Transverse banding around a decaying MCS

June 14th, 2018 |

Aqua MODIS Visible (0.65 µm), Near-Infrared

Aqua MODIS Visible (0.65 µm), Near-Infrared “Cirrus” (1.37 µm), Water Vapor (6.7 µm) and Infrared Window (11.0 µm) images, with pilot reports of turbulence plotted in cyan [click to enlarge]

A comparison of Aqua MODIS Visible (0.65 µm), Near-Infrared “Cirrus” (1.37 µm), Water Vapor (6.7 µm) and Infrared Window (11.0 µm) images (above) showed widespread transverse banding along the northern and eastern periphery of a decaying Mesoscale Convective System (MCS) that was moving from Iowa into Illinois and Missouri on 14 June 2018.

GOES-16 (GOES-East) Near-Infrared “Cirrus” (1.37 µm), Mid-level Water Vapor (6.9 µm) and “Clean” Infrared Window (10.3 µm) images with pilot reports of turbulence are shown below.

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Cirrus” (1.37 µm) images, with hourly plots of turbulence [click to play MP4 animation]

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

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

GOES-16 "Clean" Infrared Window (10.3 µm) images, with hourly plots of turbulence [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of turbulence [click to play MP4 animation]

 

American Airlines Flight 1897 Diverted due to Hail Damage

June 4th, 2018 |

GOES-16 ABI Band 2 Imagery (0.64 µm), 0002-0202 UTC on 4 June 2018 (Click to animate)

American Airlines Flight 1897 pushed back from the gate San Antonio (SAT) Texas at 6:45 PM CDT (and lifted off at 6:58 PM CDT) (2358 UTC) on 3 June, bound for Phoenix. An encounter with convection over southeastern New Mexico cause windshield and nosecone damage, and the flight landed safely at 8:03 PM (0203 UTC) MDT in El Paso, TX. Click here and here (from Twitter user Tom Podolec) for flight paths. The Flight Tracking Log from FlightAware suggests the damage occurred at sometime between 0109 and 0116 UTC.

Visible Imagery, above, near sunset revealed strong convection developing over the southern Plains of Texas and New Mexico. In particular a strong convective tower with overshooting tops is apparent over southeast New Mexico. This could be the hail-producing cell that damaged the aircraft. (Note also the fires that continue to burn in western New Mexico!) The photograph below, from Scott Cruse/KTVK (Source), shows the substantial aircraft damage. (Original Photo from KTVK wesbite). This link shows an Incident Report from avherald.com.

Nosecone and Windshield Damage on AA1897. (Source: Scott Cruse/KTVK)

GOES-16 Clean Window Infrared (10.3 µm) imagery, below, also suggests strong convection, with very cold cloud tops over southeastern New Mexico. A complete animation spanning the flight is here: Note how two general areas of convection from the west and from the east appear to converge on southeastern New Mexico; the animation below focuses on the 0032 – 0157 UTC time frame when ongoing strong convection over southeastern New Mexico is spawning multiple overshooting tops. Near the end of this animation the flight diverts to El Paso.

GOES-16 ABI Band 13 Clean Window (10.3 µm) Infrared Imagery, 0032 – 0157 UTC on 4 June 2018 (Click to animate)

A GOES-16 Mesoscale Domain Sector was positioned over the region, providing 1-minute data — Infrared (11.2 µm) and Visible (0.64 µm) images, below (courtesy of Rick Kohrs, SSEC), include plots of the location of the aircraft. The storm in far southeastern New Mexico did produce hail of 2.5 inches in diameter, but there were no SPC storm reports farther northwest near the aircraft encounter with damaging hail. In addition, there was a pilot report of severe turbulence around the same time and location of the Flight 1897 hail damage (albeit at a higher altitude).

GOES-16 Infrared (11.2 µm, left) and Visible (0.64 µm, right) images, with plots of the aircraft location [click to play animation]

GOES-16 Infrared (11.2 µm, left) and Visible (0.64 µm, right) images, with plots of the aircraft location [click to play animation]

A GOES-16 Visible/Infrared Sandwich product is shown below (courtesy of Joleen Feltz, CIMSS)

GOES-16 Visible/Infrared Sandwich product [click to play MP4 animation]

GOES-16 Visible/Infrared Sandwich product [click to play MP4 animation]

Kudos to the crew for landing this hail-damaged aircraft.

Turbulence associated with transverse banding

June 2nd, 2018 |

GOES-16 (GOES-East) Near-Infrared “Cirrus” (1.37 µm), Mid-level Water Vapor (6.9 µm) and Upper-level Water Vapor (6.2 µm) images (below) showed the evolution of this transverse banding — a cloud signature often associated with turbulence — early in the day on 02 June 2018.

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Cirrus” (1.37 µm, left), Mid-level Water Vapor (6.9 µm, center) and Upper-level Water Vapor (6.2 µm, right) images, with hourly pilot reports of turbulence [click to play MP4 animation]

A toggle between 1-km resolution Aqua MODIS Water Vapor (6.7 µm) and Cirrus (1.37 µm) images at 1842 UTC is shown below; the transverse banding was beginning to dissipate around that time.

Aqua MODIS Water Vapor (6.7 µm) and Cirrus (1.37 µm) images, with pilot reports of turbulence [click to enlarge]

Aqua MODIS Water Vapor (6.7 µm) and Cirrus (1.37 µm) images, with pilot reports of turbulence [click to enlarge]

Contrails off the coast of Southern California

April 23rd, 2018 |

As pointed out by NWS San Diego, an interesting pattern of contrails formed off the coast late in the day on 23 April 2018. A comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm), Near-Infrared “Cirrus” (1.37 µm) and “Clean” Infrared Window (10.3 µm) images (below) showed signatures during the daylight hours — Visible images revealed contrail shadows being cast upon the low-altitude cloud tops at 0142 and 0147 UTC — with an Infrared signature persisting after sunset. These contrails were likely caused by military aircraft performing training exercises, since chaff was seen with radar in that same area on the previous day.

GOES-16

GOES-16 “Red” Visible (0.64 µm, left), Near-Infrared “Cirrus” (1.37 µm, center) and “Clean” Infrared Window (10.3 µm, right) images [click to play animation | MP4]

A better post-sunset signature was seen on a NOAA-15 Infrared Window (10.8 µm) image at 0212 UTC (below). A comparison with the corresponding GOES-16 “Clean” Infrared Window (10.3 µm)  image displayed a significant northwestward GOES-16 displacement due to parallax — and the 1.1 km spatial resolution of AVHRR data resulted in a clearer contrail signature.

NOAA-15 AVHRR Infrared Window (10.8 µm) and GOES-16 ABI

NOAA-15 AVHRR Infrared Window (10.8 µm) and GOES-16 ABI “Clean” Infrared Window (10.3 µm) images [click to enlarge]

The pattern of contrails could also be followed after sunset using GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) imagery (below).

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play animation | MP4]

The GOES-16 Water Vapor weighting function plots (below) displayed a bi-modal distribution for all 3 spectral bands, with peaks near 300 hPa and 500 hPa. The absence of a distinct contrail signature on the 6.2 µm imagery suggests that these features were located closer to the 500 hPa pressure level.

GOES-16 Water Vapor weighting functions, calculated using rawinsonde data from San Diego CA [click to enlarge]

GOES-16 Water Vapor weighting functions, calculated using rawinsonde data from San Diego CA [click to enlarge]