Rapid intensification of Super Typhoon Surigae

April 16th, 2021 |

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

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

2.5-minute interval rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (above) showed Typhoon Surigae undergoing rapid intensification (ADT | SATCON) to become a Category 4 storm as of 18 UTC on 16 April 2021.

A DMSP-16 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) displayed a well-defined eye, with distinct spiral bands feeding into the eyewall.

DMSP-16 SSMIS Microwave (85 GHz) image at 1944 UTC [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) image at 1944 UTC [click to enlarge]

After sunrise, Himawari-8 “Red” Visible (0.64 µm) images (below) showed the relatively compact eye, with hints of low-level mesovortices within the eye.

JMA Himawari-8 "Red" Visible (0.64 µm) images [click to play animation]

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

===== 17 April Update =====

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

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

Another period of rapid intensification occurred overnight, and as of 12 UTC on 17 April Surigae had become a Category 5 Super Typhoon — 2.5-minute interval rapid scan Himawari-8 Infrared images (above) showed the well-defined eye as the storm tracked northwestward across the Philippine Sea (just east of the Philippines). A faster animation (GIF | MP4) helped to highlight the trochoidal motion (wobble) of the eye — a behavior often seen with intense tropical cyclones. The 21 UTC advisory from JTWC listed sustained winds of 165 knots, and objective intensity estimates from ADT and SATCON were around 170 knots.

An animation of Himawari-8 Infrared images with an overlay of deep-layer wind shear (below) indicated that Surigae was moving through a region of low to moderate wind shear; the storm was moving across very warm water (SST + OHC).

Himawari-8 Infrared images, with contours of deep-layer wind shear at 18 UTC [click to enlarge]

Himawari-8 Infrared images, with contours of deep-layer wind shear at 18 UTC [click to enlarge]

Around the time that Surigae was reaching its peak intensity, a Suomi NPP VIIRS Day/Night Band (0.7 µm) image several hours before sunrise (below) revealed concentric mesospheric airglow waves propagating away from the energetic Category 5 tropical cyclone. There were also some bright pixels indicating lightning activity along the inner edge of the northern eyewall.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Cold cloud tops associated with Tropical Storm Surigae in the West Pacific

April 15th, 2021 |

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

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

2.5-minute interval rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (above) revealed intermittent cloud-top infrared brightness temperatures of -100ºC and colder (red pixels embedded within yellow-to-black inner cores) — with the coldest being -101.7ºC at 1342 UTC — within the Central Cold Cover (CCC) pattern of Tropical Storm Surigae on 15 April 2021.

A zoom-in of NOAA-20 VIIRS Infrared Window (11.45 µm) imagery at 1644 UTC as viewed using RealEarth (below) also showed 2 clusters of red -100ºC and colder pixels, with a minimum of -103.6ºC (incidentally, the coldest pixels on the 1644 UTC Himawari-8 Infrared image were -96ºC). About an hour and 15 minutes after this NOAA-20 image, Surigae was upgraded to a Category 1 typhoon (the first typhoon of the 2021 season in the West Pacific basin).

NOAA-20 VIIRSI Infrared Window (11.45 µm) image at 1644 UTC [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image at 1644 UTC [click to enlarge]

A plot of 12 UTC rawinsonde data from Yap Island showed that the coldest air temperature was -84.7ºC at 100 hPa (16.7 km) — so an overshooting top of -100ºC or colder indicated a significant vertical ascent above the tropopause.

Plot of 12 UTC rawinsonde data from Yap Island [click to enlarge]

Plot of 12 UTC rawinsonde data from Yap Island [click to enlarge]

Multi-day eruptions of the La Soufrière volcano in the West Indies

April 9th, 2021 |

GOES-16 Ash RGB images [click to play animation | MP4]

GOES-16 Ash RGB and SO2 RGB images [click to play animation | MP4]

GOES-16 (GOES-East) Ash RGB and SO2 RGB images (above) displayed signatures of two distinct eruptions of the La Soufrière volcano on the island of Saint Vincent in the West Indies on 09 April 2021. Signatures of high ash or SO2 concentrations appear as brighter shades of pink on the RGB images. Significant ash fall on parts of the island forced evacuations of some communities. The SO2 signature for the second eruption was much more pronounced and widespread.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images (below) showed that coldest cloud-top infrared brightness temperatures associated with the first eruption (which began shortly before 1250 UTC) were -62ºC, while the second and more explosive eruption (which began shortly after 1900 UTC) exhibited temperatures as cold as -78ºC.

GOES-16 "Clean" Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 True Color RGB images created using Geo2Grid (below) showed the characteristic tan-colored hues of a volcanic cloud having significant ash loading.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images (credit: Tm Schmit, NOAA/NESDIS/ASPT) [click to play animation | MP4]

A number of quantitative radiometrically-retrieved products are available from the NOAA/CIMSS Volcanic Cloud Monitoring site — some of which include Ash Height, Ash Probability, Ash Loading and Ash Effective Radius (below).

Ash Height product [click to play animation | MP4]

Ash Height product [click to play animation | MP4]

Ash Probability product [click to play animation | MP4]

Ash Probability product [click to play animation | MP4]

Ash Loading product [click to play animation | MP4]

Ash Loading product [click to play animation | MP4]

Ash Effective Radius product [click to play animation | MP4]

Ash Effective Radius product [click to play animation | MP4]

===== 10 April Update =====

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) displayed the volcanic cloud associated with numerous explosive eruptions that continued during much of the day on 10 April. The coldest cloud-top infrared brightness temperature of -84.8ºC occurred at 1058 UTC (and would have been missed by the routine 10-minute images over that area). This cold overshooting top infrared brightness temperature roughly corresponded to an altitude of 18.2 km, or 1.8 km above the tropopause according to 12 UTC rawinsonde data from Barbados (below).

