Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Thursday November 20, 1997
Figure 1 shows the visible image. There was an extensive white region over the Dakota's, Minnesota, northern Iowa and extreme northern Illinois. There was also a small east west white band over southern Wisconsin.
Figure 2 is a display of channel 2. An examination of this shows that the white region over the Dakota's is mostly snow since it appears dark in this channel. The snow extends over extreme southwest Minnesota, northern Iowa and northern Illinois. Note the sharp contrast between the bright liquid water cloud over most of Minnesota and the dark snow around it. There was a small region of liquid water cloud over extreme northeast South Dakota. Note also the bright liquid water cloud over southern Wisconsin. The reflectivity product, Figure 3, also shows the same features as seen in channel 2 only with better contrast.
The dark region in Figures 2 and 3 show a dark region over western Wisconsin. This same region shows up white in the visible. One is unable to determine if this is snow on the ground or an ice water cloud above the liquid water cloud deck. What channel would one need in order to figure this out?
As the past few satellite discussions on snow detection have shown, multichannel analysis is necessary in this endeavor.