Overview
Several rounds of strong to severe thunderstorms occurred across much of southeast Michigan through the morning and afternoon hours of July 19, 2020. These thunderstorms occurred in a very warm, moist, and unstable airmass ahead of a passing cold front. These thunderstorms produced widespread reports of wind damage across the region, along with numerous rainfall reports well over an inch in several locations. News reports indicated that as much as 100,000 people lost power across southeast Michigan from the severe weather.
Photos
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Belleville Credit: Nick Dewhirst |
Belleville Credit: Nick Dewhirst |
Radar
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Click to Enlarge Radar loop courtesy of Iowa Environmental Mesonet (IEM) |
Storm Reports
Map of severe weather reports.
Severe Weather Local Storm Reports:
PRELIMINARY LOCAL STORM REPORT...SUMMARY NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 615 PM EDT SUN JUL 19 2020 *SEVERAL LOCATIONS ACROSS SOUTHEAST MICHIGAN ALSO RECEIVED RAINFALL TOTALS OVER 1 INCH...INCLUDING AMOUNTS THAT FELL IN AS LITTLE AS A HALF OF AN HOURS TIME. ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 0820 AM MARINE TSTM WIND 8 ESE AU GRES 44.02N 83.54W 07/19/2020 M56.00 MPH LHZ421 MI BUOY 49 KNOTS MEASURED AT GRAVELLY SHOAL LIGHT. 0830 AM MARINE TSTM WIND 1 NW CASEVILLE 43.95N 83.29W 07/19/2020 M45.00 MPH LHZ421 MI MESONET 39 KNOTS MEASURED AT CASEVILLE LIGHT. 0830 AM MARINE TSTM WIND 8 ESE AU GRES 44.02N 83.54W 07/19/2020 M40.00 MPH LHZ421 MI BUOY 35 KNOTS MEASURED AT GRAVELLY SHOAL LIGHT. 0840 AM MARINE TSTM WIND 12 NNW BAY PARK 43.81N 83.72W 07/19/2020 M43.00 MPH LHZ422 MI BUOY 37 KNOTS MEASURED AT SAGINAW BAY LIGHT 1. 0847 AM TSTM WND DMG 3 WNW SANFORD 43.69N 84.43W 07/19/2020 MIDLAND MI 911 CALL CENTER NUMEROUS WIRES DOWN. TIME ESTIMATED BY RADAR. 0851 AM TSTM WND DMG SANFORD 43.68N 84.38W 07/19/2020 MIDLAND MI 911 CALL CENTER NUMEROUS WIRES DOWN. TIME ESTIMATED BY RADAR. 0855 AM TSTM WND DMG 5 W MIDLAND 43.61N 84.33W 07/19/2020 MIDLAND MI 911 CALL CENTER NUMEROUS WIRES DOWN. TIME ESTIMATED BY RADAR. 0901 AM TSTM WND DMG MIDLAND 43.62N 84.23W 07/19/2020 MIDLAND MI 911 CALL CENTER NUMEROUS TREES DOWN THROUGHOUT THE CITY. TIME ESTIMATED BY RADAR. 0907 AM TSTM WND DMG 4 W FREELAND 43.51N 84.19W 07/19/2020 MIDLAND MI 911 CALL CENTER NUMEROUS TREES DOWN. TIME ESTIMATED BY RADAR. 0909 AM TSTM WND DMG BAY CITY 43.59N 83.89W 07/19/2020 BAY MI 911 CALL CENTER NUMEROUS TREES AND WIRES DOWN ACROSS CITY. TIME ESTIMATED BY RADAR. 0910 AM MARINE TSTM WIND 12 NNW BAY PARK 43.81N 83.72W 07/19/2020 M41.00 MPH LHZ422 MI BUOY 36 KNOTS MEASURED AT SAGINAW BAY LIGHT 1. 