A line of thunderstorms developed the evening of the 13th across the eastern Dakotas and pushed east overnight into northern Minnesota. While storms weakened during the early morning hours, winds produced some minor damage to some patio furniture in Douglas County but were otherwise benign as they moved across northwest Wisconsin.
Every event with a place to put it. Tap one for its entry below.
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 line of thunderstorms developed the evening of the 13th across the eastern Dakotas and pushed east overnight into northern Minnesota. While storms weakened during the early morning hours, winds produced some minor damage to some patio furniture in Douglas County but were otherwise benign as they moved across northwest Wisconsin.
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 Aug 13, 11:20 PM CST, 3 hours 40 minutes earlier.
Area Forecast Discussion National Weather Service Duluth MN 1220 AM CDT Fri Aug 14 2020 .UPDATE... Issued at 928 PM CDT Thu Aug 13 2020 Strong to severe thunderstorms were occurring over far western Minnesota as of 0225Z. A very unstable airmass is in place with MLCAPE values from 2500-4000 J/KG over or near the western half of the Northland. However, the effective shear has been limited over our area to 20 to 25 knots. Although the 925mb winds are forecast to increase some, the stronger values are forecast to occur further east of the storms. The CAMs have been too fast moving the storms into our area and they look to remain mainly west through 03Z-04Z then they should develop/move east after that. Given the instability, severe storms will be possible with damaging wind the main threat but hail would also be possible given the instability and steeper mid-upper level lapse rates seen in the 00Z KINL sounding. In addition to the severe threat will be very heavy rain as the storms have been moving over the same areas. The CAMs suggest the eventual development of a line but confidence in if and how fast the line will move is low. There is some agreement that the storms will decrease in intensity as they move into far eastern Minnesota late tonight. && .SHORT TERM...(This evening through Friday night) Issued at 403 PM CDT Thu Aug 13 2020 Showers and thunderstorms are likely to initiate farther west in northwest MN this afternoon and move into the Northland late this evening into tonight. A warm front started to lift across the CWA this morning, which increased both surface temperatures and dewpoints. This increase in both temperature and moisture has helped the atmosphere to destabilize this afternoon indicated by model MLCAPE that has been exceeding 3000 J/kg over northwest MN. Closer to our CWA, MLCAPE has also been impressive, with 2500-3000 J/kg across much of NE MN. While instability isn't in short supply today, shear has been less than favorable. 0-6 km bulk shear over the Northland will likely only be 10-20 knots. The better environment shear wise is in NW MN, where bulk shear is between 30-40 knots. Strong to severe thunderstorms move into the CWA this evening with timing being likely after 02z. While the environment over the CWA is shear starved, the strengthening of a LLJ at 850mb to 40 knots will likely sustain the storms as they move into our area. The primary hazard associated with these storms will be damaging winds, as CAMs are suggesting individual cells coming together into a linear storm mode as they move into the northwest portion of the CWA. A slight risk for large hail and QLCS tornadoes will also be possible, given the large amount of instability and 0-1 km SRH values exceeding 150 m2/s2. A brief break in the action comes Friday morning, as the main line of showers and thunderstorms dissipate. Lingering showers and isolated thunderstorms will be possible in the Arrowhead region throughout the day tomorrow. Otherwise, expect another warm and humid day. Another chance of strong to severe thunderstorms is likely for tomorrow afternoon and evening as a cold front and longwave trough approach the CWA. Instability is expected to increase in the afternoon, with over 2000 J/kg of MLCAPE possible. The shear environment will also be better, with 30-40 knots of 0-6 km bulk shear likely. Multiple severe hazards are possible tomorrow, with damaging winds, large hail, and a few tornadoes possible. The risk of tornadoes will be primarily confined to the Brainerd Lakes area and is dependent on if discrete cells can form. CAMs are hinting towards a line of severe convection forming along the cold front, with timing being after 20z. This line of storms is likely to weaken as it moves into NW WI where instability and shear are more marginal. .LONG TERM...