Cyclone Yasa strengthens rapidly in the South Pacific

December 16th, 2020 |


Himawari-8 Clean Window Infrared (10.41 µm) imagery, 0000 UTC 14 December to 0000 UTC 16 December 2020 (Click to animate)


Himawari-8 Clean Window Infrared (10.41 µm) imagery (courtesy the Japanese Meteorological Agency, JMA) from 14-15 December 2020 (click here for an animated gif) show the development of a potent storm with an obvious clear and large eye by 0000 UTC on 16 December. The Joint Typhoon Warning Center notes: ” TC 05P HAS RAPIDLY INTENSIFIED 50 KNOTS OVER THE PAST 24 HOURS, FROM 85 KNOTS AT 14/18Z TO 135 KNOTS AT 15/18Z.” Yasa further intensified to a Category 5 tropical cyclone at 0000 UTC on 16 December.


Visible imagery from GOES-17 and Himawari-8, (mp4 animation below, click here for an animated gif, and here for a full-sized mp4), during the day on 16 December show a well-developed storm with a clear eye.


Stereoscopic view of Cyclone Yasa, 1800 UTC 15 December to 0550 UTC 16 December 2020. Click to animate. GOES-17 Visible imagery on the left, Himawari imagery on the right

A storm-centered view of the storm is shown below. Click here for the full-sized mp4, and here for an animated gif.


Storm-centered stereoscopic view of Cyclone Yasa, 1800 UTC 15 December to 0550 UTC 16 December 2020. Click to animate. GOES-17 Visible imagery on the left, Himawari imagery on the right

The animation below is also storm-centered, but zoomed in on the eye of the storm.  Click here for a full-sized mp4, and here for an animated gif


Storm-centered stereoscopic view of the eye of Cyclone Yasa, 1800 UTC 15 December to 0550 UTC 16 December 2020. Click to animate. GOES-17 Visible imagery on the left, Himawari imagery on the right

Forecast models take this strong cyclone over Fiji later this week. Refer to the JTWC, to the RSMC in Fiji or the SSEC Tropical web site for more information.

Stereoscopic views of Cyclones Yasa and Zazu

December 14th, 2020 |



GOES-17 (left) and Himawari-8 (right) visible (0.64 µm) imagery over Fiji, 2100 UTC on 13 December through 0500 UTC on 14 December (Click to animate)

An active area of tropical weather has spawned two tropical cyclones that bracketed the islands of Fiji early on 14 December. Himawari-8 (data courtesy the Japanese Meteorological Agency, JMA) and GOES-17 both viewed the two storms, with Yasa on the left and Zazu on the right, and stereoscopic views are shown above. (To view the imagery in three dimensions, relax/cross your eyes until three images are present, and focus on the image in the center). Click here for a full-sized mp4, and here for an animated gif.

The storms had an interesting development, as shown below in a 3-day Himawari-8 Clean Window infrared imagery mp4 animation (Click here for a large animated gif of the same scene) from 10-13 December 2020. Yasa in particular developed in a region of considerable shear and initially followed a circuitous route (shown in this graphic from RSMC Fiji), but it has since moved into a more favorable environment.  Yasa also absorbed the remains of Tropical Storm #4.



Himawari-8 Clean window infrared (10.41 µm) imagery, 0000 UTC on 10 December – 2350 UTC on 13 December (Click to animate;  data courtesy JMA)


GOES-17 (left) and Himawari-8 (right) visible (0.64 µm) imagery over Fiji, 1900 UTC on 14 December 2020 (Click to enlarge)

Added:  The morning view of the storms, above, from 1900 UTC on 14 December reveals that Zazu is becoming sheared.  The low-level center is exposed with convection shifted to the east.  This is consistent with shear analyses from the SSEC Tropical website, below, that shows westerly shear over the storm.

850-200 mb shear analysis, 1500 UTC on 14 December 2020 (Click to enlarge)

For more information on these storms, refer to the SSEC tropical website (link), or to the RSMC in Fiji (link). At present, Yasa is forecast to make landfall in Fiji later this week as a very strong storm. Interests there should monitor this storm closely.

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 Ash Height [click to play animation | MP4]

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

Himawari-8 False Color images (below) indicated the presence of both SO2 (shades of yellow to green) and ash in the southeastward-moving volcanic cloud.

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

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


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.