Severe Thunderstorm Summary 7-20-2019

Photos

Applegate Credit: Amanda Kisielewicz	Croswell Credit: Amanda Kisielewicz	Livonia Credit: Vicki Gallinat
Columbiaville Credit: Julie Springsteen	Watertown Township Credit: Brenden Miller	Deerfield Township Credit: Brenden Miller
Dearborn Credit: Todd McInturf, Detroit News	Lincoln Park Credit: David Kautz	Additional Photos Coming Soon

Radar

Click to Enlarge Radar loop courtesy of Iowa Environmental Mesonet (IEM)

Storm Reports

Map of Local Storm Reports depicting strong to severe wind gusts (blue):

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Severe Weather Local Storm Reports:

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
927 PM EDT SAT JUL 20 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0510 PM     MARINE TSTM WIND 12 NNW BAY PARK         43.81N 83.72W 
07/20/2019  M40.00 MPH       LHZ422             MI   C-MAN STATION   

            MEASURED AT SAGINAW BAY LIGHT 1.

0533 PM     TSTM WND DMG     FRANKENMUTH             43.33N 83.74W 
07/20/2019                   SAGINAW            MI   PUBLIC          

            LARGE TREE LIMBS DOWN. TIME ESTIMATED BY RADAR.

0535 PM     TSTM WND DMG     1 ENE FLINT             43.03N 83.68W 
07/20/2019                   GENESEE            MI   PUBLIC          

            TREE DOWN AT MOTT COLLEGE BASEBALL FIELD.

0536 PM     TSTM WND DMG     1 NE FLINT              43.03N 83.68W 
07/20/2019                   GENESEE            MI   PUBLIC          

            SOCIAL MEDIA PICTURES OF LARGE TREE LIMBS DOWN AT 
            KEARSLEY PARK AND CHAVEZ ROAD.

0540 PM     TSTM WND DMG     OTISVILLE               43.17N 83.52W 
07/20/2019                   GENESEE            MI   PUBLIC          

            LARGE TREE UPROOTED ONTO HOUSE. TIME ESTIMATED VIA RADAR.


0541 PM     TSTM WND DMG     NEW LOTHROP             43.12N 83.97W 
07/20/2019                   SHIAWASSEE         MI   EMERGENCY MNGR  

            TREES DOWN THROUGHOUT TOWN, SIDING TORN OFF BUILDINGS 
            DOWNTOWN, WINDOW BLOWN OUT OF BUILDING.

0545 PM     TSTM WND DMG     3 E FLINT               43.02N 83.63W 
07/20/2019                   GENESEE            MI   BROADCAST MEDIA 

            WINDOW BLOWN IN AT COURTLAND MALL IN BURTON. TIME 
            ESTIMATED VIA RADAR.

0545 PM     TSTM WND DMG     5 WSW DAVISON           43.01N 83.61W 
07/20/2019                   GENESEE            MI   PUBLIC          

            TREES DOWN AT THE INTERSECTION OF LAPEER AND GENESEE 
            ROADS. TIME ESTIMATED BY RADAR.

0551 PM     TSTM WND DMG     2 NNW COLUMBIAVILLE     43.18N 83.42W 
07/20/2019                   LAPEER             MI   TRAINED SPOTTER 

            WEST-FACING CLOSED GARAGE DOOR PARTLY BLOWN IN. SMALL 
            TREES DOWN.

0555 PM     TSTM WND GST     5 ENE COLUMBIAVILLE     43.19N 83.32W 
07/20/2019  M72.00 MPH       LAPEER             MI   TRAINED SPOTTER 

            STATION NUMBER MI-LP-9

0558 PM     TSTM WND DMG     ENE LAPEER              43.05N 83.32W 
07/20/2019                   LAPEER             MI   PUBLIC          

            SOCIAL MEDIA PICTURES OF LARGE TREE LIMBS DOWN AT LAPEER 
            AND GENESSE ROADS.

0558 PM     TSTM WND DMG     LAPEER                  43.05N 83.32W 
07/20/2019                   LAPEER             MI   TRAINED SPOTTER 

            LARGE TREE LIMBS DOWN IN DOWNTOWN LAPEER

0613 PM     TSTM WND DMG     TYRONE TOWNSHIP         42.73N 83.75W 
07/20/2019                   LIVINGSTON         MI   911 CALL CENTER 

            TREES DOWN THROUGHOUT THE AREA.

