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Two Storms Tracking through the Southwest and Southcentral U.S.

A storm over the southwest U.S. will shift east through Thursday while another Pacific storm pivots over the region Friday through the weekend. Widespread low elevation rain and high elevation snow showers are expected with each storm. Both storms will shift over the central U.S. with the first occurring tonight through Thursday and the second Saturday night into Monday. Flood Watches issued. Read More >

Most Tornadoes in a Year on Record in NWS Chicago CWA in 2015
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PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
904 PM CDT THU AUG 27 2015

...MOST TORNADOES ON RECORD IN NWS CHICAGO FORECAST AREA IN 2015...

THE FOUR TORNADOES ON AUGUST 18 2015 BROUGHT THE TOTAL NUMBER OF
CONFIRMED TORNADOES IN THE COUNTIES OF THE NWS CHICAGO COUNTY
WARNING AREA (CWA) IN 2015 UP TO 29. THIS BROKE THE PREVIOUS RECORD
OF MOST TORNADOES IN THE NWS CHICAGO CWA COUNTIES IN A YEAR SET
IN 2004...WHICH HAD 27 TORNADOES. THE PERIOD OF RECORD IS
1950-2015.

NOTE THAT IT IS LIKELY THAT MANY OF THE EARLIER YEARS IN THE
DATASET HAD WEAK (F0-F1) TORNADOES THAT WENT UNDETECTED. THE
MODERN NETWORK OF SPOTTERS AND IMPROVED RADAR TECHNOLOGY HAS
ALLOWED FOR BETTER DETECTION OF WEAK TORNADOES. THIS INCLUDES
THE INTRODUCTION OF CURRENT DOPPLER RADAR TECHNOLOGY TO THE NWS
IN 1992 AND DUAL POLARIZATION IN 2012. WITH THAT BEING SAID...
2015 HAS BEEN AN EXCEPTIONALLY ACTIVE YEAR FOR TORNADOES IN THE
NWS CHICAGO FORECAST AREA.

TOP 10 MOST TORNADOES IN NWS CHICAGO CWA COUNTIES IN A CALENDAR YEAR
--------------------------------------------------------------------

RANK  YEAR  NUMBER OF TORNADOES 
----  ----  ------------------- 
 1    2015          29 
 2    2004          27 
 3    1974          22 
      2010          22 
 4    1965          21 
 5    2003          18 
      2008          18 
      2011          18 
      2014          18* ALL TORNADOES OCCURRED ON 6/30 
 10   1967          17 
      1972          17 
      2013          17

THE AVERAGE NUMBER OF TORNADOES PER YEAR IN THE COUNTIES OF THE
NWS CHICAGO CWA FROM 1950-2015 IS 9 (8.98).

THE CURRENT LOCATION OF NWS CHICAGO AND THE KLOT WSR-88D DOPPLER
RADAR OPENED IN 1992. THIS IS ALSO WHEN THE CURRENT ALIGNMENT OF
COUNTIES IN THE CWA DATES BACK TO. THE AVERAGE NUMBER OF
TORNADOES IN THE NWS CHICAGO CWA FROM 1992-2015 IS 11 (10.8).

NWS CHICAGO CWA COUNTIES
------------------------
IL: BOONE, COOK, DE KALB, DUPAGE, FORD, GRUNDY, IROQUOIS, KANE,
    KANKAKEE, KENDALL, LAKE, LA SALLE, LEE, LIVINGSTON, MCHENRY,
    OGLE, WILL, WINNEBAGO

IN: BENTON, JASPER, LAKE, NEWTON, PORTER

$$

RC/MTF/BMD

* These statistics were compiled largely from the 1950-2014 US Tornadoes Database at the Storm Prediction Center WCM Page.

Other Links

Past Weather Event Write-Ups at NWS Chicago Science Page