August 6, 2024 Severe Thunderstorms

Tornadoes:

Tornado -Howardsville to Three Rivers St. Joseph County, MI Date August 6, 2024 Time (Local) 8:19 AM - 8:33 AM EDT EF Rating EF2 Est. Peak Winds 115 mph Path Length 8.46 miles Max Width 700 yards Injuries/Deaths 0/0 Summary: A tornado touched down Tuesday morning at the county line border, just north of Lewis Lake. The tornado did significant tree damage and snapped power poles along the entirety of Berry Ln. The tornado moved southeast towards Day Rd where it reached maximum width of approximately 700 yards. Here, a well anchored manufactured home was slid approximately 5 feet off its foundation, along with significant tree damage. Near the intersection of Bent Rd. and Floating Bridge Rd. the tornado completely destroyed a barn. Farther east on Floating Bridge Rd., the tornado removed a two-story barn roof completely off and moved it about 30 feet away. The tornado reached  maximum intensity of EF-2 along Floating Bridge Rd. Another barn roof received major roof damage, the residence's roof was partially removed, and significant tree damage was also observed. The tornado continued southeast crossing Mount Zion Rd with major tree damage and center pivots being overturned.  Near Pulver and Null Rd., 8 power poles were snapped, an irrigation pivot was twisted, and minor/moderate roof damage was observed to three homes. Farther southeast along Cowling Rd, a well constructed shed was moved 20-30ft away from its foundation and part of the structure was thrown into the Rocky River. Finally, the tornado caused minor roof damage to a warehouse along N. Main St in Three Rivers. While a portion of the roof was thrown into the trees across the street, it is believed this is where the tornado terminated. Track Map

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Photos & Video

Extensive tree damage southeast of Howardsville, MI in St. Joseph County MI. (Chris Burrows)	Trees down and roofing removed near Marcellus, MI (Cicily Porter WSBT )	Structure damage in Marcellus, MI (Cicily Porter WSB)	Tree damage north of Lewis Lake in Cass County, MI. (Oliver Moster ABC57)

Tree damage north of Lewis Lake in Cass County, MI. (Oliver Moster ABC57)	The upper story of a barn was lofted by a tornado that moved through St. Joseph County MI. (NWS Survey)	An entire outbuilding was destroyed by a tornado that moved through St. Joseph County MI. (NWS Survey)	Significant tree damage was observed along the tornado track that moved through St. Joseph County MI. (NWS Survey)

Radar

Gif of the storm near Bryan OH that elicited a severe thunderstorm warning. Notice how 60 dBZ reached the -20C line (red) and then fell to the ground. Often this scenario produces damaging winds and heavy rain, and depending on the environment, can produce large hail.	Radar image the tornado-producing supercell. Upper left panel is reflectivity, upper right panel is storm relative velocity, bottom left is spectrum width and NROT is on the bottom left.

Storm Reports

Preliminary Local Storm Report...Summary
National Weather Service Northern Indiana
906 PM EDT Tue Aug 6 2024

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

1016 AM     Tstm Wnd Dmg     2 SSW Pioneer           41.65N 84.57W
08/06/2024                   Williams           OH   Trained Spotter  

            Trees down in the area. 

1017 AM     Tstm Wnd Dmg     3 ENE Lake Seneca       41.70N 84.61W
08/06/2024                   Williams           OH   Trained Spotter  

            Tree damage near intersection of County Road 
            11 and Road S. 

0342 PM     Tstm Wnd Dmg     1 N West Leipsic        41.12N 84.00W
08/06/2024                   Putnam             OH   Emergency Mngr   

            Several trees and power lines downed across 
            eastern portions of Putnam County. 10-13 
            power lines down on County Road 7 north of 
            US 224. Trees blocking road on County Road 
            5. 

0250 PM     Tstm Wnd Dmg     3 NW Malinta            41.36N 84.08W
08/06/2024                   Henry              OH   Emergency Mngr   

            Large tree limbs down at County Roads 11C 
            and N. Time estimated from Radar. 

0231 PM     Tstm Wnd Dmg     1 NW Okolona            41.36N 84.23W
08/06/2024                   Defiance           OH   Emergency Mngr   

            A 20 foot tree was down in Okolona. Time 
            estimated from radar. 

0253 PM     Tstm Wnd Gst     3 NW Brunersburg        41.33N 84.43W
08/06/2024  M58 MPH          Defiance           OH   ASOS             

            ASOS station KDFI Defiance. 

0320 PM     Tstm Wnd Dmg     2 S Ayersville          41.21N 84.29W
08/06/2024                   Defiance           OH   Public           

            Power lines downed. 

0820 AM     Tstm Wnd Dmg     2 W Howardsville        42.03N 85.76W
08/06/2024                   St. Joseph         MI   Trained Spotter  

            Large tree limbs down near Highway 216 and 
            Lewis Lake Drive. Time estimated from radar. 

0829 AM     Tstm Wnd Dmg     3 SW Moore Park         41.98N 85.66W
08/06/2024                   St. Joseph         MI   Emergency Mngr   

            Reports of trees and power lines down in the 
            area of Pulver Rd and Null Road. Time 
            estimated from radar. 

0832 AM     Tstm Wnd Dmg     1 N Three Rivers        41.96N 85.64W
08/06/2024                   St. Joseph         MI   Broadcast Media  

            Several large tree limbs down and power pole 
            damage near Main Street and Barnard Avenue. 

1016 AM     Tstm Wnd Dmg     5 SSW Frontier          41.71N 84.63W
08/06/2024                   Hillsdale          MI   Trained Spotter  

            Large tree down near Territorial Road and 
            Hillsdale Road. Time estimated from radar. 

0941 AM     Funnel Cloud     Kinderhook              41.80N 85.01W
08/06/2024                   Branch             MI   Trained Spotter  

            Report of a funnel cloud near the 
            intersection of S Angola Rd and E Copeland 
            Rd. 

Environment

A cold front was moving slowly east-southeast through the day. This the primary forcing mechanism for severe thunderstorms. 

Figure 1: 8am EDT Surface Analysis. The stationary front extending into southwest Michigan added additional vorticity to severe thunderstorms there.	Figure 2: 11am EDT Surface Analysis. The strongest thunderstorms moves along the warm front, analyzed here east of the low pressure center.	Figure 3: 2pm EDT Surface Analysis. Amid a hot and humid environment, this front continued to produce severe thunderstorms, this time in northwest Ohio.

Near-storm environment summary.

Figure 4: Effective shear at 8am showing how much shear was accessible to storms. We look for 30 kts of effective shear as a starting point usually, but this was more than 2x that in the area of the storm.	Figure 5: Effective helicity at 8am showing how much turning was accessible to storms. We look for around 200 m2/s2 usually.	Figure 6: LCLs indicate how saturated the lowest portion of the column of air was that the storm formed in.

Additional environmental data.

Figure 7: Given that this occurred in the morning, instability was the limiting factor for this storm. Also note the blue shading indicating mixed layer CIN which often inhibits the growth of thunderstorms. This storm was able to surpass these limiting factors and become severe/tornadic.	Figure 8: Effective Significant Tornado Parameter achieved 1, which is what we normally look for when identifying tornado-capable storms.	Figure 9: Equivalent Potential temperature can be effectively used as a measure of both temperature and moisture. It is a good indicator of boundaries, which can form as a result of a gradient of temperature and/or moisture. Notice how the storm traveled right along the gradient of this parameter.