427 
ABUS34 KGRB 011732
PNSGRB

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE GREEN BAY WI
1230 PM TUE JUL 1 1997

...20TH ANNIVERSARY OF INDEPENDENCE DAY DOWNBURSTS...

DURING THE EARLY AFTERNOON OF JULY 4, 1977, A SEVERE THUNDERSTORM COMPLEX
PRODUCED EXTREMELY STRONG WINDS AS IT MOVED ACROSS NORTHERN WISCONSIN.
ONE PERSON WAS KILLED, THIRTY-FIVE WERE INJURED, AND TENS OF MILLIONS
OF DOLLARS OF DAMAGE TO BUILDINGS AND TIMBER RESULTED FROM THE
WINDSTORM, WHICH CONTAINED GUSTS IN EXCESS OF 100 MPH.  JUST AFTER THE
EVENT, IT WAS REPORTED THAT THE EXTENSIVE DAMAGE TO TREES AND PROPERTY
LOOKED AS IF AN OVERSIZED TORNADO HAD STRUCK.

WHAT WE NOW KNOW, OF COURSE, IS THAT A SERIES OF DOWNBURSTS, KNOWN AS A
DERECHO (PRONOUNCED DAY-RAY-CHO), PRODUCED THE 166-MILE LONG, 17-MILE
WIDE SWATH OF DESTRUCTION.

A DOWNBURST IS A THUNDERSTORM DOWNDRAFT OF AN EXTREME INTENSITY
ACCOMPANIED BY DAMAGING WINDS ON THE GROUND.  TWENTY-FIVE INDIVIDUAL
DOWNBURSTS WERE IDENTIFIED IN THE JULY 4 STORM BY DR. TED FUJITA, OF
THE UNIVERSITY OF CHICAGO.  NO EVIDENCE OF A TORNADO WAS FOUND INSTEAD,
THERE WERE SCATTERED LOCAL EVENTS FROM WHICH STRAIGHT-LINE WINDS SPREAD
OUT VIOLENTLY.

WINDS WERE MEASURED OVER 100 MPH NEAR RHINELANDER (ONEIDA COUNTY) AND
PHILLIPS (PRICE COUNTY), BEFORE THE AIRPORT ANEMOMETERS BLEW AWAY. SOME
FORESTS WERE LITERALLY FLATTENED, AND VACATION HOMES WERE DAMAGED AS
TALL TREES WERE FELLED.

JKL