On the afternoon of 16 December 2015, a toggle between Suomi NPP VIIRS Visible (0.64 µm, 375-m resolution) and False-color Red/Green/Blue (RGB) images (above) showed areas of snow cover (shades of red on the RGB image) that remained from separate snowfall events during the 13 December – 15 December time period (24-hour snowfall maps). Snow depth on the morning of 16 December was as high as 14 inches in the Foothills of eastern Colorado, 12 inches in both southeastern Wyoming and western Nebraska, and 4 inches in southwestern Kansas.

Comparing the false-color RGB image with the visible image made it easier to unambiguously discriminate between snow cover and supercooled water droplet cloud features (which appear as shades of white on the RGB image). In addition, consecutive VIIRS RGB images (below) showed the areas where snow cover was beginning to melt during the ~102 minutes between overpasses of the Suomi NPP satellite.

A late-morning overpass of the Landsat-8 satellite provided a 30-meter resolution view (below) of the circular and rectangular irrigated agricultural fields in far southwestern Kansas and parts of the Oklahoma panhandle. In this RGB image (viewed using RealEarth), snow cover appears as cyan; in areas without snow cover, bare ground is brown and vegetation (crops) are green.

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On 15 December 2015 NOAA/NESDIS conducted a test of the new GOES-15 (GOES-West) Rapid Scan Operations (RSO) sector for coverage of the American Samoa region (SSD message). GOES-15 Visible (0.63 µm, 1-km resolution) images during the test period between 1711 and 1957 UTC are shown above, with plots of surface observations for Pago Pago (station identifier NSTU) and Faleolo (station identifier NSFA). Note that visible images from the Full Disk scan at 1800 UTC and Southern Hemisphere sectors at :22 past each hour are also included in the animation; during routine operations, there are periods when only 1 image per hour is available (from the Southern Hemisphere sector) which covers American Samoa.

The full size of the American Samoa RSO sector is shown below.

Displayed below is the American Samoa RSO sector is relation to the typical GOES-West Full Disk scan coverage.

The American Samoa RSO sector images were also successfully broadcast over the Satellite Broadcast Network (SBN) for display in AWIPS II; a sample GOES-15 Infrared (10.7 µm, 4-km resolution) image is shown below.

As a preview to the upcoming GOES-R series of satellites, we can examine JMA Himawari-8 Visible (0.64 µm, 0.5 km resolution) images for the same 3-hour time period, as seen below (sun glint over the open water is high during this time of day, due to the sun-satellite geometry of Himiwari-8 positioned at 140º East longitude). The images are available from the AHI instrument every 10 minutes, and show the development of organized clusters of convection just north and south of the larger islands of Samoa and Apia. Remote locations such as American Samoa will receive similar images every 5 minutes from the ABI instrument on GOES-R/S/T.

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GOES-13 (above) and GOES-15 (below) both captured the propagation of gravity waves that displayed Bore-like attributes along an inversion with a cold front over central Texas. (Click here for an animation of GOES-13 and GOES-15 side-by-side that includes observed surface winds).

There was a temperature drop across the front, and modest wind gusts occurred just after the lowest pressure associated with the feature passed, but those gusts occurred only in a narrow corridor in central Texas: KSNK (Snyder) reported gusts of 14 knots (0925 UTC); KSWW (Sweetwater) reported gusts of 15 knots (1035 UTC); KABI (Abilene) reported gusts to 17 knots (1152 UTC); KBWD (Brownwood) reported gusts to 24 knots at 1335 UTC; KMKN (Comanche) reported gusts of 22 knots at 1355 UTC (See also the image below). The narrowness of this corridor is likely related to the strength of the inversion along which the bore is propagating (The 1200 UTC Soundings from Fort Worth and from Del Rio both show a very strong inversion; perhaps there was a weakness in the inversion over central Texas that allowed for more vertical mixing).

During the preceding nighttime hours, the early stage of the undular bore feature was detected on an Aqua MODIS Water Vapor (6.7 µm) image, below, along the leading edge of the colder air and colder surface brightness temperatures (light to medium blue colors) seen on the corresponding MODIS Infrared (11.0 µm) image at 0807 UTC or 2:07 am local time.

(Hat tip to Mike Johnson, NWS in San Angelo for tweeting about this feature!)

Great example of gravity waves propagating SE across TX along a Pacific cold front. @WxSatChat #txwx pic.twitter.com/jiTTjlWLLU

— Mike Johnson (@wall_cloud) December 15, 2015

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Japanese Meteorological Agency Himawari-8 Water Vapor (6.9 µm, 2-km resolution) images (above) showed the rapid intensification of a hurricane-force extratropical cyclone over the North Pacific Ocean and Bering Sea during the 12 December – 13 December 2015 period. The 6.9 µm is one of 3 water vapor spectral bands on the Himawari AHI instrument — GOES-R will feature 3 nearly identical water vapor bands on the ABI instrument.

According to surface analyses from the Ocean Prediction Center, the storm was centered over Japan at 00 UTC on 11 December, and began rapidly intensifying later that day as it continued moving northeastward; it eventually deepened to a minimum central pressure of 924 hPa (27.29 inches of mercury) over the far southern Bering Sea at 06 UTC on 13 December. This equaled the analyzed minimum central pressure of Post-Tropical Cyclone Nuri in November 2014, which was one of the strongest storms on record in the Bering Sea.

Corresponding GOES-15 Water Vapor (6.5 µm, 4-km resolution) images (below) offered a slightly closer view of the intensifying storm. The unique satellite signature — resembling a curved scorpion tail — of a phenomenon known as a sting jet was seen to begin developing around 20 UTC on 12 December south of the Aleutian Islands. Several hours after the middle-tropospheric sting jet feature on water vapor imagery moved over Adak Island (PADK on the images) around 0130 UTC, sustained surface winds of 82 knots (94 mph) with gusts to 106 knots (122 mph) were recorded just after 09 UTC. According a Tweet from the Ocean Prediction Center, winds from the storm also produced wave heights of 63 feet.

A time series of surface observations at Adak Island (below) indicated that the minimum station pressure of 939.0 hPa (27.73 inches of mercury) was recorded just after 04 UTC.

Additional imagery from this event can be found on the RAMMB GOES-R Proving Ground Blog.

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