Heavy snow in the Black Hills region

May 4th, 2008 |

GOES-12 water vapor images (Animated GIF)

AWIPS images of the GOES-12 6.5 µm “water vapor” channel (above) showed the development of late-season winter storm that produced heavy snowfall and blizzard conditions (with wind gusts to 64 mph or 29 m s-1 at Rapid City SD) across the Black Hills region and surrounding portions of eastern Wyoming, southeastern Montana, and western South Dakota during the 30 April through 02 May 2008 period. A closer view using GOES-12 10.7 µm IR images reveals that there were a number of cloud-to-ground lightning strikes during various phases of the storm’s development, as large convective elements formed and intensified upwind of the Black Hills.

MODIS true color image

A MODIS true color image (above, viewed using Google Earth) shows the areal extent of the snow cover on 03 May 2008, as well as the locations of the heaviest total snowfall amounts: 54.5 inches (138 cm) at Lead SD, and 24.0 inches (61 cm) at Sundance WY.

MODIS true color and false color images (Animated GIF)

A comparison of MODIS true color and false color images from 03 May (above) demonstrates how the false color imagery (which uses the MODIS 2.1 µm near-IR channel) can differentiate between snow cover (which, along with ice crystal clouds and ice-covered lakes, appear as cyan-colored features) and supercooled water droplet clouds (which appear as shades of white).

Consecutive daily MODIS false color images from 02, 03, and 04 May (below) show that the snow cover was melting rapidly under the influence of the strong May sun. The 54.5 inches of snow that fell at Lead SD had a liquid equivalent of 4.64 inches (12 cm), so the rapid snowmelt led to a quick rise of creeks and streams that caused some flooding problems.

MODIS false color images (Animated GIF)