Hurricane Teddy and wildfire smoke

September 22nd, 2020 |

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) revealed that the large circulation of Hurricane Teddy (downgraded from a Category 2 to a Category 1 storm at 18 UTC) was drawing hazy filaments of smoke — likely originating from wildfires in the western US — southward from eastern Canada and New England, carrying it across the far western Atlantic Ocean on 22 September 2020. Also of interest (early in the animation) were the narrow fingers of river valley fog across parts of New York, Pennsylvania, Maryland, West Virginia and Virginia.

Although the size of Teddy’s cloud shield was still fairly large, a DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC from the CIMSS Tropical Cyclones site (below) showed that no organized core of deep convection remained as the storm began to move across colder waters (Sea Surface Temperature | Ocean Heat Content) and encounter a more hostile environment of increasing deep-layer wind shear.

DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC [click to enlarge]

GOES-16 CIMSS Natural Color RGB images, with and without an overlay of Aerosol Optical Depth [click to play animation | MP4]

GOES-16 CIMSS Natural Color RGB images, with and without an overlay of Aerosol Optical Depth [click to play animation | MP4]

A larger-scale view of GOES-16 CIMSS Natural Color RGB images — with and without an overlay of Aerosol Optical Depth (above) showed that an elongated plume of smoke stretched westward from New York and Pennsylvania to parts of Wisconsin, Illinois and Iowa. Upward-looking lidar data from the University of Wisconsin – Madison (below) depicted a thick layer of smoke between altitudes of 2-6 km.

Plots of lidar backscatter and depolarization from 12 UTC o n 22 September to 00 UTC on 23 September [click to enlarge]

Plots of lidar backscatter (top) and depolarization (bottom) from 12 UTC on 22 September to 00 UTC on 23 September [click to enlarge]

Pyrocumulonimbus clouds produced by the Mullen Fire in Wyoming

September 19th, 2020 |

GOES-16 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.35 µm, bottom) images, with hourly plots of surface reports [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.35 µm, bottom) images, with hourly plots of surface reports [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed a series of pyrocumulonimbus (pyroCb) pulses emanating from the Mullen Fire in southeastern Wyoming on 19 September 2020. Each of the  pulses exhibited 10.35 µm brightness temperatures of -40ºC and colder  (shades of blue) — assuring the heterogeneous nucleation of all supercooled water droplets to form ice crystals, thereby meeting the criteria of a pyroCb.

The coldest cloud-top infrared brightness temperatures were around -47ºC, which corresponded to altitudes near 11 km according to rawinsonde data from Riverton, Wyoming (below).

Plot of 00 UTC rawinsonde data from Riverton, Wyoming [click to enlarge]

Plot of 00 UTC rawinsonde data from Riverton, Wyoming [click to enlarge]

Hurricane Teddy rapidly intensifies to a Category 4 storm

September 17th, 2020 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images — with and without an overlay of GLM Flash Extent Density (above) showed Hurricane Teddy as it rapidly intensified (ADT | SATCON ) to a Category 4 storm on 17 September 2020. The coldest cloud-top infrared brightness temperatures were in the -80 to -85ºC range.

Metep-A ASCAT surface scatterometer wind speeds were as high as 74 knots in the northwestern portion  of the eyewall (below).

GOES-16 “Red” Visible (0.64 µm) image, with plots of Metop-A ASCAT winds [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) image, with plots of Metop-A ASCAT winds [click to enlarge]

Microwave (85 GHz) DMSP-17 (at 1023 UTC), GMI (at 1720 UTC) and DMSP-18 (at 2034 UTC) images from the CIMSS Tropical Cyclones site are shown below.

DMSP-17 SSMI Microwave (85 GHz) image at 1023 UTC [click to enlarge]

DMSP-17 SSMI Microwave (85 GHz) image at 1023 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 1720 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 1720 UTC [click to enlarge]

DMSP-18 SSMI Microwave (85 GHz) image at 2034 UTC [click to enlarge]

DMSP-18 SSMI Microwave (85 GHz) image at 2034 UTC [click to enlarge]

Hurricane Sally makes landfall in Alabama

September 16th, 2020 |

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

At 0500 UTC on 16 September 2020, Hurricane Sally rapidly intensified (ADT | SATCON) to a Category 2 storm, and soon thereafter made landfall near Gulf Shores, Alabama at 0945 UTC. During that time period, 1-minute GOES-16 Infrared imagery — with and without an overlay of GLM Flash Extent Density (above) — displayed a ragged eye structure, along with a lack of GLM-detected lightning activity in the immediate vicinity of the storm center. The eye passed just to the west of Buoy 42012, where the wind gusted to 95.2 knots or 110 mph at 0510 UTC (below).

Plot of wind speed (blue), wind gusts (red) and pressure (green) at Buoy 42012

Plot of wind speed (blue), wind gusts (red) and pressure (green) at Buoy 42012


How did Sally change the Sea Surface Temperatures (SSTs) in the Northern Gulf? The toggle below of Advanced Clear Sky Processor for Ocean (ACSPO) SSTs from VIIRS, derived using CSPP (the Community Satellite Processing Package) and direct broadcast data at CIMSS, shows SSTs about 2ºF cooler (cyan in the enhancement, about 80ºF) compared to surrounding waters that are 82-83ºF..

ACSPO SSTs at 0746 and 1912 UTC on 17 September 2020 (click to enlarge)