Dust storm over the central and southern High Plains region

March 11th, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

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

AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) show the hazy signature of an intense dust storm (sometimes locally referred to as a “haboob”) created by strong winds in the wake of a southward-moving cold front on 11 March 2014. This blowing dust reduced surface visibility to zero in parts of southwestern Kansas (where there were wind gusts of 59 mph), causing several traffic accidents. At Amarillo, Texas (KAMA) the wind gusted to 60 mph, and visibility was reduced to 0.25 mile at times. A pilot report indicated that the top of the blowing dust was as high as 11,000 feet over the Oklahoma panhandle region.

A sequence of Terra/Aqua MODIS and Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images visualized using the SSEC RealEarth web map server (below) showed the southward advancement of the lighter tan colored areas of blowing dust.

Terra/Aqua MODIS and Suomi NPP VIIRS true-color RGB images

Terra/Aqua MODIS and Suomi NPP VIIRS true-color RGB images

A signal of the airborne dust (cyan color enhancement) was also seen on Terra/Aqua MODIS images of the 11-12 µm “reverse absorption” IR difference product (below).

MODIS 11-12 µm "reverse absorption" IR difference product

MODIS 11-12 µm “reverse absorption” IR difference product

GOES-13 6.5 µm water vapor channel images (below; click image to play animation) showed the development of a “cirrus bloom” over far northeastern New Mexico as the surface cold front and blowing dust moved through that region. It is interesting to note that there was a pilot report of severe turbulence at an altitude of 45,000 feet around that time (reportedly due to a mountain wave) — this raises the question as to whether a vertically-propagating wave generated by the strong cold front might have caused that high-altitude turbulence.

GOES-13 6.5 µm water vapor channel images, with pilot reports of turbulence (click to play animation)

GOES-13 6.5 µm water vapor channel images, with pilot reports of turbulence (click to play animation)

Additional satellite images of this event can be found on the Wide World of SPoRT blog.

===== 12 March Update =====

Suomi NPP VIIRS 0.7 µm Day/Night Band image, with surface observations and frontal analysis

Suomi NPP VIIRS 0.7 µm Day/Night Band image, with surface observations and frontal analysis

During the subsequent night-time hours, a Suomi NPP VIIRS 0.7 µm Day/Night Band image at 08:35 UTC or 2:35 AM local time (above) displayed a signature of the airborne dust over far southwestern Texas — the glow of the city lights below the dust layer was more diffuse than in dust-free areas farther to the east in central Texas. Also note that an undular bore had formed along the cold frontal boundary near the coast of southeast Texas.

A comparison of the VIIRS Day/Night Band image with a MODIS 11-12 µm image (below) confirmed the presence of airborne dust over southwestern Texas. As in the MODIS example above, the brighter cyan color enhancement was a signal of dust.

Suomi NPP VIIRS 0.7 µm Day/Night Band and MODIS 11-12 µm IR difference product images

Suomi NPP VIIRS 0.7 µm Day/Night Band and MODIS 11-12 µm IR difference product images

Severe thunderstorms over the Gulf of Mexico

March 6th, 2014
Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images (with CG lightning strikes)

Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images (with CG lightning strikes)

A night-time AWIPS image comparison of Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band data (above) showed a large mesoscale convective system (MCS) over the Gulf of Mexico at 07:08 UTC (2:08 AM local time) on 06 March 2014. On the IR image, brightness temperatures were as cold as -80º C on the far southern end of the storm, which had developed in the warm sector of a developing area of low pressure (surface frontal analysis). The Day/Night Band image revealed: (1) numerous bright west-to-east oriented “lightning streaks” caused by intense lightning activity illuminating the MCS cloud and cloud top — note that there were over 1300 cloud-to-ground (CG) lightning strikes detected in a 15-minute period, and (2) arc-shaped mesospheric airglow waves propagating northward and northeastward away from the region of vigorous overshooting tops at the southern end of the MCS.

A comparison of the 375-meter resolution Suomi NPP VIIRS 11.45 µm IR image with a 4-km resolution GOES-13 10.7 µm IR image (below) showed that the higher spatial resolution of the VIIRS data provided much clearer view of the various cloud structures along with a better depiction of the values of the cloud-top IR brightness temperatures.

Suomi NPP VIIRS 11.45 µm IR and GOES-13 10.7 µm IR channel images

Suomi NPP VIIRS 11.45 µm IR and GOES-13 10.7 µm IR channel images

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

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

GOES-13 10.7 µm IR channel images (above; click image to play animation) showed the evolution of the MCS as it continued to move eastward toward Florida. A squall line developed along the leading edge of the MCS, which played a role in producing a few tornadoes and areas of damaging winds over the southern half of the Florida peninsula (below).

