Mesoscale Convective Vortex (MCV) in southern California

July 20th, 2013 |
Suomi NPP VIIRS 0,7 µm Day/Night Band and 11.45 µm IR channel images

Suomi NPP VIIRS 0,7 µm Day/Night Band and 11.45 µm IR channel images

A comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel data (above) showed a large mesoscale convective system in southwestern Arizona at 08:40 UTC or 2:40 am local time on 20 July 2013. With ample illumination from the Moon (which was in the Waxing Gibbous phase, at 96% of full), the “visible image at night” capability of the VIIRS Day/Night Band image allowed shadowing from overshooting thunderstorm tops to be clearly seen; the coldest cloud-top IR brightness temperature of the overshooting tops was -83º C (violet color enhancement). In addition, numerous cloud-to-ground lightning strikes were associated with the MCS at that time. A few hours earlier, this storm had produced reports of wind damage in the Phoenix area just after 05 UTC (SPC Storm Reports).

With the arrival of daylight, McIDAS images of GOES-15 (GOES-West) 0.63 µm visible channel data (below; click image to play animation) revealed the emergence of a well-defined and relatively compact Mesoscale Convective Vortex (MCV) that continued to move westward across southern California during the day. The MCV also played a role in helping to iniitate additional convection in areas such as the San Bernadino Mountains of southern California.

GOES-15 0.63 µm visible channel images (click image to play animation)

GOES-15 0.63 µm visible channel images (click image to play animation)

A comparison of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 20:05 UTC (below) showed that the clouds associated with the MCV were primarily low to mid-level clouds, which exhibited IR brightness temperatures that were generally warmer than -20º C.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

For aditional information on MCVs, see the VISIT lesson “Mesoscale Convective Vortices“. For additional information on VIIRS imagery, see the VISIT lesson “VIIRS Satellite Imagery in AWIPS“.