Forecast KBRD: 92/2018 90 KHIB: 88/1978 87

Record Warm Minimum Temperatures:

Tuesday, May 26: Record Forecast KASX: 60/1988 57

DLH WATCHES/WARNINGS/ADVISORIES

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