A cold front moving through a moist, unstable and strongly sheared environment produced severe thunderstorms over portions of west and central Upper Michigan from late evening on the 18th into the early morning of the 19th.
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 MQT wrote it up.
A cold front moving through a moist, unstable and strongly sheared environment produced severe thunderstorms over portions of west and central Upper Michigan from late evening on the 18th into the early morning of the 19th.
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 Marquette, MI wrote its last area forecast discussion before the first event at Jul 18, 4:28 PM CST, 5 hours 22 minutes earlier.
Area Forecast Discussion National Weather Service Marquette MI 628 PM EDT Sat Jul 18 2020 .SHORT TERM...(This evening through Sunday) Issued at 347 PM EDT SAT JUL 18 2020 Leftover MCV from ND/MN moved into the area overnight and by the start of this period, a line of strong thunderstorms was rolling east through the central UP. These storms produced a good bit of lightning and dumped about 1-2 inches of rain very quickly, which is no surprise given the amount of moisture available in the atmosphere. Following the line's exit east, low level strata filtered in, followed by clearing skies in the west and central. Much of the west has seen temperatures rebound into the 80s while parts of the central and east stayed in the 70s given the longevity of the cloud cover. At the same time moisture has increased some, mainly in the south. By 18z Menominee had a dewpoint 77! Expect moisture to continue increasing this afternoon ahead the next round of thunderstorms. 12z guidance and subsequent CAM runs dialed back a potential afternoon convective event highlighted in previous model runs, likely due to CAMS being a little aggressive with low level moisture surging north and the subsequent instability. Given that much of this looks to remain south of our forecast area, largely removed PoPs ahead of the next round. For the remainder of the afternoon, with the warm and moist airmass, it won't take much to support the next wave of thunderstorms and SPC maintained the slight risk for severe weather over the UP. An MCS is anticipated to develop upstream along an approaching cold front and with some clearing skies and increasing moisture this afternoon, we should be able to realize much of the MUCAPE suggested by models out ahead of the boundary. ~3000 j/kg of elevated CAPE looks to be available and model soundings are highlighting fat profiles with steep lapse rates. Overall, as the system develops this afternoon west of the forecast area, its possible there could be some hail early on in the west before the MCS develops into more of a QLCS- bowing structure. In terms of severe weather, this means the event will primarily present a wind threat across the forecast area as it moves west to east. Another aspect of this is that heavy rain will once again be possible. Given PWATS climbing during the day to 1.75- 2", these storms will be able to produce heavy rain and its likely ponding on the roads or in low lying areas will be possible. WPC once again has the region in a slight risk for excessive rainfall. In terms of timing, models are in good agreement that the system will roll into the western UP around 2-4z, the central 3-5z and the east by 5-7z. Given how the models have flopped on the already- discussed afternoon convection, I wouldn't be surprised if timing was skewed by an hour or two. Once again it'll be important for anyone with outdoor plans to reevaluate their plans and identify a sturdy structure just in case a strong to severe storm rolls through. By morning, the complex should have exited the forecast area, followed by height rises which will help clear the skies out by afternoon. Daytime high are expected in the upper 70s to low 80s. With flow from the NW, some downslope areas in the south and along the Bay could see highs climb a little higher into the mid-80s. The big story tomorrow will be the wind. Strong low level winds moving over the region will mix down to the surface. By afternoon when the better mixing is anticipated, 30-35 mph gusts will be possible over much of the west. Some places in the Keweenaw could see some gusts approaching 40 mph. Given that this is a little abnormal for the time of year, folks should keep outside items secured through tomorrow afternoon. .LONG TERM...