A Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image visualized using the SSEC RealEarth web map server (above) showed large areas of blowing dust across parts of the central Plains states on the afternoon of 27 April 2014. Surface winds were gusting in excess of 60 mph at some locations.

McIDAS images of 1-km resolution GOES-13 0.63 µm visible channel data (below; click image to play animation) displayed the formation of a well-defined “blowing dust front” that moved eastward across Kansas.

 

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel data with overlays of SPC storm reports (below; click image to play animation) showed the cold cloud top IR brightness temperatures (as cold as -81º C, violet color enhancement) associated with severe thunderstorms that produced widespread hail, damaging winds, and tornadoes (which were responsible for 16 fatalities).

A 1-km resolution POES AVHRR 12.0 µm IR channel image with SPC storm reports at 02:13 UTC or 9:23 PM local time (below) showed the large mesoscale convective system that was responsible for a number of tornadoes in Arkansas a few hours earlier. Note the appearance of subtle cloud-top gravity waves propagating northwestward away from the storm center.

Several hours later, a comparison of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 11.45 µm IR channel images at 07:15 UTC or 2:15 AM local time (below) revealed the presence of ripples of mesospheric airglow waves propagating northeastward across Missouri and far southern Illinois and Indiana. These mesospheric airglow waves were likely caused by intense overshooting cloud tops associated with the severe thunderstorms as they were producing tornadoes over Arkansas. Several bright “lightning streaks” could also been seen on the VIIRS DNB image, as these electrically-active thunderstorms were responsible for over 2000 cloud-to-ground (CG) lightning strikes in the 15-minute period and over 8000 CG lightning strikes in the 1-hour period preceding the VIIRS images. The SPC storm reports plotted on the IR image cover the 5.5 hour span from 02:00 to 07:30 UTC.

===== 28 April Update ======

A comparison of “before” (25 April) and “after” (28 April) 250-meter resolution Aqua MODIS true-color RGB images from the SSEC MODIS Today site (below) showed much of the southwest-to-northeast oriented damage path resulting from the EF-4 rated Mayflower/Vilonia/El Paso tornado in Arkansas (NWS Little Rock storm summary).

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A McIDAS-V image comparison of “before” (01 April) and “after” (22 April) Suomi NPP VIIRS 0.7 µm Day/Night Band data (above; courtesy of William Straka, SSEC/CIMSS) revealed the bright lights of the ongoing recovery operations associated with the sinking of the MV Sewol ferry on 16 April 2014 (Wikipedia). The bright illumination of the recovery site is located near the center of the 22 April image; the larger cluster of bright lights seen near the bottom of the 01 April image is likely a signature of extensive squid fishing operations. Numerous smaller and more dim lights from fishing boats can be seen on both images.

The ferry was taking a southbound route across the Yellow Sea, with a final destination of Jeju City (whose bright lights can be seen on the north edge of Jeju Island, at the bottom of the images).

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Mostly clear skies over the Great Lakes and a near-Full Moon allowed the Suomi NPP VIIRS Day/Night Band (DNB) imager to record the remaining extent of ice on the five Great Lakes with remarkable clarity at night.

Portions of Georgian Bay (Lake Huron), Green Bay (Lake Michigan) and southeastern Lake Superior continue to be ice-covered. Ice also remains in eastern Lake Erie, over northeastern Lake Michigan, and in parts of Lake Huron. Lake Ontario and Lake St. Clair are ice-free.

Taking a closer look at Lake Superior (above), it is interesting to compare the previous daytime VIIRS DNB image (at 19:23 UTC on 15 April) with the subsequent nighttime DNB image about 17 hours later (at 07:40 UTC on 16 April):

(1)  You can ascertain changes in the ice motion and areal coverage, even at night

(2) The later 16 April image showed that far northern portions of the Lake Superior ice had become snow-covered (exhibiting a brighter white appearance), after a weak disturbance brought small bands of lake-effect snow over that area (GOES-13 10.7 µm IR image animation). Even though the MODIS Sea Surface Temperature product showed that SST values over the open waters of northern Lake Superior were only in the low 30’s F, surface reports on the GOES-13 IR image animation indicated that the air moving across those waters in the wake of the weak disturbance was significantly colder. This fresh snow cover could have an impact on the ice melting rate in those areas.

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A Total Lunar Eclipse occurred over North America early in the morning of 15 April 2014. The resultant lack of lunar illumination had a profound impact on the “visible image at night” quality of the VIIRS 0.7 µm Day/Night Band imagery during the Suomi NPP satellite overpass at around 0800 UTC over the midsection of the United States. The animation above shows excellent illumination from the Full Moon at 0619 UTC (2:19 AM Eastern time) along the East Coast, and also at 0940 UTC (2:40 AM Pacific time) along the West Coast; however, the image at 0800 UTC (3:00 AM Central time), in the middle of eclipse totality, resembles Day/Night Band images seen during a New Moon. The three images can also be combined into a collage, as shown below, to illustrate the changes in the Day/Night band that occur as lunar intensity changes.

A comparison of three similar Day/Night Band images from the day before is here.

Even though the 08:00 UTC VIIRS Day/Night Band image exhibited a comparatively dull and “washed-out” appearance (due to very little illumination from eclipsed moonlight), there were still features of interest that could be seen. For example, a closer look over the southeastern US using the 0.7 µm Day/Night Band and 11.45 µm IR channel images (below) showed the effect of lightning activity associated with a pre-cold-frontal squall line over the Florida panhandle and the adjacent offshore waters of the Gulf of Mexico: a pair of long, narrow bright streaks (caused by cloud illumination from intense lightning activity as the sensor was rapidly scanning from northwest to southeast), abruptly followed by dark black streaks that eventually faded away. These dark black streaks represent post-saturation “recovery periods” after the sensor scanned the extremely bright cloud features. Incidentally, the coldest 11.45 µm IR brightness temperature over the Florida panhandle was -80º C (very near the area of dense cloud-to-ground lightning strikes).

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