During the early morning hours on Sep. 22nd, a strong line of thunderstorms pushed east across Western Lake Superior bringing strong and gusty winds.
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.
During the early morning hours on Sep. 22nd, a strong line of thunderstorms pushed east across Western Lake Superior bringing strong and gusty winds.
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 Sep 22, 7:00 AM EST, 2 hours 43 minutes earlier.
Area Forecast Discussion National Weather Service Marquette MI 800 AM EDT Fri Sep 22 2017 .SHORT TERM...(Today and tonight) Issued at 504 AM EDT FRI SEP 22 2017 Tricky forecast today with convection potential through at least late morning. Hi-res models have been back and forth on when and if a line of showers and thunderstorms tracks across the U.P. If the storms do cross the area this could keep the temperatures a bit lower through at least the first half of the day. Today: Strong moisture transport/moisture convergence on the nose of a LLJ and along a warm front lifting northward through the area will continue to be the focus of showers and thunderstorms this morning. Some of the hi-res models try to develop an MCS over western MN early this morning and them shift it eastward into the west half of the area by mid morning into the early afternoon hours, but it may be tough for the storms to make it too far east into the U.P. with 850mb ridging in place along with diminishing LLJ/convergence and a bit lower MUCAPE over the east half of the U.P. Still worth keeping the mention of at least scattered showers and thunderstorms in the forecast through early afternoon. The moisture transport weakens throughout the day as the LLJ diminishes by mid to late morning and the associated convergence weakens and lifts to the northeast of the area. This should bring an end to the shower and thunderstorm activity across much of the area as a very warm nose of air slides in aloft by early to mid afternoon. In fact, 850 temps are progged to warm to around 25C by early afternoon, which will allow temperatures to warm into at least the mid 80s across much of the area. The exceptions will be over the east half of the U.P. down wind of Lake MI on southerly winds. On top of the hot temperatures today, increasing moisture, with dewpoints in the upper 60s to around 70, will make it feel very uncomfortable. Many locations will likely see heat index values around 90 or in the low 90s by mid to late afternoon. Tonight: A surface low over the Plains is expected to lift northeastward to the MN/Ontario border by 06Z/23. This along with another developing LLJ over the far western U.P./Western Lake Superior and much of norhtern MN will allow for increasing chance of showers and thunderstorms. Again, similar to last night into early Friday morning, the main area of concentraition will mostly likely be over northn MN; however, where the stronger moisture transport/convergence is likely to set up on the nose of the LLJ. Where thunderstorms do form, some of them may become strong to marginally severe as effective shear increases with LLJ development. The rest of the U.P. will remain capped and far enough away from the main system dynamics to force any showers and thunderstorms. .LONG TERM...(Saturday through Thursday) Issued at 455 AM EDT FRI SEP 22 2017 Models suggest that a slowly progressive but amplified pattern will prevail with a prominent mid/upper level ridge over the Great Lakes this weekend giving way to troughing by the middle of next week. Much above normal temps and dewpoints are expected into Monday with record highs and record high mins likely for many locations. Saturday into Sunday, even with a strong subsidence inversion under the 590 DM ridge over the region, forecast mixing to near 850 mb temps around 20C will support readings in the upper 80s over much of the area except downwind of Lake Michigan. Adding to the discomfort will be dewpoints into the mid and upper 60s. Low temps should also remain in the upper 60s with some downslope locations around 70. Capping should be strong to minimize shra/tsra chances, per NAM/ECMWF keeping the pcpn to the north and west. However, the frontal zone over ne MN into wrn Lake Superior by late Saturday may allow some shra/tsra into the far west from IWD to CMX by late Saturday into Saturday evening, per GEM/GFS/GEFS. Mon-Tue, shra/tsra chances should increase by late Monday into Monday night as the mid level trough advances into the plains and the front approaches. The best chance for rain is expected by Tuesday as a stronger shrtwv and associated low lifts ne near Lake Superior and drags the front through the area. Although temps will remain above normal, greater cloud cover will keep max readings mainly in the 70s Monday and the upper 60s to mid 70s Tuesday. Wed-Thu, Cooler/drier air should finally take over with breezy wnw winds behind the front. 850 mb temps dropping to around 1C along with wrap-around moisture will bring potential for some sct light showers. Highs will drop back into upper 50s to mid 60s Wed and the upper 50s by Thursday. