October 12th EF0 Tornadoes and Wind Damage in South Bend (Updated 10/21/16)

Overview

Two EF-0 tornadoes have been confirmed in St. Joseph county Indiana, on the south/southwest side of South Bend from October 12th, 2016. These two tornadoes were embedded within two larger areas of straight line wind damage associated with a microburst. Showers and isolated storms developed across the area during the afternoon of Wednesday October 12th. The storm that produced the microburst and two tornadoes developed immediately ahead of a cold frontal boundary advancing through the area.

A National Weather Service damage survey team from this office was dispatched to investigate storm damage on the south side of South Bend. Two EF-0 tornadoes briefly touched down and details regarding these tornadoes can be found below. The only other severe weather report outside of St. Joseph County was in Elkhart County near Goshen were some tree damage was noted at a residence.

Tornadoes Overview
South bend, IN Tornado
Environment

Tornadoes:

Tornado 1: 3.5 miles SW South Bend, IN
St. Joseph IN County

Date	October 12th, 2016
Time (Local)	6:26-6:27 PM EDT
EF Rating	EF0
Est. Peak Winds	60-65 mph
Path Length	1.26 miles
Max Width	30 yards
Injuries/Deaths	0
Summary: Video evidence and spotter reports indicate a brief EF-0 tornado occurred. The start of the damage path is associated with a video depicting the tornado at the intersection of Route 23 and the bypass. A second observation of the tornado occurred just to the southwest of the intersection of Calvert Street and Renewable Road where a narrow corridor of corn damage was found near the end of the damage path. Damage along the tornado path was classified as EF-0. This tornado was embedded within a larger area of wind damage associated with a microburst. In addition, some straight line wind damage was observed on West Indiana Avenue.

Track Map

Tornado 2: South Bend, IN
St. Joseph IN County

Date	October 12th, 2016
Time (Local)	6:30-6:30 PM EDT
EF Rating	EF0
Est. Peak Winds	60-65 mph
Path Length	0.04 miles
Max Width	40 yards
Injuries/Deaths	0
Summary: The National Weather Service concluded that a second weak EF-0 tornado occurred on the south side of South Bend in the Belmont Avenue vicinity. A small area of tornadic wind damage was found centered in the Belmont Avenue/Sunnyside Avenue vicinity. Some convergence of the tree damage was noted in this area indicative of tornadic winds. Large tree limbs were tilted with several large limbs downed. A large tree limb fell on a shed and lifted it up on its side. This tornado was embedded within a larger area of wind damage associated with microburst. The larger area of straight line wind damage extended from Northside Blvd just north of Beyer Avenue, to Longfellow Road just west of Twyckenham Drive. Tree damage and some damage to shingles at a residence were noted along this larger damage path associated with the microburst.

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

Radar Loop -South Bend

KIWX Radar Loop from 6:06 - 6:52 PM EDT on 10/12/2016

This radar loop contains reflectivity and storm relative velocity. An embedded cell within a larger line began to intensify as it moved Northeast from Crumstown, IN towards South Bend, IN and had a broad circulation as seen by radar storm relative velocity. The storm was just southeast of South Bend, IN around 6:27 pm when the first tornado touched down and one minute later it lifted. The second tornado touched down at 6:30 pm and lifted within one minute. Both tornadoes were associated with a larger microburst event that led to strong winds at the surface. While the velocity couplet is broad at most times, it is likely that for a short period it tightened and hence produced both short lasting tornadoes.

Photos - South Bend


Shed lifted off its foundation	Large tree blown over	Tree branches snapped

Tree fell on top of a pickup truck	Shingles blown off roof	Aerial view of tornado damage

Environment

Showers and isolated storms developed across the area during mid/afternoon hours ahead of lead short wave trough. Storms formed along a line with mainly 25-40 mph winds as they lifted northeast across central/northeast portions of the forecast area. Additional showers/isolated storms developed closer to the approaching cold front early in the evening. One of these storms produced significant wind damage (fairly localized) on south side of South Bend. Narrow pre-frontal moisture axis lifted into the area, with fairly strong low/mid level flow ahead of the front (40-50 knots). Lead short wave appeared to aid in convective development along weak instability axis (200-500 J/kg). Effective shear was on the order of 30 knots, although low level shear was in the 20-25 knot range along narrow pre-frontal axis in the South Bend vicinity.


Figure 1: SPC 22Z 0-1km shear	Figure 2: SPC 22Z Precipitable Water	Figure 3: SPC 22Z Surface Based CAPE

SPC Products

Figure 4: SPC Day 1 Convective Outlook 4:00pm October 12, 2016

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