A Preliminary Look at the Severe Thunderstorms that Produced Large Hail and Wind Damage Across Central and Eastern Wisconsin on 2 August 2015.
Severe thunderstorms with large hail and damaging straight-line winds affected parts of central and northeast Wisconsin during the afternoon of August 2, 2015. The most intense storms developed near a west-east orientated surface boundary that stretched from near Wausau to Green Bay by early afternoon (Figure 1). Surface convergence along the boundary helped to initiate and organize the storms.
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Some of the first severe storms of the event developed just north of Green Bay, over parts of Oconto and Marinette counties producing large hail in excess of 3 inches in diameter (Figure 4). These storms were part of a larger line of storms that raced eastward across the Bay of Green Bay, eventually producing widespread damaging winds and power outages across much of Door County (Figure 3). Note the portion of the line in Figure 3 that appears to accelerate (or bow eastward) from near Egg Harbor to Jacksonport. This bowing line segment (bow echo) produced some of the strongest winds which caused widespread wind damage and power outages. Meanwhile, additional storms developed westward toward the Wausau area. These storms moved southeast during the late afternoon and produced large hail and damaging winds from Marathon and Wood counties eastward to Sheboygan County. Finally, interesting radar evolution was also noted as the storms moved into Sheboygan County shortly after 5 pm CDT (Figure 5). The radar animation in Figure 5 below shows how the storms further to the north generated a large organized thunderstorm outflow boundary (gust front) that raced southward across the Fox Valley. The gust front is indicated by the narrow line of weak radar returns (blue colors) racing southward. As this outflow intersected a separate area of storms moving out of Fond du Lac County, a compact bowing radar signature (an indication that this portion of the line is accelerating faster than the rest of the storms) developed over northwest Sheboygan County. This bowing line of storms may have been responsible for the swath of wind damge that was reported from Elkhart Lake to Plymouth. |
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| Oconto Co. - Suzi Runge Lagerquist |
Figure 1. Surface map around 1 pm CDT Sunday August 2. Solid lines are surface pressure. The red dashed line
denotes a wind-shift. Note how the winds shift from northwest to southwest across the boundary. This boundary helped to
initiate and organize the storms.
Figure 2. NWS Green Bay Doppler radar animation of the severe storm evolution during the afternoon of August 2, 2015.
The radar animation is for the period beginning at 130 pm CDT and ending at about 530 pm CDT.
Figure 3. A close-up radar animation of the storms that raced across the waters of Green Bay and Door County producing
widespread wind damage and power outages.
Figure 4. NWS Green Bay reflectivity image (left) and the dual polarization correlation coeficient (CC) product right at 228 pm CDT.
This particular storm produced 2 inch hail near Abrams a few minutes earlier (220 pm CDT) and produced 3.5 to 4.0 inch hail south of
Pensaukee near the time of this radar scan. The image on the right denotes the area where there was large hail mixed in with the
heavy rain.
Figure 5. Radar animation illustrating the interaction bewteen an area of storms and a thunderstorm outflow boundary
over Sheboygan County. This interaction may have been helped to intensify the storms over Sheboygan County enhancing the
wind damage there.
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Figure 6. Hail greater than 3 inches in diameter was reported in Oconto County and widespread wind damage occurred in Door County.
Here is a preliminary list of storm reports from spotters and the public across the area after 1:30 pm:
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0149 PM HAIL 2 W BEAVER 45.13N 88.05W
08/02/2015 E0.50 INCH MARINETTE WI TRAINED SPOTTER
SPOTTER DROVE THROUGH HAIL ON CTY HIGHWAY P
0149 PM TSTM WND DMG PESHTIGO 45.04N 87.75W
08/02/2015 MARINETTE WI PUBLIC
CALLER REPORTS SEVERAL TREES DOWN NEAR TOWN. TIME
ESTIMATED FROM RADAR
0157 PM HAIL MARINETTE 45.09N 87.61W
08/02/2015 M0.25 INCH MARINETTE WI TRAINED SPOTTER
PEA SIZE HAIL AND SMALL TREE LIMBS DOWN
0205 PM MARINE TSTM WIND 1 W SISTER BAY 45.18N 87.13W
08/02/2015 U0.00 MPH DOOR WI COAST GUARD
32 FOOT SAILBOAT CAPSIZED ONE MILE OFF SISTER BAY DUE TO
HIGH WINDS AND WAVES. PASSANGERS WERE RESCUED BY COAST
GUARD.