(Saturday through Thursday) Issued at 403 PM CDT Thu Aug 13 2020 Following the passage of the cold front, temperatures will return to the 70s, along with a reduction in humidity. A slight chance for a few lingering showers and isolated thunderstorms will be possible Saturday afternoon along the northern half of the Arrowhead. Otherwise, expect next week to be cooler and dry as a longwave trough remains over the eastern half of the US. The next chance of rain arrives next week Thursday, as a shortwave trough moves over the area. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1219 AM CDT Fri Aug 14 2020 A line of strong to severe storms stretched from near International Falls to Bemidji into far southeast North Dakota as of 05Z. These storms were moving east and will continue to do so overnight. The storms are expected to diminish in intensity as they near far eastern Minnesota late tonight. Until then, damaging winds and hail to one inch will be possible as will very heavy rainfall. Most areas will start out VFR but there were pockets of MVFR ceilings. The MVFR ceilings will expand over northern Minnesota later tonight. IFR conditions will occur with the stronger storms. Low level wind shear will also occur, mainly affecting KDLH and KHIB. Another round of storms will be possible Friday afternoon and night ahead of a cold front. Some of the storms may be severe with large hail and damaging winds the main threats. Gusty southerly winds will also occur ahead of the front with a switch to westerly behind the front. && .MARINE... Issued at 928 PM CDT Thu Aug 13 2020 Chances for showers and thunderstorms will increase later tonight, after midnight. A few storms late tonight into early Friday morning may be severe. Easterly winds tonight will be from 10 to 15 knots with some higher gusts with them remaining easterly for much of western Lake Superior into most of Friday. The wind will veer to southerly for all areas Friday night and be from 10 to around 15 knots with higher gusts. Another round of showers and thunderstorms are possible Friday evening. A few storms Friday evening may be severe, with strong and gusty winds, large hail, and heavy rainfall being the primary hazards. Winds and waves will be higher in and near any thunderstorms tonight into Friday night. && .PRELIMINARY POINT TEMPS/POPS... DLH 65 82 57 77 / 60 70 80 10 INL 63 80 52 77 / 80 60 60 10 BRD 67 83 53 77 / 70 50 50 0 HYR 64 85 58 77 / 20 20 80 10 ASX 65 87 60 79 / 30 20 70 20 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && UPDATE...Melde SHORT TERM...Unruh/Huyck LONG TERM...Unruh/Huyck AVIATION...Melde MARINE...Unruh/Huyck
Hazardous Weather Outlook National Weather Service Duluth MN 728 PM CDT Thu Aug 13 2020 MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-141200- 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- 728 PM CDT Thu Aug 13 2020 This Hazardous Weather Outlook is for portions of northeast Minnesota and northwest Wisconsin. .DAY ONE...Tonight Chances for strong to severe thunderstorms will return to portions of northern Minnesota later this evening and overnight, starting around or after 9 PM over western parts of the Northland. The main threats will be damaging winds up to 70 MPH, large hail, and heavy rainfall that may lead to localized flash flooding. Areas most likely to see severe weather will be along and west of a line from Crane Lake, MN to Walker, MN but the threat will extend east to far western Lake Superior. .DAYS TWO THROUGH SEVEN...Friday through Wednesday More chances for strong to severe thunderstorms will be possible Friday afternoon and evening across most of northeast Minnesota and into northwest Wisconsin. The main hazards will be damaging winds, large hail, and heavy rainfall that may lead to flash flooding. One or two tornadoes will also be possible, mainly over east-central into north-central Minnesota. Chances of thunderstorms will linger into Saturday. Severe weather is not anticipated. .SPOTTER INFORMATION STATEMENT... Skywarn spotters may be needed tonight. LSZ121-140>148-141200- 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- 728 PM CDT Thu Aug 13 2020 This Hazardous Weather Outlook is for portions of the Nearshore waters of western Lake Superior. .DAY ONE...Tonight Chances of thunderstorms will be possible later tonight. Some strong to severe storms will be possible, with strong winds and large hail being the main threats, along with frequent lightning. .DAYS TWO THROUGH SEVEN...Friday through Wednesday More chances of strong to severe thunderstorms are possible for Friday, particularly in the afternoon and evening hours. Strong winds and large hail will be the main threats, along with frequent lightning. Chances of thunderstorms will linger into Saturday. Severe weather is not anticipated. Melde 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
209 AM CDT Fri Aug 14 2020
MNZ019-026-035-037-140745-
Central St. Louis-Northern Aitkin-Carlton/South St. Louis-South
Itasca-
209 AM CDT Fri Aug 14 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN ITASCA...
NORTHERN AITKIN AND SOUTHWESTERN ST. LOUIS COUNTIES...
