A complex of thunderstorms developed over the Dakotas the evening of the 24th and pushed eastward overnight into the morning of the 25th. While the storms were sub-severe for the most part, some stronger winds were able to reach the surface in the vicinity of Leech Lake in north-central Minnesota causing some tree damage.
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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.
A complex of thunderstorms developed over the Dakotas the evening of the 24th and pushed eastward overnight into the morning of the 25th. While the storms were sub-severe for the most part, some stronger winds were able to reach the surface in the vicinity of Leech Lake in north-central Minnesota causing some tree damage.
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 24, 11:27 PM CST, 3 hours 48 minutes earlier.
Area Forecast Discussion National Weather Service Duluth MN 1227 AM CDT Sat Jul 25 2020 .UPDATE... Issued at 816 PM CDT Fri Jul 24 2020 Even though there will still be some high heat indices this evening, will be below advisory levels and have let the advisory expire. Latest CAMS have slowed down the arrival of thunderstorms overnight and adjusted pops accordingly. Made other minor adjustments. && .SHORT TERM...(This evening through Saturday night) Issued at 346 PM CDT Fri Jul 24 2020 Very warm and humid conditions covered most of the Northland this afternoon, especially across our southern areas. Dewpoints were from the upper sixties to mid seventies for most areas and heat indices were in the lower 90s to around 100. We will keep the Heat Advisory going for our southern areas into early evening. Moisture advection will continue tonight and low level convergence over northern Minnesota may cause showers and storms to develop this evening over portions of far northern Minnesota with a better chance later tonight as showers and storms that form over the Dakotas move east into the area. These storms will be maintained by a southerly low level jet of 30 to 35 knots. It's very unstable this afternoon with MLCAPE values from 2500-3500 J/KG over the western half of Minnesota. Effective shear was lacking though with values less than 25 knots as of 20Z. However, this will increase later tonight once the low level jet strengthens. There is a risk for severe storms, mainly late tonight over our far western area with damaging wind and very heavy rain the main threats. The CAMs are in pretty good agreement with the showers/storms later tonight. The showers/storms will continue east Saturday morning and most of the guidance has them weakening during the day. However, southerly 850MB winds will continue to be around 35 knots so we think they may not weaken as much as the CAMs suggest. Additional storm development is expected during the afternoon and evening, some of which could be severe. The severe potential is still in question. We expect most areas will be mostly cloudy through most of the day which will have an effect on instability. The guidance is picking up on this as well with MLCAPE values from 1000-1500 J/KG for most areas. Deep layer shear is more supportive of strong to severe storms over western portions of the Northland but diminishes east to 25 knots or less over far eastern Minnesota and northern Wisconsin. A few severe storms will be possible with damaging wind the main threat. Forecast soundings do show decent low level curvature and 0-1KM shear is 20 to around 25 knots. There could be a tornado that occurs as well, but this will depend on instability and storm mode. Heavy rain will also be one of the main threats with the storms Saturday afternoon and evening with PWAT values a bit over 2" in spots, which is very high. If the CAMs can be believed, storms motions should minimize the threat some. However, any area that see 2 to 3 storms move across the same area will be at risk for some flash flooding given the high PWAT values. We don't expect we'll need a Heat Advisory for Saturday as cloud is expected to hold temperatures down some. Thunderstorms will gradually diminish in intensity and coverage Saturday night. .LONG TERM...(Sunday through Friday) Issued at 346 PM CDT Fri Jul 24 2020 Much of the extended period will be dry after Sunday or only feature low chances for showers and storms. Highs will be a bit below normal Monday then warm toward normal values for the rest of the week. A cold front will continue to works its way through the Northland on Sunday with chances for showers and storms along and ahead of it. The best chance will be over our far eastern areas including all of northern Wisconsin. Lower humidity and temperatures will occur behind the front but it will be another very muggy day across northern Wisconsin and east central Minnesota as the front will not move through there until later in the day or in the evening. An upper low over far northwest Ontario into northern Manitoba Sunday afternoon will move slowly east Monday into Tuesday with a trough extending south into the Northland. We have low chances for showers/storms over parts of the region during that time but we don't expect widespread coverage or severe storms. A dry period will then occur Wednesday into Thursday for most areas thanks to high pressure. