Hurricane Danielle undergoes an Eyewall Replacement Cycle

August 28th, 2010 |
Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product

Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product

An animation of the Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product (above) revealed that Hurricane Danielle (which had intensified into a Category 4 storm) was undergoing an Eyewall Replacement Cycle (ERC) during the 27 August – 28 August 2010 period. Note how the smaller inner eyewall deteriorated and became replaced by a much larger outer eyewall during the ERC process.

Following the ERC, GOES-13 10.7 µm IR images from the CIMSS Tropical Cyclones site (below) showed Danielle beginning the recurvature process after weakening to a Category 2 storm.

GOES-13 10.7 µm IR images

GOES-13 10.7 µm IR images

Even though Hurricane Danielle was quite far from the US East Coast (below), long period ocean swells and increasing onshore winds were creating dangerous rip currents along much of the nearshore waters and beaches from Florida to the Mid-Atlantic states.

GOES-13 10.7 µm IR image

GOES-13 10.7 µm IR image

Be sure to check out the PREDICT Field Experiment Blog for additional insights on other tropical cyclone activity in the Atlantic basin.

Unusual Double Eyewall structure in Himawari-8 Infrared Imagery of Typhoon Nangka

July 13th, 2015 |
Himawari-8 10.35 µm infrared imagery, 0540-1540 UTC on 13 July 2015 (Click to animate)

Himawari-8 10.35 µm infrared imagery, 0540-1540 UTC on 13 July 2015 (click to animate)

Himawari-8 10.35 µm infrared imagery showed an unusual (for infrared imagery) double-eyewall structure in Typhoon Nangka over the western Pacific Ocean on 13 July 2015. For such a feature to appear in infrared imagery, the secondary circulations of both the inner and outer eyewall need to be intense enough to support the downdraft/cloud-clearing necessary to create the “moats” between them. Microwave imagery of the storm, below, viewed via MIMIC (from this site), also showed the double eyewall structure quite well. This double-eyewall signature typically indicates that a tropical cyclone is experiencing an eyewall replacement cycle (ERC), which signals that a (temporary) decrease in intensity is soon to follow.

MIMIC imagery of Typhoon Nangka, 0000 - 1200 UTC on 13 July 2015 (Click to enlarge)

MIMIC imagery of Typhoon Nangka, 0000 – 1200 UTC on 13 July 2015 (click to enlarge)

Several hours later, a DMSP SSMIS 85 GHz microwave image at 1756 UTC, below, indicated that the ERC was essentially complete. Subsequently, the Joint Typhoon Warning Center slightly downgraded the intensity of Typhoon Nangka for their 21 UTC advisory. While not as well-defined as in the Himawari-8 imagery, the double-eyewall signature was still evident in the lower-resolution (4-km, vs  2-km) MTSAT-2 IR imagery (animation).

DMSP SSMIS 85 GHz microwave image and MTSAT-2 10.8 µm Infrared image (click to enlarge)

DMSP SSMIS 85 GHz microwave image and MTSAT-2 10.8 µm Infrared image (click to enlarge)

The Himawari-8 Target Sector was centered over Typhoon Nangka during this time; an IR image animation with a 2.5-minute timestep, below (courtesy of William Straka, SSEC), showed the evolution of the double eyewall signature, along with 2 pulses of storm-top gravity waves which propagated radially outward away from the center in the northern semicircle of the typhoon.

Himawari-8 10.4 µm IR channel images (click to animate large 115-Megabyte file)

Himawari-8 10.4 µm IR channel images (click to animate large 115-Megabyte file)

Cyclone Fani makes landfall in India

May 3rd, 2019 |

EUMETSAT-8 Meteosat-8 Infrared Window (10.8 µm) umages [click to play animation | MP4]

EUMETSAT Meteosat-8 Infrared Window (10.8 µm) images [click to play animation | MP4]

EUMETSAT Meteosat-8 Infrared Window (10.8 µm) images (above) showed the intensification of Cyclone Fani to a high-end Category 4 storm on 02 May 2019 (ADT | SATCON | PGTW advisory), before eventually making landfall in northeastern India at 0230 UTC on 03 May. During its life cycle, Fani moved over warm sea surface temperature values of 29-30ºC — and deep-layer wind shear of only 5-10 knots on 02 May provided an environment favorable for rapid intensification.