At 209 AM CDT, strong thunderstorms were along a line extending from
8 miles north of Chisholm, to near Pengilly, to near Swatara, and
moving east at 25 mph.
Wind gusts up to 45 mph, pea size hail, heavy downpours, and
occasional cloud to ground lightning can be expected with these
storms.
Locations impacted include...
Hibbing, Virginia, Chisholm, Eveleth, Mountain Iron, Gilbert, Aurora,
Keewatin, Buhl, Nashwauk, Biwabik, Cherry, Swan River, Hill City,
Floodwood, Warba, Toivola, Meadowlands, Swatara, and Pengilly.
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. Weakly rooted and damaged
trees and branches could be blown down with these winds.
LAT...LON 4728 9325 4746 9310 4746 9307 4750 9307
4761 9298 4759 9220 4723 9255 4675 9312
4690 9377
TIME...MOT...LOC 0709Z 275DEG 22KT 4761 9287 4728 9316 4691 9359
MeldeSpecial Weather Statement
National Weather Service Duluth MN
213 AM CDT Fri Aug 14 2020
MNZ025-026-033>037-140800-
Northern Aitkin-Crow Wing-North Cass-Carlton/South St. Louis-South
Itasca-South Cass-South Aitkin-
213 AM CDT Fri Aug 14 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN ITASCA...
AITKIN...SOUTHEASTERN CASS...SOUTHWESTERN ST. LOUIS...NORTHWESTERN
CARLTON AND CROW WING COUNTIES...
At 212 AM CDT, strong thunderstorms were along a line extending from
7 miles southwest of Warba, to Pillager, and moving east at 40 mph.
Wind gusts up to 45 mph, half inch diameter hail, torrential
rainfall, and frequent cloud to ground lightning can be expected with
these storms.
These storms will be near...
Baxter, Swan River and Jacobson around 225 AM CDT.
Saint Mathias around 235 AM CDT.
South Long Lake and Upper South Long Lake around 245 AM CDT.
Floodwood around 250 AM CDT.
Other locations impacted by these storms include Waukenabo, Cedar
Lake, Camp Lake, Waldeck, Trommald, Lake Shore, Barrows, Flowage
Lake, Mission and Woodrow.
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 4716 9342 4708 9305 4703 9305 4703 9273
4699 9251 4624 9363 4624 9380 4616 9381
4616 9425 4621 9440 4627 9434 4632 9441
4631 9457 4633 9463
TIME...MOT...LOC 0712Z 290DEG 33KT 4707 9341 4633 9448
JDSSpecial Weather Statement
National Weather Service Duluth MN
242 AM CDT Fri Aug 14 2020
MNZ011-012-019-026-037-140830-
Northern Cook/Northern Lake-Central St. Louis-North St.
Louis-Carlton/South St. Louis-South Itasca-
242 AM CDT Fri Aug 14 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN ITASCA...
ST. LOUIS AND NORTHWESTERN LAKE COUNTIES...
At 241 AM CDT, strong thunderstorms were along a line extending from
14 miles southwest of Rainy Lake East, to 12 miles southwest of
Tower, to 8 miles east of Swan River, and moving east at 30 mph.
Wind gusts up to 40 mph, heavy downpours, and occasional cloud to
ground lightning can be expected with these storms.
Locations impacted include...
Hibbing, Ely, Lake Vermilion, Virginia, Chisholm, Eveleth, Mountain
Iron, Hoyt Lakes, Gilbert, Aurora, Babbitt, Buhl, Biwabik, Cherry,
Embarrass, Tower, Cotton, Winton, Toivola, and Meadowlands.
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 4827 9200 4823 9195 4824 9190 4821 9186
4820 9172 4812 9171 4809 9158 4771 9179
4689 9236 4704 9320 4772 9272 4831 9245
4822 9235 4825 9227 4832 9231 4835 9228
4836 9206
TIME...MOT...LOC 0741Z 267DEG 24KT 4838 9221 4771 9250 4706 9302
MeldeSpecial Weather Statement
National Weather Service Duluth MN
248 AM CDT Fri Aug 14 2020
MNZ034>038-140830-
Northern Aitkin-Crow Wing-Pine-Carlton/South St. Louis-South Aitkin-
248 AM CDT Fri Aug 14 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT AITKIN...NORTHWESTERN
PINE...SOUTHWESTERN ST. LOUIS...CARLTON AND SOUTHEASTERN CROW WING
COUNTIES...
