Overview
Two brief tornadoes developed within a low-topped supercell on the southeast side of South Bend Sunday evening.
Tornadoes:
South Bend Tornado #1
Track Map Downloadable KMZ File |
South Bend Tornado 2
Track Map Downloadable KMZ File |
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
Header
Damage at the Growing Kids Learning Center in South Bend (NWS Storm Survey) |
Damage at the Growing Kids Learning Center in South Bend (WSBT-Kristin Bien) |
Damage at the Irish Hills Apartments in South Bend (WNDU-Ibrahim Samra) |
Damage in Marshall County, IN (Jack Garner) |
Damage along Ireland Rd near Ironwood in South Bend (South Bend Tribune- Robert Franklin) |
Damage along Ireland Rd near Ironwood in South Bend (South Bend Tribune- Robert Franklin) |
Damage along Ireland Rd near Ironwood in South Bend (South Bend Tribune- Robert Franklin) |
Damage in Marshall County, IN (Jack Garner) |
Radar
Radar from 735 pm EDT to 9:06 pm EDT. | Base reflectivity and velocity data at the time of tornado touchdown, 8:38 PM EDT | Radar image at 8:41 PM EDT. A well-defined velocity couplet is visible. | Radar image at 8:43 PM EDT. The tornado lifted a few minutes later at 8:48 PM EDT. |
Environment
Shortly after 23Z (7 PM EDT) a broken area of non-convective (no lightning) low-topped showers developed over Starke, LaPorte, St Josephe and Marshall counties. This was in an area of weak low level shear (20kts) and < 1K j/kg surface-based CAPE. A narrow theta-e ridge advanced slowly east out of northeast IL late Sunday afternoon/evening and was evident in surface observations as a distinct moisture discontinuity. Otherwise, general warm advection (weak) overspread the area in the afternoon ahead of a strong southwest disturbance over western KS.
Figure 1: 5pm Surface analysis via the WPC indicating a warm front across the region and a low pressure system to our northwest. | Figure 2: WPC surface analysis at 8pm indicated a stalled warm front still draped across the region with a low pressure system to our northwest. This front likely helped to initiate the low level turning that forced the tornadic cell. | Figure 3: WPC surface analysis at 10pm indicated the warm front has moved north away from the region. |
Near-storm environment summary.
Figure 4: Storm Relative Helicity at 8pm EDT indicating rotation in the area of the storm with the tornado | Figure 5: Effective bulk shear at 8pm EDT indicating rotation in the area of the storm with the tornado | Figure 6: Note the counterclockwise turning winds in Northwest Indiana at 8pm in the area of the storm with the tornado. This is a favorable environment for a tornado especially with surface vorticity and convergence in the neighborhood. |
Additional environmental data.
Figure 7: Tornadic environments often need moisture and strong low level winds. A strong low level jet and a very moist atmospheric column is evident in this photo at the spot of the tornado. | Figure 8: Low LCLs are important for cells to produce tornadoes. This photo indicates that the LCLs were right around 1000m or in the upper limits for LCLs to form tornadoes. | Figure 9: Instability is another important ingredient in the formation of severe thunderstorms. Here, SBCAPE has risen to over 1000 J/kg in the area of the tornado. |
Figure 10: 5pm Equivalent potential temperature indicating areas of warmth and moisture showing a drastic change across the area from little warmth/moisture to more warmth/moisture. | Figure 11: 8pm Equivalent potential temperature indicating areas of warmth and moisture showing more warmth and moisture has moved into the area. |
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