The author expresses his appreciation to S. Dore and B. Sullivan (NAU School of Forestry) for kindly providing the quality-controlled wind dataset. B. Klimowski (NOAA/NWS) provided the tornado track figures.
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Twelve surveyed damage paths were considered for this study: 21 February 2000 (1), 9 September 2003 (1), 4 September 2004 (1), 18 October 2005 (2), 14 October 2006 (1), and 6 October 2010 (6).
This is for a Northern Hemisphere cyclonic vortex.
Cool-season tornadoes (mid-September–May) in northern Arizona are more likely to be associated with supercell thunderstorms than tornadoes occurring during the low-shear warm season (June–early September).
Local time (mountain standard time, MST) is UTC − 7.
Disclaimer: The National Oceanic and Atmospheric Administration/National Weather Service (NOAA/NWS) does not approve, recommend, or endorse any proprietary product or proprietary material mentioned in this publication.
D. Speheger (2011, personal communication) asked the same question after viewing an Oklahoma tornado in the spring of 2011. He noted “The tornado was probably 20–30 yards wide and the angular momentum and vertical motion were among the most intense I have witnessed. Any damage-based intensity estimate will likely be underrated given the very short dwell time at any location and any time averaging (even the 3s wind speed estimates of the EF scale) will be significantly lower than the near-instantaneous wind speeds at any point in space with such a small, dynamic tornado.”
Although no live trees were left standing in the vicinity of the sonic anemometer (35.4454°, −111.77184°), there were several dead snags that were toppled. These were used to determine the path and most probable vortex center. Using this information, it was likely that the vortex center passed with a few tens of meters of the instrument.