A thunderstorm moving through Saginaw Bay produced a 55 knot wind gust.
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 DTX wrote it up.
A thunderstorm moving through Saginaw Bay produced a 55 knot wind gust.
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 Detroit, MI wrote its last area forecast discussion before the first event at Jul 27, 2:57 AM EST, 1 hour 23 minutes earlier.
Area Forecast Discussion National Weather Service Detroit/Pontiac MI 357 AM EDT Tue Jul 27 2021 .DISCUSSION... Complicated convective evolution is ongoing across the northern Great Lakes early this morning. The leading MCS has surface base origins from yesterday's upstream peak heating cycle and is in decay mode leading up to sunrise. This weakening trend continues through the morning in between some additional flare-ups as the low level moisture/instability axis spreads eastward ahead of the cold front. Moisture transport is much better to the west in northern WI where the advective component of the low level jet is stronger in support of elevated convection into the west flank of the meso high. The future of these storms is somewhat in question as the low level flow veers westerly into northern Lower MI and Lake Huron. Veered flow reduces moisture transport, however the moisture/instability axis ahead of the front may help slow the decay of this cluster and/or result in some new development along and north of the outflow boundary approaching the Saginaw valley during the morning. A loosely organized MCV remnant from the early morning convective complex combines with passage of the low amplitude upper wave from northern Ontario into Quebec to give the front an additional southward nudge during the morning. This reinforces the hybrid front/outflow position into the Tri Cities and northern Thumb this afternoon. A potential scenario has the ongoing storms in WI holding on in entry level MCS organization while tracking east and becoming surface based along the front/outflow. The boundary could also support its own scattered storm development independently of any upstream influence during mid to late afternoon peak heating. The marginal risk of severe intensity covers the damaging wind potential from any organized convection upstream and also discrete development taking advantage of a respectable wind profile offering about 40 kts of 0-6 km bulk shear in a straight line hodograph. MLCAPE reaching the 1000-1500 J/kg range would be adequate if it can materialize under at least some convective debris clouds from upstream. Given all of these moving parts, chance POPs are maintained for now with targeted updates planned late in the morning as conditions are monitored. After any lingering storms early this evening, trailing NW flow aloft brings a low amplitude short wave ridge into the region. This results in weak but broad subsidence and surface pressure rise over the Great Lakes tonight which helps push the front south of the Ohio border. There is reasonable model agreement given the diffuse nature of the boundary in the pressure pattern. What it lacks in terms of pressure/wind reflection it makes up for in moisture parameters. A notable surface Td gradient is shown north of the front over the Great Lakes while the low to mid level theta-e ridge maintains integrity through the day Wednesday. Surface high pressure reaches into the region from Quebec during the day ensuring dry weather and less humid conditions into Wednesday evening. While this is occurring, the next low pressure system organizes in central Canada associated with a deeper upper level trough. The surface low connects with the front stalled from the Ohio valley back into the northern Plains along which it tracks Wednesday night. Strong low level jet forced moisture transport is expected to launch a convective complex that grows upscale and quickly progresses along the front in a wind field of 50+ knots of 0-6km bulk shear. Early indications are that downstream MLCAPE reaching toward 2000 J/kg will provide a favorable corridor for MCS maintenance into Lower MI after midnight into Thursday morning in support of the SPC slight risk severe storm outlook and the WPC marginal risk for excessive rainfall. The associated cold front follows close behind to carry in dry, cooler, and less humid air to finish the week. && .MARINE... Ongoing passage of a cold front to bring numerous showers and some thunderstorms across Lake Huron through the morning. This line of activity will continue to move south across the Saginaw Bay and central Lake Huron through the mid-morning hours. A subtle wind direction from the north will occur after the passage of the front. Activity will likely dwindle before reaching Lake St. Clair and Lake Erie as the frontal boundary stalls. A chance for