An area of low pressure moving through Manitoba into western Ontario during the day and pulled a cold front through Minnesota during the afternoon and evening hours. Strong southerly flow ahead of the front brought warm temperatures and moisture to the region to help fuel the storms that developed ahead of the cold front.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS DLH wrote it up.
An area of low pressure moving through Manitoba into western Ontario during the day and pulled a cold front through Minnesota during the afternoon and evening hours. Strong southerly flow ahead of the front brought warm temperatures and moisture to the region to help fuel the storms that developed ahead of the cold front. While a line of storms did develop, afternoon cloud cover delayed their development and prevented the storms from being as strong as the environment would have supported. Only a few wind damage reports were received with the storms with the most significant being a pole barn that was completely destroyed.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Duluth, MN wrote its last area forecast discussion before the first event at Jul 13, 5:57 PM CST, 2 hours 31 minutes earlier.
Area Forecast Discussion National Weather Service Duluth MN 657 PM CDT Mon Jul 13 2020 .SHORT TERM...(This evening through Tuesday night) Issued at 351 PM CDT Mon Jul 13 2020 An approaching cold front will lead to developing showers and thunderstorms this evening. An upper level trough currently located over eastern Montana will continue to work its way eastward, which will help to provide additional lift. The combination of the cold front and upper level trough is expected to lead to thunderstorm development after 00z this evening. The primary mode of these storms is expected to be linear, as CAMs have been in decent agreement. However, there is the potential for some discrete convection, primarily in the southwestern portion of the CWA. A few of these storms may be severe, particularly in the Brainerd Lakes area. Main hazards include damaging winds, large hail, isolated tornadoes, and very heavy rain. Assessing the environment this evening, the ingredients for severe convection are present. 0-6 km bulk shear values are forecasted to be between 40-50 knots. MLCAPE values are expected to be between 1500-2000 J/kg. This amount of instability should help to maintain the storms, but limit the ability for large hail development. Moisture advection is expected to be plentiful as a lower level jet from the south is expected to advect a moist airmass northward. PWAT values around 1.5 inches could potentially lead to very heavy rainfall. When assessing the potential for tornadoes, the Brainerd Lakes have the most favorable environment according to SPC. 0-1 km SRH from the HRRR has been quite impressive, with over 400 m2/s2 around the time of storm development. One potential limiting factor towards tornado development would be the high LCLs, which are currently forecasted to be above 2 km. Regardless, the risk for tornadoes is still present and will be something to watch for in the storms this evening. For Tuesday, showers and thunderstorms are possible, particularly in Northwest Wisconsin. A few of these storms may become severe in the afternoon. SPC currently has most of NW WI under a marginal risk for severe storms tomorrow. Looking at the environment, shear of 40-50 knots is possible, with MLCAPE values of 500-1000 J/kg. Possible threats include damaging winds, large hail, and a few isolated tornadoes. By Tuesday evening, the showers and thunderstorms will exit the area, leading to dry conditions for Tuesday night. Temperatures tomorrow are expected to feel much more comfortable, with highs being in the mid 70s. .LONG TERM...(Wednesday through Monday) Issued at 351 PM CDT Mon Jul 13 2020 A progressive pattern will be in place for the extended period while still maintaining above normal temperatures. Overall, broadscale moisture is limited through the week, but a large plume of rich PWAT air gets advected northward by the weekend. This will set the stage for another good opportunity for stronger storms - especially since shear becomes a lot more prevalent as flow turns zonal. So, Friday through Sunday may be an active period for storms. Afterwards, a drier air mass moves in and a weak upper level ridge tries to build to our west. