First December tornadoes on record in the Amarillo, Texas forecast area

December 14th, 2012 |
GOES-13 10.7 µm IR images with surface reports and storm reports (click image to play animation)

GOES-13 10.7 µm IR images with surface reports and storm reports (click image to play animation)

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel images with overlays of surface reports and SPC storm reports (above; click image to play animation) showed the development of thunderstorms across the Panhandle region of Texas on 14 December 2012. As these storms intensified into an organized squall line, they produced small hail, widespread damaging winds, and 3 tornadoes. These tornadoes were the first tornadoes on record during the month of December in the Amarillo forecast area (NWS Amarillo news story).

A comparison of McIDAS images of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel images (below; click image to play animation) revealed an interesting cloud-top gravity wave structure with some of these thunderstorms.

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

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

POES AVHRR 0.86 µm visible channel images

POES AVHRR 0.86 µm visible channel images

1-km resolution POES AVHRR 0.86 µm visible channel images (above) and 12.0 µm IR channel images (below) showed the rapid development of a organized cluster of convection west of Amarillo (station identifier KAMA) between 20:24 UTC and 20:52 UTC (3:24 and 3:52 PM local time). Note how the surface winds were backing and becoming more southeasterly at Amarillo, likely helping to enhance surface convergence ahead of the approaching thunderstorms. To the south, winds were gusting in excess of 40 knots at Lubbock (station identifier KLBB), producing blowing dust reducing the surface visibility to 3 miles at times.

POES AVHRR 11.0 µm IR channel images

POES AVHRR 11.0 µm IR channel images

The Blended Total Precipitable Water (TPW) product (below; click image to play animation) showed the northward transport of moisture from the Gulf of Mexico during the day, with TPW values exceeding 20 mm or 0.79 inch (darker green color enhancement) across the eastern Texas Panhandle by the afternoon hours. These TPW values were in excess of 200 percent of normal for this region during this time of the year.

Blended Total Precipitable Water product (click image to play animation)

Blended Total Precipitable Water product (click image to play animation)

GOES-13 sounder Total Precipitable Water derived product imagery (click image to play animation)

GOES-13 sounder Total Precipitable Water derived product imagery (click image to play animation)

A few breaks in the widespread cloudiness across the region allowed a closer look at the moisture and instability ahead of the advancing cold front (HPC surface analysis), using 10-km resolution GOES-13 sounder Total Precipitable Water (above; click image to play animation) and GOES-13 sounder Lifted Index (below; click image to play animation) derived product imagery — TPW values were as high as 22 mm or 0.87 inch, and there were pockets of instabiity with LI values as low as -5.8º C in cloud-free areas where daytime heating was helping to destabilize the atmosphere.

GOES-13 sounder Lifted Index derived product imagery (click image to play animation)

GOES-13 sounder Lifted Index derived product imagery (click image to play animation)

Contrail detection using shortwave IR imagery

December 10th, 2012 |
Suomi NPP VIIRS 0.64 µm visible, 3.74 µm shortwve IR, and 11.45 µm IR images

Suomi NPP VIIRS 0.64 µm visible, 3.74 µm shortwve IR, and 11.45 µm IR images

 

A wide band of multi-layered clouds was oriented southwest-to-northeast along a cold frontal boundary moving through the Ohio River Valley region on 10 December 2012.  On a 1-km resolution Suomi NPP VIIRS 11.45 µm IR image at 17:42 UTC (above), much of this cloud band was topped with cirrus clouds exhibiting IR brightness temperatures in the -50 to -60 C range (orange to red color enhancement), indicating a cloud top height in the 30,000-40,000 foot range (KILM rawinsonde data | KPIT rawinsonde data)– the general cruising altitudes of most aircraft.

It is interesting to note that the Suomi NPP VIIRS 3.74 µm shortwave IR image revealed a large number of contrails across that cloud band — the contrails appeared darker than the background cirrus clouds, due to reflection of solar radiation by smaller ice crystals or by supercooled water droplets. Either the contrails themselves were located above the cirrus cloud deck, or the aircraft were flying through the top portion of the cirrus clouds and altering the microphysics of the cloud ice crystals to make them smaller.

Similar contrails were seen about an hour later on a 1-km resolution MODIS 3.7 µm shortwave IR image (below).

 

MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR images

MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR images

Significant winter storm across the Northern Plains and Upper Midwest regions

December 9th, 2012 |
GOES-13 0.63 µm visible channel images (click image to play animation)

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)

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

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

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

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

The “Black Marble”: City Lights At Night

December 5th, 2012 |
Suomi NPP VIIRS Day/Night Band composite (global view)

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)

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)

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.