Public Information Statement
Issued by NWS Chicago, IL

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NOUS43 KLOT 032212
PNSLOT
ILZ014-041015-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
512 PM CDT WED JUN 3 2015

...ABNORMALLY QUIET MAY AND SPRING FOR SEVERE WEATHER...

MAY 2015 WAS ABNORMALLY VOID OF SEVERE WEATHER ACROSS NORTH
CENTRAL AND NORTHEAST ILLINOIS AS WELL AS NORTHWEST INDIANA. IN
FACT...DATING BACK TO 1989 THERE HAVE ONLY BEEN 3 YEARS (0
WARNINGS IN 1992 AND 2002 AND ONLY 1 WARNING IN 1990) WITH FEWER
SEVERE THUNDERSTORM AND TORNADO WARNINGS ISSUED DURING WHAT IS
TYPICALLY ONE OF OUR REGION`S BUSIEST MONTHS FOR SEVERE WEATHER.
DURING MAY 2015 ONLY 2 SEVERE THUNDERSTORM WARNINGS WERE ISSUED
(ONE ON MAY 5TH, ONE ON MAY 8TH) AND NO TORNADO WARNINGS WERE
ISSUED. DATING BACK TO 1989...THE AVERAGE NUMBER OF CONVECTIVE
WARNINGS (TORNADO AND SEVERE THUNDERSTORM) ISSUED BY OUR OFFICE IN
MAY IS AROUND 28...SO 2015 WAS CERTAINLY WELL BELOW AVERAGE. THE
BUSIEST MAY IN TERMS OF SEVERE WEATHER WAS BACK IN MAY 2004 WHEN
131 CONVECTIVE WARNINGS WERE ISSUED...WHICH INCLUDES 26 TORNADO
WARNINGS!

THROUGH THE END OF MAY...IT HAS ALSO BEEN AN UNUSUALLY QUIET
SEVERE WEATHER SEASON WITH A TOTAL OF ONLY 24 CONVECTIVE WARNINGS
ISSUED BY OUR OFFICE...WHICH IS TIED FOR THE 7TH QUIETEST START
TO SEVERE WEATHER SEASON. OF THOSE 24 WARNINGS...NEARLY ALL OF
THEM (22) WERE ISSUED DURING THE APRIL 8-9TH SEVERE WEATHER
EVENT.

INTERESTINGLY...DATING BACK TO 1989...THE TOP 10 SEASONS THAT HAD
THE FEWEST WARNINGS ISSUED UP THROUGH MAY 31ST...ALSO TENDED TO
SEE THE TREND FOR BELOW AVERAGE SEVERE WEATHER CONTINUE FOR THE
REMAINDER OF THE YEAR. IN FACT...OF THE 10 YEARS WITH THE SLOWEST
STARTS...6 OF THEM SAW A BELOW AVERAGE NUMBER OF WARNINGS ISSUED
AFTER JUNE 1ST...3 WERE NEAR NORMAL...AND ONLY ONE YEAR (2010) SAW
AN ABOVE AVERAGE NUMBER OF WARNINGS AFTER JUNE 1ST.

AS WAS EVIDENCED BY THE APRIL 9TH TORNADO OUTBREAK...IT IS NOT
NECESSARY FOR A SEVERE WEATHER SEASON TO HAVE BELOW...OR EVEN
NEAR...AVERAGE NUMBER OF WARNINGS IN ORDER FOR THERE TO BE
DESTRUCTIVE...LIFE ALTERING SEVERE WEATHER EVENTS. IN
FACT...PRIOR TO THE APRIL 9TH TORNADO...THE PREVIOUS VIOLENT
TORNADO IN OUR AREA WAS BACK IN AUGUST OF 1990...ANOTHER YEAR
WHICH FEATURED A BELOW AVERAGE AMOUNT OF SEVERE WEATHER THROUGH
MAY AS WELL AS FOR THE ENTIRE YEAR.

$$

IZZI/BORCHARDT



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