textproduct: Duluth

KEY MESSAGES

- Scattered showers and storms across the Arrowhead this afternoon.

- Strong to severe storms will enter from the west after midnight and exit the region by late morning. Main hazards will be damaging winds and large hail.

- Deepening on how storms progress in the morning there could be an additional round of supercells that develop tomorrow afternoon capable of producing large hail, damaging winds, and tornadoes. The area greatest at risk is NW WI.

- A return to strong winds out of the north on Tuesday may lead to more widespread coverage of smoke across the Northland.

DISCUSSION

Issued at 257 PM CDT Sun Jul 19 2026

Current Conditions/Today:

Surface high pressure is retreating to the east this afternoon allowing for southwesterly winds to stream across the region. This warm air advection has lead to temperatures climbing into the upper 80s with some dewpoints creeping into the mid 60s. Satellite does show lingering smoke over NW WI and into the Arrowhead. This is largely upper level smoke but surface observations do show some visibility reductions as southwest winds try to shuffle off the poor air quality. There is some potential for storms this afternoon, primarily over the tip of the Arrowhead. Water vapor shows a shortwave rounding the upper level ridge over the region and diving southeast through Ontario. This has led to some areas of storms upstream which have an unstable atmosphere to continue on its path. Depending on the storm track we could see a brief bursts of strong to severe storms before this feature runs into Lake Superior.

Tonight:

A strong shortwave dives southeast overnight with an occluded front pressing in from the west. Temperatures aloft are expected to rapidly cool as an upper level low churns across Manitoba into Ontario. This will lead to steep mid level lapse rate to further aide in storm growth. Timing and placement of storms remain contested among the high res guidance but they are beginning to hone in the main activity being after midnight. The convective parameter space will boast MUCAPE over 800 J/kg and a strong upper level jet will be nudging in across the Northern Plains to increase bulk shear values of 40-50 kts. This would promote the growth of elevated storms capable of large hail and some damaging winds. SPC has this largely outlined as a marginal threat (1/5) with a small sliver along our western counties of slight risk (2/5).

Monday:

Lingering storms from the overnight hours are expected to exit by late morning. The key to Monday's forecast will be the placement of the frontal boundary. This remains a highly contested feature among all available guidance with the CAMS suggesting it will be out of CWA by the afternoon. Not confident enough to buy into this solution given how poor these suite of models have been performing as of late. It seems reasonable to stick with what SPC has outlined which is an Enhanced risk (3/5) through Price county and a Slight risk (2/5) trailing behind it through NW WI and into NE MN. With the morning activity expected to clear out fairly quickly we should have ample time to refill the ingredients for severe storms in the afternoon. MLCAPE will be high with values over 2500 J/kg paired with bulk shear of 40-50 kts. This combo of ingredients would support supercell growth and low level helicity could also induce a few tornadoes. Again, all of this is predicated on the placement of the frontal boundary for the afternoon and evening hours.

Farther north, an upper level low will be transitioning into an open wave with cyclonic flow aloft coupled with plenty of PVA. Wrap around moisture around this cyclone will spawn scattered showers across northern MN with some isolated storms possible. Weaker instability across this area should keep development of stronger storms at bay. Additionally, strong westerly winds will be filtering in across the region tomorrow with gusts over 30 mph expected through the day.

Tuesday:

Another wind shift from out of the north is in store for the Northland on Tuesday. A weak cold front will also drop from out of the north with low chances (15-20%) of precipitation, may end up with numerous areas seeing sprinkles given the dry air aloft. Wind gusts in excess of 30 mph will be possible and could reintroduce another round of smoke engulfing the region. High res smoke guidance is not properly displaying this outcome at the moment due to how the models initialize with hotpot information. But Air Quality will be something to keep an eye on for the Tuesday timeframe.

Midweek:

Fairly mild forecast midweek through the end of the work week. Temperatures will be trending back up into the upper 70s and low 80s. The northerly winds taper off on Wednesday as high pressure moves across the Upper Midwest. Our next batch of precipitation chances (20-30%) arrive Thursday afternoon as some weak surface convergence floats through the region.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 653 PM CDT Sun Jul 19 2026

VFR conditions are currently in place across the region and are expected to prevail through most of the period. An isolated thunderstorm will be possible over the next hour or so at BRD, but better chances are expected overnight. Timing and coverage still remain in question, so have kept PROB30s for this update, but did try and refine the timing a bit. Heavy downpours in any storms will likely lead to brief periods of MVFR or lower VSBYs. Some showers may linger through the day Monday, but the bigger concern will be gusty westerly winds gusting to 20 to 25 knots.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 257 PM CDT Sun Jul 19 2026

Southwest winds this afternoon with occasional gusts up to 20 kts. Winds are expected to increase later tonight with gusts up to 30 kts, a Small Craft Advisory has been issued. Early tomorrow morning there is a 40-60% chance of strong to severe storms moving over Lake Superior with the primary hazards being damaging winds and large hail. This activity wanes in the late morning hours but could see additional storms develop Monday afternoon. Additionally, winds will switch to out of the north on Tuesday, more Small Craft Advisories may be needed. This change in wind direction may also reintroduce smoke back into Lake Superior.

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

FIRE WEATHER

Issued at 257 PM CDT Sun Jul 19 2026

Scattered showers across the Arrowhead this afternoon. Strong to severe storms are expected after midnight and will exit the region by late morning. Primary hazards with these storms would be damaging winds and large hail.

Monday will see a notable increase in winds out of the west with gusts in excess of 30 mph possible. A Fire Weather Watch has been issued for the Arrowhead due to the ongoing wildfires and the uncertainty as to how much precipitation may impact the fuels for Monday. Across northern MN there may be scattered showers that develop with some embedded thunderstorms at times. Farther south into NW WI there is potential for supercells to develop ahead of the exiting front in the afternoon. All modes of severe will be possible ahead of this boundary. Monday night into Tuesday could see some lingering drizzle across northern MN before drying out in the afternoon to around 45% RH. Rainfall amounts will be around a tenth to 0.35 inches with heavier amounts in excess of an inch possible in thunderstorms. Additionally, Tuesday will see another notable wind shift to out of the north with gusts once again in excess of 30 mph.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Heat Advisory until 8 PM CDT this evening for MNZ010>012-018- 019-025-026-033>038. Fire Weather Watch from Monday afternoon through Monday evening for MNZ011-012-019. WI...Heat Advisory until 8 PM CDT this evening for WIZ001>003- 006>008. MARINE...Small Craft Advisory from 3 AM Monday to 1 AM CDT Tuesday for LSZ121-140>148-150.