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 657 PM CDT Mon Jul 13 2020 VFR conditions are currently in place with storms expected to arrive this evening and bring deteriorating conditions. The best chance for storms will be between 8PM and midnight and bring periods of MVFR and perhaps IFR conditions as they move through. Storms may be severe with damaging wind gusts and heavy rain as the primary threats. Some fog is expected to develop during the early morning hours with HIB being the most likely. A mix of MVFR and VFR conditions are expected for Tuesday as showers linger through the day. Winds will shift westerly overnight as a cold front passes along with the storms. && .MARINE... Issued at 351 PM CDT Mon Jul 13 2020 Stronger northeast winds this evening around 10-20 knots will becoming light and variable overnight as a line of showers and storms move through associated with a cold front. A few strong storms are possible across western Lake Superior, but generally thinking storms will weaken before they reach the lake. Chances for showers and a few storms again on Tuesday across the south shore with weak west winds around 5 to 10 knots. Increasing southwest winds Wednesday and Thursday at 10 to 15 knots, with wave heights building to as high as 2 to 3 feet across parts of the north shore by Thursday. && .PRELIMINARY POINT TEMPS/POPS... DLH 62 73 54 81 / 90 60 0 0 INL 59 75 55 80 / 100 30 0 0 BRD 60 73 53 80 / 100 50 0 0 HYR 65 75 52 81 / 70 90 10 0 ASX 65 78 55 83 / 70 90 20 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Beach Hazards Statement until 10 PM CDT this evening for WIZ001. MN...Beach Hazards Statement until 10 PM CDT this evening for MNZ037. LS...None. && SHORT TERM...Unruh/JJM LONG TERM...Wolfe AVIATION...BJH MARINE...JJM
Hazardous Weather Outlook National Weather Service Duluth MN 247 PM CDT Mon Jul 13 2020 MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-142000- Koochiching-North St. Louis-Northern Cook/Northern Lake- North Itasca-Central St. Louis-Southern Lake/North Shore- Southern Cook/North Shore-North Cass-South Itasca-South Cass- Crow Wing-Northern Aitkin-South Aitkin-Carlton/South St. Louis- Pine-Douglas-Bayfield-Ashland-Iron-Burnett-Washburn-Sawyer-Price- 247 PM CDT Mon Jul 13 2020 This Hazardous Weather Outlook is for portions of northeast Minnesota and northwest Wisconsin. .DAY ONE...This afternoon and Tonight Strong to severe thunderstorms are expected tonight. The main threats are for large hail, damaging wind gusts, isolated tornadoes, and heavy rainfall, which may lead to localized flash flooding. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms are possible Friday through Sunday. A few storms may be strong to severe. .SPOTTER INFORMATION STATEMENT... Skywarn spotters are encouraged to report hail of any size and rainfall amounts to the National Weather Service. LSZ121-140>148-142000- Bayfield to Oak Point WI-Grand Portage to Grand Marais MN- Grand Marais to Taconite Harbor MN- Taconite Harbor to Silver Bay Harbor MN- Silver Bay Harbor to Two Harbors MN-Two Harbors to Duluth MN- Duluth MN to Port Wing WI-Port Wing to Sand Island WI- Sand Island to Bayfield WI-Oak Point to Saxon Harbor WI- 247 PM CDT Mon Jul 13 2020 This Hazardous Weather Outlook is for portions of the Nearshore waters of western Lake Superior. .DAY ONE...This afternoon and Tonight Strong to severe thunderstorms may move over western Lake Superior after 9 PM tonight. The main threats are wind gusts of 40 knots or greater and large hail. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Strong to severe storms are possible for the South Shore waters Tuesday afternoon and early evening. There will be additional chances of thunderstorms Friday through Sunday. Wolfe More information may be obtained at the following web address: http://www.weather.gov/duluth (all lower case)
Special Weather Statement
National Weather Service Duluth MN
817 PM CDT Mon Jul 13 2020
MNZ018-025-026-140130-
North Cass-North Itasca-South Itasca-
817 PM CDT Mon Jul 13 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT WEST CENTRAL ITASCA AND
NORTHERN CASS COUNTIES...
At 816 PM CDT, strong thunderstorms were along a line extending from
Lavinia, to near Lake George, to 7 miles northeast of Osage, and
moving east at 50 mph.
