Landspout Tornado on the Southwest Side of Chicago on Tuesday August 9, 2016

Overview

A landspout tornado (or more simply, a landspout) formed on the lake breeze boundary on Tuesday afternoon August 9th just prior to 4pm CDT. This landspout was observed by Melanie Harnacke, the FAA contract observer on duty at Midway Airport. The tornado was estimated to have begun at 3:48 PM CDT and dissipated at 3:58 PM CDT. This was the first tornado within the city limits of Chicago since a brief F-0 on the campus of Loyola University on September 22, 2006.

Here is the definition of a landspout from the National Severe Storms Laboratory (NOAA NSSL): A landspout is a tornado with a narrow, rope-like condensation funnel that forms while the thunderstorm cloud is still growing and there is no rotating updraft - the spinning motion originates near the ground. In the case of the Chicago landspout, there was no rain shower or thunderstorm, just cumulus clouds along the lake breeze. Therefore, without a rain shower or thunderstorm, there was no way for the NWS Chicago radar to detect any rotation in the area where the landspout occurred.

Additional landspout definitions:

From NWS Glossary: A tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone (on radar). Landspouts typically are observed beneath Cbs or towering cumulus clouds (often as no more than a dust whirl), and essentially are the land-based equivalents of waterspouts.

Unlike most tornadoes which form beneath a rotating (supercell) thunderstorm, landspout tornadoes form when an area of preexisting rotation near the ground becomes positioned beneath a rapidly developing thunderstorm cloud. The quickly rising air lifting into the cloud stretches the area of rotation near ground level vertically, resulting in an intensification of the spin and the formation of a landspout tornado. Normally landspout tornadoes don't last very long or get very strong, though they can do minor damage before dissipating.

Comparing the Chicago Landspout to Central Illinois Landspouts on May 28, 2014


Chicago landspout information	Central IL landspouts on May 28, 2014

Photos & Video
Storm Reports

Photos & Video:


From Midway Airport Melanie Harnacke, MDW observer	From Midway Airport Melanie Harnacke, MDW observer	From Midway Airport Melanie Harnacke, MDW observer


From WGN Willis Tower Cam Courtesy of WGN 9 Chicago	From WGN Willis Tower Cam Courtesy of WGN 9 Chicago

Storm Reports

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
531 PM CDT WED AUG 10 2016

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

0348 PM     TORNADO          2 ESE CICERO            41.83N 87.73W
08/09/2016                   COOK               IL   OTHER FEDERAL

            FAA CONTRACT OBSERVER FOR MIDWAY AIRPORT SPOTTED A
            LANDSPOUT TORNADO THAT HAD FORMED ON THE LAKE BREEZE. THE
            TORNADO DISSIPATED AT 358 PM CDT. LOCATION IS APPROXIMATE
            BASED OFF PHOTOS TAKEN BY THE OBSERVER AND OTHER PHOTOS
            POSTED TO SOCIAL MEDIA...JUST SOUTHWEST OF THE
            INTERSECTION OF W 33RD STREET AND S PULASKI RD IN A LARGE
            INDUSTRIAL PARK. NO DAMAGE HAS BEEN REPORTED. THIS IS THE
            FIRST TORNADO WITHIN THE CITY LIMITS OF CHICAGO SINCE A
            BRIEF F-0 ON THE LOYOLA UNIVERSITY CAMPUS ON SEP. 22
            2006.


&&

$$

RC

Raw METAR Observation from the Midway Airport Observer

KMDW 092050Z 23007KT 10SM FC BKN055 BKN200 BKN250 32/16 A2998 RMK FUNNEL CLOUD B49 5 NE AO2

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Snow Across the Great Lakes, Central Appalachians, and Northeast; Unsettled Weather in the West

Landspout Tornado on the Southwest Side of Chicago on Tuesday August 9, 2016