At 247 AM CDT, strong thunderstorms were along a line extending from
near Floodwood, to near Tamarack, to near Saint Mathias, and moving
southeast at 35 mph.
Wind gusts up to 50 mph, heavy downpours, and frequent cloud to
ground lightning can be expected with these storms.
These storms will be near...
Floodwood, McGregor and Tamarack around 250 AM CDT.
Kettle River and Brookston around 315 AM CDT.
Moose Lake around 325 AM CDT.
Cloquet, Barnum, Willow River, Fond Du Lac Reservation and Saginaw
around 330 AM CDT.
Other locations impacted by these storms include Gowan, Grand Lake,
Waukenabo, Arthyde, Cedar Lake, Camp Lake, Sheshebee, Wright, Ripple
Lake and Dads Corner.
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 4703 9322 4703 9313 4689 9236 4636 9267
4615 9306 4616 9343 4625 9343 4624 9380
4616 9381 4616 9437
TIME...MOT...LOC 0747Z 302DEG 29KT 4699 9290 4660 9317 4615 9422
JDSSpecial Weather Statement
National Weather Service Duluth MN
325 AM CDT Fri Aug 14 2020
MNZ036>038-WIZ001-006-140915-
Pine-Carlton/South St. Louis-South Aitkin-Douglas-Burnett-
325 AM CDT Fri Aug 14 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN AITKIN...
PINE...EASTERN CARLTON...DOUGLAS AND NORTHERN BURNETT COUNTIES...
At 324 AM CDT, strong thunderstorms were along a line extending from
near Scanlon, to near Willow River, to near Isle, and moving
southeast at 40 mph.
Wind gusts up to 45 mph, heavy downpours, and occasional cloud to
ground lightning can be expected with these storms.
Locations impacted include...
Duluth, Superior, Cloquet, Hinckley, Sandstone, Hawthorne, Lake
Nebagamon, Scanlon, Carlton, Mahtowa, Barnum, Poplar, Solon Springs,
Willow River, Wrenshall, Oliver, Askov, Rutledge, Dairyland, and
Holyoke.
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 4598 9312 4598 9305 4616 9306 4616 9343
4621 9343 4642 9284 4676 9246 4652 9160
4616 9201 4616 9205 4612 9205 4584 9283
TIME...MOT...LOC 0824Z 298DEG 34KT 4669 9246 4640 9278 4619 9338
MeldeSpecial Weather Statement
National Weather Service Duluth MN
328 AM CDT Fri Aug 14 2020
MNZ011-012-019-020-037-WIZ001-140915-
Northern Cook/Northern Lake-Central St. Louis-North St.
Louis-Southern Lake/North Shore-Carlton/South St. Louis-Douglas-
328 AM CDT Fri Aug 14 2020
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHWESTERN COOK...
SOUTHEASTERN ST. LOUIS...NORTHEASTERN CARLTON...LAKE AND NORTHEASTERN
DOUGLAS COUNTIES...
At 328 AM CDT, strong thunderstorms were along a line extending from
10 miles north of Basswood Lake, to near Whiteface Reservoir, to near
Scanlon, and moving east at 40 mph.
Wind gusts up to 40 mph, heavy downpours, and occasional cloud to
ground lightning can be expected with these storms.
Locations impacted include...
Duluth, Superior, Cloquet, Ely, Hermantown, Two Harbors, Proctor,
Hoyt Lakes, Babbitt, Maple, Poplar, Winton, Fairbanks, Wolf Lake,
White Iron Lake, Wisconsin Point, City of Rice Lake, Saganaga Lake,
Whiteface Reservoir, and Fall 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 4709 9145 4678 9203 4673 9196 4672 9188
4678 9162 4656 9173 4679 9256 4821 9182
4819 9171 4811 9170 4811 9156 4805 9157
4805 9142 4808 9125 4824 9088
TIME...MOT...LOC 0828Z 268DEG 33KT 4820 9170 4734 9212 4676 9238
MeldeThe Duluth radar (KDLH), 28 km away, was scanning. The volume nearest the first event began at 08:58 UTC.
1 thunderstorm wind. Local standard time, as filed.
A patio table was flipped over and 3 to 4 gallon potted plants were knocked over by the winds as well.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2020Every state in 2020This day in weather historyWarnings in Wisconsin, August 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: 916915.