A Look Back at Sunday's Brief Tornado in LaSalle County

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Tornado
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
703 PM CDT MON SEP 2 2013 /803 PM EDT MON SEP 2 2013/

...BRIEF EF-0 TORNADO OCCURRED IN NORTHEAST LASALLE COUNTY ON SEPT
1ST..

WHILE A NATIONAL WEATHER SERVICE STORM SURVEY DID NOT LOCATE ANY
DAMAGE IN NORTHEAST LASALLE COUNTY FROM SUNDAY EVENING
STORMS...DETAILED REPORTS FROM STORM SPOTTERS AND PUBLIC
ACCOUNTS COMBINED WITH PHOTOS AND VIDEOS INDICATE THAT A BRIEF
TORNADO LIKELY OCCURRED. ACCOUNTS OF THE NEAR GROUND CONDENSATION
FUNNEL WERE USED FOR THE ESTIMATED PATH. ALMOST HALF OF THE TRACK
OF THE VISIBLE FUNNEL WAS NOT ACCESSIBLE...SO THERE CERTAINLY COULD
HAVE BEEN MINOR CROP OR TREE DAMAGE IN SOME OF THESE LOCATIONS.

* EVENT TYPE: EF-0 TORNADO.

* INJURIES: NONE.

* ESTIMATED BEGIN TIME/LOCATION: 09/01/2013...642 PM CDT
                                 4 MILES NW OF SERENA IL OR
                                 4.5 MILES W OF SHERIDAN IL
                                 LAT 41.5305 LON -88.7745

* ESTIMATED END TIME/LOCATION: 09/01/2013...647 PM CDT
                               2.5 MILES NW OF SERENA IL OR
                               4.5 MILES WSW OF SHERIDAN IL
                               LAT 41.5070 LON -88.7720

* PATH LENGTH: <2 MILES.

* MAXIMUM ESTIMATED WIND SPEEDS: 65 MPH.

* MAXIMUM ESTIMATED PATH WIDTH: <50 YARDS.

* DISCUSSION: THERE WERE NO DIRECT REPORTS OF SEEING DUST OR DEBRIS
AT GROUND LEVEL...BUT MULTIPLE EYE-WITNESS REPORTS DID INDICATE THE
GROUND UNDERNEATH THE FUNNEL WAS MASKED BY TREES OR JUST SIMPLY TOO
FAR TO SEE DUE TO DISTANCE. ALSO...THE CONDENSATION OF A FUNNEL DOES
NOT ALWAYS REACH THE GROUND WITH A TORNADO...WHILE THE ROTATING
COLUMN OF AIR DOES. AN INTERESTING NOTE WAS THAT THREE PUBLIC
ACCOUNTS FROM VERY NEARBY TO THE LIKELY TORNADO INDICATED IT WAS
VERY STILL AS THE CONDENSATION FUNNEL PASSED. BASED ON ENVIRONMENTAL
ANALYSIS THIS WAS LIKELY DUE TO WEAK LOW-LEVEL INFLOW...WHICH IS NOT
THE USUAL CASE DURING THE MORE CLASSIC SUPERCELL TORNADOES. THIS IS
PROBABLY ONE REASON THE TORNADO STRUGGLED TO PERSIST.

$$

MTF/MDB


Photos

Storm structure

Photo courtesy of Leticia Lemus

Zoomed in photo

Zoomed in from above. Photo courtesy of Leticia Lemus

Tornado photo

Tornado photo

Photo courtesy of Kelli Shanley DeWalt

 Photo courtesy of Allie Rohrer 


 

Radar

Following is approximately a 15 minute radar loop centered around the time the tornado may have touched down.  Early in the loop, a broad and weak circulation is noted just west of Sheridan.  The red outbound colors indicate movement away from the radar, while the green inbounds indicate movement toward the radar.  The circulation tightens up briefly as indicated by the brighter red and green couplet.

Radar_Loop


 

Environment

Environment

Click to enlarge


 

Storm Reports

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
845 PM CDT MON SEP 02 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0642 PM     TORNADO          4 NW SERENA             41.53N 88.77W
09/01/2013  F0               LA SALLE           IL   TRAINED SPOTTER

            WHILE AN NWS STORM SURVEY TEAM DID NOT FIND ANY
            DAMAGE...DETAILED REPORTS FROM STORM SPOTTERS AND PUBLIC
            ACCOUNTS COMBINED WITH PHOTOS AND VIDEOS INDIATE A BRIEF
            TORNADO LIKELY OCCURRED. PATH LENGTH WAS ESTIMATED TO BE
            AROUND 1.5 MILES FROM 4NW OF SERENA TO 2.5NW OF SERENA.
            MAXIMUM ESTIMATED WIND SPEED WAS 65 MPH AND WIDTH LESS
            THAN 50 YDS.

0645 PM     HAIL             SHERIDAN                41.53N 88.69W
09/01/2013  E0.75 INCH       LA SALLE           IL   PUBLIC

            THIS IS A DELAYED REPORT. REPORT RELAYED TO NWS DURING
            DAMAGE SURVEY.

0813 PM     HEAVY RAIN       CRYSTAL LAKE            42.23N 88.33W
09/01/2013  M1.00 INCH       MCHENRY            IL   AMATEUR RADIO

            RAIN FELL IN LESS THAN 45 MINUTES AT WALKUP AND CRYSTAL
            SPRINGS ROADS.

0827 PM     TSTM WND GST     INVERNESS               42.12N 88.10W
09/01/2013  E55.00 MPH       COOK               IL   TRAINED SPOTTER

0844 PM     TSTM WND GST     NILES                   42.03N 87.81W
09/01/2013  E45.00 MPH       COOK               IL   TRAINED SPOTTER

            TRAINED SPOTTER AT WISE ROAD AND ROSELLE ROAD.

0850 PM     HEAVY RAIN       5 SW WAUCONDA           42.23N 88.22W
09/01/2013  M1.94 INCH       MCHENRY            IL   COCORAHS

            RAIN FELL IN 35 MINUTES.

0930 PM     HEAVY RAIN       SSE CAROL STREAM        41.91N 88.13W
09/01/2013  M0.95 INCH       DUPAGE             IL   COCORAHS

            RAIN FELL IN PAST 25 MINUTES. TORRENTIAL RAINS THROUGHOUT
            THE PERIOD. REDUCED VISIBILITIES. GUSTY WINDS TO 40 MPH.

0950 PM     HEAVY RAIN       BARTLETT                41.98N 88.21W
09/01/2013  M1.04 INCH       DUPAGE             IL   TRAINED SPOTTER

            RAIN FELL IN LAST 40 MINUTES.

1004 PM     HEAVY RAIN       PLAINFIELD              41.62N 88.20W
09/01/2013  M1.42 INCH       WILL               IL   TRAINED SPOTTER

            RAIN IN 22 MINUTES.

1030 PM     HEAVY RAIN       JOLIET                  41.53N 88.12W
09/01/2013  M1.58 INCH       WILL               IL   CO-OP OBSERVER

1048 PM     HEAVY RAIN       3 NW JOLIET             41.56N 88.16W
09/01/2013  M1.55 INCH       WILL               IL   NWS EMPLOYEE


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