Tornadoes in Northern California
1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed thunderstorms moving eastward across Northern California on 04 January 2021, which produced 2 tornadoes (SPC Storm Reports) in the Sacramento Valley south and southeast of Red Bluff (KRBL). Vertical wind shear was evident in the Visible imagery, with low clouds moving northwestward and mid/upper-level clouds moving eastward.A toggle between Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 2148 UTC (below) showed the storm that produced a tornado in Corning approximately 8 minutes earlier. The coldest cloud-top infrared brightness temperatures were around -38ºC (darker shades of yellow).
MIMIC Total Precipitable Water images during the 02-04 January time period (below) showed a long ribbon of moisture (a necessary ingredient for convection) impinging upon Northern California — and a mid-tropospheric trough (500 hPa analysis) along with a cold front that was moving inland (surface analyses) provided forcing for ascent to further enhance convective development.