During the early morning of July 12th, a thunderstorm passed through portions of Crow Wing County producing strong wind speeds and associated wind damage. On a nearby lake, boats that were tied to a pier were blown into the pier breaking it.
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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.
During the early morning of July 12th, a thunderstorm passed through portions of Crow Wing County producing strong wind speeds and associated wind damage. On a nearby lake, boats that were tied to a pier were blown into the pier breaking it. A tree was also snapped with smaller limbs broken off.
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 11, 11:14 PM CST, 1 hour 16 minutes earlier.
Area Forecast Discussion National Weather Service Duluth MN 1214 AM CDT Wed Jul 12 2017 .UPDATE... Issued at 1214 AM CDT Wed Jul 12 2017 Updated for the new 06Z Aviation Discussion below. UPDATE Issued at 1007 PM CDT Tue Jul 11 2017 A severe thunderstorm watch was issued for Cass and Crow Wing Counties of central Minnesota through 4 am. UPDATE Issued at 747 PM CDT Tue Jul 11 2017 Updated the forecast through the rest of the evening, mainly to refine the precipitation chances and thunder in the forecast. Discreet supercells, at the time of this writing, were tracking to the east and east-southeast across the northern Red River Valley between eastern North Dakota and northwest Wisconsin. These storms will likely organize into clusters with time, and probably an MCS. Thinking strongest storms will track southeast along the instability gradient leading through central Minnesota, so still expecting the worst weather to likely affect the Brainerd Lakes region late this evening and through around midnight. UPDATE Issued at 640 PM CDT Tue Jul 11 2017 Updated for the new 00Z Aviation Discussion below. && .SHORT TERM...(This evening through Wednesday) Issued at 254 PM CDT Tue Jul 11 2017 The main focus for the short-term forecast period continues to be the threat for severe weather this evening and overnight, particularly from Walker southeast to Aitkin and Pine City and points southwest. The severe weather scenario is still a bit uncertain due to the potential for outflow boundaries that could develop to provide forcing for additional convection that the convective-allowing models (CAMs) may not be resolving. The synoptic models are still indicating a sfc low pressure, currently positioned over northeast North Dakota, a warm front boundary draped out ahead of the low from eastern North Dakota south- southeast towards southwest Minnesota, and a trailing cold front boundary, currently located over central North Dakota. The warm front should be the primary convective initiation mechanism to focus on at this time as the baroclinic zone should be situated right along our southern counties this evening. The southerly flow ahead of the sfc low will support warm air/moisture advection, as indicated by sfc dew points ranging from the mid to upper 60s across our southern counties. MLCAPE values between 1000 to 2500 J/kg, as per the 11.12z guidance by 00z Wednesday, and 40 to 50 kts of 0-6 km bulk shear magnitudes are expected along the boundary. There is still uncertainty between the current CAMs, but the general consensus is the strongest convection will enter our southwestern counties by 01 or 02z, continuing through roughly 07 to 08z. The convective modes are expected to initially be supercellular as convection fires along the warm front boundary out over the eastern Dakotas and northwest Minnesota, which should consolidate into an MCS/bowing segment over our southwestern counties. The main threats with these storms continues to be damaging winds and large hail, with a small risk of tornadoes due to a strengthening and veering low-level wind profile, providing curved hodographs. Moreover, there is a potential for heavy rainfall/flash flooding due to enhanced moisture transport, with Pwat values ranging from 1.5 to 1.8". These values are >90% of climatology, according to the NAEFS climatological anomalies analysis. After the main segment of severe weather moves through, there may be some lingering storms over our northern portions of the forecast area before dawn Wednesday morning, but there is still some disagreement between the CAMs on this. I am expecting some