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 800 AM EDT FRI SEP 22 2017 KSAW will have continued to see lowered ceilings early in the TAF period; however, this should rapidly improve after sunrise. After that all TAF sites should become VFR for much of the remaining TAF period. The main issues will be a line of ongoing showers and thunderstorms moving into KIWD first then KCMX and KSAW. IFR conditions are possible as this line of thunderstorms pushes through each site. This will be due to both heavy rainfall along with briefly lowered ceilings. LLWS will develop once again overnight tonight as a low-level jet develops. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 504 AM EDT FRI SEP 22 2017 Low to mid 60s dewpoints sliding across Lake Superoior are expected to linger into early next week bringing patchy fog for several days across the lake. Some of the fog could be locally dense at times. Expect winds to generally be below 20 knots through the early part of next week under a weak pressure gradient. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... Dense Fog Advisory until 11 AM EDT this morning for LMZ221. && SHORT TERM...KEC LONG TERM...JLB AVIATION...KEC MARINE...KEC
Hazardous Weather Outlook National Weather Service Marquette MI 550 AM EDT Fri Sep 22 2017 MIZ001>007-009>014-084-085-231000- Keweenaw-Ontonagon-Northern Houghton-Baraga-Marquette-Alger-Luce- Gogebic-Iron-Dickinson-Menominee-Delta-Southern Schoolcraft- Southern Houghton-Northern Schoolcraft- 550 AM EDT Fri Sep 22 2017 /450 AM CDT Fri Sep 22 2017/ This Hazardous Weather Outlook is for portions of western Upper Michigan and central Upper Michigan. .DAY ONE...Today and Tonight Thunderstorms are possible today over the west half of Upper Michigan. An isolated severe thunderstorm, producing large hail, is possible over western Upper Michigan. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Thunderstorms are possible periodically over western Upper Michigan late Saturday through Sunday night. Any of the thunderstorms Saturday through Sunday night could produce very heavy rainfall. .SPOTTER INFORMATION STATEMENT... The need for weather spotter reports is not anticipated at this time. LSZ162-240>251-263>267-231000- 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- 550 AM EDT Fri Sep 22 2017 /450 AM CDT Fri Sep 22 2017/ This Hazardous Weather Outlook is for portions of Eastern Lake Superior...Central Lake Superior and Western Lake Superior. .DAY ONE...Today and Tonight Thunderstorms are possible today over western Lake Superior. The strongest storms may produce some large hail. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Thunderstorms are possible periodically over mainly western Lake Superior Saturday through Sunday night. .SPOTTER INFORMATION STATEMENT... The need for weather spotter reports is not anticipated at this time. LMZ221-248-250-231000- 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- 550 AM EDT Fri Sep 22 2017 This Hazardous Weather Outlook is for portions of Northern Lake Michigan. .DAY ONE...Today and Tonight Dense fog is expected this morning. See the latest Marine Weather Message for further details. .DAYS TWO THROUGH SEVEN...Saturday through Thursday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... The need for weather spotter reports is not anticipated at this time. JLB
Special Weather Statement
National Weather Service Marquette MI
1030 AM EDT FRI SEP 22 2017
MIZ001-221530-
Keweenaw MI-
1030 AM EDT FRI SEP 22 2017
...SIGNIFICANT WEATHER ADVISORY FOR ISLE ROYALE UNTIL 1130 AM EDT...
At 1030 AM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 6 miles northeast of Grand Portage to 23 miles
southwest of Windigo. Movement was northeast at 50 mph.
Winds in excess of 40 mph will be possible with these storms.
Locations impacted include...
Mott Island Park Headquarters, Siskiwit Lake, Windigo, Rock Harbor
and Mount Desor.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Persons in campgrounds should consider seeking sturdy shelter until
these storms pass.
&&
LAT...LON 4829 8841 4818 8832 4813 8833 4800 8851
4780 8913 4778 8919 4779 8923 4794 8930
TIME...MOT...LOC 1430Z 240DEG 53KT 4805 8962 4761 8937
KluberThe Marquette radar (KMQT), 187 km away, was scanning. The volume nearest the first event began at 14:41 UTC.
9 marine thunderstorm wind. Local standard time, as filed.
Measured wind gust at Rock of Ages, ROMA4.
Wind gust recorded at the Ontonagon Lighthouse.
Measured wind gust at Freda.
Nickel to quarter size hail was also reported nearby in Keweenaw Bay and 6 miles SW of Gay, Michigan. The recorded wind gust was measured at the buoy, GTRMU.
Measured wind gust from the Charles M. Beeghly, WL3108.
Measured wind gust occurred at Granite Island, GRIM4.
Wind gust measured at Munising ASOS, KP53.
Wind gust measured at Munising ASOS, KP53.
Measured wind gust at Grand Marais, GRMM4.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Lake Superior in 2017Every state in 2017This day in weather history
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 2026-10-01. Each event’s entry at NCEI: 716494, 716491, 716493, 716499, 716496, 716500, 716505, 716506, 716507.