textproduct: Duluth

KEY MESSAGES

- Critical to near-critical fire weather conditions will gradually improve as wind gusts diminish and relative humidity increases this evening.

- Strong to severe thunderstorms are possible on Thursday afternoon and evening as a cold front moves through the area. The Storm Prediction Center forecasts a Marginal Risk, level 1 out of 5, of severe storms Thursday afternoon and evening. - Locally heavy rainfall is possible with the thunderstorms Thursday and may lead to localized minor flooding.

- Near-critical fire weather conditions may return Friday into the weekend.

DISCUSSION

Issued at 332 PM CDT Wed Apr 22 2026

Rest of the afternoon through tonight...

As of 2 pm, very dry conditions were observed with temperatures in the upper 70s to low 80s over central and north-central Minnesota with upper 50s to low 70s in the Arrowhead and upper 60s to middle 70s in northwest Wisconsin. Relative humidity values were in the teens and low 20s, except near Grand Marais and Grand Portage where upper 20s to low 30s percent RHs were found. Winds generally from the south to south-southeast with gusts of 10 to 30 mph.

Winds will relax early this evening as the boundary layer decouples from the stronger flow aloft. RH values will slowly improve as well. Red Flag Warnings remain in effect until 8 PM for portions of northeast Minnesota and northwest Wisconsin. A southerly low-level jet will strengthen this evening over central and north-central Minnesota leading to increased isentropic ascent aloft. RAP and GFS guidance point to a zone of particularly steep isentropic surfaces over the Arrowhead into northwest Ontario from 03Z to 09Z tonight. Showers and a few thunderstorms are likely to develop over that area overnight before the ascent weakens between 12Z and 15Z Thursday.

Thursday and Thursday night...

A closed upper-level low will move toward the Dakotas Thursday with a cold front arcing southeastward across the western Dakotas in the morning moving into western Minnesota during the afternoon and into the Northland by late afternoon. Ahead of the cold front a surface warm front will lift northward across southern and central Minnesota and Wisconsin to near the Lake Superior shore by late afternoon. Isentropic ascent which began overnight will continue Thursday and should support overcast skies. In the warm sector modest instability of 500-1500 J/kg is forecast with 0-6 km bulk shear of 25 to 35 knots. Storms are forecast to develop as early as mid-morning in the Minnesota River Valley and spread northward into central Minnesota by late morning. The more likely scenario has showers and storms holding off until later in the day when deep layer ascent increases ahead of the approaching trough. The cold front is expected to lag too far to the west to provide much help with parcel ascent.

Storm motions will likely be from the south-southwest at 35-40 knots. There is ample low-level hodograph curvature to support rotating storms if they can become surface-based. Forecast soundings reveal tall and skinny CAPE with ample moisture in the mid-levels. Storms will likely be efficient rain producers. Convection may become widespread in a weakly capped environment ahead of the cold front similar to last Friday's storms. While hodographs feature sufficient low-level curvature, above 3km the profile becomes unidirectional with negligible speed shear. Those conditions are sufficiently different from last Friday's environment to warrant a smaller severe weather risk.

Damaging winds will be the main hazard with a smaller risk of large hail and tornadoes. Locally heavy rainfall which may lead to minor flooding is a concern as well. If skies can clear for a few hours over northwest Wisconsin and in the I-35 corridor, the resultant increase in instability would increase the tornado potential. The most likely scenario has non-severe convection for most of the afternoon until a wind threat develops. Southerly flow aloft is forecast to strengthen between 20Z and 00Z which will enhance the damaging wind risk.

Showers and storms will push eastward ahead of the cold front Thursday evening and should be clear of the Northand by 10 PM. In the wake of the cold front winds will turn west-northwesterly and drier air will move in. The current expectation is for the dry air and gusty winds to arrive too late in the day to pose a fire weather risk. Skies will clear Thursday night and temperatures will fall into the upper 30s over north-central Minnesota to the upper 40s in northwest Wisconsin.

Friday through next Wednesday...

