A Microburst Confirmed Near Gary, Indiana on Sunday May 20th, 2012

PUBLIC INFORMATION STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE CHICAGO IL
644 PM CDT MON MAY 21 2012 /744 PM EDT MON MAY 21 2012/

...MICROBURST WIND DAMAGE CONFIRMED NEAR GARY INDIANA ON SUNDAY EVENING...

THE NATIONAL WEATHER SERVICE CONDUCTED A STORM SURVEY IN NORTH
CENTRAL LAKE COUNTY INDIANA OF DAMAGE THAT WAS EXPERIENCED FROM A
SEVERE THUNDERSTORM ON SUNDAY EVENING MAY 20TH.

EVENT...MICROBURST.

MAXIMUM WINDS...85 TO 90 MPH.

TOTAL DAMAGE PATH LENGTH...1.25 MILES. HOWEVER...MAXIMUM ESTIMATED
WINDS WERE CONFINED TO A PATH LENGTH OF 0.6 MILES...ENDING JUST
NORTHEAST OF THE STRIP MALL DAMAGE.

LOCATION...4 MILES SOUTH SOUTHWEST OF GARY INDIANA. THE MOST
SIGNIFICANT DAMAGE WAS CONFINED BETWEEN 41ST AVENUE AND 45TH
AVENUE NEAR CLEVELAND STREET (ROUTE 55).

MAXIMUM WIDTH...ESTIMATED TO BE AROUND 1/3 OF MILE.

TIME...ESTIMATED BASED OFF RADAR AND SECURITY CAMERA TIME STAMP TO
BE BETWEEN 7:18 TO 7:21 PM ON SUNDAY MAY 20TH.

DAMAGE SUMMARY...SEVERE DAMAGE OCCURRED TO A PORTION OF A STRIP
MALL LOCATED ON CLEVELAND STREET NEAR 41ST AVENUE. THE BUILDING
BECAME COMPROMISED AS THE FRONT WINDOWS WERE SHATTERED FROM THE
STRONG STRAIGHT LINE WINDS. THIS RESULTED IN THE COLLAPSE OF A
CINDER BLOCK WALL ALONG THE BUILDINGS SOUTH SIDE. ONE TENT IN
THE FRONT PARKING LOT WAS BLOWN ONTO NEARBY POWER LINES AND A
TRAILER WAS MOVED SEVERAL FEET. THE EVENT WAS CAUGHT ON SECURITY
CAMERAS...WHICH HELPED CONFIRM THAT STRONG STRAIGHT LINE WINDS
WERE RESPONSIBLE FOR THE DAMAGE. NO OTHER STRUCTURAL DAMAGE WAS
FOUND AROUND THE AREA...WITH THE EXCEPTION OF DAMAGE DUE TO TREES
AND LIMBS FALLING ON HOMES AND CARS. THERE WAS SOME SIGNIFICANT
TREE DAMAGE ON THE WEST AND SOUTHWEST SIDE OF CLEVELAND STREET.
SEVERAL SOFTWOOD TREES WERE FOUND TO BE UPROOTED AND A FEW SMALLER
TRUNKED HARDWOODS WERE SNAPPED OFF AT THE TRUNK. THERE WERE ALSO
NUMEROUS TREE LIMBS OF VARIOUS SIZES RIPPED OFF OF TREES. IN
ADDITION TO THE SECURITY CAMERA FOOTAGE SUPPORTING A STRAIGHT LINE
WIND EVENT...ALL OF THE UPROOTED OR SNAPPED TREES WERE FOUND TO BE
FACING TOWARDS THE NORTHEAST...IN THE DIRECTION OF STORM MOTION.
THERE WAS NO CONVERGENT...OR ROTATIONAL DAMAGE NOTED.

THE ABOVE DAMAGE WAS CONSISTENT WITH A MAXIMUM EQUIVALENT WIND
SPEED OF A LOW END EF-1 ON THE ENHANCED FUJITA SCALE...WITH THE
MORE SIGNIFICANT TREE DAMAGE AND WINDOW DAMAGE CAUSING THE WALL
COLLAPSE USED TO SUPPORT THE 85 TO 90 MPH ESTIMATE. OUTSIDE OF THE
MOST SIGNIFICANT DAMAGE...WIND SPEEDS WERE ROUGHLY OF LOW END
EF-0 INTENSITY...OR 65 TO 70 MPH.

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THE NATIONAL WEATHER SERVICE CHICAGO WOULD LIKE TO THANK THOSE AT
THE EMBASSIES OF CHRIST KINGDOM MINISTRIES WHO ASSISTED IN THE
SURVEY...AS WELL AS PROVIDED VIEWS OF THE INVALUABLE SECURITY
CAMERA FOOTAGE OF THE EVENT.

$$

RC/KB

Microburst Damage to a Strip Mall South of Gary, IN

Microburst Tree Damage South of Gary, IN

Downdraft CAPE at 7pm Sunday from SPC Mesoanalysis Archive Downdraft CAPE (DCAPE) is a measure that can be used to estimate the potential strength of rain-cooled downdrafts within thunderstorms. Larger DCAPE values of 1000 J/kg or higher are associated with stronger downdrafts and thus the potential for damaging wind gusts. You can see on the image below that DCAPE values of 1200-1400 J/kg were present across northwest Indiana on Sunday evening, a contributing factor to the strength of the microburst that impacted north central Lake County.