Landspout tornado southwest of Anchorage, Alaska
1-minute GOES-18 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, from 0300-0430 UTC on 20 April [click to play animated GIF | MP4]
1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed a mountain wave cloud over southcentral Alaska — beneath which a landspout tornado developed in the Chugach Mountains just southwest of Anchorage (PANC) at 0413 UTC on 20 April 2024 (8:13 PM local time on 19 April).
Taking parallax into account (source), a cursor sample of GOES-18 “Clean” Infrared Window (10.3 µm) brightness temperature, Cloud Top Temperature and Cloud Top Height derived products over the approximate location of the landspout at 0413 UTC on 20 April is shown below.
Cursor sample of GOES-18 “Clean” Infrared Window (10.3 µm) brightness temperature (white), Cloud Top Temperature (red) and Cloud Top Height (yellow) at 0413 UTC on 20 April [click to enlarge]
With an infrared brightness temperature and Cloud Top Temperature value around -60ºC along with a Cloud Top Height value around 35000 ft (10.7 km), the top of this mountain wave cloud appeared to have reached the tropopause, as indicated by a plot of Anchorage rawinsonde data at 0000 UTC on 20 April (below).
Plot of Anchorage rawinsonde data at 0000 UTC on 20 April [click to enlarge]