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“Lake effect” snow in northern Alabama

By Scott Bachmeier •

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Wheeler Lake is a reservoir along the Tennessee River in northern Alabama. The Aqua MODIS Sea Surface Temperature product (above) showed that water temperatures along the axis of the lake were as warm as the lower 50s F (cyan color enhancement) on 07 February 2016.

Following the passage of a strong cold front on 08 February, the northwesterly flow of air with surface temperatures in the 30s F on 09 February allowed for a narrow “lake effect” (or in this case, river effect) snow band to form over Wheeler Lake, which created accumulating snowfall to the southeast (downwind) of the lake. This lake effect snow band could be seen in a RealEarth composite of Suomi NPP VIIRS / Aqua MODIS true-color Red/Green/Blue (RGB) images and radar reflectivity (below). The lake effect plume began to shift northward during the afternoon hours, as surface winds briefly backed to a more westerly direction.

Suomi NPP VIIRS and Aqua MODIS true-color images, combined with radar refectivity [click to enlarge]

Suomi NPP VIIRS and Aqua MODIS true-color images, combined with radar refectivity [click to enlarge]

On 10 February, the northwesterly flow of cold air was less pronounced, but was still enough to allow for a narrow lake effect plume to be seen early in the day on 1-minute interval GOES-14 Super Rapid Scan Operations for GOES-R (SRSO-R) images (below; also available as a large 89 Mbyte animated GIF). As the clouds cleared during the afternoon hours, small patches of white snow cover could be seen just southeast of Wheeler Lake.

GOES-14 Visible (0.63 µm) images [click to play MP4 animation]

GOES-14 Visible (0.63 µm) images [click to play MP4 animation]

In a comparison of Terra MODIS true-color and false-color RGB images (below), the presence of snow cover (cyan in the false-color image) could be seen between the lines of cumulus clouds.

Terra MODIS true-color and false-color images [click to enlarge]

Terra MODIS true-color and false-color images [click to enlarge]

Data from NOHRSC (below) showed that as much as 3.0 inches of total snowfall was measured downwind of Wheeler Lake (in the higher elevation of the Union Hill area) during the 09-11 February period, and the snow depth on the morning of 10 February was 2.5 inches at that location (enough to be seen on the GOES-14 visible images above).

24-hour snowfall amounts ending at 12 UTC on 09, 10, and 11 February [click to enlarge]

24-hour snowfall amounts ending at 12 UTC on 09, 10, and 11 February [click to enlarge]

Snow depth during the 24-hour period ending at 12 UTC on 09, 10, and 11 February [click to enlarge]

Snow depth during the 24-hour period ending at 12 UTC on 09, 10, and 11 February [click to enlarge]

Additional information and images of this event can be found here.

Categories: GOES-14, MODIS, RealEarth, Red-Green-Blue (RGB) images, Suomi NPP, VIIRS, Winter weather