A very moist and unstable airmass accompanying a stalled stationary boundary resulted in multiple rounds of thunderstorms beginning during the early morning hours of August 28, 2020 and continuing into the evening hours. During the morning hours, several of these thunderstorms repeatedly trained over the same areas, resulting in 2-4+ inches of rain in just a few hour's time and numerous reports…
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 very moist and unstable airmass accompanying a stalled stationary boundary resulted in multiple rounds of thunderstorms beginning during the early morning hours of August 28, 2020 and continuing into the evening hours. During the morning hours, several of these thunderstorms repeatedly trained over the same areas, resulting in 2-4+ inches of rain in just a few hour's time and numerous reports of flooding especially in the greater Detroit metro region. As daytime instability increased during the afternoon hours, widely scattered severe thunderstorms developed producing large hail and isolated damaging winds. The stationary boundary was finally ushered east of the region during the overnight hours of August 28 into 29, 2020 as a vigorous cold front and accompanying line of strong thunderstorms moved across the region bringing an end to the much needed, but in most areas, deluge of rainfall experienced across most of southeast Michigan.
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 Aug 28, 3:05 AM EST, 2 hours 15 minutes earlier.
Area Forecast Discussion National Weather Service Detroit/Pontiac MI 405 AM EDT Fri Aug 28 2020 .DISCUSSION... Ongoing convection will extend into the mid-morning hours today as shortwave energy ripples through Lower Michigan which is currently laden with high PWATs (+2.00 inches) and sufficient elevated instability. Ample shear (EBWD near 35 knots) will enhance the longevity of any stronger storms that develop. While MLLRs in the 5- 6 C/km range will limit the morning hail threat, 2 km AGL CAPE around 500 J/kg (tall/skinny profiles) will allow for a few stronger updrafts, but the inversion at 900 mb will buffer downdraft winds. Somewhat better dynamics arrive later today as the 850-700 mb layer jet core crosses The Straits and spills slightly further south. Not expecting an overly pronounced mid-level wave as flow looks to be somewhat zonal aloft, but there will still be sufficient synoptic ascent paired with surface convergence along a quasi-stationary boundary drifting toward I-96. Dewpoints climb even further this afternoon into the mid 70s via favorable moisture convergence sourced from a developing upstream MCS and Tropical Depression Laura. Hodographs become more linear as the day progresses limiting the primary storm threat to water loaded cores and wet microbursts resulting in isolated damaging wind gusts. Some marginally severe hail with stronger afternoon updrafts will also be possible as MLCAPE values in excess of 1200 J/kg provide ample instability for strong vertical accelerations. While convective mode this morning and afternoon remains more multicellular, linear convection arrives overnight with a cold FROPA expected to take place between 02Z and 10Z. Still seeing some timing differences within the solution space and a transition to elevated convection along the front after dark. Given available shear support, could get some strong gusts along any organized segments with brief heavy rainfall. Also brought daytimes highs down and overnight lows up a bit given a cloudier forecast. Closed upper low will be just north of Lake Superior Saturday morning producing windier conditions with 25-30 mph gusts mixing down midday. Significant column drying behind the front will quickly clear skies out and drop surface dewpoints into the 50s. Thicknesses trend downward as CAA taps into cooler continental Canadian air. Temperatures will stay below 80F with overnight lows retreating below climatological norms (mid 50s). Dry weather and static stability will extend into Monday as the ridge amplifies over North- Central CONUS pushing eastward from an accelerating Pacific wave. Associated PV anomaly will pivot north of the Dakotas before ever reaching the Great Lakes, but higher ThetaE air, glancing shortwave energy, and marginal height falls may align keeping low chance PoPs into the middle of next week. && .MARINE... Active stretch of weather heading into the weekend as a series of fronts pass over the region. A stationary front over Lake Erie will transition to a warm front today as a low pressure system begins working across the central Great Lakes. There will be several rounds of thunderstorms possible first as the warm front lifts northward this afternoon and evening and additional chances later tonight as a cold front then sweeps across the region. Outside of thunderstorm activity, mild air and a light gradient will keep winds generally under 20 knots with minor wave activity. This changes on Saturday behind the cold front as northwest flow ushers in a colder and more unstable airmass through the remainder of the weekend. && .HYDROLOGY... Initial series of showers and thunderstorms this morning will produce isolated areas of 0.50-0.75 inches of rainfall west of I-75 