Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Wednesday July 9, 1997
Today's images focus on a mesoscale convective vortex (MCV) that occurred on 8 July 1997. The vortex formed in association with a mesoscale convective system (MCS) that moved from SD and NE and decayed in IA and MO.
Discussion of Images: The MCV is the cyclonically rotating cloud region embedded within a larger region of anticyclonic rotation in west-central MO (see visible loop).
http://www.cira.colostate.edu/RAMM/PICODAY/7897/loop.html).
The anticyclonic rotation around the outer edges of the spiral bands are cirrus clouds associated with the remnants of the MCS. We can use the 10.7 um imagery (Fig. 2) to identify these as higher clouds. The MCV, a mid-level phenomenon, shows up as a warmer region withing this cirrus ring. A similar pattern appears in the water vapor imagery (6.7 microns, Fig. 3). However, notice that the mid-level cloudiness which is clearly seen on the 10.7 um imagery is not apparent in the water vapor image. This is because the peak response for the 6.7 um channel is well above the level of these mid-level clouds. The anticyclonic flow visible in the cirrus motions is likely due -- at least in part -- to the synoptic scale anticyclonic flow at that level. Some of this anticyclone motion may also have to do with internal dynamics of the system.
As might be expected, convection develops within the MCV later in the afternoon. The satellite imagery is essential for identifying MCVs since the MCV is a mesoscale phenomenon theat typically cannot be detected by RAOBs.
Eric Hilgendorf