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

A strong winter storm moved across the Northern Plains and Upper Midwest regions of the US on 09 December 2012, producing widespread heavy snowfall (HPC storm summary) and creating blizzard conditions that closed a number of roads (including portions of Interstates 90 and 29 in eastern South Dakota). AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the development of a tightly-curved deformation band across Minnesota during the day — much of the heavier snowfall totals occurred beneath the pivot point of this deformation feature.

GOES-13 6.5 µm water vapor channel images (below; click image to play animation) showed the development of a dry slot along the leading edge of the core of a potential vorticity (PV) anomaly (red contours) that was moving northeastward over southern Minnesota. The approach of this PV anomaly was helping to enhance upward vertical velocities, thereby increasing snowfall rates.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

A northwest-to-southeast oriented vertical cross section using NAM40 model fields at 21 UTC (below) showed that the PV anomaly was lowering the height of the dynamic tropopause (taken to be the pressure of the PV1.5 surface) down to the 525 millibar level over southern Minnesota.

NAM40 vertical cross section

A comparison of 1-km resolution images of MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water vapor channel data at 19:48 UTC (below) revealed hints of some subtle banding structure over parts of Minnesota and Wisconsin, which was likely helping to enhance snowfall rates over those areas.

MODIS 0.65 µm visible, 11.0 µm IR, and 6.7 µm water vapor channel images

On the back side of the storm, cold arctic air was being drawn southward across wesern North Dakota and South Dakota — and a comparison of a MODIS 0.65 µm visible image with the corresponding false-color Red/Green/Blue (RGB) image using the 2.1 µm “snow/ice channel” (below) revealed small “river-effect cloud bands” forming (most notably over Lake Sakakawea in North Dakota) as this cold air moved over the still-unfrozen waters of the larger reservoirs of the Missouri River. Deeper snow cover appeared as darker shades of red, in contrast to supercooled cloud features which were brighter shades of white.

MODIS 0.65 µm visible image + False-color Red/Green/Blue (RGB) image

View only this post Read Less

Suomi NPP VIIRS Day/Night Band composite (global view)

On 05 December 2012 NASA and the NOAA National Geophysical Data Center (NGDC) jointly released a “Black Marble” global composite of night-time Suomi NPP VIIRS 0.7 µm Day/Night Band imagery (collected from multiple cloud-free satellite overpasses in April and October 2012) — the image above shows this dataset visualized using the SSEC Web Map Server. See the NASA news story and the SSEC news story for additional details.

Suomi NPP VIIRS 0.7 µm Day/Night Band composite image (North America)

A closer view of North America is shown above, with a zoomed-in image centered on Madison, Wisconsin shown below.

Suomi NPP VIIRS 0.7 µm Day/Night Band composite image (centered on Madison, WI)

Many examples of the VIIRS Day/Night Band showing a variety of phenomena can be found elsewhere on the CIMSS Satellite Blog.

View only this post Read Less

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

Two features of interest appeared on McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) on the morning of 05 December 2012: (1) fingers of valley fog across much of Kentucky, which dissipated as daytime heating and boundary layer mixing increased, and (2) a pair of aircraft dissipation trails (or “distrails”) that first appeared north of Sumter (KSSC) and drifted east-northeastward between Florence (KFLO) and Darlington (KUDG). It is likely that these distrails (highlighted with yellow ‘>’ symbols) formed as aircraft heading to or from Columbia, South Carolina (KCAE) passed through the supercooled water droplet cloud layer, causing glaciation and subsequent fallout of the ice crystals to create the elongated clearing lines.

View only this post Read Less

Suomi NPP VIIRS 0.64 µm visible and 11.45 µm IR images

Super Typhoon Bopha reached peak intensity (ADT plot | Advisory text) just before making landfall in the island of Mindanao in the Philippines on 03 December 2012. Earlier in the day, a comparison of McIDAS-X images of 375-meter resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data (above) revealed detailed patterns of cloud top wave structure: (1) the formation of “transverse bands” oriented perpendicular to the flow (which is fairly common in strong tropical cyclones), and (2) an arc-shaped gravity wave train in the northwest quadrant, which was likely propagating outward, away from the storm center. There were also a number of convective overshooting tops which exhibited IR brightness temperatures of -90 to -95º C (yellow enhancement).

MTSAT-1R 10.8 µm IR images (click image to play animation)

McIDAS-X images of MTSAT-1R 10.8 µm IR channel images (above; click image to play animation) showed Super Typhoon Bopha as the eye made landfall around 20 UTC or 4 AM local time. Media reports indicated that there were as many as 270 fatalities as a result of flooding, mudslides, and falling trees.

A few hours prior to landfall, a comparison of McIDAS-V images of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR data (below; images courtesy of William Straka, CIMSS) again showed a signature of gravity waves propagating outward from the storm center — at this time (17:09 UTC or 1:09 AM local time) these gravity waves could be seen in all four quadrants of the storm top. The eye was not entirely cloud-free, with the Day/Night Band image showing moonlight being reflected off of low-level stratus near the ocean surface.

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

During the 01-03 December period, the MIMIC or Morphed Integrated Microwave Imagery at CIMSS product (below; click image to play animation) showed that Bopha experienced multiple eyewall replacement cycles as it moved south of the island of Palau (where it produced a wind gust of 70 mph at Koror) and toward the Philippines.

Morphed Integrated Microwave Imagery at CIMSS (click image to play animation)

Bopha had an early storm track (below) that was unusually close to the Equator — in fact, the storm was classified as a typhoon at a latitude of 3.8º N on 30 November, making it the closest typhoon formation to the Equator on record for the West Pacific Basin.

Track of Super Typhoon Bopha

View only this post Read Less