Wildfire smoke across the Midwestern US

August 11th, 2018 |

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

GOES-16 Natural Color RGB images, 09-11 August [click to play MP4 animation]

Numerous wildfires burning in southwestern Canada (primarily British Columbia: NOAA HMS fire/smoke product) produced large amounts of smoke, which was subsequently transported eastward across southern Canada and then southward across the Midwestern US during the 09 August11 August 2018 period. GOES-16 (GOES-East) Natural Color Red-Green-Blue (RGB) images from the AOS site (above) showed this smoke, portions of which were optically very thick at times (and were able to cast shadows owing to its significant vertical depth).

On 09 August the smoke was most highly concentrated over the Dakotas, as shown in a comparison of GOES-16 Aerosol Optical Depth (AOD), Smoke Detection, “Blue” Visible (0.47 µm) and “Red” Visible (0.64 µm) images (below). While much of the smoke was likely aloft within the middle troposphere, some had been mixed downward into the boundary layer and was restricting the surface visibility to 3-5 miles at many locations.

Note that the hazy signature of the widespread smoke was a bit more apparent in the 0.47 µm Visible imagery than the 0.64 µm Visible imagery, especially during mid-day when the sun-satellite “forward scattering angle” was at a minimum. The AOD and Smoke Detection derived products use data from Visible and Near-Infrared bands — so it they are only available during daytime hours (and only at solar zenith angles less than 60 degrees). The Smoke Detection product was more effective during times of enhanced forward scattering (early and late in the day) — but it also was susceptible to false alarms due to solar reflectance off water surfaces. Additional information on GOES-R Aerosol Detection Products in AWIPS is available here and here.

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right).

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right). “Blue” Visible (0.47 µm, bottom left) and “Red” Visible (0.64 µm, bottom right) [click to play animation | MP4]

On 10 August, the smoke was most dense across the eastern Dakotas and Minnesota (below) — and once again, surface visibilities were restricted to 3-5 miles at some locations. On this day pilot reports mentioned flight visibility being restricted to 3 miles at altitudes as high as 12,000 feet.

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right). "Blue" Visible (0.47 µm, bottom left) and "Red" Visible (0.64 µm, bottom right) [click to play animation | MP4]

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right). “Blue” Visible (0.47 µm, bottom left) and “Red” Visible (0.64 µm, bottom right) [click to play animation | MP4]

Finally, on 11 August a north-to-south plume of particularly dense smoke drifted southward across Minnesota and Iowa, as seen in a comparison of GOES-16 Aerosol Optical Depth, “Red” Visible (0.64 µm). Near-Infrared “Cirrus” (1.37 µm) and “Clean” Infrared Window (10.3 µm) images (below). In this case the AOD values were quite high (in excess of 3.0 in northwestern Minnesota), beyond the range of values scaled for display in AWIPS — this led to the swath of black “No Data” values where the smoke was most dense. This plume of thick smoke also exhibited a signature in Near-Infrared “Cirrus” images; higher concentrations of airborne particles that are effective scatterers of light at the 1.37 µm wavelength (such as ice crystals, smoke, volcanic ash, or dust) will be detected using this imagery. Note the lack of a well defined signature on the 10.3 µm imagery — smoke is effectively transparent to radiation at these longer infrared wavelengths.

GOES-16 Aerosol Optical Depth (top left), "Red" Visible (0.64 µm, top right). Near-Infrared "Cirrus" (1.37 µm, bottom left) and "Clean" Infrared Window (10.3 µm, bottom right) [click to play animation | MP4]

GOES-16 Aerosol Optical Depth (top left), “Red” Visible (0.64 µm, top right). Near-Infrared “Cirrus” (1.37 µm, bottom left) and “Clean” Infrared Window (10.3 µm, bottom right) [click to play animation | MP4]

On a side note, the north-south plume of dense smoke over southcentral Canada and the Midwest US on 11 August was also very apparent from a distance of 983,269 miles (1,582,418.07 km) — 44 times the distance of the GOES-16 satellite — in EPIC Natural Color imagery from the DSCOVR satellite (below).

DSCOVR EPIC Natural Color images [click to enlarge]

DSCOVR EPIC Natural Color images [click to enlarge]

Waves over the Upper Midwest / Great Lakes

June 23rd, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface reports [click to play animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) revealed a curious pattern of waves moving east-northeastward across a patch of mid-level clouds over central Lake Michigan during the morning hours on 23 June 2018.

In an effort to determine the vertical extent of these waves, a look at GOES-16 Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm) and Upper-level Water Vapor (6.2 µm) images from the UW-Madison AOS site (below) showed a signature of waves propagating northeastward across the region during the 0802-2102 UTC time period.

GOES-16 Low-level Water Vapor (7.3 µm) images [click to play MP4 animation]

GOES-16 Low-level Water Vapor (7.3 µm) images [click to play MP4 animation]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play MP4 animation]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play MP4 animation]

GOES-16 Upper-level Water Vapor (6.2 µm) images [click to play MP4 animation]

GOES-16 Upper-level Water Vapor (6.2 µm) images [click to play MP4 animation]

There also were scattered pilot reports of light to moderate turbulence across the region as these waves were moving through, including one report of continuous Clear Air Turbulence at 36,000 feet over eastern Wisconsin.  Due to the subtle nature of these waves, their signature was not as obvious in the 8-bit McIDAS-X Water Vapor images shown below as they were in 16-bit imagery displayed above (or what would be displayed using AWIPS II).

GOES-16 Low-level (7.3 µm) images, with hourly pilot reports of turbulence [click to play animation]

GOES-16 Low-level Water Vapor (7.3 µm) images, with hourly pilot reports of turbulence [click to play animation]

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

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

GOES-16 Upper-level (6.2 µm) images, with hourly pilot reports of turbulence [click to play animation]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with hourly pilot reports of turbulence [click to play animation]

The waves were passing over eastern Wisconsin around the time of ascent of the 12 UTC sounding balloon launched from Green Bay (and continuous turbulence was reported at 38,000 feet) — a plot of weighting functions for the three GOES-16 Water Vapor bands (below) showed peak pressures in the 424-328 hPa (22,800-28,885 feet) range, although significant contributions of energy were still evident from the 300 hPa pressure level (31,000 feet) or higher.

GOES-16 Water Vapor weighting functions, calculated using 12 UTC rawinsonde data from Green Bay, Wisconsin [click to enlarge]

GOES-16 Water Vapor weighting functions, calculated using 12 UTC rawinsonde data from Green Bay, Wisconsin [click to enlarge]

About an hour prior to the start of the 2-km resolution (at nadir or sub-satellite point) GOES-16 Water Vapor animations, 1-km resolution Aqua MODIS Water Vapor (6.7 µm) imagery at 0801 UTC (below) showed a long narrow wave packet (oriented northwest to southeast) from far western Wisconsin to central Illinois — and these waves were also apparent along the tops of mid-level clouds along the Iowa/Illinois border. Was this the leading edge of the waves seen farther northeast over the Great Lakes during the subsequent morning and afternoon hours?

Aqua MODIS Water Vapor (6.7 µm) and Infrared Window (11.0 µm) images, with plots of pilot reports [click to enlarge]

Aqua MODIS Water Vapor (6.7 µm) and Infrared Window (11.0 µm) images, with plots of pilot reports [click to enlarge]

All things considered, the lack of a clear forcing mechanism for these waves qualifies this case to be placed into the “What the heck is this” blog category until a coherent explanation can be put forward…

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.