0927 AM TSTM WND DMG SAGINAW 43.42N 83.95W 07/19/2020 SAGINAW MI 911 CALL CENTER NUMEROUS TREES AND WIRES DOWN THROUGHOUT THE CITY. TIME ESTIMATED BY RADAR. DISPATCH ALSO REPORTED NUMEROUS TREES AND WIRES DOWN THROUGHOUT SAGINAW COUNTY. 0931 AM TSTM WND DMG CARO 43.49N 83.40W 07/19/2020 TUSCOLA MI 911 CALL CENTER TREES DOWN. TIME ESTIMATED BY RADAR. 0940 AM TSTM WND DMG KINGSTON 43.41N 83.19W 07/19/2020 TUSCOLA MI 911 CALL CENTER TREES DOWN. TIME ESTIMATED BY RADAR. 1022 AM TSTM WND DMG DAVISON 43.03N 83.52W 07/19/2020 GENESEE MI 911 CALL CENTER TREES DOWN. TIME ESTIMATED BY RADAR. 1035 AM TSTM WND DMG HADLEY 42.95N 83.40W 07/19/2020 LAPEER MI 911 CALL CENTER NUMEROUS TREES DOWN. TIME ESTIMATED BY RADAR. 1042 AM TSTM WND DMG METAMORA 42.94N 83.29W 07/19/2020 LAPEER MI 911 CALL CENTER NUMEROUS TREES DOWN. TIME ESTIMATED BY RADAR. 1150 AM TSTM WND DMG 5 SSW ROMEO 42.74N 83.04W 07/19/2020 MACOMB MI 911 CALL CENTER TREES DOWN. 1214 PM TSTM WND DMG 4 NNW CANTON 42.37N 83.51W 07/19/2020 WAYNE MI PUBLIC 2 TO 3 INCH DIAMETER TREE LIMBS DOWN WITH ESTIMATED WINDS 50 TO 55 MPH. TIME ESTIMATED BY RADAR. 0153 PM TSTM WND DMG 4 SE YPSILANTI 42.20N 83.57W 07/19/2020 WASHTENAW MI EMERGENCY MNGR WASHTENAW COUNTY EMERGENCY MANAGEMENT DEPT RELAYED A REPORT FROM A SENIOR FIRE OFFICIAL REGARDING SEVERAL LARGE TREES DOWN ON MOBILE HOMES IN THE 6400 BLOCK OF LAKE DRIVE. 0154 PM TSTM WND DMG 5 SSW CANTON 42.24N 83.53W 07/19/2020 WAYNE MI LAW ENFORCEMENT VAN BUREN TWP POLICE REPORTED DAMAGE TO SEVERAL BUILDINGS AT KYIP WILLOW RUN AIRPORT AND AN OVERTURNED SEMI. 0156 PM TSTM WND GST 5 SSW CANTON 42.24N 83.53W 07/19/2020 M62.00 MPH WAYNE MI ASOS 54 KNOT THUNDERSTORM WIND GUST MEASURED AT WILLOW RUN AIRPORT. 0157 PM TSTM WND DMG 5 SE YPSILANTI 42.20N 83.54W 07/19/2020 WASHTENAW MI TRAINED SPOTTER NUMEROUS LARGE BRANCHES, TREES, AND POWER LINES DOWN AT RAWSONVILLE RD AND TEXTILE/HURON RIVER DR. 0202 PM TSTM WND DMG 6 SSE CANTON 42.24N 83.43W 07/19/2020 WAYNE MI TRAINED SPOTTER SEVERAL TREES DOWN ALONG HANNAN ROAD SOUTH OF ECORSE ROAD. 0203 PM TSTM WND DMG 2 SW WESTLAND 42.30N 83.41W 07/19/2020 WAYNE MI PUBLIC NUMEROUS LARGE TREES DOWN AND POWER LINES. MINOR DAMAGE TO NEARBY HOMES DUE FALLEN TREES. 0205 PM TSTM WND DMG 2 S BELLEVILLE 42.17N 83.48W 07/19/2020 WAYNE MI TRAINED SPOTTER LARGE TREE DOWN ON HOME NEAR SUMPTER RD AND PARIS DR. 0226 PM TSTM WND DMG 3 WSW DETROIT 42.36N 83.16W 07/19/2020 WAYNE MI PUBLIC NUMEROUS TREES DOWN. 0240 PM MARINE TSTM WIND 2 S GROSSE POINTE 42.36N 82.91W 07/19/2020 M43.00 MPH LCZ460 MI BUOY 37 KNOTS MEASURED AT PECHE ISLAND LIGHT. 0246 PM MARINE TSTM WIND 4 NNE GROSSE POINTE 42.43N 82.87W 07/19/2020 M59.00 MPH LCZ460 MI MESONET 51 KNOTS MEASURED AT GROSSE POINTE YACHT CLUB. 0250 PM MARINE TSTM WIND 5 ESE MOUNT CLEMENS 42.57N 82.80W 07/19/2020 M50.00 MPH MACOMB MI MESONET 43 KNOTS MEASURED AT LAKE ST. CLAIR METROPARK.
