An Analysis Of The 7 July 2004

Rockwell Pass, CA Tornado:

Highest Elevation tornado documented in the US


High Resolution Figures -- Click on Image to See Higher Resolution Version



Figure 1 – Developing tornado near Rockwell Pass in Sequoia National Park, 7 July 2004. Note cinnamon-colored swirl on apparently lowered base. The sense of the rotation is counterclockwise. View towards the northwest. (Photo by Scott Newton)


Figure 2 –USGS topographic map showing location of Rockwell Pass, the Rattlesnake RAWS site and the Kern River Canyon, as explained in the text.


Figure 3 – Severe-sized hail collected by photographer during thunderstorm associated with the Rockwell Pass tornado. (Photo by Scott Newton)


Figure 4 –Rockwell Pass tornado at approximately 2342 UTC (4:42 PM PDT). Note debris at funnel base and large hail falling. (Photo by Scott Newton)


Figure 5 – Panoramic photograph of thunderstorm that spawned Rockwell Pass tornado taken on 07 July between Lone Pine and Keeler, CA, at 2317 UTC (4:17 PM PDT), looking to the northwest. Note the backsheared anvil and overshooting top. (Photo by Bill Hensley)


Figure 6 –Map of south-central California, showing locations of Rockwell Pass, KHNX, KVBG and KEYX, as discussed in the text.


Figure 7 – NCEP reanalyses at 0000 UTC 8 July 2004 showing (a) 300 mb heights (dm) and 850 mb vertical velocity (µbar s-1); and, (b) 1000-500 mb thickness (dm) and 700 mb absolute vorticity (10-4 s-1). Location of Rockwell Pass storm shown as ÒTÓ. Arrow on (b) indicates the thermal wind, and can be used to infer the region of cyclonic vorticity advection by the thermal wind and quasigeostrophic forcing for upward motion at 700 mb.


Figure 8 – Fronts and selected surface observations and infrared satellite imagery for selected hours on the day of the Rockwell Pass tornado. White dashed/blue jagged line show the positions of the 300 mb short wave trough and downstream ridge (as explained in the text) at the same times. Yellow arrow shows the position of the Rockwell Pass thunderstorm. (Charts courtesy of Unisys)



Figure 9. Proximity sounding and hodograph (generated by NSHARP) at 0000 UTC 8 July 2004, as explained in the text.



Figure 10. Radar reflectivity at 0.5¡, 1.5¡, 2.4¡, and 3.3¡ elevation angles from KEYX at 2340 UTC 7 July 2004. Location of the tornado at Rockwell Pass is shown as a red dot.



Figure 11. Doppler radar radial velocity at 0.5¡, 1.5¡, and 2.4¡ elevation angles, and reflectivity at 0.5¡ elevation angle from KEYX at 2340 UTC 7 July 2004. Location of the tornado at Rockwell Pass is shown as a red dot.