0215 PM TSTM WND DMG 2 N JACKSONPORT 45.01N 87.18W
08/02/2015 DOOR WI BROADCAST MEDIA
TREES DOWN AND NO POWER. PICTURE FROM PUBLIC RELAYED BY
WFRV-TV. TIME ESTIMATED BASED ON RADAR.
0215 PM TSTM WND DMG EGG HARBOR 45.04N 87.28W
08/02/2015 DOOR WI AMATEUR RADIO
TREES DOWN AND POWER OUT. ESTIMATED 60 TO 70 MPH WINDS.
TIME BASED ON RADAR.
0215 PM HAIL OCONTO 44.88N 87.88W
08/02/2015 E1.00 INCH OCONTO WI PUBLIC
HAIL FELL FOR A FEW MINUTES STARTING AROUND 215. NOT MANY
STONES
0220 PM HAIL 6 W MARSHFIELD 44.66N 90.28W
08/02/2015 E0.75 INCH WOOD WI PUBLIC
WINDS GUSTED TO AROUND 50 MPH AND DOWNED SMALL BRANCHES.
0221 PM TSTM WND GST STURGEON BAY 44.83N 87.38W
08/02/2015 E50.00 MPH DOOR WI TRAINED SPOTTER
0221 PM HAIL ABRAMS 44.78N 88.06W
08/02/2015 E4.00 INCH OCONTO WI PUBLIC
0222 PM TSTM WND DMG MARINETTE 45.09N 87.61W
08/02/2015 MARINETTE WI TRAINED SPOTTER
SPOTTER/HAM OPERATOR RELAYED REPORTS OF SEVERAL TREES
DOWN IN THE COUNTY WITH STORMS
0224 PM HEAVY RAIN ABRAMS 44.78N 88.06W
08/02/2015 E1.75 INCH OCONTO WI BROADCAST MEDIA
ESTIMATED GOLF BALF SIZE HAIL BASED ON PHOTO RELAYED BY
NBC26. TIME ESTIMATED BASED ON RADAR.
0229 PM HAIL 5 NNE LITTLE SUAMICO 44.78N 87.95W
08/02/2015 E2.50 INCH OCONTO WI PUBLIC
NEAR OAK ORCHARD. REPORT VIA SOCIAL MEDIA. TIME ESTIMATED
BY RADAR.
0233 PM HAIL 3 ESE ABRAMS 44.76N 88.00W
08/02/2015 E4.00 INCH OCONTO WI PUBLIC
HAIL SIZE BASED ON PHOTO.
0253 PM HAIL SHAWANO 44.78N 88.59W
08/02/2015 E0.50 INCH SHAWANO WI TRAINED SPOTTER
PEA TO DIME SIZE HAIL.
0300 PM HAIL 2 SE SHAWANO 44.76N 88.56W
08/02/2015 E0.88 INCH SHAWANO WI CO-OP OBSERVER
NICKEL SIZE HAIL AND HEAVY RAIN.
0306 PM HAIL RUDOLPH 44.50N 89.80W
08/02/2015 M2.00 INCH WOOD WI BROADCAST MEDIA
PICTURE AND REPORT RELAYED VIA WSAW-TV. TIME ESTIMATED BY
RADAR.
0310 PM HAIL SHAWANO 44.78N 88.59W
08/02/2015 M1.75 INCH SHAWANO WI TRAINED SPOTTER
AT SHAWANO HIGH SCHOOL.
