Destructive Straight Line Winds in LaPorte County

August 23rd, 2006 - Destructive Straight Line Winds in LaPorte County

A National Weather Service assessment team has preliminarily concluded a damage survey of the affected areas. All damage that was observed was consistent with straight line wind damage. There was no evidence of a tornado.

A supercell thunderstorm developed Wednesday afternoon along a lake breeze boundary just south of Milwaukee, Wisconsin. The storm moved southeast and then south over the lake continuing to intensify. As the storm moved onshore in Michigan City, Indiana, a 106 mph wind gust was recorded at the GLERL observation site near the Michigan City lighthouse. The storm produced extensive damage in in Michigan City with numerous trees and power lines down, some on cars and buildings. A train was blown off the tracks in northern Porter County . Golf ball sized hail, which covered the ground in places, was also reported with this storm. Washington Park was especially hard hit as thunderstorm winds swept in off the lake. The largest in water boat show in the Great Lakes was setting up in the park for a 4 day show. Several boats and trailers were destroyed, and the tents and merchandise were significantly damaged and scattered all over.

The storm continued to produce damage as it moved south through Laporte County with extensive damage in Westville and the City of LaPorte. As the storm continued south into Starke County , tennis ball sized hail was reported along U.S. Route 30, a few miles west of Hamlet. The storm continued to produce large hail and strong winds as it dropped south through Pulaski and White counties with damage reported in Winamac, Medaryville, and Monticello .

Click for a list of wind damage and hail reports.

NWUS53 KIWX 241621
LSRIWX

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1220 PM EDT THU AUG 24 2006

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

0705 PM     TSTM WND GST     3 NW MICHIGAN CITY      41.74N  86.92W        
08/23/2006  M106 MPH         LA PORTE           IN   MESONET         

            MEASURED BY MICHIGAN CITY GLERL STATION  


0706 PM     TSTM WND DMG     2 NW MICHIGAN CITY      41.73N  86.90W       
08/23/2006                   LA PORTE           IN   COAST GUARD     

            2 VEHICLES DESTROYED FROM FALLING TREES. NUMEROUS TREES 
            AND POWER LINES DOWN. MOORINGS BROKEN AND BOATS MISSING 
            FROM MICHIGAN CITY HARBOR.  


0708 PM     HAIL             MICHIGAN CITY           41.71N  86.88W                
08/23/2006  M1.00 INCH       LA PORTE           IN   TRAINED SPOTTER 

            HWY 12 AND ROAD 35  


0715 PM     HAIL	     MICHIGAN CITY           41.71N  86.88W
08/23/2006	             LA PORTE           IN   TRAINED SPOTTER

            HAIL COVERED THE GROUND. 75 MPH WIND GUST MEASURED. 
	    FUNNEL CLOUD SPOTTED. NUMEROUS TREES BLOWN DOWN. 


0723 PM     TSTM WND DMG     2 N WESTVILLE           41.57N  86.91W              
08/23/2006                   LA PORTE           IN   TRAINED SPOTTER 

            SEMI BLOWN OVER  


0727 PM     TSTM WND DMG     WESTVILLE               41.54N  86.91W          
08/23/2006                   LA PORTE           IN   AMATEUR RADIO   

            LARGE TREE DOWN ONTO POLICE VEHICLE  


0755 PM     HAIL             5 WNW HAMLET            41.41N  86.67W             
08/23/2006  M1.75 INCH       STARKE             IN   TRAINED SPOTTER 


0805 PM     HAIL             5 WNW HAMLET            41.41N  86.67W           
08/23/2006  M2.50 INCH       STARKE             IN   TRAINED SPOTTER 


0807 PM     HAIL             1 W KNOX                41.29N  86.64W            
08/23/2006  M1.00 INCH       STARKE             IN   TRAINED SPOTTER


0914 PM     TSTM WND DMG     15 NNW WINAMAC          41.25N  86.71W         
08/23/2006                   STARKE             IN   LAW ENFORCEMENT 

            TREES AND POWERLINES DOWN  


0915 PM     TSTM WND DMG     WINAMAC                 41.05N  86.60W     
08/23/2006                   PULASKI            IN   LAW ENFORCEMENT 

            TREES REPORTED DOWN IN SPOTS ACROSS THE COUNTY.  


0925 PM     TSTM WND DMG     MONTICELLO              40.75N  86.76W    
08/23/2006                   WHITE              IN   LAW ENFORCEMENT 

            TREES AND POWER LINES DOWN COUNTYWIDE.  


0945 PM     TSTM WND DMG     WINAMAC                 41.05N  86.60W      
08/23/2006                   PULASKI            IN   LAW ENFORCEMENT 

            REPORTS OF TREES DOWN IN SEVERAL SPOTS ACROSS THE COUNTY 
             


1140 PM     HAIL             BENTON HARBOR           42.12N  86.45W   
08/23/2006  E0.75 INCH       BERRIEN            MI   TRAINED SPOTTER 

            REPORTED DOWNTOWN. RELAYED BY NWS GRR.  


$$

HITCHCOCK

The following is a chart from the Michigan City GLERL observation site. Note the wind gust on the top chart of 92 knots (106 mph). Also of note, the third chart down shows the temperature dropping from the low 80s to the low 60s in one hour as rain cooled air rushed out of the thunderstorm.

The following image is a cross section of the supercell thunderstorm just before it moved onshore in Michigan City. Note the 60-65 dBz returns elevated at up to 35 thousand feet. This represents the hail and heavy rain being held up at high altitudes by the intense storm updraft. Also note the notch of weaker reflectivity (greens and oranges) in the lower parts of the storm below 20 thousand feet. This is what is known as a Bounded Weak Echo Region, or BWER, a classic radar signature of a supercell. The BWER is co-located with the intense thunderstorm updraft. The updraft is so intense that is does not allow much hail or rain to fall down through it, resulting in the notch of weaker radar returns.