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

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)

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

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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

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MIMIC Total Precipitable Water product with track of Tropical Cyclone Nadine (click image to play QuickTime movie)

A sequence of MIMIC Total Precipitable Water product images at 3-hour intervals from 12 UTC on 07 September 2012 to 00 UTC on 04 October 2012 (above) shows the track of long-lived Tropical Cyclone Nadine as it meandered across the Atlantic Ocean. In the final (88th) advisory issued for Nadine by the National Hurricane Center, they stated:

PENDING A POST-STORM ANALYSIS…NADINE WILL TIE GINGER OF 1971 AS THE SECOND-LONGEST-LASTING ATLANTIC TROPICAL STORM ON RECORD AT 21.25 DAYS. AS A TROPICAL CYCLONE…WHICH INCLUDES THE TROPICAL DEPRESSION STAGE…IT IS THE FIFTH-LONGEST-LASTING TROPICAL CYCLONE ON RECORD IN THE BASIN…AT 21.75 DAYS.

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GOES-14 3.9 µm shortwave IR images (click to play animation)

Numerous wildfires began to burn across parts of northeastern North Dakota, northwestern Minnesota, and southeastern Manitoba during the afternoon hours on 02 October 2012. Strong south to southwest winds in advance of an approaching cold front were gusting into the 35-45 mph range, helping many of these fires to grow rather quickly. 4-km resolution GOES-14 3.9 µm shortwave IR images (above; click image to play animation) showed the appearance of several prominent “hot spots” (red to yellow to black color enhancement) associated with the larger fires.

A sequence of 1-km resolution MODIS 3.7 µm shortwave IR images (below) showed the increase in size of some of the larger fire hot spots during the day as the cold front approached.

MODIS 3.7 µm shortwave IR images

Two comparisons of 4-km resolution GOES-14 3.9 µm shortwave IR images with their corresponding 1-km resolution MODIS 3.7 µm shortwave IR images (below) demonstrated the advantage of higher spatial resolution for not only detecting some of the smaller fires, but for also more accurately locating the hot spots associated with the fires themselves. For example, mandatory evacuations were ordered for parts of the town of Karlstad in far northwestern Minnesota (located about 20 miles southeast of Hallock, station identifier KHCO), due to a large fire along the Kittson and Marshall county line. The MODIS images correctly dislayed the hot spot of this fire along that particular county line, placing it just south of Karlstad.

GOES-14 3.9 µm and MODIS 3.7 µm shortwave IR images

GOES-14 3.9 µm and MODIS 3.7 µm shortwave IR images

During the subsequent overnight hours, the fire located north of Upper Red Lake and Lower Red Lake in northwestern Minnesota continued to grow very rapidly, and produced an unusually long smoke plume that was quite evident on Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) images at 07:33 UTC (2:33 AM local time) and 09:14 UTC (4:14 AM local time) as it drifted northeastward over southern Ontario (below). Illumination from the nearly full (waning gibbous phase, 87% full) Harvest Moon allowed the smoke plume and surrounding cloud features to be easily seen at night.

Suomi NPP VIIRS 0.7 µm Day/Night Band images

Comparisons of the Suomi NPPP VIIRS 0.7 µm Day/Night Band images with their corresponding 3.74 µm shortwave IR images at those two times (below) showed the large fire hot spots (yellow to red to black color enhancement) on the shortwave IR imagery along with the brightly glowing signature of the fire on the DNB imagery.

Suomi NPP VIIRS 0.7 µm Day’Night Band and 3.74 µm shortwave IR images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

Since smoke is essentially transparent to longwave InfraRed (IR) thermal radiation, comparisons of the Suomi NPP VIIRS 0.7 µm Day/Night Band images with their corresponding 11.45 µm IR images (below) showed that there was no discernable signature of the smoke plume on the IR imagery.

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

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11/45 µm IR images

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