Severe Tropical Cyclone Ita

April 10th, 2014
MTSAT-2 10.8 µm IR channel images (click to play animation)

MTSAT-2 10.8 µm IR channel images (click to play animation)

McIDAS images of MTSAT-2 10.8 µm IR channel data (above; click image to play animation) showed the development of a distinct eye associated with Intense Cyclone Ita (23P) as it moved southwestward across the Coral Sea toward the coast of Queensland, Australia on 10-11 April 2014. Cyclone Ita exhibited a period of rapid intensification (Advanced Dvorak Technique plot) early on 10 April, reaching Category 4 intensity (JTWC advisory) on the Saffir-Simpson scale (or a Category 5 on the Australian intensity scale: BOM advisory). Ita had been moving through an environment with weak deep layer wind shear and over warm sea surface temperatures, which aided in its intensification.

A timely overpass of a Metop polar-orbiting satellite provided ASCAT surface scatterometer winds at 11:26 UTC, as seen on an image from the CIMSS Tropical Cyclones site (below).

MTSAT-1 10.8 IR image with Metop ASCAT surface scatterometer winds

MTSAT-1 10.8 IR image with Metop ASCAT surface scatterometer winds

The structure of the eye of Ita was nicely displayed on a TRMM satellite TMI 85 GHz microwave image at 14:32 UTC (below).

TRMM TMI 85 GHz microwave image

TRMM TMI 85 GHz microwave image

A McIDAS-V image comparison of Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band data at 14:58 UTC (below; courtesy of William Straka, SSEC/CIMSS) showed great detail of the eye and surrounding eyewall region of Ita.

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images

The first available early-morning MTSAT-2 0.675 µm visible channel image at 20:32 UTC (below) revealed a convective tower within the northeastern portion of the eyewall region, with a distinct overshooting top (10-11 April animation of MTSAT-2 visible images).

MTSAT-2 0.675 µm visible channel image

MTSAT-2 0.675 µm visible channel image

The MTSAT InfraRed/Water Vapor difference product (below; click image to play animation) indicated that overshooting tops were likely around a large area surrounding the core of Ita.

MTSAT IR/WV Difference product (click to play animation)

MTSAT IR/WV Difference product (click to play animation)

===== 11 April Update =====

A TRMM satellite TMI 85 GHz microwave image at 05:23 UTC showed that Ita had a double-eyewall structure as it was close to making landfall, indicating that the cyclone was undergoing an eyewall replacement cycle — this suggests that Ita was in a weakening phase as it made landfall.

TRMM TMI 85 GHz microwave image

TRMM TMI 85 GHz microwave image

Re-suspended ash from the Katmai volcano in Alaska

September 22nd, 2013
GOES-15 0.63 µm visible channel images (click image to play animation)

GOES-15 0.63 µm visible channel images (click image to play animation)

GOES-15 0.63 µm visible channel images (above; click image to play animation) showed a distinct hazy plume streaming southeastward from the Katmai volcano area in Alaska on 22 September 2013. This was a signature of re-suspended volcanic ash — a deep layer of ash has remained on the ground near the volcano following the massive 1912 eruption — which was carried aloft by strong winds on the back side of a deep area of low pressure over the Gulf of Alaska (below).

Suomi NPP VIIRS 0.7 µm Day/Night Band image

Suomi NPP VIIRS 0.7 µm Day/Night Band image

A closer view using a sequence of four Suomi NPP VIIRS 0.7 µm Day/Night Band images (below) showed the evolution of the ash plume as it moved over southeastward over Kodiak Island and then out over the Gulf of Alaska. Winds at Kodiak (station identifier PADQ) gusted as high as 55 knots or 63 mph. With limited snow cover and strong winds (which were enhanced by local terrain effects), the surface volcanic ash was easily lofted to great heights.

Suomi NPP VIIRS 0.7 µm Day/Night Band images

Suomi NPP VIIRS 0.7 µm Day/Night Band images

An image of a MODIS-based NOAA/STAR/CIMSS Volcanic Ash Height product is shown in combination with the Volcanic Ash Advisory that was issued by the Anchorage Volcanic Ash Advisory Center (below).

MODIS Ash Height product with Volcanic Ash Advisory

MODIS Ash Height product with Volcanic Ash Advisory

MODIS Ash Height product

MODIS Ash Height product

A sequence of three MODIS Volcanic Ash Height product images (above) suggested that the average height of the re-suspended ash plume was around 9,000 – 11,000 feet. A vertical profile of CALIPSO satellite-based lidar data near the source of the ash plume (below; courtesy of Mike Pavolonis, NOAA/NESDIS/STAR) indicated that the top of the plume was around 3.5 km or 11,000 feet (at 12:57 UTC, near latitude/longitude 58 N / 155 W).

CALIPSO total attenuated backscatter

CALIPSO total attenuated backscatter

The corresponding MODIS Ash Mass Loading product (below) indicated values of 2-3 tons per square kilometer existed over much of the ash plume.

