GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed the formation of a standing wave cloud along the Minnesota shoreline of Lake Superior, followed by the development of a sequence of standing waves over western Lake Superior on 01 November 2020. This cloud and subsequent wave features were formed by a vertically-propagating internal gravity wave that resulted from the interaction of strong post-frontal northwesterly flow with the topography of the shoreline — the terrain quickly drops from an elevation of about 2000 feet above sea level (over northeastern Minnesota) to about 600 feet above sea level (over Lake Superior) in a very short distance.

A northwest-to-southeast oriented cross section of RAP40 model fields along line segment A-A’ (below) showed a deep pocket of positive Omega (upward vertical motion, yellow to red colors) that aided in development of the cloud band along the Minnesota Lake Superior shoreline. Note that this Omega feature was vertically tilted in an “upshear” direction (toward the northwest), and extended upward to the 350-400 hPa pressure level. There was also an increasing upward component of the ageostrophic vertical circulation, which was likely the initial forcing mechanism leading to formation of the standing wave cloud and standing waves seen on Water Vapor imagery. As the boundary layer wind speeds diminished during the day, the magnitude of the upward forcing also began to decrease.

It's been windy overnight! Here's a snippet of the list of the strongest wind reports we've received in the past 24 hours. The entire list, which includes stations sorted by value and also by location then by value is found at https://t.co/hEUsiIIHzJ. pic.twitter.com/qIliwobKqL

— NWS Duluth (@NWSduluth) November 1, 2020

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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).

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.

===== 31 October Update =====

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.

A DMSP-16 SSMIS Microwave (85 GHz) image at 2032 UTC is shown below.

 A NOAA-20 VIIRS Infrared Window (11.45 µm) image (below) showed Goni just after 16 UTC.

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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 =====

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.

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.

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).

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

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.

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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.

#Zeta has formed in the NW Caribbean – the 27th named storm of the 2020 Atlantic #hurricane season to date and earliest forming 27th Atlantic named storm on record. Prior record for earliest Atlantic 27th named storm formation was November 29, 2005. pic.twitter.com/9ugeQDkvx5

— Philip Klotzbach (@philklotzbach) October 25, 2020

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

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 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.

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