0312 PM HAIL KRAKOW 44.75N 88.25W
08/02/2015 E2.50 INCH SHAWANO WI PUBLIC
HAIL SIZE ESTIMATED BY PHOTO ON SOCIAL MEDIA. TIME
ESTIMATED BY RADAR.
0318 PM HAIL 1 E SUAMICO 44.63N 88.03W
08/02/2015 M1.75 INCH BROWN WI LAW ENFORCEMENT
BOATERS IN LONGTAIL POINT REPORTED GOLF BALL SIZE HAIL.
TIME ESTIMATED BY RADAR.
0321 PM HAIL BIRON 44.43N 89.78W
08/02/2015 E1.50 INCH WOOD WI EMERGENCY MNGR
REPORTED BY HAM OPERATOR AND RELAYED VIA COUNTY EOC
0328 PM HAIL PLOVER 44.45N 89.53W
08/02/2015 M1.25 INCH PORTAGE WI CO-OP OBSERVER
MEASURED 41MPH WIND GUST. 0.10 INCH OF RAIN IN LAST 5
MINUTES.
0333 PM HAIL STEVENS POINT 44.51N 89.56W
08/02/2015 M1.75 INCH PORTAGE WI PUBLIC
PHOTO SUBMITTED VIA SOCIAL MEDIA
0345 PM LIGHTNING SUAMICO 44.63N 88.05W
08/02/2015 BROWN WI LAW ENFORCEMENT
HOUSE FIRE DUE TO LIGHTNING STRIKE.
0345 PM HAIL 2 S ABRAMS 44.76N 88.05W
08/02/2015 E1.00 INCH OCONTO WI PUBLIC
PENNY TO QUARTER SIZE HAIL FELL NEAR ABRAMS. TIME IS
APPROXIMATE.
0349 PM HAIL BANCROFT 44.31N 89.51W
08/02/2015 M1.00 INCH PORTAGE WI TRAINED SPOTTER
ESTIMATED 40MPH WINDS
0356 PM HAIL SEYMOUR 44.51N 88.33W
08/02/2015 E0.50 INCH OUTAGAMIE WI TRAINED SPOTTER
PEA TO DIME SIZE HAIL AND HEAVY RAIN.
0401 PM HAIL KING 44.33N 89.13W
08/02/2015 M1.00 INCH WAUPACA WI TRAINED SPOTTER
ESTIMATED 50MPH WIND GUSTS.
0407 PM TSTM WND DMG WILD ROSE 44.18N 89.25W
08/02/2015 WAUSHARA WI TRAINED SPOTTER
COUPLE OF MEDIUM SIZE TREES DOWN
0409 PM HAIL MOSINEE 44.78N 89.69W
08/02/2015 E1.00 INCH MARATHON WI TRAINED SPOTTER
OBSERVED AT CENTRAL WISCONSIN AIRPORT
0430 PM HAIL 3 S POY SIPPI 44.09N 89.00W
08/02/2015 M1.50 INCH WAUSHARA WI EMERGENCY MNGR
1 3/8 INCH HAIL MEASURED
0432 PM HAIL AURORAVILLE 44.04N 89.00W
08/02/2015 M1.75 INCH WAUSHARA WI TRAINED SPOTTER
0441 PM HAIL 8 SE OSHKOSH 43.93N 88.44W
08/02/2015 M1.00 INCH WINNEBAGO WI TRAINED SPOTTER
REPORT VIA SOCIAL MEDIA WITH PICTURE. TIME ESTIMATED BY
RADAR.
0448 PM TSTM WND GST OSHKOSH 44.01N 88.55W
08/02/2015 M50.00 MPH WINNEBAGO WI ASOS
MEASURED AT WITTMANN AIRPORT.
0453 PM HAIL 4 N IOLA 44.56N 89.11W
08/02/2015 E1.00 INCH WAUPACA WI TRAINED SPOTTER
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