Colorado Eight-Day Maximum Snow Extent

The following images show eight-day maximum snow extent in May of each year, beginning in 2000 when MODIS data were first available. May was chosen to show variations in mountain snow pack during the snowmelt season; however, 2002 and 2004 were drought years. Spatial extent is just one variable that indicates potential snowmelt runoff (other indications include snow depth and snow water equivalent), but it is routinely used with snow survey measurements, snowmelt runoff models, and basin Digital Elevation Models (DEMs) to develop snowmelt runoff curves and water supply forecasts for downstream water users.

A quick look at the 2002 and 2003 images below shows how significant the effects of the widespread drought in 2002 were on the snowpack in the Colorado Rockies, the headwaters for four of the nation's major river systems. For an article about the 2004 winter and spring drought in Colorado, visit the Dry Denver news article on NASA's Earth Observatory Web site.

Images are derived from the Maximum Snow Extent field of the MODIS/Terra Snow Cover 8-Day L3 Global 500m Grid, Version 4 data set, available from NSIDC. Click on the thumbnails below to view larger images.

17-23 May 2000 View larger image (23 KB)	17-23 May 2001 View larger image (21 KB)
09-16 May 2002 View larger image (19 KB)	17-23 May 2003 View larger image (21 KB)
24-31 May 2004 View larger image (20 KB)	09-16 May 2005 View larger image (20 KB)