0623 PM     TSTM WND DMG     1 W APPLEGATE           43.35N 82.66W 
07/20/2019                   SANILAC            MI   TRAINED SPOTTER 

            MANY TREES, INCLUDING LARGE ONES, ARE DOWN AROUND ACROSS 
            APPLEGATE

0624 PM     TSTM WND DMG     1 SSE NORTH BRANCH      43.22N 83.18W 
07/20/2019                   LAPEER             MI   PUBLIC          

            TREES DOWN. TIME ESTIMATED BY RADAR.

0625 PM     TSTM WND DMG     1 NW PONTIAC            42.66N 83.30W 
07/20/2019                   OAKLAND            MI   TRAINED SPOTTER 

            CONSTRUCTION SPEED LIMIT SIGNS SNAPPED AND BLOWN DOWN

0630 PM     TSTM WND DMG     NNW CROSWELL            43.28N 82.62W 
07/20/2019                   SANILAC            MI   PUBLIC          

            PICTURES OF A TREE DOWN ON A HOUSE.

0636 PM     MARINE TSTM WIND 5 E CROSWELL            43.27N 82.52W 
07/20/2019  M54.00 MPH       LHZ443             MI   MESONET         

            MEASURED AT LEXINGTON HARBOR.

0652 PM     TSTM WND DMG     6 W WARREN              42.49N 83.14W 
07/20/2019                   OAKLAND            MI   PUBLIC          

            SOCIAL MEDIA PICTURES OF TREE DOWN AT CURRY RD AND 11 
            MILE.

0655 PM     TSTM WND DMG     N DETROIT               42.38N 83.11W 
07/20/2019                   WAYNE              MI   PUBLIC          

            LARGE DOWNED TREES AND BRANCHES. TIME ESTIMATED BY RADAR.


0702 PM     TSTM WND GST     3 ENE MOUNT CLEMENS     42.61N 82.84W 
07/20/2019  M62.00 MPH       MACOMB             MI   OTHER FEDERAL   

            A THUNDERSTORM WIND GUST, 54 KNOTS, 62 MPH, WAS MEASURED 
            AT SELFRIDGE AIR NATIONAL GUARD BASE.

0703 PM     MARINE TSTM WIND 4 NNE GROSSE POINTE     42.43N 82.87W 
07/20/2019  M53.00 MPH       LCZ460             MI   MESONET         

            MEASURED AT GROSSE POINTE YACHT CLUB.

0704 PM     MARINE TSTM WIND 2 S GROSSE POINTE       42.36N 82.91W 
07/20/2019  M59.00 MPH       LCZ460             MI   MESONET         

            MEASURED AT PECHE ISLAND LIGHT.

0705 PM     TSTM WND DMG     1 S LINCOLN PARK        42.23N 83.18W 
07/20/2019                   WAYNE              MI   PUBLIC          

            SOCIAL MEDIA PICTURES OF LARGE TREE LIMBS DOWN.

0740 PM     MARINE TSTM WIND 9 SSE STONY POINT       41.83N 83.19W 
07/20/2019  M44.00 MPH       LEZ162             MI   C-MAN STATION   

            MEASURED AT TOLEDO LIGHT 2.

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National Storm Reports:

Environment

July 19 and 20th were both very hot days across lower Michigan with high temperatures in the 90s and dew points in the 70s resulting in heat index values well into the 100s for most areas. On the morning and early afternoon of the 20th, a mesoscale convective system traveled across Minnesota/Wisconsin, crossed Lake Michigan, and was able to tap into bountiful instability present over Michigan - CAPE values over 3000 J/kg range (see Figure 6). The complex grew upscale into a line as it crossed the state. Low-level lapse rates of around 7.5 C/km developed during peak afternoon heating and were conducive to strong to severe gusts reaching the surface across much of the area. Wind shear was relatively weak ahead of the line of storms (Figure 7) and the line eventually became unbalanced with the gust front rushing out ahead of the convective updrafts. This gust front still resulted in wind gusts of over 50 mph across the far southeast.

Figure 1: Surface map, valid 12 UTC July 20, 2019.	Figure 2: Surface map, valid 18 UTC July 20, 2019.	Figure 3: Surface map, valid 00 UTC July 21, 2019.
Figure 4: DTX upper air sounding, valid 12 UTC July 20, 2019.	Figure 5: DTX upper air sounding, valid 00 UTC July 21, 2019. Note - this data was recorded shortly after the line of storms moved through.
Figure 6: Loop of surface-based Convective Available Potential Energy (CAPE), valid from 17 UTC July 20, 2019 to 02 UTC July 21, 2019.	Figure 7: Loop of bulk 0-6km wind shear, valid from 20 UTC July 20,2019 to 01 UTC July 21, 2019.