The tornado hit EL Reno, OK , is now classified as EF-5 and believe to 2.6 miles. Making it the widest tornado on record over the United States.  This tornado is also responsible for the deaths several veteran storm chasers. Tim Samaras, his son Pat Samaras, and his partner Carl Young. Official statement from the National Weather Service is below

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE NORMAN OK
1206 PM CDT TUE JUN 4 2013

…UPDATE ON MAY 31 EL RENO TORNADO…

METEOROLOGISTS WITH THE NATIONAL WEATHER SERVICE AND RESEARCHERS FROM
THE UNIVERSITY OF OKLAHOMA CONTINUE TO INVESTIGATE INFORMATION
RELATED TO THE MAY 31 EL RENO TORNADO.

WITH THIS INVESTIGATION… THE TORNADO HAS BEEN UPGRADED TO AN EF5
TORNADO BASED ON VELOCITY DATA FROM THE RESEARCH MOBILE RADAR DATA
FROM THE UNIVERSITY OF OKLAHOMA RAXPOL RADAR. IN ADDITION… THE
WIDTH OF TORNADO WAS MEASURED BY THE MOBILE RADAR DATA TO BE 2.6
MILES AFTER THE TORNADO PASSED EAST OF US HIGHWAY 81 SOUTH OF EL
RENO. THIS WIDTH IS THE WIDTH OF THE TORNADO ITSELF AND DOES NOT
INCLUDE THE DAMAGING STRAIGHT-LINE WINDS NEAR THE TORNADO AS
DETERMINED BY THE HIGH-RESOLUTION MOBILE RADAR DATA. THE 2.6 MILE
TORNADO PATH WIDTH IS BELIEVED TO BE THE WIDEST TORNADO ON RECORD
IN THE UNITED STATES.

.EL RENO TORNADO

RATING: EF5
PATH LENGTH /STATUTE/: 16.2 MILES
PATH WIDTH /MAXIMUM/: 2.6 MILES
FATALITIES: N/A
INJURIES: N/A

START DATE: MAY 31 2013
START TIME: 6:03 PM CDT
START LOCATION: 8.3 WSW OF EL RENO /CANADIAN COUNTY /OK
NEAR COURTNEY ROAD ABOUT 1 MILE NORTH
OF REUTER ROAD
START LAT/LON: 35.495 / -98.095

END DATE: MAY 31 2013
END TIME: 6:43 PM CDT
END LOCATION: 6.2 ESE OF EL RENO /CANADIAN COUNTY /OK
NEAR INTERSTATE 40 AND BANNER ROAD
END LAT/LON: 35.502 / -97.848

$$

SMITH/GARFIELD/SPEHEGER/AUSTIN