Tornadic Storms in San Joaquin Valley, 11/22/96

On November 22, 1996, several lines of thunderstorms developed over north-central California and then moved into the San Joaquin Valley. At around 2200 UTC a number of tornadoes touched down, including an F1 near Merced, an F1 at Lemoore Naval Air Station, and F0 tornadoes at Lemoore and Bakersfield. The Lemoore tornadoes were associated with a supercell thunderstorm that developed on the south end of a line that extended into Kings County. This storm showed a pronounced "right-moving" tendency and had a mesocyclone that was monitored on KMUX WSR-88D site in the Santa Cruz Mountains, over 140 miles away. The Merced tornado was associated with a thunderstorm that may have been rotating given the buoyancy and shear parameters that were occurring in the area at the time. These pages are underdevelopment and will eventually include sections on radar, buoyancy and shear.

Supercell--a thunderstorm with a deep (1/3 to 1/4 of the depth of the precipitation echo) and persistant (circulation lasts at least 15 minutes) mesocyclone [definition from Johns and Doswell (1992)].

Visible Satellite, GOES 9, 2345 UTC, 11/22/96 Showing Lemoore Supercell Shortly After Tornado Touchdowns Note the overshooting top highlighted by the setting sun. This storm developed on the south end of a line of storms moving into a buoyancy-rich environment characterized by very favorable shear. Bulk Richardson Numbers were in the 10 to 20 range in the prestorm environment over this portion of California. Storm-relative helicities approached 400 m^2/^2 for the motion of the storm.

Comparison of Visible Satellite, GOES 9,
2345 UTC, 11/22/96 to Model of Supercell

The expanded visible image of the cumulonimbus evident in the larger view above shows the storm about 1 hour after two damaging tornadoes and giant hail (>2 in diameter) struck Naval Air Station Lemoore. The schematic at the right shows some features associated with a typical supercell (after Doswell (1985)). Note the correspondence of the flanking line and anvil edge of the Lemoore storm to the schematic view.

This shows schematic radar sections intersecting a classic supercell at 1, 4, 7, 10 and 13 km above ground level. Contours are radar reflectivity in dBZ. Note the low level hook (1 and 4 km) surmounted by the symmetric echo at 10 km producing a Bounded Weak Echo Region (BWER). Click on map or chart to obtain larger version. Note: Actual doppler imagery showing rotation at high levels of Lemoore storm monitored from KMUX radar, over 100 miles away, will be place here soon.