National Storm Reports (for July 19, 2020):
Environment
Before sunrise even occurred the morning of July 19, 2020, it was already an active severe weather day across Michigan. Strong dynamics accompanying a cold front was already producing a line of severe thunderstorms across northern Lower Michigan that quickly dived southeast towards the Tri-Cities region by 8 AM EDT. At 8 AM (Fig. 1), the cold front was draped across western Lake Michigan and would be slow to move eastward heading into the afternoon hours, which would allow for the multiple rounds of thunderstorms experienced throughout the course of the day. Broad-scale height falls associated with a shortwave trough located near Lake Superior (Fig. 2) accompanied by strong upper-level diffluence (Fig. 3) also provided plenty of dynamical lift for thunderstorm development. This dynamic lift proved crucial to sustaining the thunderstorm activity through the morning hours instead of it waning and/or dissipating as it encountered a fair amount of boundary layer capping noted by substantial CIN on the 12 UTC 19 July 2020 KDTX observed sounding (Fig. 4), and also noted on the 13 UTC 19 July 2020 MLCAPE Storm Prediction Center (SPC) mesoanalysis. The first round of thunderstorms featured Severe Thunderstorm Warnings across the Tri-Cities, portions of the Saginaw Valley and Thumb, as well as Special Marine Warnings for Saginaw Bay. Hard hit areas included portions of Bay, Tuscola, Midland, and Saginaw counties where numerous trees and wires down were reported.
As this first wave of activity began to slightly fade, an outflow boundary diving southward from it quickly fired additional thunderstorms along central portions of the region down towards portions of the northern Detroit metro. The outflow boundary played a crucial mesoscale role in providing a local source of lift to break the aforementioned cap that remained in place across the region, which could be visibly seen in the KDTX sounding in the 850-750 hPa layer (Fig. 4). While the outflow boundary was certainly important for round two, the overall environment setup was primed for reinvigorated thunderstorm development. Surface dewpoints were into the low/mid 70s F across the region, with an enhanced region of southwesterly low-level winds transporting additional moist unstable air into the region ahead of the cold front (Fig. 6). Although forecast high temperatures ultimately did not reach the anticipated lower 90s F, the combination of 80s/70s yielded plenty of instability with MLCAPE values above 1500 J/kg. Strong enough winds aloft ahead of the cold front allowed for effective bulk shear values in excess of 35 knots (Fig. 7), which enabled robust updraft organization and the observed strong to severe multicell clusters. The second round of thunderstorms resulted in Severe Thunderstorm Warnings along the I-69 corridor and several reports of wind damage in Genesee and Lapeer counties.
A third and final wave of thunderstorms moved through during the early afternoon hours along the I-94 corridor and into the greater Detroit metro with damaging winds. This final wave developed along a composite theta-e boundary (Fig. 8) and weak differential heating boundary (not shown) from the earlier morning convection. Hardest hit areas in this third and final wave included portions of Ypsilanti, western Wayne county, and Lake St. Clair where wind gusts around 50 knots were observed.
Click on the images below to see them expanded.
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| Figure 1: Weather Prediction Center (WPC) surface map, valid 12 UTC 19 July 2020. | Figure 2: SPC 500 hPa map, valid 12 UTC 19 July 2020. | Figure 3: SPC 300 hPa map, valid 12 UTC 19 July 2020. |
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| Figure 4: KDTX observed sounding, valid 12 UTC 19 July 2020. | Figure 5: SPC MLCAPE mesoanalysis, valid 13 UTC 19 July 2020. | Figure 6: SPC 700 hPa map, valid 12 UTC 19 July 2020. |
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| Figure 7: SPC bulk effective shear mesoanalysis, valid 15 UTC 19 July 2020. | Figure 8: SPC surface theta-e mesoanalysis, valid 18 UTC 19 July 2020. |
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