Tropical cyclones « CIMSS Satellite Blog

Super Typhoon Lekima in the West Pacific Ocean

August 8th, 2019 | Scott Bachmeier

Himawari-8 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.4 µm, right) images [click to play animation | MP4]

JMA 2.5-minute rapid scan Himawari-8 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.4 µm) images (above) showed the eye and eyewall region of Category 4 Super Typhoon Lekima on 07-08 August 2019. Features of interest included surface mesovortices within the eye, eyewall cloud-top gravity waves, and a quasi-stationary “cloud cliff” notch extending northwestward from the eye (infrared brightness temperature contours). This cloud cliff feature has been observed with other intense tropical cyclones (for example, Typhoon Neoguri in 2014).

VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as viewed using RealEarth are shown below.

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

The trochoidal motion (or wobble) of the eye of Lekima became very pronounced as it crossed the Ryukyu Islands, as seen in an animation of 2.5-minute rapid scan Himawari-8 Infrared images (below). The center of the tropical cyclone moved between Miyakojima (ROMY) and Ishigakijima (ROIG), which reported wind gusts to 67 knots and 64 knots respectively.

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

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

Himawari-8 Infrared images with contours and streamlines of deep-layer wind shear at 15 UTC from the CIMSS Tropical Cyclones site (below) indicated that Lekima was moving through an environment of very low shear, which was a factor aiding its intensification.

Himawari-8 “Clean” Infrared Window (10.4 µm) images, with contours and streamlines of deep-layer wind shear at 15 UTC [click to play animation]

Posted in Himawari-8, RealEarth, Red-Green-Blue (RGB) images, Suomi NPP, Tropical cyclones, VIIRS | No Comments »

Tropical Depression Flossie near Hawai’i

August 5th, 2019 | Scott Bachmeier

GOES-17 “Red” Visible (0.64 µm), “Clean” Infrared Window (10.35 µm) and Upper-level Water Vapor (6.2 µm) images [click to play animation | MP4]

An animation that cycles through GOES-17 (GOES-West) “Red” Visible (0.64 µm), “Clean” Infrared Window (10.35 µm) and Upper-level Water Vapor (6.2 µm) images (above) showed Tropical Depression Flossie just northeast of Hawai’i on 05 August 2019. Note that (1) the exposed low-level circulation center (LLCC) was very apparent in the visible imagery, (2) deep convection offset to the east/northeast of the LLCC exhibited cloud-top infrared brightness temperatures as cold as -83ºC , and (3) a series of gravity waves were propagating westward away from the convection, moving toward Hawai’i.

GOES-15 Infrared imagery and deep-layer wind shear data from the CIMSS Tropical Cyclones site (below) showed that the tropical cyclone was in an environment of strong shear, which was responsible for the displacement between the exposed LLCC and the convection. In addition to the wind shear, the weakening trend of the system was also due to its motion over cold Sea Surface Temperatures and low Ocean Heat Content.

GOES-15 Infrared Window (10.7 µm) images, with contours and streamlines of deep-layer wind shear [click to enlarge]

GOES-15 Infrared Window (10.7 µm) images, with contours and streamlines of deep-layer wind shear at 18 UTC [click to enlarge]

Posted in GOES-15, GOES-17, Satellite winds, Tropical cyclones | No Comments »

Hurricane Erick in the East Pacific Ocean

July 30th, 2019 | Scott Bachmeier

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) and “Clean” Infrared Window (10.35 µm) images (above) showed the well-defined eye of Hurricane Erick on 30 July 2019. Mesovortices could be seen within the eye on the visible imagery, along with periodic convective bursts within the surrounding eyewall region — and cloud-top infrared brightness temperatures as cold as -84ºC were associated with these convective bursts.

Prior to sunrise Erick experienced a period of rapid intensification, as seen in a Advanced Dvorak Technique plot from the CIMSS Tropical Cyclones site (below). Erick was classified as a Category 4 hurricane as of the 18 UTC advisory.

Advanced Dvorak Technique (ADT) plot for Hurricane Erick [click to enlarge]

Around the time that the period of rapid intensification was beginning, a NOAA-20 VIIRS Infrared Window (11.45 µm) image viewed using RealEarth (below) revealed a distinct eye around 11 UTC.

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

Posted in GOES-17, NOAA-20, Tropical cyclones, VIIRS | No Comments »

Tropical Storm Barry

July 11th, 2019 | Scott Bachmeier

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images, with plots of buoy and ship reports [click to play MP4 animation]

Tropical Storm Barry formed in the far northern Gulf of Mexico on 11 July 2019 — 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) displayed increasing convection associated with the tropical cyclone. The coldest cloud-top infrared brightness temperatures were -86ºC.

As was seen in an animation of GOES-16 Infrared imagery from the CIMSS Tropical Cyclones site (below), Barry was in an environment of low deep-layer wind shear — a factor that was favorable for further intensification.

GOES-16 Infrared (11.2 µm) images, with contours of deep-layer wind shear [click to enlarge]

===== 12 July Update =====

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

1-minute GOES-16 Visible images (above) revealed a mesovortex that was rotating counter-clockwise around the low-level circulation center of Barry, which was approaching the coast of Louisiana on 12 July. Note that the METAR site located immediately east of the mesovortex around 17 UTC — KMDJ, Mississippi Canyon Oil Platform — had a wind gust of 73 knots or 84 mph around that time (and later had a wind gust to 90 mph at 2135 UTC or 4:35 PM CDT)

The corresponding GOES-16 Infrared images (below) showed that deep convection remained to the south of the center of Barry.

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

===== 17 July Update =====

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Aqua MODIS Sea Surface Temperature product on 09 July [click to enlarge]

An Aqua MODIS Sea Surface Temperature image 2 days prior to the formation of Tropical Storm Barry (above) showed SST values in the upper 80s to low 90s F (darker shades of orange to red) in the northern Gulf of Mexico just south of Louisiana.

8 days later, a Terra MODIS SST image (below) revealed values predominantly in the lower to middle 80s F (green to yellow enhancement) — the slow movement of Barry as it eventually reached hurricane intensity just prior to landfall induced an upwelling of cooler sub-surface water over that area.