Using Channel 3 (water vapor) Imagery to Derive Winds

GOES Channel 3 imagery sequences can be used to derive upper-level wind vectors, with the winds plotted on the image valid at the time of the winds. The wind speeds and directions are derived from the images while the height assignments are done using model forecasts and quality assurance procedures to correct heights which may not fit the analysis.

In this 28 August 1998 water vapor image, over Hurricane Bonnie, the white areas and areas where cirrus are present (overlayed with the blue wind barbs) are assigned a height of 100-250 mb. Bonnie's cirrus clouds can clearly be seen in the outflow pattern of the hurricane. Cirrus bands provide excellent targets to be tracked by the wind vector generating algorithm. The yellow wind barbs represent cloud heights between 251-350 mb. These clouds are "lower" than the clouds which have colder temperatures in the nearby area. The green barbs represent heights of 351-500 mb, which is the lowest height assignment layer for winds derived from water vapor imagery. The areas with green barbs are often the result of significant sinking and warming as can be seen to the west and north of Bonnie's circulation.