Wind gusts up to 50 mph, pea size hail, heavy downpours, and frequent
cloud to ground lightning can be expected with these storms.
These storms will remain over mainly rural areas of North Cass,
southwestern North Itasca and northwestern South Itasca Counties,
including the following locations... Boy Lake, Pheasant Lake, Lake
Ada, Ball Club Lake, Portage Lake, Mud Lake, Wilkinson, Goose Lake,
Schley and Ten Mile Lake.
Seek shelter inside a sturdy building and away from windows until
these storms pass. Get off area lakes and seek shelter on shore in a
sturdy shelter or a hard topped vehicle.
LAT...LON 4741 9467 4741 9442 4754 9441 4748 9372
4707 9399 4681 9427 4686 9466
TIME...MOT...LOC 0116Z 285DEG 43KT 4750 9479 4725 9496 4702 9519
BJHSpecial Weather Statement
National Weather Service Duluth MN
857 PM CDT Mon Jul 13 2020
MNZ018-140215-
North Itasca-
857 PM CDT Mon Jul 13 2020
...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN ITASCA COUNTY...
At 856 PM CDT, a strong thunderstorm was near Alvwood, or 26 miles
northeast of Bemidji, moving northeast at 50 mph.
Wind gusts up to 50 mph, half inch diameter hail, heavy downpours,
and frequent cloud to ground lightning can be expected with this
storm.
This storm will be near...
Alvwood around 905 PM CDT.
Squaw Lake around 910 PM CDT.
Oslund around 915 PM CDT.
Other locations impacted by this storm include Whitefish Lake, Decker
Lake, Dixon Lake, Rosy and Wirt.
Seek shelter inside a sturdy building and away from windows until
this storm passes. Get off area lakes and seek shelter on shore in a
sturdy shelter or a hard topped vehicle.
This storm may intensify, please monitor local media outlets for
additional information and possible warnings from the National
Weather Service.
LAT...LON 4785 9419 4784 9403 4766 9389 4754 9440
4756 9442 4775 9442
TIME...MOT...LOC 0156Z 243DEG 45KT 4766 9437
BJHSpecial Weather Statement National Weather Service Duluth MN 928 PM CDT Mon Jul 13 2020 MNZ025-140245- North Cass- 928 PM CDT Mon Jul 13 2020 ...A STRONG THUNDERSTORM WILL AFFECT WEST CENTRAL CASS COUNTY... At 928 PM CDT, a strong thunderstorm was near Akeley, or 10 miles south of Walker, moving east at 40 mph. Wind gusts up to 40 mph, nickel size hail, heavy downpours, and frequent cloud to ground lightning can be expected with this storm. This storm will be near... Walker and Hackensack around 935 PM CDT. Woman Lake around 945 PM CDT. Other locations impacted by this storm include Whipholt, Webb Lake, Pontoria, Pheasant Lake, Ten Mile Lake and Big Portage Lake. Seek shelter inside a sturdy building and away from windows until this storm passes. Get off area lakes and seek shelter on shore in a sturdy shelter or a hard topped vehicle. LAT...LON 4713 9435 4686 9426 4684 9466 4704 9466 TIME...MOT...LOC 0228Z 257DEG 35KT 4695 9465 BJH
The Duluth radar (KDLH), 159 km away, was scanning. The volume nearest the first event began at 02:26 UTC.
5 thunderstorm wind. Local standard time, as filed.
A tree roughly 4 inches in diameter was snapped by the winds and fell onto a trailer.
A few small tree limbs approximately 1 to 2 inches in diameter were downed.
Photos were received showing a metal pole barn that had been destroyed during the storm. Winds infiltrated the building through a large garage door, slid the building off the foundation, where the walls then collapsed, bringing the entire structure down.
The St. Louis County Sheriffs Department received reports of downed trees on the east side of Cook.
The St. Louis County Sheriff's Department received a report of downed trees on the east side of Ely.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2020Every state in 2020This day in weather historyWarnings in Minnesota, July 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 893498, 893499, 893503, 893504, 893505.