National Weather Service Weather Forecast Office

       Updated - noon CDT Wednesday May 21, 2011

         What's new - a weak tornado documented in Green Lake County

Although the major metro areas like Madison, Milwaukee, and Chicago were spared, at least 15 tornadoes, including four strong tornadoes (EF2 or EF3), were documented in portions of mainly rural central and northern Wisconsin.  The potential for a tornado outbreak in the Wisconsin area was advertised almost a week out with the models showing favorable conditions ripe for the tornado outbreak.  

April 10 2011 will go down as the biggest daily April tornado outbreak (in terms of total tornadoes) in Wisconsin history.  The other big April tornado outbreak was on April 27 1984, when 10 tornadoes occurred, of which 6 were considered at least strong.  This included the violent Wales Tornado in Waukesha County, rated an F4, and another F4 tornado in Winnebago and Outagamie Counties.

The EF3 tornado on April 10, 2011 occurred near Merrill in Lincoln County. EF2 tornadoes were also documented in Adams County, Forest County, and Brown County (see table and graphic below for locations). 

These are the first strong tornadoes in 17 years for the month of April in Wisconsin (the last being April 26 1994 in NW Wisconsin).  They are also the first strong tornadoes in 27 years in the month of April for central or southern WI (April 27 1984). 

Damage assessment continues, which means more tornadoes may be found and recorded in the next few days.  Below is a rough plot of the tornado locations and EF-rating.

 Below is a listing of the April 10th tornadoes in Wisconsin...subject to change as new information becomes available.

 

Time (PM CDT)	County	Start	End	EF	Path Length	Path Width	Max Wind
457-503	Eau Claire	5SW Augusta	3.5SW Augusta	EF1	1.5 miles	unknown	105 mph
504-506	Eau Claire	1.3 NW Augusta	2NNW Augusta	EF1	¾ mile	unknown	100 mph
608-641	Lincoln	2N Hamburg	Near Gleason	EF3	21.2 miles	1050 yds	140 mph
612-630	Adams	3W Arkdale	5.5NW Coloma	EF2	17 miles	800 yds	125 mph
614-621	Juneau	2.4 SSW Necadah	3.5 ESE Necadah	EF1	4.5 miles	150 yds	95 mph
633–642	Adams – Waushara	6SW Hancock	2SE Hancock	EF1	9.3 miles	140 yds	100 mph
650-658	Langlade	S of Parrish	E of Parrish	EF1	5.3 miles	400 yds	110 mph
706-743	Waushara-Waupaca – Outagamie	Saxeville	Hortonville	EF1	27.7 miles	200 yds	100 mph
730-751	Forest – Florence	3 SE Argonne	6 SE Long Lake	EF2	12 miles	600 yds	115 mph
753-807	Waushara- Winnebago	Poy Sippi	2W Windchester	EF1	14.9 miles	150 yds	105 mph
803-808	Forest	4W Armstrong Creek	1NW Armstrong Creek	EF1	3.3 miles	250 yds	105 mph
827-829	Green Lake	3.5 SSE Berlin	3.4 SE Berlin	EF0	2.0 miles	50 yds	80 mph
843-846	Outagamie	Kaukauna (sw)	Kaukauna (s)	EF2	1.5 miles	175 yds	120 mph
853-855	Brown	1 S Greenleaf	1 S Greenleaf	EF1	1.2 miles	75 yds	95 mph
859-901	Calumet	1 S Stockbridge	1 S Stockbridge	EF1	1.7 miles	100 yds	90 mph

 

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Below is a rough plot of the tornado locations and EF-rating (click on image for larger version)

 

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APRIL 10 2011 SO FAR IS ONE OF THE BIGGEST DAILY TORNADO OUTBREAKS IN WISCONSIN HISTORY...NOW IN 6TH PLACE.

APRIL 10 2011, IS THE BIGGEST TORNADO OUTBREAK IN TERMS OF NUMBERS OF TORNADOES IN ONE CALENDAR DAY IN THE MONTH OF APRIL.   THE PREVIOUS RECORD WAS APRIL 27, 1984 WHICH HAD 10 TORNADOES. AT THE BOTTOM OF THIS STORY IS A PLOT OF THE TORNADO PATHS FOR APRIL 27, 1984.  TWO F4 TORNADOES OCCURRED ON APRIL 27, 1984 - ONE NEAR WALES AND THE OTHER IN WINNEBAGO AND OUTAGAMIE COUNTIES.  THE TORNADOES IN THAT OUTBREAK WERE STRONGER OVERALL...WITH 6 STRONG AND VIOLENT TORNADOES (F2 OR GREATER).  THIS COMPARES WITH 4 STRONG TORNADOES ON APRIL 10, 2011 (EF2 OR GREATER).

SO FAR...AT LEAST 15 TORNADOES HAVE BEEN CONFIRMED ON APRIL 10, 2011...WITH FOUR NWS OFFICES COMPLETING STORM SURVEYS.

