The NWS determined that the El Reno, Okla., tornado was 2.6 miles wide, the widest ever recorded.
A tornado outbreak killed at least 1 and injured dozens more as twisters hit Oklahoma, Kansas and Iowa on Sunday.
A wild weather weekend may be in store for much of the Plains and Midwest, as rain comes with threat of tornadoes.
Chicago enjoyed last year's mild winter, but it now has to deal with a rat infestation usually kept in check by the cold.
Sizzling heat continues to affect Oklahoma with near-record heat and temperatures propelled by extreme drought conditions.
Oklahoma City may set an all-time high temperature record, after sweating through the warmest day since 1936.
Dangerous heat is scorching a region from Kansas to Mississippi, with all-time temperature records in jeopardy.
High temperatures are soaring into the triple digits from Oklahoma to Arkansas, as the record warm summer of 2012 drags on.