textproduct: Duluth

KEY MESSAGES

- There is a chance of several severe thunderstorms through early evening east of a line from near Brainerd to McGregor to Duluth in Minnesota and over all of northwest Wisconsin. Risks include large hail, gusty winds, and tornadoes. Storm chances decrease from west to east through the afternoon.

- Scattered showers and non-severe storms are forecast over the remainder of the Northland through this afternoon.

- Colder into the weekend with breezy northwest winds. Some snowflakes are possible along the International Border Saturday afternoon.

- Warmer temperatures return next week with some near-critical fire weather possible Sunday - Tuesday.

UPDATE

Issued at 115 PM CDT Fri Apr 17 2026

Thunderstorm coverage and intensity will increase east of a Brainerd to Hibbing line this afternoon. A cold front stretched from near Ely to Cloquet to the eastern Twin Cities per surface observations and radar fineline returns. SPC 17Z RAP mesoanalysis reveals a plume of 500-1000 J/kg of MUCAPE nosing into southern Itasca County. The plume of MLCAPE of 500-2000 J/kg was farther east from eastern Pine County south to the Iowa border. GOES-East band 13 clean window IR imagery features warming cloud tops over southwest into east-central Minnesota (with the exception of thunderstorms) which suggests large scale subsidence. The storms over Crow Wing, Aitkin, western Carlton, and southwest St. Louis counties and those farther upstream to the northwest of the Twin Cites Metro appear to be the strongest updrafts and may benefit from the suppressive effects of the subsidence. East of the cold front over northwest Wisconsin a small cluster of strong storms was located near Spooner as of 1 PM. Skies were clearing over northwest Wisconsin except around and downstream of the storm cluster.

The subsidence and clearing skies will support a trend toward stronger storms through this afternoon. The severe weather risk will be maximized east of the cold front over northwest Wisconsin where all types of severe weather remain possible. West of the front, hail will be the main risk. Recent storm reports indicate the short storms near and east of Brainerd were producing large amounts of small hail. Freezing levels behind the cold front were quite low quickly descending from around 9kft along the I-35 corridor to a few hundred feet west of Brainerd.

UPDATE

Issued at 1026 AM CDT Fri Apr 17 2026

A strong southerly 40-50 kt low-level jet was located over the Minnesota/Wisconsin border into northwest Wisconsin late this morning. Convergence and isentropic lift on the western periphery of the jet will support thunderstorms, some strong to severe, east of the surface cold front which stretched from just east of Aitkin to just west of Hibbing to just east of Orr as of 15Z. Rapid increase in Theta-E due to moisture advection and diurnal warming led to a rapid expansion of MUCAPE northward into central Minnesota and northwest Wisconsin. Expect these trends to continue through the afternoon.

Within the past hour convection initiated over central MN and the I-35 corridor and should persist as storms move quickly north-northeast at 50-60 mph. While instability increased over this area, the latest SPC RAP mesoanalysis reveals 250-750 J/kg of MUCAPE where those storms were located. As instability increases through early afternoon we anticipate storms to deepen and the severe weather risk to increase. Hail is the most likely threat at this time. Early convective development will complicate the MLCAPE situation for this afternoon over northwest Wisconsin. If storms remain elevated, the risk of damaging wings will increase and the potential for tornadoes will be small. If storms can become rooted near the surface, the risk of tornadoes and hail would remain the greatest concern. Subsidence in the wake of this early convection may erode the cloud cover and provide several hours of surface heating by mid- afternoon. Therefore the risk for all convective hazards remains unchanged.

DISCUSSION

Issued at 320 AM CDT Fri Apr 17 2026

A longwave trough is digging its way east early this morning over the Plains, creating several areas of surface low pressure from northern Minnesota to the Central Plains, with an attending cold front connecting between them and pushing west to east. That front, analyzed right along the edge of our western CWA border early this morning, will be the feature to follow today. Temperatures are still in the 50s and 60s in the warm sector ahead of the front with a 50-55F dewpoint airmass expected to advect north into the area through midday. We have a screaming LLJ coincident with this front, with up to 65 knots at ~1.5km off the deck from the KDLH VAD. We should see all these ingredients come together as an unstable airmass stretching up to Lake Superior this afternoon with plentiful shear to work with.

