Tropical Invest 90E becomes Tropical Storm Andres

May 8th, 2021 |

GOES-17 “Red” Visible (0.64 µm) and "Clean" Infrared Window images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) showed the convective banding associated with Tropical Invest 90E in the East Pacific Ocean on 08 May 2021. Invest 90E was centered along a northward bulge in the ITCZ/Monsoon Trough (below).

GOES-17 “Clean” Infrared Window (10.35 µm) image (Mesoscale Sector), with an overlay of the 12 UTC surface analysis [click to enlarge]

Invest 90E was located over water characterized by modest Ocean Heat Content and very warm Sea Surface Temperature values (below), favorable factors for further intensification.

Ocean Heat Content and Sea Surface Temperature [click to enlarge]

Ocean Heat Content and Sea Surface Temperature [click to enlarge]

===== 09 May Update =====

GOES-17 “Red” Visible (0.64 µm) and "Clean" Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute GOES-17 Infrared and Visible images on 09 May (above) showed the period where Invest 90E intensified to a Tropical Depression (at 0900 UTC) and then to Tropical Storm Andres at 1500 UTC — the earliest calendar year tropical storm on record in the East Pacific basin. The convective overshooting tops occasionally exhibited infrared brightness temperatures of -90ºC or colder (yellow pixels embedded within dark purple regions).

A GOES-17 Infrared / Water Vapor Difference product (reference) from the CIMSS Tropical Cyclones site (below) highlighted areas of deep convection where overshooting tops were likely penetrating the tropopause (yellow to red enhancement).

GOES-17 Infrared - Water Vapor Difference product [click to enlarge]

GOES-17 Infrared – Water Vapor Difference product [click to enlarge]

GOES-17 Infrared images, with an overlay of deep-layer wind shear (below) indicated that Andres was approaching an environment of moderate to high shear, which would limit intensification.

GOES-17 Infrared images, with an overlay of deep-layer wind shear [click to enlarge]

GOES-17 Infrared images, with an overlay of deep-layer wind shear [click to enlarge]

===== 10 May Update =====

GOES-17 “Red” Visible (0.64 µm) and "Clean" Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

On 10 May, 1-minute GOES-17 Infrared and Visible images (above) showed that after one final convective burst, the low-level center of Tropical Storm Andres became exposed — and the storm was then downgraded to a Tropical Depression at 2100 UTC.

Tropical Cyclone Joba makes landfall in Tanzania

April 24th, 2021 |

US Space Force EWS-G1 Infrared (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared (10.7 µm) images (above) showed Tropical Cyclone Jobo as it moved west-northwestward across the Indian Ocean during the 23-24 April 2021 period, eventually making landfall in Tanzania as a weakening Tropical Depression. Jobo was traversing warm sea surface temperatures during its westward trek.

A sequence of VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP as viewed using RealEarth (below) provided higher-resolution views of the various stages of convection associated with Jobo during the 22-24 April period.

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

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

Subtropical Storm Potira off the coast of Brazil

April 20th, 2021 |

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

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the circulation of Subtropical Storm Potira (warning issued by MARINHA) off the southeast coast of Brazil on 20 April 2021.

In the corresponding 1-minute GOES-16 “Clean” Infrared Window (10.35 µm) images (below), intermittent convective overshooting tops exhibited infrared brightness temperatures as cold as -60 to -65ºC (shades of orange).

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]

Combined plots of all GOES-16 Atmospheric Motion Vector types — Visible, Infrared and Water Vapor — and pressure levels at 15-minute intervals (below) displayed the cloud motions of Potira (credit: Dave Stettner and Chris Velden, CIMSS). The algorithm used to generate these AMVs differs slightly from that used to create operational Derived Motion Winds: some constraints are relaxed/removed, and Visible winds are calculated at pressure levels above 700 hPa — all of which results in the display of a higher density of tracked targets and their calculated wind vectors.

Combined plot of all GOES-16 Atmospheric Motion Vector types (Visible, Infrared and Water Vapor) at 15-minute intervals [click to play animation | MP4]

Combined plots of all GOES-16 Atmospheric Motion Vector types (Visible, Infrared and Water Vapor) and pressure levels, at 15-minute intervals [click to play animation | MP4]

A sequence of EUMETSAT Metop ASCAT surface scatterometer winds (source) is is shown below — the strongest winds were located within the southern sector of the storm, well away from the center of circulation.

Metop ASCAT surface scatterometer winds [click to enlarge]

Metop ASCAT surface scatterometer winds [click to enlarge]

===== 22 April Update =====

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

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

1-minute GOES-16 Visible images (above) showed that the low-level circulation center of Potira remained exposed on 22 April — while GOES-16 Infrared images (below) indicated that deep convection remained south and west of the storm center.

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]

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]

The prolonged period of rapid intensification continued 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), making Surigae the only tropical cyclone on record to reach that intensity during the month of April.



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 also 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 (reference) propagating away from the energetic Category 5 tropical cyclone.

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]

In closer view of time-matched Himawari-8 Infrared and Suomi NPP Day/Night Band images (below), a cluster of bright DNB pixels highlighted the presence of lightning activity along the inner edge of the northern eyewall.

Himawari-8 Infrared Window (10.4 µm) and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]