The National Weather Service office near Sullivan, Wi, sent two separate damage survey teams out into the field on Tuesday, July 27th. One team headed to the counties of Marquette and Green Lake. The other team headed out to the counties of Lafayette and Iowa. Two tornadoes have been confirmed in South-Central Wisconsin as part of Monday's round of severe weather. Another tornado was confirmed by the National Weather Service office in La Crosse, WI in southwest Wisconsin.
Here is the basic information on each tornado:
First Tornado - Marquette and Green Lake Counties
***A special "thanks" is extended to the Sheriff Department and Emergency Management teams in both Marquette and Green Lake Counties for their assistance in helping us find and survey the damage in order to document this tornado!***
This tornado was assigned a preliminary rating of EF1 on the Enhanced Fujita Scale with winds around 95 mph. This tornado moved slowly at about 10 to 15 mph, which allowed spotters a chance to position themselves for a good look. Most likely, the condensation funnel didn't extend all the way to the ground, based on spotter and citizen reports. Also, several trees were laid down in different directions and some of the damaged corn crop showed convergent damage patterns. Last, but not least, it appeared that the tornadic circulation periodically weakened along its track which led to sporadic damage.
Heavy rains accompanied the supercell thunderstorm that generated this tornado. A farmer on Grand Rd. in southwest Green County measured 4 inches of rain. Partial gravel washouts along roadsides and driveways were observed along and within about 5 miles of the tornado track. Hail damage to corn, soybeans, and wheat was observed in both Marquette and Green Lake Counties, as well as in northeastern Columbia County. This supercell thunderstorm moved south into Columbia County, south of the Dalton area of southwest Green Lake County, and weakened. Damage indicative of tornadoes could not be found in Columbia County.
0548 PM TORNADO 3 SW MONTELLO 43.76N 89.38W
07/27/2009 F1 MARQUETTE WI NWS STORM SURVEY
TORNADO BEGAN ABOUT 2.9 SW OF MONTELLO IN MARQUETTE
COUNTY AND TRACKED TO ABOUT 1.5 NW OF DALTON IN GREEN
LAKE COUNTY...ENDING AROUND 616 PM. PATH LENGTH WAS
APPROXIMATELY 9 MILES WITH A MAX PATH WIDTH OF ABOUT 100
YARDS. MAINLY TREE DAMAGE WAS NOTED ALONG THE ENTIRETY OF
THE TRACK...WITH SOME UPROOTED TREES. MAX WINDS IN THE
TORNADO WERE LIKELY AROUND 95 MPH...OR IN THE EF-1 RANGE.
HAIL AND STRAIGHT LINE WIND DAMAGE WERE ALSO OBSERVED 1
TO 3 MILES EITHER SIDE OF THE TORNADO TRACK.
Below is an image produced by the Marquette County Emergency Management team showing location of some of the damage. The three northern-most damage locations/reports are not directly-related to the tornado. Rather, they are associated with thunderstorm wind damage generated on the backside of the forward flank downdraft where strong easterly inflow winds were feeding into the rotating wall cloud area. The roof damage on Grand Ave. was related to the tornado itself.
Below are two pictures of the supercell thunderstorm as it moved through southeastern Marquette County. It was taken by Doug Raflik who was in the Dalton area looking northwest. The main features of the supercell are annotated on the image. The third image shows a condensation funnel. Dough and other spotters indicated that inflow into the rotating wall cloud was impressive - from the east and from the south!
Below is a picture taken of the supercell just before it entered Marquette County.
Below is an image of the supercell as it was approaching CTH D south-southwest of Montello.
Below are a few damage pictures from the area (click for larger images):
Hail was found in a corn field about 1 to 1.5 miles north of the tornado path, intact, almost 18 hours after it fell! Some of the hail was still as large as 1 inch in diameter! (click for larger images):
This tornado was assigned a preliminary rating of EF-0 on the Enhanced Fujita Scale with winds around 80 mph.
Below is a map of the area with tornado damage just northeast of Gratiot in Lafayette County, and downburst winds near, and north of Darlington.
0810 PM TORNADO 2 NE GRATIOT 42.60N 90.00W
07/27/2009 F0 LAFAYETTE WI NWS STORM SURVEY
THIS TORNADO SPUN UP ABOUT 0.2 MILES SOUTH OF THE
INTERSECTION OF CHURCH ROAD AND HIGHWAY 78...OR ABOUT 2.6
MILES NORTHEAST OF GRATIOT. TREE LIMBS ABOUT 1 FOOT IN
DIAMETER WERE BLOWN DOWN AND SMASHED THREE VEHICLES. SOME
TREES WERE ALSO BLOWN DOWN. THERE WAS MINOR ROOF DAMAGE
TO TWO FARM HOUSES. PATH WIDTH ABOUT 25 YARDS. PATH
LENGTH ABOUT 0.1 MILES. BRIEF TORNADO. MAX WIND SPEED
ABOUT 80 MPH...OR AT THE TOP END OF THE EF-0 RANGE.
Below are pictures of damage from the Gratiot tornado. (click for larger images):
Below are pictures from a swath of damage caused by a downburst along Highway 23 from Darlington to about 4 miles north of Darlington between 740 pm and 750 pm. Winds with this downburst were estimated around 75 mph. Trees were blown down in the Darlington park (first two images) and corn was flattened, with some structural damage noted, about two miles north of Darlington (last two images). (click for larger images):