Strong thunderstorms moved into southern Wisconsin Friday afternoon and persisted well into the evening hours. While the thunderstorms produced heavy rains, frequent lightning, and small hail in many locations, many of the storms remained below our severe weather criteria (winds > 58 mph, hail > 1" in diameter, tornado). However, a couple more intense thunderstorms showed signs of rotation and moved across Marquette and Green Lake Counties. We received a few reports of damage and sightings of wall clouds or tornadoes.
The NWS in Sullivan, WI sent two members of our staff to survey the damage in Green Lake County. Forecaster, Denny VanCleve, and Science Operations Officer, Jeff Craven returned late Saturday afternoon with their findings.
Here's a map showing the location of the tornadoes (a detailed description follows in the Public Information Statement):
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
655 PM CDT SAT MAY 1 2010
...RESULTS OF NWS STORM SURVEYS FINDS 3 WEAK TORNADOES...
THUNDERSTORMS PRODUCED 3 WEAK TORNADOES EARLY FRIDAY EVENING IN THE
MARQUETTE AND GREEN LAKE COUNTY AREA. THERE WAS ONE EF1 TORNADO AND
TWO EF0 TORNADOES SURVEYED. THESE TORNADOES WERE FAST MOVING...WITH
ESTIMATED FORWARD MOTION OF ROUGHLY 60 MPH.
GREEN LAKE COUNTY- EF1
700-702 PM: TORNADO TOUCHED DOWN ABOUT 3.5 MILES SOUTHEAST OF
BERLIN AND WAS ON THE GROUND FOR ABOUT 3 MINUTES. THE TORNADO
DISSIPATED 3.3 MILES EAST-SOUTHEAST OF BERLIN...JUST 0.25 MILE FROM
THE WINNEBAGO COUNTY LINE.
SEVERAL HIGH TENSION WOOD POWER POLES WERE SNAPPED. A FEW TREES
WERE UPROOTED...INCLUDING ONE THAT FELL ON AND DAMAGED A CAR. THERE
WAS MINOR ROOF DAMAGE TO A BARN. SEVERAL SMALL BARRELS WERE THROWN
OVER 100 YARDS INTO A NEARBY FIELD. A PORTABLE TOILET WAS MOVED
ABOUT 50 FEET. NEAR THE END OF THE TRACK...A TV ANTENNA WAS SNAPPED
AND THERE WAS DAMAGE TO THE FACIA OF A HOME. A SMALL SHED WAS
DESTROYED...AND A COUCH THAT WAS OUTDOORS WAS THROWN ABOUT 75 FEET.
ESTIMATED WINDS WERE 80 TO 90 MPH ALONG MUCH OF THE PATH...BUT 100
TO 110 MPH AT THE BEGINNING OF THE TRACK WHERE THE POWER POLES WHERE
EF1 RATING. PATH LENGTH 2.2 MILES. PATH WIDTH 100 YARDS. TRACK
BEGINS AT 43.92N 88.92W AND ENDS AT 43.95N 88.89W.
MARQUETTE COUNTY- EF0
715-724 PM: SPORADIC DAMAGE PATH STARTING 2.5 MILES EAST-SOUTHEAST
OF GLEN OAK AND ENDING 4.3 MILES SOUTHWEST OF PRINCETON...JUST WEST
OF THE GREEN LAKE/MARQUETTE COUNTY LINE. SEVERAL TREES OR LARGE
LIMBS WERE SNAPPED ALONG THIS RURAL PATH. THIS WAS THE NORTHERN OF
TWO PARALLEL CIRCULATIONS IN THE STORM THAT EACH PRODUCED A WEAK
TORNADO. THE PUBLIC SIGHTED THIS TORNADO FROM ACROSS THE FOX RIVER
NEAR PRINCETON JUST BEFORE IT DISSIPATED.
ESTIMATED WINDS WERE 65 MPH.
EF0 RATING. PATH LENGTH 8.5 MILES. PATH WIDTH 50 YARDS. TRACK
BEGINS AT 43.73N 89.32W AND ENDS AT 43.80N 89.18W.
MARQUETTE COUNTY/GREEN LAKE COUNTY- EF0
715-723 PM: SPOTTY TREE DAMAGE ALONG A PATH STARTING 4.6 MILES
EAST-SOUTHEAST OF GLEN OAK AND ENDING 1.1 MILES NORTHWEST OF
MARQUETTE. MOST OF THE PATH WAS IN MARQUETTE COUNTY...WITH ABOUT
THE LAST MILE IN GREEN LAKE COUNTY. A FEW TREES WERE SNAPPED AND
NUMEROUS PARTIALLY UPROOTED. MOST OF THE TREE DAMAGE WAS NEAR THE
END OF THE TRACK IN GREEN LAKE COUNTY. THIS WAS THE SOUTHERN OF TWO
PARALLEL CIRCULATIONS IN THE STORM THAT EACH PRODUCED A WEAK
ESTIMATED WINDS WERE 70 MPH.
EF0 RATING. PATH LENGTH 7.5 MILES. PATH WIDTH 50 YARDS. TRACK
BEGINS AT 43.71N 89.28W AND ENDS AT 43.76N 89.15W.
THE NATIONAL WEATHER SERVICE WOULD LIKE TO THANK EMERGENCY
MANAGEMENT OFFICIALS IN GREEN LAKE AND MARQUETTE COUNTIES FOR THEIR
VALUABLE ASSISTANCE IN COMPLETING THIS TORNADO DAMAGE SURVEY.
Radar reflectivity imagery of the two storms that produced the tornadoes (click to enlarge).
Storm relative velocity from the radar showing the rotation in these thunderstorms. The circles highlight areas of rotation, which are the broader circulations in the parent thunderstorms. The tornadic circulation is too small to be detected by radar, but the tornadoes formed beneath these broader areas of rotation (click to enlarge).
Crews repair several downed high tension power poles caused by the Green Lake County EF1 tornado (click to enlarge).
Downed tree lands on car just outside of Berlin, WI in Green Lake County.
Sporadic tree damage associated with the Marquette/Green Lake County EF0.