…PRELIMINARY DAMAGE SURVEY RESULTS FOR MARION…JASPER AND POWESHIEK COUNTIES…
THE STORM SURVEY INVESTIGATION IS STILL ONGOING AND SUBJECT TOFURTHER COORDINATION WITH LOCAL EMERGENCY MANAGEMENT AGENCIES….DAMAGING STRAIGHT LINE WINDS AND LARGE HAIL…
THE FOLLOWING IS A PRELIMINARY ASSESSMENT FOR THE DAMAGE THAT OCCURRED OVER MARION…JASPER AND POWESHIEK COUNTIES ON APRIL 6TH.
* EVENT DATE: APRIL 6TH* EVENT TYPE: STRAIGHT LINE DAMAGING WINDS WITH EMBEDDED LARGE HAIL.* PEAK WIND: 95 TO 105 MPH JUST WEST OF GRINNELL.* AVERAGE PATH WIDTH: PEAK DAMAGE AREA AROUND 1 MILE WIDE WITH UP TO 60 MPH EXPANDING OUT 2 TO 3 MILES ON EITHER SIDE OF PRIMARY DAMAGE PATH.*
DISCUSSION/DAMAGE: A VERY STRONG THUNDERSTORM MOVED NORTHEAST THROUGH MARION…JASPER AND INTO POWESHIEK COUNTY LATE TUESDAY AFTERNOON. LARGE HAIL BROKE A FEW WINDOWS OUT OF HOMES ON THE NORTHWEST SIDE OF KNOXVILLE. AN ISOLATED AREA OF STRONG WINDS WAS LOCATED 5 MILES NORTHWEST OF PELLA. THE GREATEST DAMAGE IN THIS LOCATION WAS 2 WALLS OF AN ATTACHED GARAGE BLOWN OUT. THE GARAGE WALLS WERE ONLY ATTACHED WITH NAILS INTO THE CONCRETE FOUNDATION. WIND COMING IN FROM THE OPEN GARAGE DOOR WAS ABLE TO BLOW THE 2 WALLS OUT FROM BOTTOM TO TOP. THERE WAS ALSO SOME HAIL DAMAGE WITH BROKEN WINDOWS AND HOLES IN VINYL SIDING. ONE OPEN ENDED FARM SHED LOST A ROOF JUST DOWN THE ROAD…WHICH WAS BLOWN APPROXIMATELY HALF A MILE. WIND SPEED ESTIMATES IN THIS AREA ARE CONSISTENT WITH 75 TO 85 MPH STRAIGHT LINE WINDS. THE STORM CONTINUED TO MOVE NORTH WITH LITTLE EVIDENCE OF STRONG WIND DAMAGE…WITH THE EXCEPTION OF ONE BENT OVER STREET SIGN AND DOWNED POWER POLES NEAR SULLY. THE AREA ON THE WEST SIDE OF GRINNELL HAD THE MOST SIGNIFICANT DAMAGE WITH THIS STORM. NUMEROUS VEHICLES WERE BLOWN OFF INTERSTATE 80. LITTLE ADDITIONAL DAMAGE WAS NOTED OVER THIS AREA HOWEVER…A VALLEY RUNNING THROUGH THE REGION MAY HAVE LOCALLY ENHANCED WIND SPEEDS AS THE STORM APPROACHED THE INTERSTATE. NUMEROUS FARM OUT BUILDINGS SUFFERED SIGNIFICANT DAMAGE ON THE WEST SIDE OF GRINNELL ALONG WITH DOWNED POWER LINES IN THE REGION. SEVERAL HOUSES SUFFERED SIGNIFICANT VINYL SIDING AND WINDOW DAMAGE. ANOTHER HOUSE HAD BOTH GARAGE DOORS BLOWN IN AND THE WEST SIDE WALL REMOVED AND DEPOSITED NORTH OF THE LOCATION. SEVERAL OTHER SOUTH FACING GARAGE DOORS WERE BLOWN IN AS WELL…ALONG WITH SEVERAL TREES WHICH WERE SNAPPED OR UPROOTED OVER THE REGION. THE DAMAGE ENDED 2 MILES NORTH OF GRINNELL. DAMAGE INDICATORS SUGGEST DAMAGING STRAIGHT LINE WINDS OF 95 TO 105 MPH.