Friday and into the weekend, the upper level cut off low continues to churn over the southern Canadian Prairies along the International Border with the Dakotas. This will keep our area on the cooler side, relative to the temperatures we've experienced so far this week. Expect highs in the high 40s to low 60s with overnight lows in the 30s. That slightly cooler trend should continue into next week. As the aforementioned upper level low creeps through southern Canada, there could be some clouds and intermittent showery activity this weekend, but chances are low with the best potential along the International Border.

Into early next week, global guidance suggests that an embedded upper level shortwave on the retreating underside of the upper level low could move across the Northern Plains, supported synoptically and thermodynamically by a deeper upper level trough pulling moisture and instability from the gulf. This looks to be our next best chance of widespread precipitation for the Northland, with rain shower and thunderstorms possible somewhere in the late Sunday-Tuesday timeframe. There are even some solutions that keep some cooler air hanging around that makes for a few snowflakes.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 114 PM CDT Wed Apr 22 2026

VFR conditions with gusty south winds expected through sunset. A southerly low-level jet will develop tonight and create low- level wind shear at the terminals overnight. VFR stratus will develop this evening and overnight. There is a small chance of a few showers or storms which may impact INL and HIB between 03Z and 09Z. Opted for VCSH for now. The chance of showers and storms are higher at ORB, CQM, ELO, and CKC than the other locations. Stratus will gradually lower to MVFR at HIB and INL between 10Z and 14Z. Showers and storms are forecast to develop and will impact the terminals after 23.18Z. They may arrive earlier at BRD and a few models feature storms moving into central Minnesota by late morning/early afternoon. Opted to include VCSH there for the moment since chance of precip before 23.18Z is less than 30%.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 332 PM CDT Wed Apr 22 2026

Northeast winds this afternoon over the southwest arm of Lake Superior will lead to building waves near the Twin Ports by this evening. Wave heights of 2 to 5 feet are forecast and will subside this evening. Easterly winds are forecast tonight along the North Shore and will persist through Thursday. Waves will build along the North Shore. A cold front will move eastward across the waters Friday morning. Winds will back westerly and northwesterly and strengthen again by Friday afternoon. Scattered showers and thunderstorms are possible over the waters Thursday afternoon and evening. A few may be strong to severe. Small Craft Advisories are in effect for the Twin Ports into this evening and for the North Shore from this evening through Friday evening. Conditions may become hazardous again early next week due to waves and wind.

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

FIRE WEATHER

Issued at 114 PM CDT Wed Apr 22 2026

Very dry RHs will gradually improve overnight with values recovering to 75 to 85 percent. Southerly winds will bring in higher dewpoints Thursday and afternoon RHs are expected to be in the 40 to 60 percent range. Wind gusts of 15 to 25 mph are forecast from late morning through the afternoon. Showers and thunderstorms will develop Thursday afternoon ahead of a cold front. The most likely areas for measurable rain are generally east of a line from Brainerd to Grand Rapids to Orr. Rainfall amounts will vary. A broad one-tenth to half an inch of rain appears likely with locally heavier amounts likely. The cold front will move into central Minnesota during the late afternoon. Winds will veer westerly behind the front and RH values will quickly drop as drier air moves into the region. It appears the front will arrive to late in the day to create near- critical conditions for areas which do not receive rainfall. Friday is shaping up cooler with highs in the 50s and 60s. West winds with gusts of 15 to 20 mph are forecast along with minimum RH values of 25 to 35 percent. Portions of Minnesota have the potential for near-critical fire weather conditions. Saturday and Sunday will also see low RH values and may experience near- critical conditions in Minnesota.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Red Flag Warning until 8 PM CDT this evening for MNZ018-025- 026-033>036-038. WI...Red Flag Warning until 8 PM CDT this evening for WIZ006-007. MARINE...Small Craft Advisory from 10 PM this evening to 10 PM CDT Friday for LSZ140>143. Small Craft Advisory until 10 AM CDT Thursday for LSZ144-145.