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1226 AM CDT Sat Jul 25 2020 Showers and thunderstorms will begin to affect the INL and BRD terminals by 09Z, then affect the rest of the terminals by sunrise. VFR is expected initially, then MVFR cigs with the more robust storms. Gusty winds are also expected with some pockets of heavy rain. Low confidence in timing and have used VCTS at several sites. Where confidence is higher, used a predominate TSRA mention. This activity will be percolating near the terminals to the end of the forecast. && .MARINE... Issued at 923 PM CDT Fri Jul 24 2020 Winds will be less than 15 knots tonight with waves less than 2 feet. On Saturday, showers and thunderstorms will become likely with a few severe storms possible in the afternoon. Outside of thunderstorms, winds will be southerly 15 knots or less. Expect winds to gradually veer Saturday night into Sunday to westerly. and be 15 knots or less for most areas. Waves will be less than 2 feet. && .PRELIMINARY POINT TEMPS/POPS... DLH 70 84 68 83 / 10 60 60 40 INL 69 84 64 79 / 50 70 30 20 BRD 72 85 68 80 / 70 70 50 30 HYR 71 87 69 85 / 0 70 70 60 ASX 72 88 70 87 / 0 60 70 50 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && UPDATE...GSF SHORT TERM...Melde LONG TERM...Melde AVIATION...Britt/GSF MARINE...GSF
Hazardous Weather Outlook National Weather Service Duluth MN 413 AM CDT Sat Jul 25 2020 MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-260915- 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- 413 AM CDT Sat Jul 25 2020 This Hazardous Weather Outlook is for portions of northeast Minnesota and northwest Wisconsin. .DAY ONE...Today and Tonight There will be chances for thunderstorms today and tonight. The first round of storms is moving through north-central Minnesota early this morning, with additional storms possible this afternoon and evening. An isolated strong to severe storm will be possible, mainly for this afternoon and evening, with the main threats being large hail, strong, damaging winds, and frequent lightning. Torrential downpours will also be possible today, which may lead to very localized flash flooding. .DAYS TWO THROUGH SEVEN...Sunday through Friday Additional chances of thunderstorms will be possible Sunday. Severe weather is not expected. .SPOTTER INFORMATION STATEMENT... Skywarn spotters may be needed this afternoon and evening. LSZ121-140>148-260915- 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- 413 AM CDT Sat Jul 25 2020 This Hazardous Weather Outlook is for portions of the Nearshore waters of western Lake Superior. .DAY ONE...Today and Tonight Chances of thunderstorms will increase this afternoon and evening across western Lake Superior, some of which could be strong to severe. The main threats will be large hail, strong winds, and frequent cloud-to-water lightning. Some torrential downpours will be possible as well, which may reduce visibility. .DAYS TWO THROUGH SEVEN...Sunday through Friday Additional chances of thunderstorms will be possible Sunday. Severe weather is not expected. JTS 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
353 AM CDT Sat Jul 25 2020
MNZ025-033-250945-
North Cass-South Cass-
353 AM CDT Sat Jul 25 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT WESTERN CASS COUNTY...
At 353 AM CDT, strong thunderstorms were along a line extending from
near Park Rapids, to 6 miles east of Sebeka, to near Bertha, and
moving northeast at 35 mph.
Wind gusts up to 40 mph, heavy downpours, and occasional cloud to
ground lightning can be expected with these storms.
These storms will be near...
Leader around 425 AM CDT.
Poplar around 430 AM CDT.
Backus around 435 AM CDT.
Hackensack around 445 AM CDT.
Other locations impacted by these storms include Oshawa, Casino,
Esterdy, Pheasant Lake, Cass Lake, Wilkinson 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 4680 9479 4680 9466 4734 9467 4741 9459
4741 9449 4699 9445 4644 9445 4635 9466
4635 9472 4639 9478
TIME...MOT...LOC 0853Z 221DEG 32KT 4697 9500 4660 9496 4632 9498
JTSThe Duluth radar (KDLH), 184 km away, was scanning. The volume nearest the first event began at 09:16 UTC.
2 thunderstorm wind. Local standard time, as filed.
Many large trees were downed near Walker during the storm.
A few trees were downed at the Red Wing Resort on Leech Lake by the storm.
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: 908356, 908360.