Plot of SPC storm reports

Plot of SPC storm reports

Ice coverage in Lake Michigan

March 5th, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

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

According to the 04 March 2014 Great Lakes Environmental Research Laboratory ice analysis, much of Lake Michigan had over 90% median ice concentration, with a total ice coverage of around 95%. However, AWIPS images of GOES-13 0.63 µm visible channel data on 05 March (above; click image to play animation) showed the effect of northerly winds on the ice , with large leads (cracks) opening up in the northern portion of the lake.

A comparison of AWIPS 0.64 µm visible channel and false-color Red/Green/Blue (RGB) images at 18:49 UTC (below) confirmed that most of Lake Michigan was cloud-free — snow and ice appear as varying shades of red on the RGB image, which supercooled water droplet clouds appear as shades of white.

Suomi NPP VIIRS 0.64 µm visible channel and False-color RGB images

Suomi NPP VIIRS 0.64 µm visible channel and False-color RGB images

A toggle between the 17:04 UTC Terra MODIS and 18:47 UTC Aqua MODIS true-color RGB images  from the SSEC MODIS Today site (below) showed the amount of ice motion within that 103 minute period of time.

Terra and Aqua MODIS true-color RGB images

Terra and Aqua MODIS true-color RGB images

===== 06 March Update =====

As winds changed to southerly and southwesterly in the wake of a retreating surface high pressure on 06 March, a corresponding change in Great Lakes ice motion was seen on GOES-13 0.63 µm visible channel images (below; click image to play animation).

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

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

15-meter resolution Landsat-8 0.59 µm panochromatic visible imagery viewed using the SSEC RealEarth web map server (below) offered a very detailed view of the Lake Superior ice in the vicinity of the Keweenaw Peninsula and Marquette  in the Upper Peninsula of Michigan.

Landsat-8 0.59 µm panochormatic visible channel image

Landsat-8 0.59 µm panochormatic visible channel image

Changes to the routine GOES-13 Scanning Schedule

March 4th, 2014
GOES-13 10.7 µm images (click to play animation)

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

Tests are underway this week to determine the impact of augmented GOES-13 (GOES-East) imager coverage. The animation above shows the coverage for routine scanning on 3 March 2014 between 1645 UTC and 1945 UTC. CONUS, Extended Northern Hemisphere and Full Disk images are included. The Optimized GOES-East schedule is available at this link. Note the presence of local solar RFI (radio frequency interference) in the 1645 UTC image; solar contamination resulted in no 1702 UTC image at all, as expected (link). Data at SSEC that are contaminated by solar RFI are typically replaced by data from CLASS, as times of local solar RFI in Madison, WI typically do not overlap with times of local solar RFI at Wallops Island, VA.

The difference in CONUS coverage is shown below in the toggle of the 1732 UTC image from 3 March and the 1730 UTC image from 4 March. The Optimized Image scan allows for more routine scanning of the Caribbean Sea, for example.

GOES-13 10.7 µm images at ~1730 UTC on 3 and 4 March (click to enlarge)

GOES-13 10.7 µm images at ~1730 UTC on 3 and 4 March (click to enlarge)

Side-by-side views of GOES-13 10.7 µm images.  CONUS from 3 March, 1732 UTC (left) and Optimized CONUS from 4 March, 1730 UTC (right) (click to enlarge)

Side-by-side views of GOES-13 10.7 µm images. CONUS from 3 March, 1732 UTC (left) and Optimized CONUS from 4 March, 1730 UTC (right) (click to enlarge)

A side-by-side image of the regular and optimized CONUS scans is shown above. Note that the optimized scan has a slightly different time (Nominal times for each image are in the panel labels). Thus, batch jobs that access imagery by time must be altered. Side-by-side imagery for the entire test period is below. The 1645 UTC imagery should cover the same domain, but RFI interference is different on the two days. The test period ends before the 1902 UTC image. In the animation below, the CONUS images at half-past the hour show the increase in domain size.

Side-by-side views of GOES-13 10.7 µm images, 1645 UTC through 1902 UTC on March 3 2014 (Left, default schedule) and March 4, 2014 (right, optimized schedule). (click to animate)

Side-by-side views of GOES-13 10.7 µm images, 1645 UTC through 1902 UTC on March 3 2014 (Left, default schedule) and March 4, 2014 (right, optimized schedule). (click to animate)

Four-hour animation of Puerto Rico Regional Sector, 17-20 UTC on 4 March 2014 (click to enlarge)

Four-hour animation of Puerto Rico Regional Sector, 17-20 UTC on 4 March 2014 (click to enlarge)

As noted above, the optimized scan strategy significantly improves coverage in the Caribbean. In fact, the Puerto Rico Regional Sector is now almost completely covered. The animation above shows that sector for 2 hours with the expanded coverage during the test, and the subsequent two hours. Compare, for example, the 1830 UTC image, during the test, to the 1931 UTC image after the test (image toggle comparison).