Long-range transport of California wildfire smoke across the Upper Midwest

August 24th, 2020 |

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

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

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) revealed the hazy signature of dense smoke aloft moving eastward across much of the Upper Midwest on 24 August 2020 — smoke that had been transported from large wildfires burning in California.

Images of 532 nm and 1064 nm lidar attenuated backscatter collected and processed by the University of Wisconsin Lidar Group at Madison from 00 UTC on 24 August to 00 UTC on 25 August (below) indicated that this smoke existed within altitudes between 2 km and 6 km.

532 nm and 1064 nm lidar attenuated backscatter during 24 August at Madison, Wisconsin [click to enlarge]

532 nm and 1064 nm lidar attenuated backscatter over Madison, Wisconsin [click to enlarge]

CIMSS Natural Color RGB images with plots of Pilot Reports are shown below. While this “simple” RGB does not depict the haziness of the smoke as well as the True Color RGB images above — which are corrected for the effect of Raleigh scattering — s subtle smoke signature was still apparent. Not many of the available Pilot Reports (PIREPs) explicitly mentioned any effects of the smoke, but one 1955 UTC PIREP indicated a reduction to Marginal Visual Flight Rules (MVFR, visibility of 3-5 miles) at at altitude of 11,500 feet (3.5 km).

CIMSS Natural Color RGB images, with plots of Pilot Reports [click to play animation | MP4]

CIMSS Natural Color RGB images, with plots of Pilot Reports [click to play animation | MP4]

Turbulence associated with transverse banding

July 16th, 2020 |

GOES-16

GOES-16 “Clean” Infrared Window (10.35 µm) and Near-Infrared “Cirrus” (1.38 µm) images [click to play animation | MP4]

As a Mesoscale Convective System (MCS) over Kansas and Oklahoma decayed during the morning hours of 16 July 2020, GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) and Near-Infrared “Cirrus” (1.38 µm) images (above) depicted widespread transverse banding — tendrils of cirrus clouds oriented perpendicular to the upper-tropospheric wind flow — along the northern periphery of the MCS. An AIRMET was issued for that region (advising of moderate turbulence between 30,000 and 43,000 feet), and there were numerous Pilot Reports (PIREPs) of light to moderate turbulence in the general vicinity of these transverse banding features.

A GOES-16 Turbulence Probability product (below) did show scattered pockets of 25-35% probability in the transverse banding region. However, this product is designed to diagnose turbulence potential in the vicinity of features such as fronts and fields of convection.

GOES-16 Turbulence Probability product, with plots of PIREPs and AIRMETs [click to play animation | MP4]

GOES-16 Turbulence Probability product, with plots of PIREPs and AIRMETs [click to play animation | MP4]

Such transverse banding cloud features are frequently observed around the periphery of decaying MCSs (for example, June 2018 and July 2016) and in the vicinity of strong upper-tropospheric jet streaks (for example, February 2020 and March 2016).

Boundary layer wave clouds over Kansas

May 2nd, 2020 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with plots of pilot reports of turbulence and AIRMET boundaries [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed widespread boundary layer wave clouds across much of Kansas and far eastern Colorado on 02 May 2020. Although there was a temporary outage of pilot report data from 18-19 UTC, there was one pilot report of light turbulence over Hays, Kansas (KHYS) at an altitude of 6500 feet at 2041 UTC. An AIRMET for the potential of turbulence below 7000 feet had been issued at 14 UTC. There was a hint of some wave interference, which may have enhanced turbulence potential.

There was also a subtle signature of these waves seen in GOES-16 Low-level Water Vapor (7.3 µm) images (below).

GOES-16 Low-level Water Vapor (7.3 µm) images, with plots of pilot reports of turbulence and AIRMETs boundaries [click to play animation | MP4]

GOES-16 Low-level Water Vapor (7.3 µm) images, with plots of pilot reports of turbulence and AIRMETs boundaries [click to play animation | MP4]

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]