convection to continue over the northern portions of the forecast area as this will be in proximity to the sfc low and the trailing cold front making its way eastward. Winds should remain east to northeasterly for tonight through the day Wednesday, especially for locations upstream of the flow from Lake Superior and northward over the Iron Range. A mid-level shortwave trough will help keep cyclonic flow over the Northland Wednesday, with a few waves of positive vorticity advection translating across the region. Chances of showers will continue, with thunderstorms possible in some locales. The best instability appears to be over the southern counties of northwest Wisconsin, where MLCAPE of 1000 to 2000 J/kg is progged by the 11.12z GFS and NAM models. The Storm Prediction Center has issued a Marginal Risk of severe weather south of a Pine City to Butternut to Lac Du Flambeau line. The better likelihood of severe weather should remain to our south over Iowa, southern Wisconsin, and northern Illinois. Temperatures on Wednesday will be the coolest for the remainder of the week, with high temperatures ranging from the upper 50s and lower 60s over the Minnesota Arrowhead region, into the upper 60s and lower 70s further inland, and even some mid to upper 70s over our extreme southern counties. .LONG TERM...(Wednesday night through Tuesday) Issued at 237 PM CDT Tue Jul 11 2017 Cooler temperatures Thursday, then back to the warm and humid conditions for the weekend into early next week. A chance for showers and storms as a cold front moves across the region Friday night into Saturday night, then the next chance for showers and storms looks to be Monday night. On the synoptic scale a typical summer ridge over the Rockies and Great Plains will build late week into the weekend resulting in a stretch of hot and humid weather. Wednesday night into Thursday morning light rain showers are possible in the post-frontal environment due to weak mid-level lift from the tail end of a mid- level shortwave trough tracking across northwest Ontario. Temperatures cooler due to an area of surface high pressure over Lake Superior resulting in winds off the lake. Highs mid 60s to mid 70s. Skies clear out Thursday night into Friday and a warm front builds east as warmer air returns to the Upper Midwest. Highs in the low 80s Friday. Friday night a chance for showers and storms as a subtle mid-level trough axis across southern Canada into the northern Plains produces just enough broad-scale lift to break the cap and produce precipitation. Not expecting too much in the way of strong storms, just some scattered showers with isolated storms. High pressure builds in behind this front by Sunday which may lead to some cooler temperatures, especially by Lake Superior. On Monday the area of high pressure over the Upper Midwest drifts east resulting in more southerly warm air advection across the Great Plains and Upper Midwest and thus warmer temperatures. Highs could reach 90 in some areas of north-central Minnesota Monday and Tuesday. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1214 AM CDT Wed Jul 12 2017 Showers and thunderstorms will continue spreading east across northeast Minnesota and then northwest Wisconsin through the rest of the night. Some of the storms could be strong to severe, with strong winds, hail, and heavy rain. Areas from central Minnesota into northwest Wisconsin have the greatest potential for severe weather, including hte KBRD and KHYR areas. Cool and humid easterly flow from Lake Superior, combined with residual low-level moisture from overnight storms, will likely result in lower ceilings and visibilities to widespread LIFR/IFR conditions by late tonight or Wednesday morning. Showers, and some thunderstorms, could continue through Wednesday, and it looks like it will be difficult to lift the ceilings. Therefore, bet on widespread IFR/MVFR conditions to continue through the day. && .PRELIMINARY POINT TEMPS/POPS... DLH 55 60 52 65 / 70 30 30 20 INL 56 64 50 70 / 70 50 50 20 BRD 62 74 56 72 / 80 20 20 10 HYR 63 75 53 69 / 60 30 30 20 ASX 57 65 52 65 / 70 40 40 30 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory until 10 AM CDT Thursday for LSZ121-140>148. && UPDATE...Grochocinski SHORT TERM...JTS LONG TERM...JJM AVIATION...Grochocinski
