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]

Blowing dust in Texas and Oklahoma

January 21st, 2018 |

GOES-16

GOES-16 “Moisture” Infrared brightness temperature difference (10.3-12.3 µm) images, with hourly surface reports plotted in cyan [click to play animation]

Strong winds in the wake of a cold frontal passage created large areas of blowing dust across the Panhandle Plains of northwestern Texas after 16 UTC on 21 January 2018. GOES-16 “Moisture” or “split-window difference” (10.3 µm12.3 µm) images (above) showed that the leading edge of this airborne dust moved over far southwestern Oklahoma after 20 UTC. (Note to AWIPS users: the default enhancement for this GOES-16 “Moisture” Channel Difference product was changed to “Grid/lowrange enhanced” to better highlight the dust with shades of yellow)

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images (below) also displayed blowing dust signatures; the surface visibility was restricted to 2-3 miles at some locations, with Big Spring briefly reporting only 1/4 mile from 20-21 UTC. The dust signature was apparent on the Cirrus imagery because this spectral band can be used to detect any airborne particles that are effective scatterers of light (such as cirrus ice crystals, volcanic ash, dust/sand or haze).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly reports of surface weather plotted in red and surface visibility (miles) plotted in red [click to play animation]

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Cirrus” (1.37 µm) images, with hourly reports of surface weather plotted in red and surface visibility (miles) plotted in red [click to play animation]

A Cirrus band is also available with the MODIS instrument on the Terra and Aqua satellites (as well as the VIIRS instrument on Suomi NPP and NOAA-20) — a comparison of Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images from Terra and Aqua (below) highlighted the differing appearance of the blowing dust features as sensed by each of those spectral bands. The airborne dust exhibited a darker signature in the Shortwave Infrared images since the small dust particles were efficient reflectors of incoming solar radiation, thus appearing warmer at 3.7 µm.

Terra MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Terra MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Aqua MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Aqua MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Pilot reports within 20-45 minutes after the Terra overpass time (below) revealed Moderate to Severe turbulence at an elevation of 8000 feet, just southeast of the most dense dust plume feature (highlighted by the cooler, lighter gray infrared brightness temperatures) — this was likely due to strong wind shear in the vicinity of the rapidly-advancing cold front. Farther to the southwest, another pilot report indicated that the top of the blowing dust was at 7000 feet, with a flight-level visibility of 3 miles at 10,000 feet.

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of turbulence highlighted in red [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of turbulence highlighted in red [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of dust layer top and flight level visibility highlighted in red [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of dust layer top and flight level visibility highlighted in red [click to enlarge]