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]

Hurricane Zeta over the Gulf of Mexico

October 27th, 2020 |

GOES-16 “Clean” Infrared Window (10.35 µm) images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

After making landfall as a Category 1 Hurricane along Mexico’s Yucatan Peninsula a day earlier, a weakened Tropical Storm Zeta (NHC advisories) began to slowly re-intensify as it moved northward across the Gulf of Mexico after sunset on 27 October 2020 — 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images with an overlay of GLM Flash Extent Density (above) displayed increasing organization, with the gradual emergence of a ragged eye. Zeta once again reached hurricane intensity at 0600 UTC on 28 October.

===== 28 October Update =====

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0739 UTC (credit: William Straka, CIMSS) [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0739 UTC (credit: William Straka, CIMSS) [click to enlarge]

In a toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0739 UTC (above), the coldest cloud-top infrared brightness temperature just east-northeast of the eye was -96ºC. Ample illumination from the Moon (in the Waxing Gibbous phase, at 91% of Full) helped to highlight the “visible image at night” utility of the Day/Night Band.

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

Zeta experienced a period of rapid intensification during the day on 28 October (ADT | SATCON) — 1-minute GOES-16 Infrared images (with and without an overlay of GLM Flash Extent Density) and Visible images (above) showed a trend of increasing organization and the emergence of a fairly well-defined eye. Periodic lightning activity within the inner eyewall region began after 1800 UTC (when Zeta was upgraded to a Category 2 hurricane), along with overshooting tops exhibiting cloud-top infrared brightness temperatures as cold as -90ºC. The hurricane made landfall along the coast of Louisiana around 2100 UTC.

GOES-16 Longwave Infrared (11.2 µm) images, with contours of 20 UTC deep-layer wind shear [click to enlarge]

GOES-16 Longwave Infrared (11.2 µm) images, with contours of 20 UTC deep-layer wind shear [click to enlarge]

Zeta was intensifying in spite of the fact that it was moving across progressively colder water, and approaching an atmospheric environment that was more hostile in terms of increasing deep-layer wind shear (above) — however, these factors were likely offset by a broad and well-defined upper level outflow channel north of the hurricane, shown by 6.2 µm Derived Motion Winds with velocities around 100 knots over Arkansas (below).

GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds [click to play animation | MP4]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds [click to play animation | MP4]

===== 29 October Update =====

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

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

On the day after Zeta’s landfall, GOES-16 True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) showed an increase in turbidity within the shallow shelf waters off the Texas and Louisiana coasts. Also of note were the patches of fresh snow cover across portions of New Mexico, Texas and Oklahoma — areas having less snow depth experienced melting during the day.

A higher-resolution view of the nearshore turbidity was provided by 250-meter resolution Terra MODIS True Color RGB imagery from the MODIS Today site (below). Vigorous mixing of the water by the strong winds of Zeta stirred up a great deal of sediment.

Terra MODIS True Color RGB image [click to enlarge]

Terra MODIS True Color RGB image [click to enlarge]

Tropical Storm Zeta in the Caribbean Sea

October 25th, 2020 |

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) and “Red” Visible (0.64 µm) images (above) showed Tropical Storm Zeta in the northwest Caribbean Sea on 25 October 2020. While it remained somewhat disorganized, Zeta slowly intensified from 35 knots to 45 knots during that time period. The coldest cloud-top infrared brightness temperature observed was -94.4ºC.

GOES-16 Infrared images with an overlay of GLM Flash Extent Density (below) did reveal intermittent lightning activity with some of the more persistent areas of deep convection south of the analyzed storm center.

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

===== 26 October Update =====

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

Zeta was upgraded to a Hurricane as of 1910 UTC as it approached the Yucatan Peninsula of Mexico on 26 October — 1-minute GOES-16 Infrared (with and without an overlay of GLM Flash Extent Density) and Visible images (above) showed the period of transition from Tropical Storm to Hurricane. The coldest cloud-top infrared brightness temperature was -95.4ºC near the storm center.

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

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

Sea Surface Temperature and Ocean Heat Content images from the CIMSS Tropical Cyclones site (above) showed that Zeta was moving over very warm water, and deep-layer wind shear over the storm was very low (below) — all factors which were favorable for tropical cyclone intensification.

GOES-16 Longwave Infrared (11.2 µm) images, with contours of 22 UTC deep-layer wind shear [click to enlarge]

GOES-16 Longwave Infrared (11.2 µm) images, with contours of 22 UTC deep-layer wind shear [click to enlarge]

Record-setting cold in Montana

October 25th, 2020 |

Suomi NPP VIIRS Infrared Window (11.45 µm) and Topography images [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) and Topography images [click to enlarge]

A toggle between Suomi NPP VIIRS Infrared Window (11.45 µm) and Topography images (above) showed a pocket of cold air exhibiting a minimum infrared brightness temperature of -35.2ºC (-31.4ºF) in the vicinity of Potomac, Montana at 0915 UTC (3:15 am MDT) on 25 October 2020 — the overnight low air temperature at Potomac was -29ºF, which turned out to be the coldest officially observed air temperature for this early in the winter season for the Lower 48 states.



According to the NOHRSC site, Potomac had a snow depth of 18 inches that morning (below).