Hazardous Weather Outlook National Weather Service Duluth MN 1005 PM CDT Tue Jul 11 2017 MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-121200- 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- 1005 PM CDT Tue Jul 11 2017 This Hazardous Weather Outlook is for portions of northeast Minnesota and northwest Wisconsin. .DAY ONE...Tonight Thunderstorms are expected to increase over much of the Northland late this evening and overnight. Some of the storms may be severe with large hail, damaging winds, heavy rainfall, and frequent cloud- to- ground lightning being the main threats. There is also a small risk of a tornado or two. The heavy rainfall may lead to localized flash flooding. The greatest potential for severe weather is for areas of central Minnesota, including the Brainerd Lakes region, and areas to its west and south. A severe thunderstorm watch is in effect for parts of central Minnesota, including Cass and Crow Wing Counties, until 4 am. .DAYS TWO THROUGH SEVEN...Wednesday through Monday A few thunderstorms are possible across northwest Wisconsin on Wednesday into Wednesday night. The next chance for thunderstorms arrives Friday night across the International Border region, then Saturday afternoon and evening across east central Minnesota into northwest Wisconsin. .SPOTTER INFORMATION STATEMENT... Skywarn Spotters may be needed . LSZ121-140>148-121200- 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- 1005 PM CDT Tue Jul 11 2017 This Hazardous Weather Outlook is for portions of the Nearshore waters of western Lake Superior. .DAY ONE...Tonight Strong northeast winds will result in hazardous winds and waves for much of western Lake Superior late today through tonight. In addition, thunderstorms are possible tonight, some of which could be strong. Please see the latest Marine Weather Message and Nearshore Marine Forecast for more information. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Northeast winds are expected to persist across western Lake Superior through Thursday which will result in continued higher waves. Thunderstorms are possible late Friday night into Saturday. These storms are not expected to be severe. G2/JJM/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 1220 AM CDT WED JUL 12 2017 MNZ037-038-120545- Pine-Carlton/South St. Louis- 1220 AM CDT WED JUL 12 2017 ...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN PINE AND SOUTHWESTERN CARLTON COUNTIES... At 1219 AM CDT, a strong thunderstorm was near Willow River, or 25 miles north of Hinckley, moving east at 25 mph. Wind gusts up to 30 mph and half-inch hail can be expected with this storm. This storm will be near... Bruno around 1235 AM CDT. Other locations impacted by this storm include Duquette, Denham, Moose Lake State Park, Sturgeon Lake, Kerrick, and Nickerson. Seek shelter inside a sturdy building and away from windows until this storm passes. LAT...LON 4630 9301 4645 9301 4646 9250 4627 9250 TIME...MOT...LOC 0519Z 269DEG 23KT 4638 9284 G2
Special Weather Statement
National Weather Service Duluth MN
1233 AM CDT WED JUL 12 2017
MNZ033-034-036-120600-
Crow Wing-South Cass-South Aitkin-
1233 AM CDT WED JUL 12 2017
...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN AITKIN...SOUTHERN
CASS AND SOUTHERN CROW WING COUNTIES...
At 1233 AM CDT, a strong thunderstorm was near Gull Lake, or 8 miles
west of Brainerd, moving east at 45 mph.
Wind gusts up to 30 mph, half-inch hail, and heavy downpours can be
expected with this storm.
This storm will be near...
Brainerd and Merrifield around 1245 AM CDT.
Ironton, Upper South Long Lake and South Long Lake around 1255 AM
CDT.
Deerwood and Garrison around 100 AM CDT.
Other locations impacted by this storm include Sylvan, Legionville,
North Long Lake, Camp Lake, Riverton, Crow Wing State Park, Cuyuna
Country State Park, Lake Hubert, Lake Shore, and Barrows.
Seek shelter inside a sturdy building and away from windows until
this storm passes.
LAT...LON 4654 9436 4647 9371 4624 9376 4624 9381
4616 9381 4616 9438 4618 9437 4621 9439
4623 9439 4627 9434 4629 9435 4630 9439
4633 9441 4633 9444
TIME...MOT...LOC 0533Z 281DEG 39KT 4640 9435
G2Special Weather Statement
National Weather Service Duluth MN
1244 AM CDT WED JUL 12 2017
MNZ037-038-120615-
Pine-Carlton/South St. Louis-
1244 AM CDT WED JUL 12 2017
...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN PINE AND SOUTHERN
CARLTON COUNTIES...