(Sunday night through Saturday) Issued at 423 PM EDT SAT JUL 18 2020 Vigorous shortwave trof now over the Canadian Prairies into the western Dakotas/eastern MT will reach Quebec by Mon, but Upper MI will remain under a weakness in the mid-level height field/low amplitude troffing that will linger back across the northern Great Lakes into the midweek period. This low amplitude trof will feature a shortwave that will move across the area late Tue/Wed. Thereafter, medium range models have shown consistency in building heights across the central and eastern U.S. with ridge axis probably building n thru the Mississippi Valley/western Great Lakes. For Upper MI, this pattern evolution will favor temps easing back to around normal to even a little blo normal during the early and mid portion of the coming week under the low amplitude trof. Heat will then begin to build back into Upper MI late week into the weekend as mid-level ridge builds. As for pcpn, best potential of organized, wider coverage pcpn will occur with the shortwave passing late Tue/Wed. Then, attention will turn to the potential of convective complexes riding the edge of the heat dome building across the Plains toward the Great Lakes during the last half of the week. Beginning Sun night, although main shortwave will be heading out of northern Ontario into Quebec, a trailing weak shortwave and its associated cold front will sweep across the area. Some of the shra along the front may survive the trip across Lake Superior into at least nw Upper MI, but with loss of instability by the time the front arrives, potential is quite low. Only schc pops were utilized w and nw. Weakly confluent flow aloft and sfc ridging should ensure a dry day on Mon. However, steep low-level lapse rates and the passage of 850mb thermal trof will likely support a fair amount of diurnal cu, especially over the central U.P. along converging lake breeze boundaries. Expect highs in the 70s with mid/upper 60s lakeside along Lake Superior. Dwpts will be comfortably lower into mostly the low to mid 50s with maybe some upper 40s interior w. Overall, should be a pleasant U.P. summer day. Clouds will begin to increase later Mon night ahead of shortwave shifting out across the Northern Plains. This wave will move across the area later Tue into Wed. Greatest coverage of shra/tsra will occur Tue into Tue evening, followed by some lingering isold to sct shra into Wed. GFS is slower/deeper with wave and would result in more persistent shra on Wed, especially n and e. Not really any support from the UKMET/ECMWF for that idea. CMC is on the deeper side, but remains more progressive. Although ridge will be building into the area late week, there is decent agreement for a shortwave to round it and affect the area. Right now, looks like Fri will have the best chc of shra/tsra with this wave. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 627 PM EDT SAT JUL 18 2020 VFR conditions are expected through the evening before an MCV out ahead of an approaching cold front moves into the region. Current guidance suggests line of strong to severe thunderstorms will move into KIWD around 02z, with additional terminals joining through the evening as the line moves toward the east. Thunderstorms will be capable of producing strong winds and heavy rain capable of quickly reducing visibilities to IFR. Will briefly be some LLWS overnight at KCMX. Model consensus brings strong low level westerly winds to all sites Sunday. Sustained winds of 20kts will be possible by early afternoon. Wind gusts of 25 kts will be possible at all terminals as well. Higher confidence is at KCMX, which could see wind gusts approaching 30-35kts by the end of this TAF period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 347 PM EDT SAT JUL 18 2020 Lingering fog will continue this afternoon and evening across the region and some pockets could be dense. Fog should generally migrate across the lake toward the north given the primary wind direction will be from the south. Another round of strong to severe thunderstorms is expected to roll through the region this evening. During these storms, wind will likely be the biggest hazard. Additionally, heavy rain will result in quick reductions of visibility. This line of thunderstorms is expected to reach the far western by 1-3z and continue pushing east through the night. Current thinking is for storms to clear the Keweenaw Peninsula by 7z and move through the eastern portions of the lake in the early-mid morning. Tomorrow, strong low level winds are anticipated tomorrow afternoon. Westerly wind gusts could reach 20-30 kts and higher platforms could experience higher winds for a period of time in the afternoon. Beyond tomorrow, the next round of thunderstorm potential will be Tuesday into Wednesday. At the moment confidence is not high on how much of a wind threat this will be. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ014. Lake Superior... None. Lake Michigan... None. && SHORT TERM...JP LONG TERM...Rolfson AVIATION...07 MARINE...JP
