MODIS 0.65 µm visible channel and 6.7 µm water vapor channel images

AWIPS images of 1-km resolution 6.7 µm water vapor channel data (above) revealed interesting wave patterns over parts of southern California, Baja California, and the adjacent offshore waters of the Pacific Ocean on 07 January 2013. A comparison with the corresponding 0.65 µm MODIS visible image showed that there were no clouds associated with any of these water vapor wave features. The mountain waves over southern California and northern Baja California were caused by strong winds on the western periphery of an upper-level low pressure system — and there were  isolated pilot reports of moderate turbulence  over southern California at the 30,000-34.000 foot altitude range.

Also of interest is the “bow shock wave” feature seen on the water vapor image, which fans out downwind (southward) of Guadalupe Island (station identifier 76151). These waves were caused by the interaction of lower-tropospheric winds from the north interacting with the high terrain of the volcanic island (whose highest point is Mount Augusta at 4257 feet or 1298 meters). Lower-tropospheric satellite winds off the west coast of Baja California were as strong as 37 knots at the 812 hPa pressure level.

McIDAS images of 4-km resolution GOES-15 6.5 µm water vapor channel data (below; click image to play animation) suggested that there was strong middle-tropospheric subsidence over the region surrounding Guadalupe Island  — as seen by the warming/drying trend (the transition to brighter yellow colors) — which allowed the weighting function of the water vapor channel to peak at lower altitudes in order to detect the  lower-level signature of the bow shock wave.

GOES-15 6.5 µm water vapor channel images (click image to play animation)

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Suomi NPP VIIRS 11.45 µm IR image (with METAR surface reports)

The coldest temperature in the United States (including Alaska) was -33 F (-36 C) at Alamosa, Colorado on 03 January 2013. AWIPS images of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 11.45 µm IR data with METAR surface reports (above) showed a few areas in parts of the higher elevations of central Colorado which exhibited IR brightness temperatures as cold as -44 C or -47 F (white color enhancement). In the lower left portion of the image, the warmer signature (red color enhancement) of the Colorado River basin could be seen running southwestward across Utah and into the Grand Canyon region of Arizona.

Alamosa (station identifier KALS) is located in south-central Colorado, and is situated in the eastern portion of the broad high-altitude basin of the San Luis Valley. The Suomi NPP VIIRS 0.7 µm Day/Night Band image (below) showed the brighter white signature of the moonlit snow-covered San Luis Valley at night (08:49 UTC = 1:49 AM local time). Much of the western (high-elevation) half of Colorado had substantial snow cover, and there were a few other sites that recorded minimum temperatures of -30 F or colder.

Suomi NPP VIIRS 0.7 µm Day/Night Band image (with METAR surface reports)

A comparison of the Suomi NPP VIIRS IR brightness temperature difference “fog/stratus product” and the corresponding GOES-13 Cloud Thickness and IFR Probability products (below) indicated that most of the higher elevations of central Colorado were generally cloud-free, which allowed for strong radiational cooling to reach such cold surface temperatures.

Suomi NPP VIIRS “fog/stratus product” + GOES-13 Cloud Thickness and IFR Probability products

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Suomi NPP VIIRS 0.7 µm Day/Night Band image

The Suomi/NPP Day/Night Band “nightime visible” image early on 2 January captured a rope cloud extending over the central Gulf of Mexico southwestward from the northwest Florida panhandle. Rope Clouds are handy features because they accurately place the location of the cold front at the leading edge of the rope structure. METARS overlain above the Suomi/NPP image (below) over the north-central Gulf Coast demonstrate how the Rope Cloud is a Cold Front.

Suomi NPP VIIRS 0.7 µm Day/Night Band image

Visible imagery during the day on 2 January, from GOES-East, below, shows that the Rope Cloud maintained its structure as it continued pushing eastward towards the Florida Peninsula.

GOES-13 0.63 µm visible imagery (click image to play animation)

(Added: Portions of the Rope Cloud persisted into the early morning hours of 3 January 2013, as shown by the Day/Night Band image from Suomi/NPP VIIRS, below)

Suomi NPP VIIRS 0.7 µm Day/Night Band image

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GOES-15 6.5 µm water vapor channel images (click image to play animation)

McIDAS images of GOES-15 6.5 µm water vapor channel data (above; click image to play animation) showed the intensification of a deep low pressure system that was moving northward in the western Gulf of Alaska during the 31 December 2012 – 01 January 2013 period. Strong storm-force winds and high seas associated with this storm played a role in the grounding of the Royal Dutch Shell Kulluk oil drilling rig around 9 PM local time on 31 December (or 06 UTC on 01 January), just off Sitkalidak Island close to Kodiak Island’s southeast shore. PADQ denotes the location of the Kodiak Airport on the northeastern part of Kodiak Island.

POES AVHRR 12.0 µm IR images

A sequence of three AWIPS images of POES AVHRR 12.0 µm InfraRed (IR) data (above) showed the storm as its center was just south-southwest of Kodiak Island. In addition, a comparison of the 01 January 2013 00:16 UTC 0.86 µm visible channel and the corresponding 12.0 µm IR channel images is also shown (below). Surface reports were plotted on the satellite images — the peak wind gust at buoy 46077 located just northwest of Kodiak Island in the Shelikof Strait was 51 knots or 59 mph at 00:16 UTC (3:16 PM local time on 31 December), and ship NZPO located just southeast of Kodiak Island reported a sustained wind speed of 55 knots or 63 mph at 00:00 UTC (3:00 PM local time on 31 December).

POES AVHRR 0.86 µm visible channel image + 12.0 µm IR channel image

A time series of surface report data from Kodiak Airport PADQ (below) indicated that a peak wind gust of 47 knots or 54 mph occurred at 04 UTC and 09 UTC on 01 January (or 7 PM and Midnight local time on the night of 31 December).

Surface observations at Kodiak (PADQ)

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