At 1243 AM CDT, a strong thunderstorm was near Barnum, or 23 miles
southwest of Cloquet, moving east at 20 mph.
Wind gusts up to 30 mph and half-inch hail can be expected with this
storm.
This storm will be near...
Mahtowa around 1255 AM CDT.
Nemadji around 100 AM CDT.
Other locations impacted by this storm include Duquette, Nickerson,
Moose Lake State Park, Sturgeon Lake, Automba, and Kerrick.
Seek shelter inside a sturdy building and away from windows until
this storm passes.
LAT...LON 4635 9289 4650 9306 4654 9306 4654 9244
4631 9231
TIME...MOT...LOC 0543Z 273DEG 18KT 4642 9270
G2Special Weather Statement
National Weather Service Duluth MN
105 AM CDT WED JUL 12 2017
MNZ038-120615-
Pine-
105 AM CDT WED JUL 12 2017
...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN PINE COUNTY...
At 105 AM CDT, a strong thunderstorm was over Quamba, or 14 miles
northwest of Pine City, moving east at 30 mph.
Wind gusts up to 50 mph, dime-size hail, and heavy downpours can be
expected with this storm.
This storm will be near...
Brook Park and Henriette around 115 AM CDT.
Other locations impacted by this storm include Greely and West Rock.
Seek shelter inside a sturdy building and away from windows until
this storm passes.
LAT...LON 4598 9314 4598 9305 4610 9305 4608 9289
4573 9303 4573 9314
TIME...MOT...LOC 0605Z 289DEG 25KT 4594 9322
G2Special Weather Statement
National Weather Service Duluth MN
114 AM CDT WED JUL 12 2017
MNZ038-120630-
Pine-
114 AM CDT WED JUL 12 2017
...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN PINE COUNTY...
At 113 AM CDT, a strong thunderstorm was near Mora, or 15 miles
northwest of Pine City, moving east at 25 mph.
Wind gusts up to 40 mph, half-inch hail, and heavy downpours can be
expected with this storm.
This storm will be near...
Brook Park and Henriette around 130 AM CDT.
Other locations impacted by this storm include Grindstone Lake Pine
County, Greely, Friesland, Beroun, West Rock, and Banning State Park.
Seek shelter inside a sturdy building and away from windows until
this storm passes.
LAT...LON 4573 9314 4598 9314 4598 9305 4614 9306
4612 9282 4573 9297
TIME...MOT...LOC 0613Z 276DEG 17KT 4592 9326
G2Special Weather Statement
National Weather Service Duluth MN
128 AM CDT WED JUL 12 2017
MNZ038-WIZ006-120700-
Pine-Burnett-
128 AM CDT WED JUL 12 2017
...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN PINE AND
SOUTHWESTERN BURNETT COUNTIES...
At 128 AM CDT, a strong thunderstorm was over Henriette, or 8 miles
west of Pine City, moving southeast at 30 mph.
Wind gusts up to 40 mph, half-inch hail, and heavy downpours can be
expected with this storm.
This storm will be near...
Pine City around 145 AM CDT.
Rock Creek around 150 AM CDT.
Other locations impacted by this storm include Cloverdale, Greely,
Beroun, Randall, West Rock, and Saint Croix State Park.
Seek shelter inside a sturdy building and away from windows until
this storm passes.
LAT...LON 4570 9287 4572 9287 4573 9285 4573 9314
4598 9314 4598 9305 4607 9305 4602 9263
4564 9280 4564 9289
TIME...MOT...LOC 0628Z 292DEG 28KT 4586 9315
G2The Duluth radar (KDLH), 171 km away, was scanning. The volume nearest the first event began at 06:31 UTC.
1 thunderstorm wind. Local standard time, as filed.
Several boats that were tied to a pier were blown into the pier breaking it. One tree was also snapped.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2017Every state in 2017This day in weather historyWarnings in Minnesota, July 2017
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: 712108.