Hazardous Weather Outlook National Weather Service Marquette MI 507 PM EDT Sat Jul 18 2020 MIZ001>007-009>014-084-085-191200- Keweenaw-Ontonagon-Northern Houghton-Baraga-Marquette-Alger-Luce- Gogebic-Iron-Dickinson-Menominee-Delta-Southern Schoolcraft- Southern Houghton-Northern Schoolcraft- 507 PM EDT Sat Jul 18 2020 /407 PM CDT Sat Jul 18 2020/ This Hazardous Weather Outlook is for portions of western Upper Michigan and central Upper Michigan. .DAY ONE...Tonight Thunderstorms are expected to develop from west to east tonight. Some of the storms could become severe, producing damaging winds and large hail. Frequent lightning and torrential rainfall will accompany some of the storms, leading to the potential of localized flooding from the heavy rainfall. If camping, pay close attention to the latest forecast updates. A high swim risk continues into the evening for the Lake Michigan beaches of Schoolcraft County. See the latest Beach Hazards Statement. .DAYS TWO THROUGH SEVEN...Sunday through Friday A high swim risk will continue for the Lake Michigan beaches of Schoolcraft County Sunday morning. A high swim risk is expected for the Lake Superior beaches of Alger County on Sunday afternoon. West wind gusts could exceed 40 mph over northwest portions of Upper Michigan Sunday afternoon. Thunderstorms are possible Tuesday afternoon and night and also on Friday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any observed hail, wind damage or flooding from thunderstorms to the National Weather Service in Marquette. The public may also submit reports to the National Weather Service via phone, on our website, or through Facebook or Twitter using #906wx. LSZ162-240>251-263>267-191200- Lake Superior west of a line from Saxon Harbor WI to Grand Portage MN beyond 5NM-Saxon Harbor WI to Black River MI- Black River to Ontonagon MI- Ontonagon to Upper Entrance of Portage Canal MI- Upper Entrance of Portage Canal to Eagle River MI- Eagle River to Manitou Island MI- Manitou Island to Point Isabelle MI- Point Isabelle to Lower Entrance of Portage Canal MI- Lower Entrance of Portage Canal To Huron Islands MI Including Keweenaw and Huron Bays-Huron Islands to Marquette MI- Marquette to Munising MI-Munising to Grand Marais MI- Grand Marais to Whitefish Point MI- Lake Superior from Saxon Harbor WI to Upper Entrance to Portage Canal MI 5NM off shore to the US/Canadian border including Isle Royale National Park- Lake Superior from Upper Entrance to Portage Canal to Manitou Island MI 5NM off shore to the US/Canadian Border- Lake Superior West of Line from Manitou Island to Marquette MI Beyond 5NM from shore- Lake Superior East of a line from Manitou Island to Marquette MI and West of a line from Grand Marais MI to the US/Canadian Border Beyond 5NM from shore- Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off shore to the US/Canadian border- 507 PM EDT Sat Jul 18 2020 /407 PM CDT Sat Jul 18 2020/ This Hazardous Weather Outlook is for portions of Eastern Lake Superior...Central Lake Superior and Western Lake Superior. .DAY ONE...Tonight Thunderstorms are expected to develop from west to east tonight. Some of the storms could become severe, producing strong winds and large hail. Frequent lightning and torrential rainfall will accompany some of the storms. .DAYS TWO THROUGH SEVEN...Sunday through Friday Thunderstorms are possible Tuesday afternoon and night and also on Friday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any observed hail or wind damage from thunderstorms to the National Weather Service in Marquette. The public may also submit reports to the National Weather Service via phone, on our website, or through Facebook or Twitter using #906wx. LMZ221-248-250-191200- Green Bay North of line from Cedar River MI to Rock Island Passage-Seul Choix Point to Point Detour MI- 5NM East of a line from Fairport MI to Rock Island Passage- 507 PM EDT Sat Jul 18 2020 This Hazardous Weather Outlook is for portions of Northern Lake Michigan. .DAY ONE...Tonight Thunderstorms are expected to develop tonight. Some of the storms could become severe, producing strong winds and large hail. Frequent lightning and torrential rainfall will accompany some of the storms. .DAYS TWO THROUGH SEVEN...Sunday through Friday Thunderstorms are possible Tuesday afternoon and night and also on Friday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any observed hail or wind damage from thunderstorms to the National Weather Service in Marquette. The public may also submit reports to the National Weather Service via phone, on our website, or through Facebook or Twitter using #906wx. Rolfson
The Duluth radar (KDLH), 178 km away, was scanning. The volume nearest the first event began at 03:48 UTC.
30 thunderstorm wind, 1 hail. Local standard time, as filed.
A power pole was reported down on Putnam Street in Wakefield. The time of the report was estimated from radar.
Law enforcement reported a tree down near the intersection of Airport Road and Lake Road in Ironwood.
