GOES-12 10.7 µm IR images

The Super Tuesday 2008 Tornado Outbreak has been one of the deadliest tornado outbreaks on record in the US — with 59 fatalities reported so far, it ranks in the top 15 deadly tornado outbreaks (and the highest number of tornado deaths since 1985). According to the SPC Storm Reports, there were over 300 reports of tornadoes, large hail (up to 4.25 inches in diameter in Texas, Arkansas and Missouri), and damaging wind gusts from Texas to Ohio and West Virginia. The outbreak produced a total of 87 tornadoes, some producing EF-3 and EF-4 damage.

AWIPS images of GOES-12 10.7 µm IR channel (above) and GOES-12 6.5 µm “water vapor channel” data (below) showed the development of widespread severe convection along and ahead of an advancing cold frontal boundary during the 05 February – 06 February 2008 period.

GOES-12 6.5 µm water vapor images

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GOES-12 sounder Total Precipitalbe Water

Hourly images of GOES sounder Total Precipitable Water (above) showed that moisture was increasing ahead of the cold front, with TPW values of 30-40 mm (1.2-1.6 inches) ahead of the front; the air mass ahead of the cold front was also marginally unstable, with GOES sounder CAPE values (below) of 1000-2000 J/kg.

GOES-12 sounder CAPE

AWIPS images of 1-km resolution MODIS 11.0 µm IR channel data (below) showed closer views of the severe convection around 03:39 UTC and 07:50 UTC — tornadoes and large hail were being reported in parts of Tennessee around those 2 times. As is often the case with winter season severe convection, no classic “enhanced-V” signatures were evident on the IR imagery.

MODIS 11.0 µm IR image

MODIS 11.0 µm IR image

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GOES-12 6.5 µm water vapor images

Farther to the north, in the cold air, parts of southern Wisconsin received as much as 21 inches of snowfall, accompanied by strong winds that created near-blizzard conditions with significant blowing and drifting snow. The 13.3 inches that fell in Madison was the city’s second largest 24-hour snowfall amount on record, and about 2000 vehicles became stranded on Interstate 90 in southern Wisconsin (between Madison and Janesville). GOES-12 6.5 µm water vapor channel images (above) revealed several important signatures during the long-duration winter storm event: a dry slot (which helped to release convective instability along the Illinois/Wisconsin border region), a well-defined deformation zone that set up across Iowa/Wisconsin, and a Trough of Warm Air Aloft (TROWAL) that developed westward from southern Michigan into Wisconsin/Illinois. A vertical cross section of equivalent potential temperature (GEMPAK wizardry courtesy of J. Gerth, CIMSS) oriented north-to-south from Iron Mountain, Wisconsin (IMT) to Paducah, Kentucky (PAH) showed the TROWAL structure very well (below).

Cross Section of theta-e

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A MODIS true color image displayed using Google Earth (above) shows striking variations in the color of the water in the region around the Bahamas and southern Florida on 05 February 2008. The lighter blue water colors indicate the extent of the relatively shallow banks (water generally less than 25 meters deep) that surround the islands, where sunlight is reflecting off the sand and coral reefs just below the water surface; in contrast, the much darker blue colors indicate significantly deeper waters (generally 2000-4000 meters deep) where the ocean floor drops off dramatically.

An AWIPS image of the MODIS Sea Surface Temperature (below) indicated that the SST values were several degrees cooler in the shallow water banks (72º-75ºF, yellow to light orange enhancement) than in the adjacent deeper waters (77º-79ºF, darker orange to red enhancement). The cloud streets seen over Florida in the true color image were oriented parallel to the boundary layer winds around the southwestern periphery of a large area of high pressure centered over the western Atlantic Ocean (note the relatively cloud-free “shadow” immediately downwind of Lake Okeechobee).

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Amato Evan captured some awesome Google Earth AVHRR images of a large dust storm that was affecting the Arabian Peninsula during the 01-04 February 2008 period. A rare winter case of northerly “shamal” winds (producing gusts of 35 mph) was creating the massive cloud of blowing dust and blowing sand.

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A very cold arctic air mass was in place across parts of the Canadian Prairies, with many sites in Alberta reporting surface temperatures colder than -40º F (-40º C) on the morning of 29 January 2008; the leading edge of this arctic air was surging rapidly southward across the Great Plains of the US as a strong cold frontal boundary. AWIPS images of the GOES-12 6.5µm “water vapor channel” (above) actually showed a signature of a gravity wave along the leading edge of the cold front as it moved southward across Nebraska and Kansas into Texas and Oklahoma. This lee-side cold frontal gravity wave feature could be detected on the water vapor channel imagery due to the fact that the airmass ahead of the front was quite dry, which shifted the altitude of the GOES-12 water vapor channel weighting function to much lower altitudes compared to what would be seen in a more typical airmass.

Strong pre-frontal and post-frontal winds were responsible for creating a large area of blowing dust across Texas during the afternoon hours, as seen on consecutive Terra (18:15 UTC, or 12:15 pm local time) and Aqua (19:50 UTC, or 1:50 pm local time) MODIS true color images from the SSEC MODIS Today site (below). This blowing dust reduced surface visibility to as low as 2 miles at San Angelo, Texas.

The windy conditions (several wind gusts in Texas were in excess of 60 mph) and very dry air were also creating an environment favorable for small wildfires; note that a number of fire “hot spots” (black pixels) could be seen on an AWIPS image of the MODIS 3.7µm shortwave IR channel (below).

The SSEC MODIS Today true color image from the Aqua satellite displayed using Google Earth (below) showed exactly which counties and highways in Texas were being impacted by the large cloud of blowing dust. In addition, a smoke plume from small wildfire that was burning just southeast of Abilene, Texas could be seen streaming south/southeastward.

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