Chinook winds and an atmospheric river affect south-central Alaska

December 9th, 2019 |

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images, along with

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images, along with “Red” Visible (0.64 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), Upper-level (6.2 µm) Water Vapor and “Red” Visible (0.64 µm) images (above) showed orographic wave clouds and banner clouds associated with strong winds across south-central Alaska on 09 December 2019. These strong winds were associated with flow around a deepening Storm Force low that was moving from the Gulf of Alaska to the Bering Sea (surface analyses). Downsloping (southeasterly) chinook winds (topography) caused the air temperature at Anchorage International Airport (PANC) to rise to 51ºF** at 2200 UTC (11:00 am local time) — which set a new record high for the month of December at that site (** the 5-minute ASOS temperatures are reported in ºC — and rounding errors caused the converted temperature to be listed as 52ºF).



The Storm Force low was also helping to advect an atmospheric river of moisture northward toward south-central Alaska, which was depicted in hourly images of the MIMIC Total Precipitable Water product (below). Heavy rainfall (including 1.30 inch at Homer) resulting from this influx of moisture produced rises in some rivers in the Kenai Peninsula south of Anchorage.

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

 

Eruption of the Whakaari volcano on White Island, New Zealand

December 9th, 2019 |

“Red” Visible (0.64 µm) images from Himawari-8 (left) and GOES-17 (right) [click to play animation | MP4]

A brief eruption of the Whakaari volcano on White Island, New Zealand occurred around 0110 UTC on 09 December 2019 — “Red” Visible (0.64 µm) images from JMA Himawari-8 and GOES-17 (GOES-West) showed the small volcanic cloud as it fanned out east of the island (above).

A signature of the volcanic cloud was also seen in VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, as viewed using RealEarth (below). The cloud exhibited a rather warm infrared brightness temperature, since the Wellington VAAC only estimated the maximum height to be

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

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

The volcanic plume contained elevated levels of SO2 which drifted south-southeastward, as seen in a McIDAS-V image of Sentinel-5 TROPOMI Vertical Column SO2 at 0206 UTC (below).

Sentinel-5 TROPOMI Vertical Column SO2 (credit: Bob Carp, SSEC) [click to enlarge]

Sentinel-5 TROPOMI Vertical Column SO2 (credit: Bob Carp, SSEC) [click to enlarge]