textproduct: Duluth

KEY MESSAGES

- Well above average temperatures (15-25 degrees) will persist through Saturday. The exception with be along the north shore of Lake Superior where onshore flow will keep highs in the 50s and 60s.

- Areas of dense fog are likely once again tonight near the Twin Ports, portions of the North Shore, portions of the South Shore, and the St. Louis River Valley.

- Light rain chances return late Friday over central and north- central Minnesota. Rain chances spread eastward through Saturday. A few rumbles of thunder are possible, though severe storms are not expected.

- Near-normal temperatures return Sunday and through next week.

DISCUSSION

Issued at 148 PM CDT Thu Oct 22 2026

TONIGHT:

High pressure continues to depart to the east as surface low pressure approaches from the west. Low stratus and fog over western Lake Superior is expected to advance inland once again tonight. Areas near the Twin Ports, along the North Shore, portions of the South Shore, and the St. Louis River Valley have the best chance of dense fog tonight. Areas farther inland including the Iron Range and Brainerd Lakes may see fog develop as well provided skies become clear and winds become calm. The tightening pressure gradient as low pressure approaches may keep the winds high enough to provide a shallow mixed boundary layer through the night. A few of the high-res models point to a few sprinkles over north-central Minnesota tonight in response to isentropic lift and a strengthening 850 mb LLJ.

FRIDAY:

A subtle warm front is expected to lift northeastward across the region Friday and Friday evening. Isentropic lift associated with the boundary will lead to some scattered showers over central and north-central Minnesota. Models indicate weak instability generally less than 100 J/kg will develop in the warm sector through the afternoon. There appears to be sufficient vertical motion and instability to support occasional lightning with the showers. I am hesitant to call them thunderstorms, per se. Rain amounts during the day and evening will be meager, less than a tenth of an inch. Showers along and near the warm front will lift into northwest Ontario overnight while convergence near the 850 mb LLJ ahead of the cool front will increase. It seems the shower chances will dwindle over the Arrowhead of Minnesota while persisting over central and north- central Minnesota. Highs on Friday will top out 15-25 degrees above normal with readings in the low to middle 70s. Areas which see fog and low stratus in the morning will likely be cooler, as will areas along the North Shore where highs will be in the 60s to low 70s.

SATURDAY:

By Saturday the mature low pressure system propagate eastward across the northern Canadian Prairies and into far northern Ontario. It's associated cold front will be cruising east across the Northland providing another dose of light rain chances and perhaps a rumble of thunder across the region. MUCAPE increases a bit along the boundary as upper-levels cool and mid-level lapse rates increase to 7C/km. This could lead to some isolated storms at times but not expecting anything severe. Rain chances will quickly taper off west to east through Saturday night as the boundary moves into central WI. Additionally, out ahead of this boundary through the day the strong southerly flow will lead to widespread 70s, our last day of 15-25 degrees above normal for a while.

SUNDAY THRU NEXT THURSDAY:

A return to more seasonable temperatures as surface high pressure settles in behind the exiting cold front. Highs will be in the 40s and 50s with overnight lows dropping below freezing. The work week could see another uptick in rain chances but confidence remains low at this juncture. The 12Z suite of guidance suggests a pair of upper-level lows could impact the region as early as Sunday night. The first low of concern is ejecting eastward out of the central Rockies but will have to fight through the dry and cool air mass over the Northland. The overall trend has been shifting this system further south over the past several runs with only the Brainerd Lakes eastward into NW WI now seeing a 20-40% chance of rain Monday.

The second upper-level system seems to hang back over the Canadian Prairies until midweek. A weak shortwave trough may propagate eastward over the Northland from that system Monday night and Tuesday which extends small rain chances north to the Canadian Border. The closed low itself will scoot eastward into northwest Ontario by early Wednesday morning providing a more widespread chance of light rain to the Northland. Temperatures aloft may be cool enough for a few "conversational" snowflakes to appear north of US-2 in Minnesota. Accumulation is not expected from any flurries at this time.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1236 PM CDT Thu Oct 22 2026

Low stratus over Lake Superior will expand inland once again tonight. Expect IFR/LIFR ceilings to develop at DLH and HIB. Reduced visibility is expected at DLH and HIB. There is a potential for fog at HYR and BRD as well, though fog development at those terminals is dependent on the lake-induced stratus pushing well inland. Visibility will improve Friday morning though it will take a little longer for low ceilings to scatter out. Rain chances and a small chance of a thunderstorm enter the picture for BRD and INL after 18Z Friday and may pass near HIB during the evening.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 148 PM CDT Thu Oct 22 2026

Northeast winds of 5 to 15 knots with gusts 10 to 20 knots are forecast this afternoon. Winds should relax a bit tonight before strengthening again Friday. Low stratus over western Lake Superior will persist through this afternoon and expand tonight. Webcams along portion of the South Shore near Cornucopia and Ashland revealed fog persisted late this morning. Extended the Dense Fog Advisory to include Port Wing to Sand Island until 2 PM. It may need to be extended further. Webcams along the North Shore revealed reduced visibility and low stratus. Therefore we expanded the Dense Fog Advisory there through 10 AM Friday. Visibility may improve for a time this afternoon before trending lower again tonight. The Twin Ports may need to be added to the advisory if visibility deteriorates. A low pressure system will move through the region Friday and Saturday. Winds will turn southerly and eventually southwesterly Saturday and wind gusts will increase. Conditions will become hazardous to smaller vessels. Winds will veer southwesterly Saturday night and westerly on Sunday ending the risk to smaller vessels.

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

FIRE WEATHER

Issued at 148 PM CDT Thu Oct 22 2026

No fire weather concerns at this time. Winds strengthen out of the south Friday as a warm front moves through the region. There is a chance of showers and a few non-severe thunderstorms Friday over central and north-central Minnesota. Rain chances continue Saturday as a cold front sweeps across the region. Rainfall amounts will be generally less than a tenth of an inch. A few spots may see close to two tenths of an inch if a heavier shower/storm moves overhead. Conditions will dry out on Sunday behind the cold front but winds at the moment don't look strong enough to warrant fire weather headline concerns.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...Dense Fog Advisory until 2 PM CDT this afternoon for LSZ121- 146-147. Dense Fog Advisory until 10 AM CDT Friday for LSZ140>143.