Strong cyclone near Antarctica

March 26th, 2019 |

Composites of geostationary and polar orbiter Infrared imagery [click to play animation]

Composites of geostationary and polar orbiter Infrared imagery [click to play animation]

Composites of Infrared imagery (above) and Water Vapor imagery (below) from the AMRC site showed an anomalously strong (MSLP | 925 hPa winds | source) cyclone that was moving southeastward across the South Pacific Ocean toward the coast of Antarctica on 26 March 2019. These composites blend images from both geostationary and polar orbiting satellites; the storm is located in the upper right quadrant of the images. On the Infrared imagery, brighter white shades over much of the middle of Antarctica indicated a very cold surface — in fact, surface air temperatures were as cold as -84ºF over the interior of the continent at 23 UTC.

Composites of geostationary and polar orbiter Water Vapor imagery [click to play animation]

Composites of geostationary and polar orbiter Water Vapor imagery [click to play animation]

The storm was evident along the southern limb of GOES-16 Full Disk scans, as seen on Mid-level Water Vapor (6.9 µm) and “Red” Visible (0.64 µm) images (below). The location of AMRC AWS station 8930 (Thurston Island) near the coast of Ellsworth Land in West Antarctica is indicated in red.

GOES-16 Mid-level Water Vapor images [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

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]

This storm was also evident at the bottom center of a GOES-17 + GOES-16 composite of north-to-south True Color Red-Green-Blue (RGB) swaths of 15-minute illumination at local solar noon — beginning at 12 UTC in the east, and ending at 03 UTC in the west — combined and displayed in a Mollweide projection (below; courtesy of Rick Kohrs, SSEC).

GOES-17 + GOES-16 True Color RGB image [click to enlarge]

GOES-17 + GOES-16 True Color RGB image [click to enlarge]

A time series of surface observation data from AWS station 8930 on Thurston Island (below) showed that southeasterly winds peaked at 113 knots (58 m/s) late in the day on 26 March as the strong low pressure system approached. According to AMRC staff, this particular AWS is located on a nunatak near Parker Peak in the Walker Mountains (map) — such an exposure is prone to periods of strong winds, requiring a recent retrofitting of special instrumentation designed to withstand and measure higher wind speeds.

Tiime series of surface observation data from AWS station 8930 Thurston Island [click to enlarge]

Time series of surface observation data from AWS station 8930 Thurston Island [click to enlarge]

A closer look with GOES-16 Visible and Low-level Water Vapor (7.3 µm) images (below) revealed small wave perturbations in the cloud field and the eventual formation of a banner cloud as Peter I Island was acting as an obstacle to the strong boundary layer winds south of the storm center.

GOES-16 "Red" Visible (0.64 µm. left) and Low-level Water Vapor (7.3 µm, right) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm. left) and Low-level Water Vapor (7.3 µm, right) images [click to play animation | MP4]

A timely overpass of the Landsat-8 satellite provided a 30-meter resolution Landsat-8 False Color RGB image, viewed using RealEarth (below), of these orographically-induced cloud perturbations.

Landsat-8 False Color image [click to enlarge]

Landsat-8 False Color RGB image [click to enlarge]

The orographic wave clouds downwind of Peter I Island could also be seen on 375-meter resolution Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 19 UTC and 21 UTC (below).

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images 1t 19 UTC and 21 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 19 UTC and 21 UTC [click to enlarge]