Once inland, Fani was in the process of rapidly weakening to a Category 1 storm as it passed over Bhabaneswar (VEBS), and surface wind gusts to 75 knots were reported at that site (below).

Time series plot of surface observations from Bhabaneswar, India [click to enlarge]

Time series plot of surface observations from Bhabaneswar, India [click to enlarge]

A sequence of VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP as viewed using RealEarth (below) showed snapshots of Fani from 19 UTC on 01 May (over the Bay of Bengal) to 07 UTC on 03 May (after landfall).

Sequence of NOAA-20 and Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

Sequence of NOAA-20 and Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

A comparison of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP on 02 May (below) showed Fani shortly after it had reached Category 4 intensity.

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 1230 UTC + Meteosat-8 Infrared Window (10.8 µm) image at 1300 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 1230 UTC + Meteosat-8 Infrared Window (10.8 µm) image at 1300 UTC [click to enlarge]

A toggle between a DMSP-17 SSMIS Microwave image at 1230 UTC and a Meteosat-8 Infrared Window image at 1300 UTC  from the CIMSS Tropical Cyclones site (above) showed the eye and totally closed eyewall of Fani when it was at its peak intensity on 02 May. However, the MIMIC TC product (below) indicated that the eastern portion of the eyewall started to erode as Fani approached the coast and began to undergo an eyewall replacement cycle.

MIMIC TC morphed microwave product, 01-02 May [click to enlarge]

MIMIC TC morphed microwave product, 01-02 May [click to enlarge]

On 30 April, VIIRS DayNight Band (0.7 µm) images (below, courtesy of William Straka, CIMSS) revealed widespread mesospheric airglow waves (reference) within the western semicircle of the storm, along with numerous bright lightning streaks associated with convection south of the storm center.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1939 UTC on 30 April [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1939 UTC on 30 April [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 2029 UTC on 30 April [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 2029 UTC on 30 April [click to enlarge]

Cyclone Idai makes landfall in Mozambique

March 14th, 2019 |

Meteosat-8 Infrared (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Cyclone Idai — which had been slowly intensifying over warm water within the Mozambique Channel since 09 March — made landfall as a Category 2 storm along the coast of Mozambique on 14 March 2019 (storm track). A toggle between Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (above) revealed a large and well-defined eye and eyewall structure at 1630 UTC. Idai had been rated at Category 3 intensity during 3 periods of time during its life cycle, most recently at 12 UTC on the day of landfall.

At 1911 UTC, Metop-A ASCAT winds in excess of 60  knots were sampled just west of the eyewall region (below).

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

A comparison of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, visualized using RealEarth, is shown below.

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

Idai had been moving through an environment of very low deep-layer wind shear — a favorable factor for maintaining its intensity — as shown in an animation of Meteosat-8 Infrared Window (10.8 µm) images (below).

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

The MIMIC TC product (below) suggested that Idai might have been in the early stage of an eyewall replacement cycle (ERC) just prior to making landfall. This, after completing a separate ERC during the preceding 48 hours.

MIMIC TC morphed microwave imagery [click to enlarge]

MIMIC TC morphed microwave image product [click to enlarge]

The eye of Idal was becoming cloud-filled as it approached the Mozambique coast, as seen on EUMETSAT Meteosat-8 High Resolution Visible (0.8 µm) images (below).

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

A time series of surface data from the port city of Beira FQBR (below) showed deteriorating conditions before observations ceased at 15 UTC.

Surface observation data from Beira, Mozambique [click to enlarge]

Surface observation data from Beira, Mozambique [click to enlarge]


Incidentally, an overpass of the Landsat-8 satellite on 11 March provided a 30-meter resolution view of the eye (below), soon after Idai’s first period of rapid intensification to Category 3 strength (SATCON). Surface mesovortices were apparent within the eye.

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Flooding from Idai led to hundreds of fatalities in Mozambique and Zimbabwe.