Plot of 12 UTC rawinsonde data from Grantley Adams, Barbados [click to enlarge]

Plot of 12 UTC rawinsonde data from Grantley Adams, Barbados [click to enlarge]

GOES-16 True Color RGB images within +/- 30 minutes of the -84.8ºC infrared brightness temperature are shown below — an abrupt penetration of the existing volcanic cloud top was seen by the newly-developed overshooting top.

GOES-16 True Color RGB images [click to play animation MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 Ash RGB images (below) indicated high concentrations of volcanic ash (brighter shades of pink) spreading out slowly around the island of Saint Vincent at lower altitudes, and being transported rapidly eastward at higher altitudes. To the north, light ash fall was limiting the surface visibility to 2-3/4 miles at Saint Lucia (TLPL) — while farther to the east heavier ash fall on the island of Barbados visibility was occasionally being restricted to around 1/2 mile (1000 meters) at Grantley Adams Airport (TBPB).

GOES-16 Ash RGB images [click to play animation | MP4]

GOES-16 Ash RGB images [click to play animation | MP4]

GOES-16 SO2 RGB images (below) showed that high concentrations of SO2 (shades of red to orange) were also being emitted during the series of eruptions.

GOES-16 SO2 RGB images [click to play animation | MP4]

GOES-16 SO2 RGB images [click to play animation | MP4]

GOES-17 (GOES-West) provided an oblique view of these volcanic clouds, which were very near the extreme limb of the satellite view — a comparison of GOES-17 and GOES-16 Full Disk sector “Red” Visible (0.64 µm) images for one of the more explosive events on 10 April is shown below. The magnification factor is identical in both sets of GOES images, though they are displayed in the native projection of each satellite. A similar comparison of 10-minute Full Disk sector GOES-17 and 1-minute Mesoscale sector GOES-16 Visible images is available here.

“Red” Visible (0.64 µm) images from GOES-17 (left) and GOES-16 (right) [click to play animation | MP4]

A toggle between True Color RGB images from GOES-16 and GOES-17 at 1930 UTC (below) further illustrates the parallax displacement associated with the large viewing angle from GOES-17.

True Color RGB images from GOES-16 and GOES-17, at 1930 UTC (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to enlarge]

True Color RGB images from GOES-16 and GOES-17, at 1930 UTC (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to enlarge]

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

NOAA-20 VIIRS Day/Night Band (0.7 µm) image (credit: William Straka, CIMSS) [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) image (credit: William Straka, CIMSS) [click to enlarge]

A nighttime NOAA-20 VIIRS Day/Night Band (0.7 µm) image (above) revealed mesospheric airglow waves propagating northeastward and eastward away from the volcano, which was still actively erupting every few hours.

The periodic violent eruptions continued into the daytime hours on 11 April — and GOES-16 Mid-level Water Vapor (6.9 µm) images (below) showed shock waves emanating radially outward from the initial volcanic cloud location following each eruption.

GOES-16 Mid-level (6.9 µm) Water Vapor images [click to play animation | MP4]

GOES-16 Mid-level (6.9 µm) Water Vapor images [click to play animation | MP4]

===== 13 April Update =====

GOES-16 "Clean" Infrared Window (10.35 µm) and Ash RGB images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) and Ash RGB images [click to play animation | MP4]

Eruptions continued on the morning of 13 April, as seen in GOES-16 Infrared and Ash RGB images (above).

A 4-day animation of GOES-16 Ash RGB images — covering the period from 1230 UTC on 09 April to 1230 UTC on 13 April — is shown below.

GOES-16 Ash RGB images, 09-13 April [click to play MP4 animation]

GOES-16 Ash RGB images, 09-13 April (credit Tim Schmit, NOAA/NESDIS/ASPB) [click to play MP4 animation]

Heavy rainfall and flooding associated with Tropical Cyclone Seroja

April 4th, 2021 |

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

The incipient circulation of Cyclone Seroja moved very slowly across the island of Timor in Indonesia during the 03 April – 04 April 2021 period — and the MIMIC Total Precipitable Water product (above) depicted very high values over that area (just northwest of Australia).

At Kupang’s El Tari Airport, precipitation amounts included 547 mm (21.5 inches) during the 48 hours ending at 00 UTC on 05 April — with the heaviest amounts of 106 mm (4.2 inches) in 6 hours and 80 mm (3.1 inches) in 3 hours occurring during the 00-06 UTC period on 04 April when the pressure was falling as Cyclone Seroja began to slowly organize and intensify (below). Flash flooding affected much of the island, with multiple deaths being reported.

Time series plot of surface observations at El Tari Airport, Kupang [click to enlarge]

Time series plot of surface observations at El Tari Airport, Kupang, Indonesia [click to enlarge]

JMA 2.5-minute interval rapid scan Himawari-8 “Clean” Infrared Window (10.4 µm) images (below) revealed a few convective bursts — with cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels embedded within darker shades of purple) — in the vicinity of Kupang (station identifier WATT) between 04 UTC on 04 April and 00 UTC on 05 April.

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]

A NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC visualized using RealEarth (below) showed one lone -90ºC pixel within a convective burst centered just north of Kupang.

NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC on 04 April [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC on 04 April [click to enlarge]


CMORPH estimates of 7-day precipitation (available in RealEarth) over the region show 300-400 mm over West Timor, and values exceeding 700 mm (!!) over the adjacent ocean.

7-day CMORPH accumulation of precipitation ending 0000 UTC 5 April 2021 (Click to enlarge)