Snow cover across southern Manitoba, northeastern North Dakota and northwestern Minnesota

October 6th, 2012 |
Suomi NPP VIIRS 0.64 µm visible image + VIIRS false-color Red/Green/Blue (RGB) image

Suomi NPP VIIRS 0.64 µm visible image + VIIRS false-color Red/Green/Blue (RGB) image

The first significant winter storm of the season over the north-central US and south-central Canada produced snowfall amounts as high as 14 inches over northwestern Minnesota and 4 inches over northeastern North Dakota on 04 October 2012. It is interesting to note that this snow event occurred 2 days after that same region was impacted by significant wildfire activity ahead of an advancing cold front.

The snow cover that remained on 06 October 2012 could be seen in an AWIPS comparison of a Suomi NPP VIIRS 0.64 µm visible channel image and the corresponding false-color Red/Green/Blue (RGB) image created using the 1.61 µm “snow/ice” channel (above), where the snow on the ground was enhanced with a brigher pink color. Note the lack of development of cumulus clouds over the deeper snow cover in northwestern Minnesota, where boundary layer stability was maintained by the lack of surface heating over the high-albedo snow surfaces.

A comparison of the MODIS 0.65 µm visible channel image with the corresponding MODIS Land Surface Temperature (LST) product (below) showed that LST values over the areas of deeper snow cover in northwestern Minnesota were only in the upper 20s to low 30s F (darker green color enhancement), while LST values just to the west over bare ground in far eastern North Dakota LST values were in the upper 40s to low 50s F (lighter green to yellow color enhancement). Surace air tempertures were alo recoverng more rapidly at nearby stations with no snow cover.

MODIS 0.65 µm visible image + MODIS Land Surface Temperature product

MODIS 0.65 µm visible image + MODIS Land Surface Temperature product

GOES-14 0.63 µm visible channel images (below; click image to play animation) showed the rapid melting of snow cover in areas wherre the snow depth was only on the order of 1-2 inches on the morning of 06 October.

GOES-14 0.63 µm visible channel images (click image to animate)

GOES-14 0.63 µm visible channel images (click image to animate)

On the following night, the deep snow cover remaining across northwestern Minnesota could be seen (via illumination by moonlight) in a Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) image at 07:58 UTC (2:58 AM local time). The corresponding VIIRS fog/stratus product image confirmed that this bright area on the DNB image was not a low cloud or fog feature; however, there there were some thin cirrus features over the area at the time, which showed up as darker black on the fog/stratus product image and brighter white to cyan to blue colors on the 11.45 µm IR image.

Suomi NPP VIIRS 0.7 µm Day/Night Band, Fog/stratus product, and 11.45 µm IR images

Suomi NPP VIIRS 0.7 µm Day/Night Band, Fog/stratus product, and 11.45 µm IR images

Ship tracks in the East Pacific Ocean, and valley fog in British Columbia

October 6th, 2012 |
Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

A comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel data at 11:32 UTC (4:32 AM local time) on 06 October 2012 (above) demonstrated the value of using the Day/Night Band as “visible imagery at night” to aid in the detection of features such as ship tracks that were difficult to identify in the IR image. Snow cover in the higher terrain of western British Columbia cuould also be seen, appearing as brighter white areas on the Day/Night Band image.

Additional ship tracks could be identified within the marine boundary layer stratus clouds by examining the coresponding Suomi NPP VIIRS IR brightness temperature difference “Fog/stratus product” image (below) — as well as numerous fingers of valley fog across interior British Columbia.

Suomi NPP VIIRS 0.7 µm Day/Night Band and Fog/stratus product images

Suomi NPP VIIRS 0.7 µm Day/Night Band and Fog/stratus product images