2011-2013 Tornado Warning Drought Has Ended (Updated 06/16)

There are two types of tornado droughts to consider....one based on warnings issued and one on actual tornado events.

Tornado Warning Drought (SC & SE Wisconsin)

It was nearly 2 years between tornado warnings issued by WFO Milwaukee/Sullivan (MKX), from 2011 into 2013, for some location within the 20 counties which comprise its County Warning Area (CWA)!  This CWA covers south-central, east-central, and southeast Wisconsin.

The 2011-2013 tornado warning drought was easily twice as long as the next longest tornado warning drought - which is remarkable!  See 4th bullet below.

  • For the period of 1986 through June 11, 2013, the 2011-2013 tornado warning drought was the longest we could find in the books: 1 year, 11 months, and 21 days.  We issued a tornado warning on June 12, 2013.  We had to stop with 1986 since we don't have easy access to warning information prior to 1986.
  • WFO Milwaukee/Sullivan has issued a tornado warning in every calendar year going back to at least 1986.  The only year it didn't issue a tornado warning was in 2012.  The next fewest number of tornado warnings issued in a calendar year was 5 in 1990.
  • The lack of tornado warnings in 2012 through June 11, 2013 is related to several factors:
    • The 2012 precipitation drought resulted in fewer thunderstorms and severe weather.
    • A cool 2013 spring which limited influxes of warm, moist, unstable air that typically can lead to thunderstorms and severe weather.
    • Greater forecaster restraint issuing tornado warnings during marginally favorable weather situations due to increased scientific knowledge on tornado formation (this includes more in-house training sessions).
    • Higher quality severe weather spotter reports and other reports from the general public.
  • For the period of 1986 through June 11, 2013, the longest tornado warning droughts were:
    • 1 yr 11 mo 21 days from 06/21/2011 thru 06/11/2013
    • 11 mo 8 days from 07/03/1998 thru 06/11/1999
    • 10 mo 24 days from 08/10/1993 thru 07/04/1994

Tornado Event Drought (SC & SE Wisconsin)

The other type of a tornado drought is the longest period of time between actual, documented tornado events.

  • For the period of 1950 through June 11, 2013, the longest tornado event droughts are...

        1.    2 yr 6 mo 12 days from 09/26/1951 thru 04/07/1954
        2.    1 yr 10 mo 3 days from 08/08/2011 thru 06/11/2013
        3.    1 yr 1 mo 12 days from 04/19/1957 thru 05/31/1958

  • So, the current tornado event drought has a long way to go to meet or exceed the tornado event drought in the early 1950s. The year of 1953 was a drought year over many parts of southern Wisconsin. However, tornado documentation in the early 1950s may not have been as accurate as it is today - but it is what it is.              
  • WFO Milwaukee/Sullivan has had a documented tornado event in its County Warning Area (CWA) every calendar year going back to at least 1986, except for 2012.  In 2012 there were no tornado events in its CWA due to a precipitation drought and fewer thunderstorms.

Number of Tornado Warnings & Events (SC & SE Wisconsin)

For years of 1994 through 2012, when MKX had use of an in-house radar, we averaged 22 tornado warnings per year and 10 tornado events per year in our county warning area.

Milwaukee/Sullivan CWA

Year

Tor Wrngs

Tor Events

1994

33

8

1995

17

2

1996

22

13

1997

16

4

1998

8

2

1999

8

2

2000

15

6

2001

8

4

2002

15

4

2003

31

9

2004

29

15

2005

50

19

2006

44

10

2007

19

5

2008

42

25

2009

15

8

2010

42

25

2011

9

8

2012

0

0

Total

423

169

Average

22

9

Earliest & Latest Starts of Tornado Season (SC & SE Wisconsin)

The earliest start in the MKX County Warning Area (CWA)...Jan 7, 2008...when two tornadoes spun up in Kenosha and Walworth Counties.

The latest start to the tornado event season in MKX's CWA...September 22, 1961.  That was the only day with a tornado in the MKX County Warning Area that year.  We had 2 tornado events in the MKX county warning area that year...both on Sep 22nd.

The latest "last" tornado in the MKX county warning area...November 22, 2010.

Typical Start Month of Tornado Season (SC & SE Wisconsin)

Below is a table showing which calendar months were the "start" month of the tornado season in WFO Milwaukee's CWA, for the period of 1950 through 2012, or 63 years.  Note the 3 months of April, May, and June are the most common months for the first tornado to spin up in the MKX CWA.  There were 3 years with no tornadoes in the MKX CWA - 1952, 1953, and 2012. 

WFO MKX CWA

Tornado Start Months

Jan

2

Feb

0

Mar

5

Apr

15

May

14

Jun

17

Jul

4

Aug

2

Sep

1

None

3


Kapela, WFO Milwaukee/Sullivan



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