Snowfall across northern Alaska

September 18th, 2019 |

GOES-17

GOES-17 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Day Snow-Fog RGB and Day Cloud Phase Distinction RGB images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Day Snow-Fog Red-Green-Blue (RGB) and and Day Cloud Phase Distinction RGB images (above) showed portions of the Brooks Range and eastern North Slope of Alaska that had significant snow cover on 18 September 2019. Some areas received 4-6 inches of snowfall during the previous day (a Winter Storm Warning had been issued, forecasting accumulations in the 4-8 inch range).

Snow cover appeared brighter white in the Visible images, and darker shades of gray in the Snow/Ice images; in the RGB images, snow was darker shades of red in the Day Snow-Fog, vs brighter shades of green in the Day Cloud Phase Distinction. Note that the Day Cloud Phase Distinction RGB provided sharper images than the Day Snow-Fog RGB (below), since the former makes use of higher spatial resolution 0.64 µm data for its Green component.

GOES-17 Day Cloud Phase Distinction RGB and Day Sow-Fog RGB images at 2030 UTC [click to enlarge]

GOES-17 Day Cloud Phase Distinction RGB and Day Sow-Fog RGB images at 2030 UTC [click to enlarge]

Although much of the Bettles (PABT) area was masked by cloudiness on 18 September, that site received moderate to heavy snow for a few hours on 17 September (below), and reported a snow depth of 4 inches at 17 UTC (9 am local time).

Time series of surface data from Bettles, Alaska on 17 September [click to enlarge]

Time series of surface data from Bettles, Alaska on 17 September [click to enlarge]

Smoke plumes from Saudi Arabian oil facilities

September 15th, 2019 |

VIIRS Day/Night Band (0.7 µm) and Visible (0.64 µm) imagery from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS Day/Night Band (0.7 µm) and Visible (0.64 µm) images from Suomi NPP and NOAA-20 (courtesy of William Straka, CIMSS) [click to enlarge]

VIIRS Day/Night Band (0.7 µm) and Visible (0.64 µm) imagery from Suomi NPP and NOAA-20 (above) revealed dark smoke plumes from oil refineries and other facilities damaged by drone strikes early in the day on 14 September 2019.

EUMETSAT Meteosat-8 Visible (0.8 µm) images (below) showed the south-southwestward transport of the smoke plumes. Thick smoke drifted over Al Ahsa (OEAH), and at one point restricted to 2.8 miles.

EUMETSAT Meteosat-8 Visible (0.8 µm) images, with hourly plots of surface reports [click to play animation | MP4]

EUMETSAT Meteosat-8 Visible (0.8 µm) images, with hourly plots of surface reports [click to play animation | MP4]

Before (13 September) and after (14-15 September) True Color Red-Green-Blue (RGB) images from Terra MODIS and Suomi NPP VIIRS as viewed using RealEarth are shown below.

True Color RGB images from Terra MODIS and Suomi NPP VIIRS, from 13-15 September [click to enlarge]

True Color RGB images from Terra MODIS and Suomi NPP VIIRS, from 13-15 September [click to enlarge]

A sequence of 3 VIIRS Day/Night Band images from Suomi NPP and NOAA-20 (below) showed nighttime views of the smoke plumes, illuminated by the Moon (which was in the Waning Gibbous phase, at 98% of Full).

VIIRS Day/Night Band (0.7 µm) from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS Day/Night Band (0.7 µm) from Suomi NPP and NOAA-20 (courtesy of William Straka, CIMSS) [click to enlarge]

A Meteosat-8 Visible animation spanning portions of 14, 15 and 16 September is shown below.

EUMETSAT Meteosat-8 Visible (0.8 µm) images, with hourly plots of surface reports [click to play animation | MP4]

EUMETSAT Meteosat-8 Visible (0.8 µm) images with hourly plots of surface reports, 14-16 September [click to play animation | MP4]

===== 17 September Update =====

Landsat-8 False Color image [click to enlarge]

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

A 30-meter resolution Landsat-8 False Color RGB image (above) showed a number of smoke plumes from oil facility fires that continued to burn on 17 September.

Severe thunderstorms in Wyoming, Nebraska and South Dakota

September 10th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC Storm Reports plotted in red [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed  the development of thunderstorms that produced large hail, tornadoes and damaging winds (SPC Storm Reports) across eastern Wyoming, northern Nebraska and southern South Dakota on 10 September 2019. Note that many of the storms exhibited Above-Anvil Cirrus Plumes. Pulsing overshooting tops reached -80ºC and colder (violet pixels) just east of Valentine, Nebraska (KVTN) from 0001-0004 UTC (0002 UTC image) — and a few minutes following their collapse, a wind gust of 60 mph was reported in that general vicinity.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images are shown below.

GOES-16 "Clean" Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

The animation shown below is from an experimental product at CIMSS/SSEC, whereby the contours were produced using a ‘deep learning’ artificial intelligence model that was trained on ABI imagery and GLM gridded products to generate the ‘probability of supercell-like features inferred from satellites’, or more concisely, the ‘probability of supercell’. Note that the model does a decent job of identifying active portions of the storms (e.g., persistent Overshooting Tops), which correspond well with severe weather reports.

GOES-16 Visible/Infrared Sandwich RGB and

GOES-16 Visible/Infrared Sandwich RGB and “Clean” Infrared Window (10.35 µm) images, with “probability of supercell” contours and SPC Storm Reports (courtesy of John Cintineo, CIMSS) [click to play MP4 animation]

During the subsequent nighttime hours, GOES-16 Infrared images (below) showed a convective cluster which produced 3 EF-2 tornadoes and damaging winds in and around Sioux Falls, South Dakota (NWS summary). Note that pulsing overshooting tops west of Sioux Falls (KFSD) exhibited infrared brightness temperatures of -80ºC and colder (violet pixels) from 0402-0406 UTC (0404 UTC image), which was about 20 minutes prior to the first tornado reports.

GOES-16 "Clean" Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

 

Dorian moves across the Maritime Provinces of Canada

September 8th, 2019 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [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 (above) showed Hurricane Dorian as it briefly intensified from a Category 1 to a Category 2 storm during the morning of 07 September 2019. Later in the day, Dorian transitioned to a post-tropical storm before making landfall over Nova Scotia around 2215 UTC. Due to high amounts of  deep-layer wind shear, the low-level circulation center of Dorian remained exposed while deep convection remained to its north and northeast. The eye of Dorian moved over Buoy 44011, which recorded a wind gust to 82 knots; in western Nova Scotia, winds gusted to 70 knots at Yarmouth.

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

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

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as visualized using RealEarth (above) revealed a brighter region exhibiting a somewhat hazy appearance within the cloud-free slot southwest of the eye during the 16-17 UTC period. This could have been a signature of diffuse solar reflection off highly-agitated ocean waves — a NHC discussion noted strong Metop-B ASCAT winds of 80 knots or higher in that area around 15 UTC (below).

Metop-B ASCAT winds [click to enlarge]

Metop-B ASCAT winds [click to enlarge]

On the following day, Suomi NPP VIIRS True Color and Infrared  images (below) showed Post-Tropical Cyclone Dorian when its center was over the Gulf of St. Lawrence. Wind gusts included 68 knots at Heath Point, Quebec (CWHP) and 57 knots at Deer Lake, Newfoundland (CYDF).

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

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