GOES-15 10.7 µm IR images with surface analysis and pilot reports of turbulence (click image to play animation)

The AWIPS images above (click to play animation) showed low-resolution GOES-15 10.7 µm IR data with an overlay of the surface analysis and pilot reports of turbulence. A number of reports of moderate turbulence could be seen in the vicinity of the Hawaiian Islands (at altitudes between 9,000 and 27,000 feet), and the diffuse southern end of a surface cold frontal boundary had become semi-stationary over the area. The overall motion of the colder (lighter gray) IR cloud features suggested that the southwesterly flow aloft was becoming diffluent over and northeast of Hawaii.

A closer view using McIDAS images of 1-km resolution GOES-15 0.63 µm visible channel data (below; click image to play animation) revealed the formation of several small banded “billow cloud” features just to the northeast of the island chain. While there appeared to be no pilot reports of turbulence directly associated with the billow cloud features, the continued development of new billow cloud formations could have been a signal that turbulence was possible across the region. In addition, it is unclear whether their formation was due to flow interacting with the topography of the islands.

GOES-15 0.63 µm visible channel images (click image to play animation)

The corresponding GOES-15 10.7 µm IR channel images (below; click image to play animation) showed that IR cloud top brightness temperatures were as cold as -27º C (darker blue color enhancement) with the most prominent band of billow clouds at 18:30 UTC. According the the 12 UTC Hilo rawinsonde data, clouds reaching this temperature level would have ascended into the very dry air aloft. It is possible that these billow cloud features formed near the 700 hPa pressure level (where some speed and directional wind shear existed), then continued to build vertically.

GOES-15 10.7 µm IR channel images (click image to play animation)

GOES-15 6.5 µm water vapor channel images (below; click image to play animation) seemed to suggest that groups of individual billow cloud formations were developing along north-to-south oriented lines that were propagating eastward across the region during this period.

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

It is interesting to note that similar billow cloud formations were seen in that same region northeast of the Hawaiian Islands on Suomi NPP VIIRS 11.45 µm IR images at various times during the previous 24 hours (below).

Suomi NPP VIIRS 11.45 µm IR channel images

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Suomi NPP VIIRS 11.45 µm IR images (click image to play animation)

AWIPS II images of 375-meter resolution Suomi NPP VIIRS 11.45 µm IR channel data (above; click image to play animation) revealed a surprising amount of sea ice motion in the vicinity of Barrow, Alaska (station identifier PABR) during the 30-hour period between 12:14 UTC on 24 January and 18:30 UTC on 25 January 2013. Large sea ice features with several ice leads and fractures can be seen moving southward against the land-fast ice to the east of Barrow — while to the west of Barrow, strong winds were helping to break the sea ice into smaller ice floes and transport them rapidly westward.

Suomi NPP VIIRS imagery is now being broadcast at the full native 375-meter resolution over the new “POLARSAT” NOAAPORT SBN channel (currently only available for the Alaska Region), for display in the next generation of AWIPS (AWIPS II).

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Suomi/NPP VIIRS Visible Image

The Arctic airmass that has overspread the eastern two-thirds of the United States is cold enough that sustained northerly winds down the length of Chesapeake Bay yielded snow showers over extreme southeastern Virginia and northeastern North Carolina. The Suomi/NPP Visible image, above, shows a distinct cloud band over the eastern side of Chesapeake Bay that stretches southwards towards the Outer Banks of North Carolina. Snow was being reported at a number of stations across the Hampton Roads area in southeastern Virginia, with visibility being restricted to 2 miles at Oceana Naval Air Station (KNTU) — and snow was reported as far south as Currituck, North Carolina (KONX).

Bay-effect (or Lake-effect) snows typically occur when the temperature difference between the water surface and lower tropopshere (for example, 850 mb) exceeds about 13 to 15 C. The sounding from Roanoke, VA, from 1200 UTC on 24 January shows temperatures near -12 C at 850 mb. Sea-surface temperatures over the lower Bay are around 5 C. This animation of two MODIS visible images, from 1506 UTC and from 1640 UTC, shows the snow band shifting from the western shore to the eastern shore of the Bay. This event was also caught on radar.

POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel images

A comparison of 1-km resolution POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel images at 14:11 UTC or 9:11 AM local time on the morning of 24 January 2013 (above) showed a prominent bay-effect cloud band as it was becoming well-organized over the northern portion of Chesapeake Bay. Cloud top IR brightness temperatures were as cold as -25.5 C (darker blue color enhancement), indicating that the cloud band was almost certainly glaciated. Note the observation of blowing snow (reducing visibility to 2 miles) at Patuxent River Naval Air Station (station identifier KHNK) near the southern end of the cloud band.

The development and movement of the bay-effect snow bands could be seen on 1-km resolution GOES-13 0.63 µm visible channel images (below; click image to play animation).

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

On the previous day, the 1-km resolution MODIS Sea Surface Temperature (SST) product (below) revealed SST values greater than 40 F or 4.4 C (lighter blue color enhancement) over the central and southern portions of Chesapeake Bay.

MODIS Sea Surface Temperature image

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Suomi NPP VIIRS 0.64 µm visible channel images

AWIPS II images of Suomi NPP VIIRS 0.64 µm visible channel images (above) showed a very detailed view of “transverse banding” cloud features across parts of northwestern Canada (primarily in northeastern British Columbia) on 23 January 2012. This transverse banding — with the cloud features oriented perpendicular to the flow — is a satellite signature that indicates an increased potential for turbulence. Suomi NPP VIIRS imagery is now being broadcast at full 375-meter resolution over the new “POLARSAT” NOAAPORT channel (currently only available for the Alaska Region), for display in the next generation of AWIPS (AWIPS II).

The corresponding Suomi NPP VIIRS 11.45 µm IR channel images are shown below. Cloud top IR brightness temperatures were colder than -60º C (dark red color enhancement) in many of the bands.

Suomi NPP VIIRS 11.45 µm IR channel images

A comparison of the the VIIRS visible and IR images at 19:05 UTC (11:05 AM local time) are shown below.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

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