As that more moist airmass noses up I-35 through this morning we could see some areas of showers and thunderstorms begin to develop across NE MN and up the MN-WI border in the 9am-1pm timeframe. Through the afternoon, our cold front pushes east and convection should grow upscale quickly from 1-5pm. This will likely be the best window for potentially severe storms to develop. If some discrete cells can develop (somewhat conditional on how much morning precipitation there is and where), brief supercellular structures are expected with all hazards possible. Just ahead of the front surface winds could be slightly more southeasterly which would increase hodograph curvature favoring tornadic development. This environment will likely be short-lived as the front will be progressive and surface winds become more southwesterly nearer to the front (and then NW once it passes). Discrete cellular convection will also be more favorable for large hail up to golf bail size. As convection grows upscale a more linear mode is favored with a damaging wind threat. There is the potential that morning and midday showers and thunderstorms could work to muddy the atmosphere enough that any severe storms potentially stay to our south. Should severe storms be able to develop, they should be largely out of the area by 6-8pm.

Any thunderstorms could be capable of producing some locally heavier rain up to 1"+. Flooding concerns are fairly minimal with the progressive nature of this system, but extra water will likely keep things wet in NW WI with high streamflows. Rain over melting snow on the North Shore will also keep streamflows high there.

A decent blast of CAA follows this system with winds turning around to the NW Friday evening into Saturday. Guidance suggests that these NW winds could get fairly breezy and strong along the North Shore where gusts in excess of 30-45mph are possible. Forecasts will need to be monitored here and a Wind Advisory may be needed. Much cooler conditions this weekend will result in a return to overnight lows below freezing and afternoon highs in the 30s and 40s. Some light show showers are possible along the International Border Saturday afternoon with little to no accumulation expected.

Ridging returns next week, bringing temperatures back into the 40s, 50s, and 60s in the afternoon. Most global guidance doesn't show our next widespread chance of precipitation until late next week into the weekend. High pressure Sunday and Monday are expected to lead to breezy winds and dry afternoons with minimum RH of 25-30% or less. These days will need to be monitored for possible near-critical fire weather concerns.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 115 PM CDT Fri Apr 17 2026

A low pressure system will move across the region this afternoon and tonight. A cold front from near the Minnesota/ Wisconsin border to near KELO will propagate eastward this afternoon and evening. HYR will start out with VFR conditions descending to MVFR behind the front. Scattered showers and thunderstorms will persist through early evening and will taper off from west to east through tonight. Low stratus may loiter behind the front for tonight. Winds will turn northwesterly behind the front and will be gusty overnight and Saturday morning. A few snow showers are possible Saturday afternoon and evening after 18.18Z and could impact INL and HIB.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 320 AM CDT Fri Apr 17 2026

Winds become northwest through the afternoon and evening and strengthen. Gusts of 20-35 knots are expected today into Saturday evening. Small Craft Advisories have been issued except for portions of the North Shore where a Gale Warning is in effect. Gale force gusts are only expected for a brief period this evening, after which a Small Craft Advisory will be needed for those areas through Saturday. Thunderstorms are expected Friday this and early evening which may bring gusty and erratic winds, hail, and brief heavy downpours.

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

FIRE WEATHER

Issued at 115 PM CDT Fri Apr 17 2026

A low pressure system and associated cold front will propagate through the region this afternoon and tonight. Showers and thunderstorms will gradually pass eastward through the afternoon. A few severe storms are possible with large hail, damaging winds, and a few tornadoes. The greatest severe weather risk will be over northwest Wisconsin through this evening. Precipitation may turn over to snow before ending over central and north-central Minnesota. Saturday will feature strong and gusty northwest winds. RH values will dip into the 30-35% range. Temperatures begin to trend warmer on Sunday and closer to normal on Monday. The warmer temperatures Monday and again on Wednesday may pose a risk of near-critical fire weather conditions due to low RH values and gusty winds.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...Small Craft Advisory from 4 PM this afternoon to 10 PM CDT Saturday for LSZ121-143>148. Gale Warning from 5 PM this afternoon to midnight CDT tonight for LSZ140>142. Small Craft Advisory from 4 PM this afternoon to 4 AM CDT Sunday for LSZ150.