Numerous trees were reported down along old Highway US-2 near Gogebic Medical Care Facility. The time of the report was estimated from radar.
Law enforcement reported a tree fell on a vehicle near Gogebic Lodge and the nearby bait and tackle shop. The male occupant in the car was injured. The time of the report was estimated from radar.
Widespread power outages were reported across Ontonagon County by UPPCO, especially from White Pine northeast to Ontonagon.
There was a public report of a barn collapsed onto vehicles along with trees and power lines down in Nisula. The time of the report was estimated from radar.
There were social media photos of power poles snapped near the intersection of Cadeau Road and Alston Road in Alston. Time of the delayed report was estimated from radar.
Social media photos revealed extensive tree damage on a property in Alston, including a few large healthy trees completely uprooted. The time of the delayed report was estimated from radar.
Widespread power outages were reported across Houghton County by UPPCO, especially from Houghton to Calumet.
Numerous power outages were reported across northwest Baraga County by UPPCO.
There was a public report of one-inch diameter hail in Houghton.
There were social media reports of a few spruce trees knocked down in Paulding. The time of the delayed report was estimated from radar.
Law enforcement and social media photos indicated numerous trees, large branches and power lines down blocking roads in the Pelkie area.
There were social media photos of power poles snapped near the intersection of Johnson Road and Bayshore Road near Zeba. Time of the delayed report was estimated from radar.
There was a social media video taken just northeast of Nisula of at least twenty healthy trees snapped off about a quarter of the way from the ground with numerous other trees uprooted. The time of the delayed report was estimated from radar.
Law enforcement reported a roof blown off a house in Pequaming. Numerous softwood trees were also snapped about a third of the way off the ground along 2nd Sand Road. Time of the report was estimated from radar.
Online photos received showed numerous spruce trees snapped just east of Pelkie. Time of the delayed report was estimated from radar.
Social media photos revealed a tree snapped off a quarter of the way off the ground, falling onto power lines on Lehto Road. The delayed report was estimated from radar.
There was a public report of a heavy chair and wood missing from a yard west of Three Lakes. Thunderstorm winds also bent an analog antenna and knocked the power out for two hours. Time of the damage was estimated from radar.
There was a report of several trees snapped or uprooted between Ewen and Bruce Crossing. The time of the delayed report was estimated from radar.
There was a public report from a campground in Big Bay of lots of broken tents and awnings, downed branches and small trees. Most branches were 4 inches in diameter. The largest one was 12 feet long and 12 inches in diameter. Time of the damage was estimated from radar.
There was a report of a pontoon boat pushed over and a dock flung up onshore on Lake Independence. The time of the delayed report was estimated from radar.
Social media photos revealed several trees blown down near the intersection of County Roads KD and KCB just southeast of Big Bay. The time of the delayed report was estimated from radar.
There was a social media photo of a pine tree knocked down across a driveway near the Dead River Basin. The location of the report is approximate and the time is estimated from radar.
There were social media photos of a few tree limbs down in a backyard in Negaunee. The time of the delayed report was estimated from radar.
There were a couple of trees knocked down along County Road 492 between Marquette and Negaunee. The time of the delayed report was estimated from radar.
Several healthy poplar trees were knocked down at Greywalls Golf Course. The time of the delayed report is estimated from radar.
There was a photo received of a tree laying down on a building in Marquette. The time of the delayed report was estimated from radar.
The Delta County Road Commission reported a few minor trees down partially blocking a lane near the intersection of Highway US-2 and Highway US-41 in Rapid River. The time of the delayed report was estimated from radar.
The Delta County Road Commission reported a few minor trees down blocking a lane along Highways US-41/US-2 near Bark River. The time of the delayed report was estimated from radar.
The Delta County Road Commission reported a few minor trees down blocking a lane on County Road 511 in Stonington. The time of the delayed report was estimated from radar.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2020Every state in 2020This day in weather historyWarnings in Michigan, 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: 902254, 902253, 902255, 902256, 902262, 902260, 902282, 902280, 902261, 902263, 902264, 902286, 902259, 902283, 902768, 902258, 902284, 902285, 902265, 902729, 902266, 902737, 902756, 902274, 902290, 902294, 902293, 902291, 902747, 902752, 902750.