textproduct: Duluth

KEY MESSAGES

- Hot today with strong west winds today in the wake of a cold front this morning leading to near-critical fire weather conditions as west winds gust to 20 to 30 mph.

- There is a risk for isolated strong to severe storms to rapidly develop in northwest Wisconsin along the exiting the cold front this afternoon in the 4 PM to 7 PM timeframe. While the probability for any storms developing is very low (10 to 30 percent), if storms develop there is a high likelihood they would quickly become severe and capable of producing very large hail, damaging winds, and possible a tornado.

- Drier with more seasonable temperatures on Wednesday, gradually warming up again towards next weekend.

UPDATE

Issued at 203 AM CDT Mon Jul 20 2026

Low pressure was located just north of Lake Winnipeg early this morning with an occluded front extending to near Winnipeg. A warm front then extended southward across the eastern Dakotas with a cold front extending to the southwest to south-central North Dakota and northwest South Dakota. An area of thunderstorms was moving into far western Minnesota south of I-94 with other isolated showers and thunderstorms just north of the International Border. Additionally, a few isolated showers were seen across northwest Wisconsin. Models continue to develop showers and storms across northern Minnesota over the next few hours and move that activity through mid-morning. Questions remain as to when and where these showers and thunderstorms develop, if at all. While the airmass ahead of the cold front is favorable for severe elevated storms, forcing with the front is weak. If any storms do develop, elevated CAPE of 2000-3000 J/kg along with shear around 40 knots will allow for storms capable of producing damaging winds and large hail.

Further convective evolution for later this morning and afternoon will depend on what happens with this possible first round of activity and the speed of the cold front across the region. There are indications that the bulk of the strong convection this afternoon will be east and south of our CWA, but there are a few CAMs that do develop this activity across northwest Wisconsin. This remains a conditional threat, but all modes of severe weather will be possible should storms develop ahead of the cold front. Additional showers and thunderstorms will be possible this afternoon and evening behind the cold front, but will likely not be strong or severe. The main change for the forecast today is the issuance of a Heat Advisory across the southern half of the forecast area. WBGTs will be above 79F this afternoon in these areas along with a Moderate Heat Risk in place, prompting the advisory. Some areas may need to be cancelled early depending on the timing of the front.

DISCUSSION

Issued at 257 PM CDT Sun Jul 19 2026

Early this Morning:

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 hotspot 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 /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 720 AM CDT Mon Jul 20 2026

Increasing west winds today with generally VFR conditions today, then MVFR stratus clouds late tonight. A few isolated showers and storms may impact INL and HYR this afternoon but any storms are expected to be brief in duration. West to west-northwest winds gusting to 20 to 30 knots through today, peaking with a few gusts to 35 knots late this afternoon. Winds turn more northwesterly as cold front moves north to south across northeast Minnesota tonight bringing the low-level stratus clouds and MVFR ceilings, with northwest winds remaining sustained at 10 to 15 knots through the overnight hours.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 203 AM CDT Mon Jul 20 2026

Southwesterly winds of 10 to 20 knots with gusts to 25 knots will be in place through through the day before becoming northwesterly as a cold front moves through late this afternoon and evening. Winds will diminish a bit overnight before increasing again on Tuesday. Small Craft Advisories are currently in effect for today with additional advisories possible for Tuesday with gusts to 20 to 30 knots, highest along the North Shore. Winds will then quickly diminish Tuesday evening to 5 to 10 knots from the northwest for Tuesday night. These northwesterly winds tonight and tomorrow may bring smoke back into the area.

Strong to severe thunderstorms remain possible early this morning with wind gusts in excess of 40 knots and large hail being the primary threats. After a break for the late morning and early afternoon hours, additional thunderstorms will be possible that may be strong to severe, but confidence on the timing and location of this activity remains lower than normal.

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

FIRE WEATHER

Issued at 203 AM CDT Mon Jul 20 2026

Showers and thunderstorms remain possible early this morning, but coverage and timing remains in question. Should any storms develop, they may be strong to severe with damaging wind gusts and large hail as the main threats. Winds will increase out of the west today with gusts to 20 to 30 mph. Gusts in excess of 30 mph will be possible as well. A Fire Weather Watch remains for the Arrowhead due to the ongoing wildfires and the uncertainty as to how much precipitation may impact the fuels today. Additional showers and thunderstorms will be possible across northeastern Minnesota this afternoon and evening with strong to severe storms possible ahead of the cold front across northwest Wisconsin. This activity may develop to the east, however. Rainfall amounts of a tenth of an inch to 0.35 inches will be possible with heavier amounts under any storms. Winds will be more northerly for Tuesday with gusts again of 20 to 30 mph plus. Highs will be in the 70s with afternoon RH values likely remaining above 40%.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Heat Advisory from 11 AM this morning to 7 PM CDT this evening for MNZ020-034>038. WI...Heat Advisory from 11 AM this morning to 7 PM CDT this evening for WIZ001>004-006>009. MARINE...Small Craft Advisory until 1 AM CDT Tuesday for LSZ121-140>148- 150. Heat Advisory from 11 AM this morning to 7 PM CDT this evening for LSZ142.