Low pressure over the Gulf of Alaska

November 26th, 2020 |

GOES-17

GOES-17 “Red” Visible (0.64 µm), Mid-level Water Vapor (6.9 µm) and Air Mass RGB images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Mid-level Water Vapor (6.9 µm) and Air Mass Red-Green-Blue (RGB) images (above) showed a Storm Force low (surface analyses) developing in the Gulf of Alaska on 26 November 2020. As the storm intensified, trends of warming//drying on the Water Vapor images and brighter orange/red hues on the Air Mass RGB images near the center of circulation indicated the development of a potential vorticity anomaly that lowered the dynamic tropopause (bringing dry, ozone-rich  air into the upper portion of the atmospheric column).

A toggle between Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images (below) showed the storm at 2228 UTC.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Medicane makes landfall in Tunisia

November 22nd, 2020 |

EUMETSAT Meteosat-11 High Resolution Visible (0.8 µm) images [click to play animation | MP4]

EUMETSAT Meteosat-11 High Resolution Visible (0.8 µm) images [click to play animation | MP4]

EUMETSAT Meteosat-11 High Resolution Visible (0.8 µm) images (above) showed a westward-moving medicane which developed a fairly distinct eye shortly before making landfall along the eastern coast of Tunisia on 22 November 2020.

A Suomi NPP VIIRS True Color Red-Green-Blue (RGB) image displayed using RealEarth (below) provided a higher-resolution view of the medicane’s eye and convective banding at 1152 UTC.

Suomi NPP VIIRS True Color RGB image valid at 1152 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB image valid at 1152 UTC [click to enlarge]

A plot of surface observations for Monastir’s Habib Bourguiba International Airport DTMB (below) showed that winds gusted to 43 knots as the system made landfall.

Plot of surface observations for Monastir's Habib Bourguiba International Airport [click to enlarge]

Plot of surface observations for Monastir’s Habib Bourguiba International Airport [click to enlarge]

Tropical Storm Eta over the Gulf of Mexico

November 10th, 2020 |

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images at 0734 UTC [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images at 0734 UTC [click to enlarge]

A toggle between Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images at 0734 UTC (above) showed Tropical Storm Eta over the Gulf of Mexico (northwest of Cuba) on 10 November 2020. A large convective burst was seen southeast of the storm center, with concentric cloud-top gravity waves propagating radially outward from its lightning-illuminated core (intense lightning activity was causing the cluster of bright pixels on the Day/Night Band image).

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm), GLM Flash Extent Density and “Red” Visible (0.64 µm) images (below) showed Tropical Storm Eta from sunrise to sunset, as it continued a slow northward movement — pulsing overshooting tops occasionally exhibited infrared brightness temperatures of -90ºC and colder (yellow pixels embedded within darker shades of purple), and lightning activity persisted for much of the day.

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 MP4 animation]

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 MP4 animation]

===== 11 November 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]

Eta once again reached Hurricane intensity at 1235 UTC on 11 November, as it approached the west coast of Florida. 1-minute GOES-16 Visible images (above) showed the partially exposed low-level circulation of Eta; however, it then weakened back to a Tropical Storm several hours later, at 1800 UTC.

Individual Great Lake true-color sectors available at the CIMSS Direct Broadcast site

November 4th, 2020 |

VIIRS True Color Imagery from Suomi-NPP (1729 UTC) and NOAA-20 (1818 UTC) on 4 November 2020  over the pre-defined Great Lakes domain (click to enlarge)

The CIMSS Direct Broadcast site is now routinely creating True-Color imagery over 6 different domains: The Great Lakes, and each of the 5 individual lakes: Superior, Huron, Michigan, Erie, Ontario (Click on each image to see the domain). File name examples are shown here. Suomi NPP and NOAA-20 are in similar orbits, about 50 minutes apart, so it’s common to be able to create an animation, as shown below with Lake Erie. Note that the colors in the toggle below, and in the Basin-wide toggle above, can show differences because of view angles. In particular, the slanted view angle over Lakes Michigan and Superior in the 1729 UTC Suomi-NPP image in the toggle above allows for the true-color imagery to show a thin layer of smoke over portions the those lakes.

VIIRS True Color Imagery from Suomi-NPP (1729 UTC) and NOAA-20 (1818 UTC) on 4 November 2020  over the pre-defined Lake Erie domain (click to enlarge)

If NOAA-20 or Suomi-NPP only samples part of the lake, then a partial image is created, as shown below from NOAA-20 pass viewing Lake Ontario at 1639 UTC on 4 November. (NOAA-20 viewed the entirety of Lake Ontario at 1818 UTC).

VIIRS True Color Imagery from NOAA-20 (1639 UTC) on 4 November 2020 over the pre-defined Lake Ontario domain (click to enlarge)