showers and thunderstorms will then be possible around central Michigan, including portions of Saginaw Bay, southern Lake Huron, and Lake St. Clair, depending on where the boundary stalls. A weak area of high pressure will settle in behind the cold front which will maintain light winds through the midweek period. Passage of a warm front and area of low pressure will then move in early Thursday morning, which will bring a new chance to see showers and thunderstorms. && .PREV DISCUSSION... Issued at 1159 PM EDT Mon Jul 26 2021 AVIATION... Remnants of an MCS now over the UP/northern WI will dissipate as it moves into the area late tonight/early Tuesday morning with shower activity most likely in KMBS and perhaps KFNT/KPTK. Additional scattered convection will be possible in the afternoon as boundary from this overnight activity acts as low level focus. Will include prob30 for shras KPTK north, but may very well end up with a bit better tsra coverage than that (although that seems more likely over towards the Thumb). DTW THRESHOLD PROBABILITIES... * None. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && DISCUSSION...BT MARINE.......AM AVIATION.....DG You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Hazardous Weather Outlook National Weather Service Detroit/Pontiac MI 437 AM EDT Tue Jul 27 2021 MIZ047>049-053>055-060>063-068>070-075-076-082-083-280845- Midland-Bay-Huron-Saginaw-Tuscola-Sanilac-Shiawassee-Genesee-Lapeer- St. Clair-Livingston-Oakland-Macomb-Washtenaw-Wayne-Lenawee-Monroe- 437 AM EDT Tue Jul 27 2021 This hazardous weather outlook is for southeast Michigan. .DAY ONE...Today and Tonight There is a chance of thunderstorms today and this evening with a marginal risk of severe intensity mainly during the afternoon. Scattered thunderstorms this morning produce locally heavy rainfall before the pattern transitions to stronger storms this afternoon. The strongest storms then will be capable of damaging wind gusts reaching near 60 mph and hail around 1 inch while moving west to east around 30 mph. .DAYS TWO THROUGH SEVEN...Wednesday through Monday There is a chance of thunderstorms late Wednesday night into Thursday morning and a slight risk of severe intensity. An organized complex of thunderstorms is likely to move in from Wisconsin and Illinois and through southern Lower Michigan after midnight. Damaging wind gusts in excess of 60 mph will be possible into Thursday morning. .SPOTTER INFORMATION STATEMENT... Spotter activation is not currently planned for today or tonight. LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-280845- Lake St Clair- Michigan Waters of Lake Erie from Detroit River to North Cape MI- Lake Huron from 5NM east of Mackinac Bridge to Presque Isle Lt beyond 5 NM off shore- Lake Huron from Presque Isle Light to Sturgeon Point MI beyond 5NM off shore- Lake Huron from Sturgeon Point to Alabaster MI beyond 5NM off shore- Outer Saginaw Bay SW of Alabaster to Port Austin MI to Inner Saginaw Bay-Inner Saginaw Bay SW of Point Au Gres to Bay Port MI- Port Austin to Harbor Beach MI-Harbor Beach to Port Sanilac MI- Port Sanilac to Port Huron MI- Lake Huron from Port Austin to Harbor Beach beyond 5NM Off Shore- Lake Huron from Harbor Beach to Port Sanilac beyond 5NM Off Shore- Lake Huron from Port Sanilac to Port Huron beyond 5NM Off Shore- 437 AM EDT Tue Jul 27 2021 This hazardous weather outlook is for portions of Lake Erie, Lake Huron and Lake St Clair. .DAY ONE...Today and Tonight Numerous thunderstorms move across northern Lake Huron during the morning which are capable of 35 knot wind gusts and heavy rainfall. The chance of thunderstorms migrates southward during the day with a marginal risk of severe intensity. The strongest storms will be capable of damaging wind gusts reaching near 50 knots and hail around 1 inch while moving west to east around 25 knots. .DAYS TWO THROUGH SEVEN...Wednesday through Monday There is a chance of thunderstorms late Wednesday night into Thursday morning and a slight risk of severe intensity mainly toward Lake St Clair and western Lake Erie. An organized complex of thunderstorms is likely to move in from Wisconsin and Illinois and through southern Lower Michigan after midnight. Damaging wind gusts in excess of 50 knots will be possible into Thursday morning. .SPOTTER INFORMATION STATEMENT... Spotter activation is not currently planned for today or tonight. You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit. BT
The NCL Michigan radar (KAPX), 136 km away, was scanning. The volume nearest the first event began at 09:20 UTC.
1 marine thunderstorm wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Lake Huron in 2021Every state in 2021This 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 2026-09-24. Each event’s entry at NCEI: 975966.