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

McIDAS images of 1-km resolution GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the large smoke plume emanating from the so-called “County Line Fire” that was burning in the Pinhook Swamp area (along the Baker and Columbia County line) of the Osceola National Forest in far northern Florida on 07 April 2012. Strong easterly winds early in the day promoted a long westward fetch of smoke transport toward the Florida Panhandle region, but a change in wind direction along with a reduction in wind speeds allowed the smoke to become more densely concentrated around the burn area later in the day. The smoke was reducing surface visibility and causing air quality problems (see the US Air Quality blog) at some locations across northern Florida.

A 250-meter resolution MODIS true-color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below; viewed using Google Earth) showed a closer view of the source region of the smoke plume.

MODIS true-color Red/Green/Blue (RGB) image (viewed using Google Earth)

Even though the smoke was quite thick over the fire source region, a comparison of AWIPS images of MODIS 0.65 µm visible channel and 3.7 µm shortwave IR channel data (below) showed how the fire “hot spot” (red to yellow to black color enhancement) could still easily be detected with the shortwave IR imagery.

MODIS 0.65 µm visible image + MODIS 3.7 µm shortwave IR image

A sequence of 1-km resolution MODIS and POES AVHRR 3.7 µm shortwave IR images (below) showed the diurnal change in size of the fire hot spot signature (red to yellow to black color enhancement).

MODIS and POES AVHRR 3.7 µm shortwave IR images

A comparison of 4-km resolution GOES-13 3.9 µm shortwave IR imagery with 1-km resolution MODIS 3.7 µm shortwave IR imagery in the early afternoon hours (below) demonstrated the advantage of higher spatial resolution for more accuately determining the exact location of the County Line fire in far northern Florida, as well as the ability to detect a few of the smaller fires that were burning at that time in other parts of Florida and southern Georgia.

MODIS 3.7 µm shortwave IR + GOES-13 3.9 µm shortwave IR images

Finally, a comparison of 375-meter resolution Suomi NPP VIIRS 3.74 µm shortwave IR and 11.450 µm longwave IR images (below) provided even greater detail about the location and size of the fire. Even though the core portion of the fire was hot enough to exhibit a “hot spot” on the longwave IR image, the superior high temperature sensitivity of the shortwave IR channel gave a much more accurate view of the full areal coverage of the most intense portion of the fire (red color enhancement) as well as the location of active fire lines (black enhacement) out ahead of the main fire hot spot.

Suomi NPP VIIRS 3.74 µm shortwave IR and 11.450 µm longwave IR images

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Aqua MODIS true-color RGB image (viewed using Google Earth)

Strong winds across southern Colorado (gusting as high as 60 mph at Alamosa, and 77 mph at Monarch Pass) were creating areas of blowing dust across that region on 06 July 2012. A 1-km resolution Aqua MODIS true-color Red/Green/Blue (RGB) image (above; viewed using Google Earth) showed a long plume of blowing dust originating in the San Luis Valley, which was then being lofted northeastward over the Sangre de Cristo Range (which contains some peaks over 14,000 feet high).

A comparison of the 18:07 UTC Terra MODIS and the 19:47 UTC Aqua MODIS true-color RGB images from the SSEC MODIS Today site (below) revealed how much the blowing dust plume grew in size during that relatively short time period. At times the blowing dust reduced surface visibility to 1 mile at Alamosa, and 6 miles at Colorado Springs.

Terra and Aqua MODIS true-color RGB images

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GOES-13 6.5 µm water vapor channel image + Pilot report of extreme turbulence

United Airlines flight 1727 from Tampa, Florida to Houston, Texas (aircraft flight path | plot of aircraft altitude/speed, from FlightAware.com) encountered extreme turbulence near the coast of Louisiana just before 12:00 UTC on 04 April 2012, which resulted in injures to 12 passengers. An AWIPS image of 4-km resolution GOES-13 6.5 µm water vapor channel data at 11:40 UTC with the text of the pilot report is shown above — note that there was also a pilot report of moderate turbulence at 37,000 feet just to the north.

A southward-propagating squall line was intensifying during the morning hours as it crossed the Gulf Coast — the leading edge of the squall line was evident from the numerous cloud-to-ground lightning strikes  (below; click image to play animation).

GOES-13 6.5 µm water vapor images + Lightning strikes (click image to play animation)

4-km resolution GOES-13 10.7 µm IR channel images (below; click image to play animation) showed a few cold overshooting cloud tops, with an IR brightness temperature as cold as -70 C at 11:01 UTC and -67 C at 11:40 UTC.

GOES-13 10.7 µm IR images (click image to play animation)

1-km resolution POES AVHRR 12.0 µm IR channel images before and after the turbulence encounter (below) revealed cloud top IR brightness temperatures as cold as -77 C over Louisiana at 09:03 UTC.

POES AVHRR 12.0 µm IR images

One interesting question to ask is: was this southward-propagating squall line initiated by outflow boundaries from the large mesoscale convective system that produced the widespread large hail and tornado event across northeastern Texas during the afternoon and evening hours on 03 April? A long sequence of GOES-13 10.7 µm IR channel images (below; click image to play animation) does suggest a possible connection.

GOES-13 10.7 µm IR images (click image to play animation)

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GOES-13 10.7 µm IR channel images (click image to play animation)

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel images (above; click image to play animation) showed the development of a line of severe thunderstorms along an advancing cold frontal boundary as it approached the Dallas/Fort Worth, Texas region during the afternoon hours on 03 April 2012. These storms produced a number of tornadoes, hail as large as 2.75 inches in diameter, and damaging winds (SPC storm reports | NWS Fort Worth outbreak summary).

A closer view using a 1-km resolution MODIS 11.0 µm IR channel image at 17:29 UTC (below) showed much better details regarding the cloud top IR brightness temperature structure of the storms. In particular, note the pronounced cold/warm (-63º C / -52º C, respectively) thermal couplet exhibited by the storm located just east of Cleburne (station identifier KCPT), where the first tornado was reported by spotters at 17:35 UTC.

MODIS 11.0 µm IR channel image + Surface reports + Surface frontal analysis + Cloud-to-ground lightning strikes

A comparison of the 1-km resolution MODIS 11.0 µm IR channel image with the corresponding 4-km resolution GOES-13 10.7 µm IR channel image (below) demonstrated (1) the advantage of higher spatial resolution for more accurately identifying and quantifying storm top signatures, and (2) the parallax shift of the storm top features, due to the large viewing angle from the GOES-13 (GOES-East) satellite.

GOES-13 10.7 µm IR channel image + MODIS 11.0 µm IR channel image

A similar MODIS vs GOES-13 IR image comparison about 90 minutes later (below) again showed how the numerous cold overshooting tops were much more apparent on the 1-km resolution MODIS image.

MODIS 11.0 µm IR channel image + GOES-13 10.7 µm IR channel image

Even greater detail could be seen on a 375-meter resolution Suomi NPP VIIRS 11.450 µm IR channel image at 19:33 UTC (below), which showed a number of cold overshooting tops with IR brightness temperature values in the -70 to -79 C range (dark black to white color enhancement). Hail of 2.0 inches in diameter was being reported just to the west and just to the east of Dallas/Fort Worth International Airport (DFW) at 19:30 UTC.

Suomi NPP VIIRS 11.450 µm IR channel image

Suomi NPP VIIRS 0.64 µm visible channel + 11.450 µm IR channel images (McIDAS)

A comparison of the 375-meter resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.450 µm IR channel images can be seen using McIDAS (above) and AWIPS (below).

Suomi NPP VIIRS 0.64 µm visible channel + 11.450 µm IR channel images (AWIPS)

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