MODIS Ash Mass Loading product

MODIS Ash Mass Loading product

Finally, the corresponding MODIS Ash Mass Effective Radius product (below) showed that much of the plume likely consisted of particles with radii in the 4-6 µm range, with a maximum value of 8.33 µm.

MODIS Ash Mass Effective Radius product

MODIS Ash Mass Effective Radius product

Additional information on the NOAA/UW-CIMSS GOES-R Volcanic Ash Products shown above can be found in this Java-based VISITview lesson (a separate Lesson Playback Control window will open to assist in viewing the lesson content).

===== 23 September Update =====

Suomi NPP VIIRS 0.7 µm Day/Night Band image

Suomi NPP VIIRS 0.7 µm Day/Night Band image

On the following day (23 September), a Suomi NPP VIIRS 0.7 µm Day/Night Band image (above) showed that the resuspended Katmai ash plume was still present, but was much less expansive than what was seen on 22 September.

Hat tip to Mark Ruminski of the NOAA/NESDIS Satellite Services Division for bringing this interesting event to our attention!

Super Typhoon Usagi

September 19th, 2013
MTSAT-2 10.8 µm IR images (click image to play animation)

MTSAT-2 10.8 µm IR images (click image to play animation)

McIDAS images of MTSAT-2 10.8 µm IR channel data (above; click image to play animation) showed Super Typhoon Usagi in the West Pacific Ocean as it continued to move northwestward across the Philippine Sea. Note the slight amount of “trochoidal wobble” seen in the path of the eye. The coldest IR brightness temperature seen on the MTSAT-2 IR images was -92º C at 12:32 UTC. At the time of these images, advisories issued by the Joint Typhoon Warning Center listed the maximum sustained winds at 140 knots, with gusts to 170 knots; at its peak intensity, Usagi had an estimated lowest pressure of 882 hPa, making it the most intense tropical cyclone so far in 2013.

TMI and SSM/I 85 GHz microwave brightness temperature images

TMI and SSM/I 85 GHz microwave brightness temperature images

From the CIMSS Tropical Cyclones site, a comparison of 85 GHz microwave images from the TRIMM Microwave Imager (TMI) at 10:35 UTC and the DMSP SSM/I at 19:13 UTC (above) displayed a very small ring of high brightness temperatures surrounding the “pinhole eye”.

MIMIC-TC morphed microwave images (below; click image to play animation) showed a well-defined closed eyewall during much of the early part of the day on 19 September.

MIMIC-TC morphed microwave imagery (click image to play animation)

MIMIC-TC morphed microwave imagery (click image to play animation)

 

MTSAT-2 IR image with AASCAT scatterometer surface winds

MTSAT-2 IR image with AASCAT scatterometer surface winds

Scatterometer surface winds from the ASCAT instrument at 13:17 UTC  (above) and the OSCAT instrument at 15:10 UTC  (below) showed the large areal coverage of strong winds around the center of Usagi.

MTSAT-2 IR image with OSCAT scatterometer surface winds

MTSAT-2 IR image with OSCAT scatterometer surface winds

 ===== 20 September Update =====

MTSAT-2 0.67 µm visible channel images (click image to play animation)

MTSAT-2 0.67 µm visible channel images (click image to play animation)

MTSAT-2 0.67 µm visible channel images (above; click image to play animation) showed the detailed structure of the compact eye of Super Typhoon Usagi.

Hurricane Barbara

May 29th, 2013
GOES-14 0.63 µm visible channel images (click image to play animation)

GOES-14 0.63 µm visible channel images (click image to play animation)

McIDAS images of GOES-14 0.63 µm visible channel data (above; click image to play animation) showed Tropical Storm Barbara as it intensified to Category 1 hurricane shortly before making landfall along the coast of the Gulf of Tehuantepec in southeastern Mexico on 29 May 2013. Since reliable records began for the Eastern Pacific Basin in 1966, Hurricane Barbara was the second-earliest hurricane landfall, as well as the easternmost landfall location.

An AWIPS image of ASCAT surface scatterometer winds overlaid on a GOES IR image (below) depicted a maximum wind speed of 53 knots at 16:01 UTC (while Barbara was still at tropical storm intensity).

ASCAT surface scatterometer winds

ASCAT surface scatterometer winds

A 375-meter resolution Suomi NPP VIIRS 11.45 µm IR image at 19:35 UTC (below) showed the very cold cloud-top IR brightness temperatures (primarily in the -80 to -90 C range, enhanced with varying shades of violet) associated with convective clusters around the center of Hurricane Barbara as the storm was making landfall along the Mexican coast.

Suomi NPP VIIRS 11.45 µm IR image

Suomi NPP VIIRS 11.45 µm IR image

 ===== 30 May Update =====

GOES-14 0.63 µm visible channel images (below; click image to play animation) seem to suggest that the low-level circulation of Barbara remained intact after crossing the rugged terrain of southern Mexico, and emerged into the Gulf of Mexico on 30 May. The GOES-14 satellite had been placed into Rapid Scan Operations (RSO), providing images as frequently as every 5-10 minutes.

GOES-14 0.63 µm visible channel images (click image to play animation)

GOES-14 0.63 µm visible channel images (click image to play animation)