Large bushfires in southeastern Australia

January 16th, 2014 |

MTSAT-2 0.68 µm visible channel (left) and 3.75 µm shortwave IR (right) images [click to play animation]

MTSAT-2 0.68 µm visible channel (left) and 3.75 µm shortwave IR (right) images [click to play animation]

An extended period of hot, dry weather led to the development of multiple large bushfires across parts of southeastern Australia, some of which began to produce pyrocumulonimbus (pyroCb) clouds during the 15-16 January 2014 period. McIDAS images of MTSAT-2 0.68 µm visible channel and 3.75 µm shortwave IR channel data (above; click image to play animation; also available as an MP4 animation) showed the development of a well-defined pyroCb associated with the Northern Grampions fire in the state of Victoria. After the visible images on the left panels faded to black during the night-time hours, the shortwave IR images on the right panels showed that many of the fire “hot spots” (denoted by the darker black pixels) continued to grow during the night.

MTSAT-2 10.8 µm longwave IR channel images (below; click image to play animation; also available as an MP4 animation) indicated that cloud-top IR brightness temperatures associated with the rapidly-growing pyroCb cloud became as cold as -38.7º C (lighter green color enhancement) at 07:32 UTC. Other areas of cold-topped thunderstorms developed near the coast, likely initiated by sea breeze and/or local terrain influences. Surface reports ploted on the IR images revealed very hot temperatures: for example, it was 109º F (42.8º C) at Melbourne Essondon (station identifier YMEN) at 04 UTC.

MTSAT-2 10.8 µm longwave IR images [click to play animation]

MTSAT-2 10.8 µm longwave IR images [click to play animation]

A larger-scale view of MTSAT-2 0.68 µm visible channel images (below, visualized using the SSEC RealEarth web map server) showed that there were some large bushfires to the northwest that were producing long, dense smoke plumes which were drifting southward off the coast.

MTSAT-2 0.68 µm visible channel images [click to play animation]

MTSAT-2 0.68 µm visible channel images [click to play animation] 

Blowing dust in Nebraska, Kansas, and Colorado

January 16th, 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)

McIDAS images of 1-km resolution GOES-13 (GOES-East) 0.63 µm visible channel data (above; click image to play animation) showed the development of widespread plumes of blowing dust across parts of southwestern Nebraska, northwestern Kansas, and eastern Colorado on 16 January 2014. Strong northerly to northwesterly winds in the wake of a morning cold frontal passage were  gusting over 40 knots across the entire region, with a peak wind gust of 64 knots in Broken Bow, Nebraska. These strong winds easily lofted the dry soils (the area was experiencing extreme drought conditions), which reduced surface visibilities and caused multiple vehicle accidents in Colorado and Kansas.

A closer view of the blowing dust using a 250-meter resolution Aqua MODIS true-color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below) clearly showed the source region of many of the dust plumes in southwestern Nebraska. The blowing dust plumes in eastern Colorado are not easily seen, due to patchy middle and high level clouds drifting over the region at that time.

Aqua MODIS true-color RGB image

Aqua MODIS true-color RGB image

A larger-scale view of the MODIS true-color image can be seen below, visualized using Google Earth.

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

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

For additional information and imagery of this blowing dust event, see the RAMMB GOES-R Proving Ground blog.

VIIRS Day/Night Band images: ice in Lake Erie, and thunderstorms over the Gulf of Mexico

January 13th, 2014 |
Suomi NPP VIIRS 0.7 µm Day/ight Band, 11.45-3.74 µm "fog/stratus product", and 11.45 µm IR channel images

Suomi NPP VIIRS 0.7 µm Day/ight Band, 11.45-3.74 µm “fog/stratus product”, and 11.45 µm IR channel images

With ample illumination by moonlight (the Moon was in the Waxing Gibbous phase, at 98% of full), an AWIPS image of Suomi NPP VIIRS 0.7 µm Day/Night Band data was able to provide a “visible image at night” that showed the extensive ice coverage in Lake Erie at 06:42 UTC or 1:42 AM local time on 13 January 2014 (above). The mean ice concentration of Lake Erie was 76.8% at that time (up from less than 20% at the begining of January). Note that there was no signal of any potential fog/stratus over the lake on the corresponding 11.45-3.74 µm IR brightness temperature difference “fog/stratus product”, and very little thermal contrast seen in the 11.45 µm IR image.

Farther to the south over the Gulf of Mexico, the 08:21 UTC or 2:21 AM local time VIIRS 0.7 µm Day/Night Band image (below) showed large thunderstorms, with cloud-top shadowing from overshooting tops as well as a few bright “lightning streaks” due to cloud illumination by intense lightning activity at the time the instrument was scanning the region. Overlays of cumulative 1-hour cloud-to-ground lightning strikes indicated over 2400 strikes ending at 08 UTC, and over 1800 strikes ending at 09 UTC over the area of the satellite scene. A comparison with the corresponding 11.45 µm IR image showed that the coldest cloud-top IR brightness temperatures were -65º C over the northern convective complex, and -73º C over the southern convective complex.

Suomi NPP VIIRS 11.45 µm IR channel, 0.7 µm Day/Night Band, and 1-hour cloud-to-ground lightning strikes

Suomi NPP VIIRS 11.45 µm IR channel, 0.7 µm Day/Night Band, and 1-hour cloud-to-ground lightning strikes

Cyclone Ian in the South Pacific Ocean

January 11th, 2014 |
Global IR image composite

Global IR image composite

Looking at a global composite of IR imagery from the SSEC RealEarth web map server (above), Cyclone Ian (07 P) in the South Pacific Ocean was a rather compact storm — however, a time series plot of the Advanced Dvorak Technique (below) showed that Cyclone Ian experienced a period of rapid intensification to Category 4 strength on 10 January 2014 (21 UTC Joint Typhoon Warning Center advisory).

Advanced Dvorak Technique (ADT) plot for Cyclone Ian

Advanced Dvorak Technique (ADT) plot for Cyclone Ian

IR images of Cyclone Ian (click to play animation)

IR images of Cyclone Ian (click to play animation)

SSEC RealEarth IR imagery (above; click image to play animation) and visible imagery (below; click image to play animation) showed the well-defined eye that was exhibited by Cyclone Ian during this period of rapid intensification on 10 January, as the storm moved slowly south-southeastward across the island nation of Tonga.

Visible images of Cyclone Ian (click to play animation)

Visible images of Cyclone Ian (click to play animation)

On 11 January, water vapor channel imagery from the CIMSS Tropical Cyclones site (below) showed the continuation of the impressive channel of poleward outflow from Cyclone Ian, which was enhanced by the presence of a mid-latitude trough passing to the south of the tropical cyclone.

Water vapor channel imagery

Water vapor channel imagery