Transverse banding over California

February 4th, 2020 |

GOES-17

GOES-17 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images, with pilot reports of turbulence [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images (above) displayed widespread “transverse banding” — elongated cirrus elements oriented perpendicular to the ambient jet stream flow — that was migrating southward across California on 04 February 2020. This satellite signature is an indicator of potential turbulence, which in this case did indeed result in several pilot reports of light to moderate turbulence.

One of the pilot reports over Salinas, California at 2150 UTC (below) indicated Clear Air Turbulence (CAT) at an altitude of 30,000 feet — this suggests that the aircraft might have been flying just above or below the actual cirrus bands.

GOES-17 "Red" Visible (0.64 µm) image with a pilot report of Clear Air Turbulence at 2150 UTC [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) image with a pilot report of Clear Air Turbulence at 2150 UTC [click to enlarge]

Severe turbulence over Arizona and New Mexico

February 3rd, 2020 |

GOES-16 Mid-level Water Vapor (6.9 µm) images, with pilot reports of turbulence [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with pilot reports of turbulence [click to play animation | MP4]

GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed numerous orographic waves over eastern Arizona and western New Mexico on 03 February 2020. There were several high-altitude pilot reports of turbulence across that region, including severe turbulence associated with mountain waves at 43,000 feet and at 39,000 feet (below). The turbulence encounter at 39,000 feet noted an aircraft speed fluctuation of +/- 20 knots, along with a drop in altitude of 1600 feet.

GOES-16 Mid-level Water Vapor (6.9 µm) image, with pilot report of severe turbulence at 43,000 feet [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) image, with pilot report of severe turbulence at 43,000 feet [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) image, with pilot report of severe turbulence at 39,000 feet [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) image, with pilot report of severe turbulence at 39,000 feet [click to enlarge]

 

Interesting circular contrail over South Dakota

January 29th, 2020 |

Multi-panel images of all 16 ABI spectral bands from GOES-16 [click to play animation | MP4]

Multi-panel images of all 16 ABI spectral bands from GOES-16 [click to play animation | MP4]

Multi-panel images of all 16 ABI spectral bands from GOES-16 (GOES-East) (above) revealed an interesting circular contrail over northeastern South Dakota on 29 January 2020. A signature of this contrail was evident in all 16 bands — visible, near-infrared and infrared. This feature was likely formed by a military aircraft performing training exercises over the area.

A sequence of GOES-16 ABI spectral band images covering that same 1751-2001 UTC time period (below) provided a larger view of the circular contrail — whose diameter was about 10-12 miles — along with a linear contrail located about 30 miles to the southwest.

Sequence of GOES-16 ABI spectral band images [click to play animation | MP4]

Sequence of GOES-16 ABI spectral band images [click to play animation | MP4]

A toggle between GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images at 1911 UTC (below) showed that the darker signature seen in the Visible imagery was a shadow cast by the higher-altitude contrail onto the top of the low-altitude stratus clouds. A similar northwestward shadow offset (of about 5 miles) was apparent with the linear contrail feature.

GOES-16

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images at 1911 UTC [click to enlarge]

The southwestward shift of the higher-altitude contrail (with respect to the surface shadow) was not due to parallax — this webapp shows that the direction of parallax shift over that region would be northwestward for cloud features at altitudes of 15,000 feet and 30,000 feet (below).

Parallax correct vectors (green arrows) and magnitudes (red. in km) for cloud features at 15,000 feet and 30,000 feet over the CONUS domain [click to enlarge]

Parallax correct vectors (green arrows) and magnitudes (red. in km) for cloud features at 15,000 feet and 30,000 feet over the CONUS domain [click to enlarge]

Plots of rawinsonde data from Aberdeen, South Dakota (below) showed an increase in moisture during the day within the 500-300 hPa layer — due to its relatively slow southeastward propagation, the circular contrail likely existed within the lower portion of that layer (where wind speeds were less).

Plots of rawinsonde data from Aberdeen, South Dakota [click to enlarge]

Plots of rawinsonde data from Aberdeen, South Dakota [click to enlarge]

A signature of the circular contrail was seen in all 3 of the GOES-16 Water Vapor spectral bands — weighting functions derived using rawinsonde data from Aberdeen, South Dakota (below) showed either primary or secondary peaks within the 500-300 hPa layer.

