textproduct: Duluth

KEY MESSAGES

- Light rain showers possible ahead of and along a cold front late tonight into Monday morning, with the greatest probability for measurable precipitation along and north of the Iron Range (40-60 percent).

- Strong northwest winds on Monday with gusts as strong as 30 to 40 mph.

- For the rest of the work week beyond Monday, generally dry with temperatures below normal.

DISCUSSION

Issued at 1222 PM CDT Sun May 3 2026

An unseasonably strong surface low to the north and associated cold frontal passage late tonight into Monday will usher in an unseasonably cool airmass for the rest of the work week.

Today into Monday:

The persistent northwest flow pattern over the Upper Great Lakes will be reinforced by a strong surface low and associated cold front tracking southeast across southern Saskatchewan/northern Ontario and into northern Minnesota and northwest Wisconsin. The actual synoptic- scale details of how the mid/upper level disturbances interact and merge is actually quite complex, with a broad upper low over Hudson Bay with a few mid-levle disturbances rotating around it while a compact fairly deep low arrives from the northwest, merging/phasing with the vort maxes around the Hudson Bay upper low as they all dive southward. The surface low will be over northwest Ontario late tonight, with a surface warm front moving east across northern Minnesota and Lake Superior today as the low approaches from the northwest, causing surface winds to back from northwest to more westerly this afternoon.

The surface cold front arrives from the northwest late tonight, entering the northwest corner of the CWA around 09z, DLH towards daybreak, and east across the rest of the region and across Lake Superior Monday morning. Fairly strong winds at low levels behind the front will mix down on Monday afternoon, with recent guidance trending stronger than previous forecasts on the max wind potential, now perhaps peak gusts to 40-50 mph across the Minnesota Arrowhead.

Precipitation amounts remain light due to dry air both at the surface and aloft, but with the strong broad-scale forcing, some light rain is still anticipated along and ahead of the front in northeast Minnesota tonight into Monday morning, with lower probabilities in northwest Wisconsin further from the low center. A bit of a dry slot wedges into northern Minnesota behind the cold front mid morning Monday, but with surface heating and deep mixing, isolated light rain (or snow) showers are possible behind the front Monday, mainly limited to areas near the international border and MN Arrowhead. Total precip amounts will be very light, on the order of a few hundredths of an inch north of the Iron Range and across the MN Arrowhead, little to none elsewhere. Parts of the region such as the Brainerd Lakes to I-35 corridor may see no precipitation at all.

Lows overnight tonight in the upper 30s to low 40s along/north of the Iron Range, elsewhere mid 40s to low 50s. Following the cold frontal passage on Monday highs will be cooler in northeast Minnesota in the 40s to low 50s, but warmer in northwest Wisconsin where surface heating should warm temps into the 60s.

Rest of the work week:

Persistent northwest flow at mid to upper levels with 850mb temps around -5C to -10C, values which are more typical of late March and early April rather than early May. Generally dry conditions, but weak disturbances in the northwest flow will still bring cloud cover and a very low chance for precip, greatest on Thursday with probabilities for precip rising to 10-20 percent for some spots, but little to no measurable precip is expected generally through the week. Relative humidity values falling to around 30-40 percent each day, with cloud cover and lack of surface winds precluding any kind of near-critical fire weather conditions. Tuesday will be the coolest day with highs in the 40s to near 50, which is unlikely to set any record low (cold) max temp records, but will be 15-20 degrees below normal for early May.

Next weekend temperatures warm back up to near normal as a mid/upper level ridge over the northwest builds eastward into the Great Plains, but there are signs that another round of reinforcing cooler Canadian air could return late weekend into next week. No significant precipitation or thunderstorm chances on the horizon through next weekend.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 642 PM CDT Sun May 3 2026

Main aviation concern this period: Wind. A strong cold frontal passage tonight into Monday morning will result in shifting wind directions, a period of low level wind shear late tonight, and very strong northwest winds on Monday gusting to 30+ knots.

Winds currently out of the southwest and will persist towards past midnight or so when the cold front begins to move through all sites from north to south, with a very strong low level jet leading to low level wind shear ahead of and along the cold frontal passage at all sites. Increasing clouds with low chance for rain at INL/HIB (perhaps DLH/HYR too), but ceilings will remain VFR except at INL where a MVFR ceilings are expected to develop towards dawn Monday morning.

On Monday strong northwest winds develop in the wake of the cold front with wind gusts of 30+ knots possible in the afternoon. Some mid-level VFR clouds and a spotty shower is possible, but the strong winds will be the most impactful aviation impact during the day.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 1222 PM CDT Sun May 3 2026

A strong cold frontal passage early Monday morning will lead to strong southwest to west winds tonight through Monday, with gusts of 30 knots possible and peak wind gusts approaching gale-force conditions on Monday afternoon, strongest in the Twin Ports and north shore, especially north of Grand Marais. A Small Craft Advisory is in effect through Monday for much of the western Lake Superior nearshore waters.

Beyond Monday, high pressure builds in with very weak winds and cooler temperatures through the rest of the work week.

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

FIRE WEATHER

Issued at 137 PM CDT Sun May 3 2026

A strong cold frontal passage tonight into Monday morning will result in shifting wind directions, a period of low level wind shear late tonight, and very strong northwest winds on Monday gusting to 30+ knots.

Today into this evening a weak warm front is passing from west to east across all sites causing winds to shift from west-northwesterly to southwesterly behind the warm front. These southwest winds will persist towards past midnight or so when the cold front begins to move through all sites from north south, with a very strong low level jet leading to low level wind shear ahead of and along the cold frontal passage at all sites. Increasing clouds with low chance for rain at INL/HIB (perhaps DLH/HYR too), but ceilings will remain VFR except at INL where a MVFR ceilings are expected to develop towards dawn Monday morning.

On Monday strong northwest winds develop in the wake of the cold front with wind gusts of 30-40 knots possible in the afternoon. Some mid-level VFR clouds and a spotty shower is possible, but the strong winds will be the most impactful aviation impact during the day.

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 10 PM this evening to 4 PM CDT Monday for LSZ121-146>148-150. Small Craft Advisory from 10 PM this evening to 10 PM CDT Monday for LSZ140>145.