Eruption of the Lewotolok volcano in Indonesia

November 29th, 2020 |

Himawari-8 True Color RGB images [click to play animation | MP4]

Himawari-8 True Color RGB images [click to play animation | MP4]

JMA Himawari-8 True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) showed the volcanic clouds produced by an eruption of Lewotolok in Indonesia on 29 November 2020 — with one cloud plume moving to the northwest, and another moving more rapidly southeastward. This difference in volcanic cloud propagation was due to directional wind shear, as revealed by rawinsonde data from Kupang on the island of Timor (below), located about 250 km southeast of Lewotolok. A shift to northwesterly winds occurred at an altitude around 9 km (the 322 hPa pressure level).

Plot of rawinsonde data from Kupang, Indonesia [click to enlarge]

Plot of rawinsonde data from Kupang, Indonesia [click to enlarge]

Himawari-8 Ash RGB images [click to play animation | MP4]

Himawari-8 Ash RGB images [click to play animation | MP4]

Himawari-8 Ash RGB images (above) displayed an ash signature for both volcanic plumes, which became more diffuse after about 5 hours. Himawari-8 retrievals of Ash Height from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) showed maximum values in the 16-18 km range for the southeast-moving cloud (the  advisory issued by the Darwin VAAC listed maximum height values of 50,000 feet or 15 km).

Himawari-8 retrievals of Ash Height [click to enlarge]

Himawari-8 retrievals of Ash Height [click to enlarge]


Typhoon Vamco approaches Vietnam

November 13th, 2020 |

Himawari-8 Infrared Imagery (10.41 µm, Band 13) from 0702 to 1942 UTC on 13 November (Click to animate)

Himawari-8 “Target” infrared imagery at 10.41 µm (above) and 7.35 µm (below) (courtesy JMA, the Japanese Meteorological Agency) show Typhoon Vamco as it crossed the South China Sea on 13 November, approaching Vietnam. Strong convection develops frequently in the region surrounding the not-quite-circular eye (click here for an mp4 animation), and dry air is far removed from the center, based on the low-level water vapor imagery below (click here for an mp4 animation), although it is wrapping around the southern half of the storm by the end of the animation.  (Click here for more information on Vamco from JMA).

Himawari-8 Infrared Imagery (7.35 µm, Band 10) from 0702 to 1947 UTC on 13 November (Click to animate)

MIMIC Total Precipitable Water fields (from this site), below, show that Vamco is preceded by relatively dry air that appears to be wrapping closer and closer to the storm (The storm is however followed by abundant moisture).  Dry air and relatively cool sea-surface temperatures (from this site) may be the reason that weakening is forecast before landfall.  Shear values remain low but are forecast to become less favorable.

MIMIC Total Precipitable Water for the 24 hours ending 2000 UTC on 13 November 2020 (Click to enlarge)

For more information on Vamco, refer the SSEC Tropical Page, the JTWC or to JMA.

Goni in the South China Sea

November 2nd, 2020 |

Himawari-8 Target (every 2.5 minutes) Infrared (10.41 µm) and visible (0.64 µm) Imagery, 0122 to 1352 UTC on 2 November 2020 (Click to animate)

Typhoon Goni hit the Phillipines as a major typhoon on 31 October.  Since then, an increase in shear and the topography of Luzon have both weakened the storm significantly.   The mp4 animation above (click here as an mp4) shows 2.5-minute Himawari-8 Target imagery Infrared (10.41 µm, left) and visible (0.64 µm, right) imagery from 0122 through 1352 UTC on 2 November.  Although significant convection continues, especially after dark near the center, suggesting strengthening, strong easterly shear, shown below, from this website, is present.  Convection in the animation above is displaced to the west of the surface circulation, as expected given the shear.  In addition, sea surface temperatures become progressively cooler along the projected track.  Environmental factors do not favor significant strengthening.

Past and predicted storm path/intensity for Goni in the South China Sea, along with 1200 UTC 2 November Tropospheric Shear (850-200 mb), click to enlarge)

A two-day animation of MIMIC Total Precipitable water (imagery from this ftp site) shows the change in circulation as Goni moved over Luzon.

MIMIC Total Precipitable Water, 0000 UTC on 31 October through 0000 UTC 2 November 2020 (Click to animate)

Super Typhoon Goni in the West Pacific Ocean

October 30th, 2020 |

JMA Himawari-8

JMA Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

2.5-minute rapid scan JMA Himawari-8 “Red” Visible (0.64 µm) images (above) showed Category 5 Super Typhoon Goni in the West Pacific Ocean on 30 October 2020. The images revealed a very small “pinhole eye”, surface mesovortices within the eye and a trochoidal motion — all characteristics of a tropical cyclone at/near its peak intensity (Goni had a satellite-derived estimate of 160 knots at 00 UTC). The trochoidal “wobble” was more evident in a faster animation.

The corresponding Infrared (10.4 µm) images (below) revealed cloud-top infrared brightness temperatures that were frequently in the -80 to -85ºC range (shades of violet).

JMA Himawari-8 "Clean" Infrared Window (10.4 µm) images [click to play animation | MP4]

JMA Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play animation | MP4]

Longwave Infrared (11.2 µm) images with contours of 00 UTC deep-layer wind shear from the CIMSS Tropical Cyclones site (above) indicated Goni was in an environment of very low shear at that time.

Himawari-8 Longwave Infrared (11.2 µm) images, with contours of 0i0 UTC deep-layer wind shear [click to enlarge]

Himawari-8 Longwave Infrared (11.2 µm) images, with contours of 00 UTC deep-layer wind shear [click to enlarge]

===== 31 October Update =====

JMA Himawari-8 "Clean" Infrared Window (10.4 µm) images [click to play animation | MP4]

JMA Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play animation | MP4]

Super Typhoon Goni maintained Category 5 intensity for over 24 hours, and actually intensified to 170 knots (JTWC advisory | ADT | SATCON) at 18 UTC on 31 October, just prior to making landfall along Catanduanes Island in the Philippines around 2050 UTC (a closer view of landfall using RealEarth is available here). At 170 knots, Goni became one of the most intense landfalling tropical cyclones on record.

Note the rapid deterioration of the eye upon landfall — this was likely due to a combination of interaction with the terrain of the island, and increasing deep-layer wind shear (below). As it was approaching the Philippines, Goni had been moving over very warm water characterized by high values of Sea Surface Temperature and Ocean Heat Content.

Himawari-8 Water Vapor images, with contours of deep-layer wind shear [click to enlarge]

Himawari-8 Water Vapor images, with contours of deep-layer wind shear [click to enlarge]

A DMSP-16 SSMIS Microwave (85 GHz) image at 2032 UTC is shown below.

DMSP-16 SSMIS Microwave image at 2032 UTC [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) image at 2032 UTC [click to enlarge]

 A NOAA-20 VIIRS Infrared Window (11.45 µm) image (below) showed Goni just after 16 UTC.

NOAA-20 VIIRS Infrared Window (11.45 ) image [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image [click to enlarge]