GOES-16 Water Vapor weighting functions derived using rawinsonde data from Aberdeen, South Dakota [click to enlarge]

GOES-16 Water Vapor weighting functions derived using rawinsonde data from Aberdeen, South Dakota [click to enlarge]

Thanks go out to Jay Trobec (@trobec), KELOLAND TV in Sioux Falls, for alerting us about this interesting example.

Another outbreak of pyrocumulonimbus clouds in Australia

January 4th, 2020 |

Himawari-8

Himawari-8 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play animation | MP4]

Following a multi-day outbreak in late December 2019, Australian bushfires flared up again across far eastern Victoria and far southeastern New South Wales (along and ahead of a cold frontal passage) on 04 January 2020. A JMA Himawari-8 Target Sector was positioned over that region, providing images at 2.5-minute intervals — “Red” Visible (0.64 µm) images displayed the large smoke plumes with embedded pyro-convection, while Shortwave Infrared (3.9 µm) images revealed the widespread fire thermal anomalies or “hot spots” (clusters of red pixels).

Himawari-8 Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.4 µm) images (below) showed the development of 2 pyrocumulonimbus (pyroCb) clouds — the first over southern New South Wales west of Cooma (station identifier YCOM), and the second to the southwest of YCOM (near the border between Victoria and New South Wales). The second pyroCb eventually exhibited cloud-top infrared brightness temperature (IRBT) values of -70ºC and colder (purple pixels). To be classified as a pyroCb, a deep convective cloud must be generated by a large/hot fire, and eventually exhibit cloud-top 10.4 µm IRBTs of -40ºC and colder (thus assuring the heterogeneous nucleation of all supercooled water droplets to ice crystals within the thunderstorm anvil).

Himawari-8 Shortwave Infrared (3.9 µm, top) and "Clean" Infrared Window (10.4 µm, bottom) images [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm, top) and “Clean” Infrared Window (10.4 µm, bottom) images [click to play animation | MP4]

An aircraft flying very near or through one of these pyroCb clouds experienced severe turbulence:



Farther to the north, another pyroCb developed near Nowra, New South Wales (YSNW) — which briefly exhibited a -40ºC cloud-top IRBT at 0319 UTC, but then re-intensified around 08 UTC (below).

Himawari-8 Shortwave Infrared (3.9 µm, top) and "Clean" Infrared Window (10.4 µm, bottom) images [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm, top) and “Clean” Infrared Window (10.4 µm, bottom) images [click to play animation | MP4]

In a sequence of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 um) images from NOAA-20 and Suomi NPP as viewed using RealEarth (below), the Nowra pyroCb was less ambiguous during the 03-04 UTC time period — and the aforementioned pair of pyroCbs straddling the border between Victoria and New South Wales were also evident.

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

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

===== 06 January Update =====

GOES-16 Natural Color RGB images + Smoke Detection derived product [click to play animation | MP4]

GOES-16 Natural Color RGB images + Smoke Detection derived product [click to play animation | MP4]

On 06 January, GOES-16 (GOES-East) Natural Color RGB images (above) displayed the hazy signature of high-altitude smoke (originating from previous episodes of Australian fires) over parts of Chile and Argentina — and the corresponding GOES-16 Smoke Detection derived product flagged much of this feature as “High Confidence” smoke (red).

In addition, GOES-17 (GOES-West) True Color RGB images created using Geo2Grid (below) showed a dense pall of smoke over the South Pacific Ocean (northeast of New Zealand). This was smoke from the 04 January outbreak of fires.

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

===== 08 January Update =====

GOES-17 True Color RGB images, 05-08 January [click to play animation | MP4]

GOES-17 True Color RGB images, 05-08 January [click to play animation | MP4]

Full Disk GOES-17 True Color RGB images from the AOS site (above) showed the slow eastward transport of a dense pall of smoke (hazy shades of tan to light brown) across the South Pacific Ocean during the 05-08 January period.

Late in the day, GOES-17 True Color images also showed a small area of smoke drifting southward across the coast of Antarctica (below).

GOES-17 True Color images [click to play animation | MP4]

GOES-17 True Color images [click to play animation | MP4]

This was confirmed by the OMPS Aerosol Index product (below), which displayed a small lobe becoming detached from one of the larger smoke features crossing the South Pacific Ocean.

Suomi NPP OMPS Aerosol Index composites, 04-08 January (credit: Colin Seftor, SSAI)

Suomi NPP OMPS Aerosol Index composites, 04-08 January (credit: Colin Seftor, SSAI)