GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible images (click image to play animation)

Snowfall amounts as high as 10-15 inches fell across parts of west Texas and southeast New Mexico on 09 January 2012 as a strong upper level disturbance moved across that region (NWS Lubbock TX storm summary). On the following morning, a comparison of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel images (above; click image to play animation) showed the areal coverage of the snow cover that remained on the ground. Note how the patch of snow began to melt from the outer edges inward as the full day of sunshine warmed the ground surface. Also note the curious “donut hole” of bare ground on the northern end of the main snow cover — this feature rapidly disappeared, as the snow depth associated with this feature was not very high.

A comparison of 250-meter resolution MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) showed greater detail in the snow cover (snow on the ground appears as darker shades of cyan on the false color image) at 18:02 UTC.

MODIS true color and false color Red/Green/Blue (RGB) images

A comparison of AWIPS images of MODIS 0.65 µm visible channel data and the corresponding false color RGB image (below) offered another tool that can be used to discriminate between snow cover (which in this example appears as darker shades of red on the false color image) and supercooled water droplet clouds (which appeared as varying shades of white).

MODIS 0.65 µm visible image + MODIS false color RGB image

A comparison of the MODIS 0.65 µm visible image with the corresponding MODIS Land Surface Temperature (LST) product (below) revealed how the deep snow cover was helping to keep surface air temperatures significantly colder than adjacent regions with bare ground. MODIS LST values were in the low to middle 30s F across the deeper snow cover, in the upper 40s to low 50s F in the “donut hole” region where the snow had just melted, and in the 60s F to the north over bare ground. Also note how the urban areas of Midland and Odessa stand out in the LST image, with LST values in the low to middle 40s F.

MODIS 0.65 µm visible image + MODIS Land Surface Temperature product

The mechanism for the creation of the “donut hole” snow cover feature is unclear at this point. A comparison the MODIS Land Surface Temperature product with the regional topography (below) seems to suggest that this feature was not topographically-driven.

MODIS Land Surface Temperature product + Topography

The MODIS true color image viewed using Google Earth (below) showed that the community of Brownfield (which did received about an inch of snowfall the previous day) was aptly named, being located within the brown-colored snow-free region at 18:02 UTC.

MODIS true color image (viewed using Google Earth)

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MTSAT-2 6.75 µm water vapor channel images (click image to play animation)

A large area of low pressure over the Southern Ocean between Australia and Antarctica on 07 January – 08 January 2012 (surface analyses) exhibited a beautiful signature of an occluding cyclone on 5-km ressolution MTSAT-2 6.75 µm water vapor channel imagery (above; click image to play animation). This storm prompted the issuance of Gale Warnings for widespread areas of winds of 30-45 knots producing high seas.

A closer view of the MTSAT-2 water vapor imagery (below) revealed very intricate detail to the plume of dry air wrapping into the ceter of the storm, along with several small vortices of dry air that became cut off and isolated along the periphery of the system as it began to decay just southwest of the island of Tasmania.

MTSAT-2 6.75 µm water vapor channel images

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MODIS Land Surface Temperature product

Much of the state of Florida experienced below-freezing temperatures on the morning of 04 January 2012. An AWIPS image of the 1-km resolution MODIS Land Surface Temperature (LST) product (above) showed that LST values of 32ª F and colder (blue color enhancement) extended far to the south at 07:27 UTC (02:27 am local time). There were even several pockets exhibiting LST values less than 20ª F (violet color enhancement), including a minimum of 10.7ª F just southwest of Gainesville (station identifier KGNV) in northern Florida, and 15.3ª F just to the west of Lake Okeechobee in southern Florida.

A map of minimum temperatures on the morning of 04 January (below) showed that the cold air had even moved as far south as Cuba, where lows in the 40s F were observed. In Florida, new record  low temperatures for the day included 18ªF at Tallahassee, 20ª F at Gainesville, 22ª F at Jacksonville, 33ª F at Melbourne, and 36ª F at Naples.

04 January 2011 minimum temperatures

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EUMETSAT Meteosat-9 Water Vapor (7.35 µm) images (click image to play animation)

A rapidly intensifying mid-latitude cyclone (named “Cyclone Ulli” by the Europeans | surface analysis) was responsible for a high wind event as it moved over Scotland on 03 January 2012. A sequence of EUMETSAT Meteosat-9 Water Vapor (7.35 µm) images (above) revealed two notable signatures: (1) the formation of a pronounced area of warm/dry water vapor brightness temperatures (bright yellow to orange color enhancement) over the open water north of Ireland, which indicated a strongly forced region of rapidly descending middle-tropospheric air, and (2) a classic “Sting Jet” signature (Monthly Weather Review | Wikipedia) which then moved eastward across Scotland. Just to the south of the sting jet signature, a wind gust of 78 knots (90 mph) was recorded at Glasgow at 08:20 UTC, followed by a wind gust of 70 knots (81 mph) at Edinburgh at 08:50 UTC.  There were additional reports of wind gusts in excess of 87 knots (100 mph) at non-METAR sites in Scotland.

The Sting Jet signature can also be seen in EUMETSAT Meteosat-9 Infrared (10.8 µm) images (Animated GIF) and EUMETSAT Meteosat-9 Visible (0.635 µm) images (Animated GIF).

A comparison of 1-km resolution NOAA-19 Visible (0.63 µm) and Infrared (10.8 µm) images at 12:54 UTC (below) showed the structure of the cyclone as it was centered over the North Sea between the British Isles and Norway.

NOAA-19 0.63 µm visible channel image + NOAA-19 10.8 µm IR channel image

Additional images of this Sting Jet event are available on the EUMETSAT and NASA Wide World of SPoRT sites.

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