Mesoscale Convective Vortex over Nevada

August 19th, 2013 |

 

GOES-13 10.7 µm IR channel images (click image to play animation)

GOES-13 10.7 µm IR channel images (click image to play animation)

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel data (above; click image to play animation) showed areas of nocturnal thunderstorms over southeastern California, western Arizona, and southern Nevada on 19 August 2013. These storms were initially producing numerous cloud-to-ground lightning strikes and exhibiting cloud-top IR brightness temperatures as cold as -66 C, but they began to dissipate toward sunrise as they continued to move northward.

A comparison of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images at 09:17 UTC (below) provided a good example of the “visible image at night” capability of the Day/Night Band.

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

The GOES-14 satellite had been placed into Super Rapid Scan Operations for GOES-R (SRSO-R) mode, and was providing images at 1-minute intervals on this day. Once the cirrus canopy from the dissipating thunderstorms eroded, the GOES-14 0.63 µm visible channel images (below; click image to play animation; also available as a QuickTime movie) revealed the presence of a small yet well-defined Mesoscale Convective Vortex (MCV) which continued to propagate northward across far eastern Nevada. Toward the end of the animation (20:57 UTC), the MCV appeared to be playing a role in the initiation of new convection along its northern (leading) edge.

GOES-14 0.63 µm visible channel images (click image to play animation)

GOES-14 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 20:43 UTC (below) showed that there were a couple of negative polarity cloud-to-ground lightning strikes (yellow) being produced by the convection that developed along the leading edge of the MCV.

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

 

Blended Total Precipitable Water product

Blended Total Precipitable Water product

The Blended Total Precipitable Water (TPW) product (above, shown at 3-hour intervals) indicated that a plume of TPW values in the 30-38 mm or 1.2-1.5 inch range (varying shades of yellow) were in place over the region where the thunderstorms had developed and moved northward. These monsoonal TPW values were 175-200% of normal for this area and this time of year (below).

Blended Total Precipitable Water Percent of Normal product

Blended Total Precipitable Water Percent of Normal product

 

GOES IR image with GFS 850-500 hPa shear

GOES IR image with GFS 850-500 hPa shear

In addition, the 850-500 hPa wind shear values across the region at 12 UTC (above) and 18 UTC (below) were relatively low, creating a favorable environment for the MCV to persist for several hours.

GOES IR image with 850-500 hPa shear

GOES IR image with 850-500 hPa shear

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