HERE ARE THE TORNADO TOTALS* SO FAR:

NWS GREEN BAY AREA:       10                         NWS LA CROSSE AREA:        3               
NWS TWIN CITIES AREA:        2                          NWS MILWAUKEE AREA        1

THE TOTAL SO FAR IS 15* TORNADOES.  ONE OF THE TORNADOES CROSSED FROM ADAMS INTO WAUSHARA COUNTY...WHICH CROSSES FROM NWS LA CROSSE'S AREA INTO GREEN BAY'S AREA  (THUS ONLY 15 TORNADOES...NOT 16 AS THE MATH ABOVE WOULD SUGGEST).

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Additionally, there were numerous reports of large hail and damaging thunderstorm winds across many parts of the state.  Hail stones up to 2.75 inches in diameter occurred and straight-line wind gusts up to 80 mph (hurricane-force) were noted by severe weather spotters.

A warm front pushed north into northern Wisconsin on Sunday, April 10th, which allowed temperatures to reach the 70s to lower 80s.  During the afternoon and evening hours a cold front punched east into this warm, humid, unstable airmass. Strong winds and the jet stream resulted in many supercell thunderstorms, some of which produced tornadoes. 

The storms started to rapidly develop around 4 p.m. and storm movement was very fast – 60 to 70 mph at times.  Moving at these speeds, the storms exited Wisconsin by 11 pm.

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Related stories, greater detail, damage pictures, radar imagery, and tornado plot maps, can be found at these URLs...

http://www.crh.noaa.gov/grb/?n=110410_tornadoes

http://www.crh.noaa.gov/arx/?n=apr1011

http://www.crh.noaa.gov/mpx/?n=11apr10

http://emergencymanagement.wi.gov/

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 HOW MANY TORNADOES HAVE OCCURRED IN WISCONSIN ON ONE DAY?

WISCONSIN NORMALLY DOESN'T HAVE MANY TORNADOES OCCURRING ON THE SAME DAY...CONSIDERING IT AVERAGES ONLY 21 TORNADOES PER YEAR (BASED ON 1971-2000).  HOWEVER...WHEN A TORNADIC WEATHER PATTERN DOES SET UP OVER WISCONSIN...THE BADGER STATE CAN HAVE MANY TORNADOES OCCURRING ON THE SAME DAY.

THE TABLE BELOW LISTS THOSE DAYS IN WISCONSIN WITH THE LARGEST NUMBER OF DOCUMENTED TORNADOES GOING BACK TO 1844. THE 15 TORNADOES DOCUMENTED ON APRIL 10, 2011 PLACES THAT DAY IN 6TH POSITION IN THE TOP-10 RANKINGS.

     ...RANK...      ...DATE...      ...NUMBER OF EVENTS...

         01          AUG 18 2005               27

         02          MAY 08 1988               24

         03          JULY 03 1983              22

         04          JUNE 08 1993              18

         05          JUNE 23 2004              17

         06          APRIL 10 2011             15

         07          JUNE 07 2008              13

         07          AUGUST 09 1979         13

         09          JULY 18 1996               12

         10          MAY 24 1989               10

         10          APRIL 27 1984             10

         10          JULY 15 1980               10

         10          JUNE 26 1969              10

         10          JULY 10 1966               10

         10          JUNE 04 2005              10

         10          JULY 22 2010               10

 

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HOW MANY TORNADOES IN ONE DAY ACROSS SOUTH-CENTRAL AND SOUTHEAST WISCONSIN?

THE NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN FORECAST OFFICE SERVICES 20 COUNTIES IN SOUTH-CENTRAL AND SOUTHEAST WISCONSIN. THIS COUNTY WARNING AREA /CWA/ CONSISTS OF THE FOLLOWING COUNTIES...

COLUMBIA...DANE...DODGE...FOND DU LAC...GREEN...GREEN LAKE...IOWA...JEFFERSON...KENOSHA...LAFAYETTE... MARQUETTE...MILWAUKEE...OZAUKEE...RACINE...ROCK...SAUK...SHEBOYGAN...WALWORTH...WASHINGTON...AND WAUKESHA...

BELOW IS THE TOP-10 RANKING FOR THOSE DAYS WITH THE LARGEST NUMBER OF DOCUMENTED TORNADOES ON A GIVEN CALENDAR DAY IN THE MILWAUKEE/SULLIVAN CWA.

     ...RANK...      ...DATE...      ...NUMBER OF EVENTS...

         01          AUGUST 18 2005         16

         02          MAY 08 1988               10

         02          AUGUST 09 1979         10

         02          JULY 18 1996               10

         02          JUNE 07 2008              10

         02          JULY 22 2010               10

         07          JUNE 08 1993               08

         07          JUNE 23 2004               08

         09          JUNE 08 1984               07

         09          JUNE 12 2008               07

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Below is a graphic produced by Dan Baumgardt, SOO, WFO La Crosse, showing the tornado locations for the day of April 27, 1984.  Note that several of the tornadoes occurred in the same counties that had tornadoes on April 10, 2011.

  

CRAVEN/KAPELA/ZABEL/GEHRING

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