and north of I-94 given the potential for training storms in an efficient moisture-rich environment. Several additional rounds of activity are expected this afternoon/evening and again overnight as upper level energy and Gulf moisture transport support convective processes. Given the multiple opportunities for heavy rainfall rates, 1.50-2.50 inch totals are possible by the time activity ceases Saturday morning. Current WPC Slight Risk for excessive rainfall during this time seems appropriate, especially if the stationary front becomes more active. Minor flooding concerns apply to low-lying and poor drainage urban areas with brief rises on small streams. Dry weather returns this weekend helping alleviate the anticipated influx of water. && .PREV DISCUSSION... Issued at 647 PM EDT Thu Aug 27 2020 AVIATION... Subtle subsidence in the wake of earlier convection and some mixing out of sfc moisture has resulted in an environment over Se Mi which is temporarily hostile to convective development. Low level SW flow across nrn Indiana and cntl/ern Wisconsin is allowing for upscale convective growth attm. While the focus for more organized convective development overnight will remain over Wisconsin, low level moisture and higher instability is expected advect back into Se Mi from the west, focusing along a stalled out front. So there is the expectation for some showers and thunderstorms to expand into Se Mi from the west during the overnight. The remnant front will develop into a warm front by Fri morning as increased sw flow to the west drives warmer and more moist air into Se Mi. The latest RAP and LAMP guidance suggests this will result in some low stratus development over the area Fri morning; MVFR with some IFR certainly possible. For DTW...Regional radar indicates some convective initiation to the northeast of metro this evening off a cold front. The better chances for deep convection off this looks to remain across srn Ontario. Chances for thunderstorms will increase markedly during the overnight. Timing of the better TSRA potential at metro carries a good deal of uncertainty. There does however seem to be at least a moderate to high potential for TSRA to be impacting much of the airspace late tonight through daybreak Friday. DTW THRESHOLD PROBABILITIES... * Moderate in thunderstorms overnight through Friday evening. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && DISCUSSION...KK MARINE.......DRK HYDROLOGY....KK AVIATION.....SC You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Hazardous Weather Outlook National Weather Service Detroit/Pontiac MI 434 AM EDT Fri Aug 28 2020 MIZ047>049-053>055-060>063-068>070-075-076-082-083-290830- Midland-Bay-Huron-Saginaw-Tuscola-Sanilac-Shiawassee-Genesee-Lapeer- St. Clair-Livingston-Oakland-Macomb-Washtenaw-Wayne-Lenawee-Monroe- 434 AM EDT Fri Aug 28 2020 This hazardous weather outlook is for portions of southeast Michigan. .DAY ONE...Today and Tonight Periods of thunderstorms are expected today and tonight. The primary threat will be wind gusts of 60 mph or greater and torrential rainfall which could lead to possible flooding. Storm motion this afternoon will be from the northwest at 35 mph then from the west at 45 mph overnight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed later today or tonight. LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-290830- 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- 434 AM EDT Fri Aug 28 2020 This hazardous weather outlook is for portions of Lake Erie, Lake Huron and Lake St Clair. .DAY ONE...Today and Tonight Periods of thunderstorms are expected today and tonight. The primary threat will be wind gusts of 60 mph or greater and torrential rainfall which could lead to possible flooding. Storm motion this afternoon will be from the northwest at 30 knots then from the west at 40 knots overnight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Strong winds from a low pressure system crossing through The Straits may lead to Small Craft Advisory wind and wave conditions on Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed later today or tonight. You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit. KK
The Detroit radar (KDTX), 42 km away, was scanning. The volume nearest the first event began at 10:18 UTC.
6 thunderstorm wind, 4 hail, 3 flash flood, 3 flood. Local standard time, as filed.
Closed roads from flooding reported in Rochester and Southfield.
M-59 closed at Utica due to flooding, as well as Mound and Thirteen mile roads in Warren.
M-10 and I-94 were closed due to flooding in Detroit, as well as I-96 between Inkster and Beech Daly in Livonia.
Flooding from the heavy morning rain slowly receded.
Flooding from the heavy morning rain slowly receded.
Flooding from the heavy morning rain slowly receded.
A 10 inch diameter tree branch was reported down on the road.
A tree was snapped from the wind.
Trees were reported down.
Trees were reported down.
Trees were reported down.
Trees were reported down.
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, 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: 914214, 914215, 914271, 914274, 914275, 914276, 914956, 914957, 914951, 914952, 914953, 914954, 914958, 914959, 914960, 914961.