Aircraft hole punch and distrail cloud features over southern Lake Michigan

December 20th, 2017 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and Near-Infrared “Snow/Ice” (1.61 µm. bottom) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed a number of aircraft “hole punch clouds” and cloud dissipation or “distrail” features drifting eastward across southern Lake Michigan and adjacent states on 20 December 2017. These cloud features were caused by aircraft that were either ascending or descending through a layer of cloud composed of supercooled water droplets — cooling from wake turbulence (reference) and/or particles from the jet engine exhaust acting as ice condensation nuclei cause the small supercooled water droplets to turn into larger ice crystals (many of which then often fall from the cloud layer, creating “fall streak holes“). The darker gray appearance of the hole punch clouds on 1.61 µm images confirms that the features were composed of ice crystals (since ice is a strong absorber of radiation at that wavelength).

A good example of a hole punch cloud adjacent to a longer distrail feature was seen over far southeastern Minnesota and the Minnesota/Wisconsin border, using 250-meter resolution Aqua MODIS true-color and false-color Red-Green-Blue (RGB) images from the MODIS Today site (below). Glaciated (ice crystal) cloud features appeared as darker shades of cyan in the false-color image.

Aqua MODIS true-color and false-color RGB images [click to enlarge]

Aqua MODIS true-color and false-color RGB images [click to enlarge]

A very detailed view of a hole punch cloud over Lake Michigan was provided by 30-meter resolution Landsat-8 false-color imagery at 1635 UTC, viewed using RealEarth (below).

Landsat-8 false-color RGB image [click to enlarge]

Landsat-8 false-color RGB image [click to enlarge]

===== 21 December Update =====

Another example of numerous aircraft hole punch and distrail cloud features was seen on Terra MODIS true-color and false-color RGB images on 21 December. over northern Illinois and northern Indiana (below).

Terra MODIS true-color and false-color images [click to enlarge]

Terra MODIS true-color and false-color RGB images [click to enlarge]

Day 14 of the Thomas Fire in Southern California

December 17th, 2017 |

GOES-15 Shortwave Infrared (3.9 µm) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

05-17 December GOES-15 Shortwave Infrared (3.9 µm) images, with surface station identifiers plotted in yellow and State Highway 101 plotted in cyan [click to play MP4 animation]

The Thomas Fire (InciWeb | Wikipedia) began to burn around 0226 UTC on 05 December 2017 (or 6:26 PM Pacific time on 04 December). By 17 December, the fire had burned 270,000 acres — the third largest wildfire on record in California — and caused 1 fatality. An animation of GOES-15 (GOES-West) Shortwave Infrared (3.9 µm) images (above) showed the evolution of the thermal signature (or “hot spots”, as depicted by darker black to yellow to red pixels) during the 0200 UTC 05 December to 0215 UTC 18 December time period. Besides the largest Thomas Fire, other smaller and more short-lived fires could also be seen — especially early in the period, when the Santa Ana winds were strongest (05-07 December blog post). Thick clouds moving over the region later in the period either attenuated or completely masked the thermal signatures, even though the fire was ongoing.

GOES-16 began transmitting imagery (from its GOES-East position at 75.2º W) at 1630 UTC on 14 December — a comparison of GOES-15 and GOES-16 Shortwave Infrared (3.9 µm) during the 14-17 December period (below) showed that in spite of the larger GOES-16 satellite view angle (62.6º, vs 43.2º for GOES-15), the improved spatial resolution (2 km vs 4 km at satellite sub-point) and improved temporal resolution (images every 5 minutes, with no 30-minute gaps due to Full Disk scans) provided a more accurate depiction of the fire trends and intensities.

GOES-15 (left) and GOES-16 (right) Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-15 (left) and GOES-16 (right) Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

In a comparison of 250-meter resolution Terra MODIS true-color and false-color Red-Green-Blue (RGB) images (source) at 1853 UTC on 17 December (below), minimal amounts of smoke and a lack of clouds allowed a good view of the large Thomas Fire burn scar (darker shades of reddish-brown) on the false-color image.

Terra MODIS true-color and false-color RGB images on 17 December [click to enlarge]

Terra MODIS true-color and false-color RGB images on 17 December [click to enlarge]

During the first full day of the fires on 05 December, a toggle between comparable Aqua MODIS true-color and false-color images (source) revealed very thick smoke plumes drifting southwestward over the adjacent offshore waters of the Pacific Ocean (below).

Aqua MODIS true-color and false-color images, 05 December [click to enlarge]

Aqua MODIS true-color and false-color RGB images on 05 December [click to enlarge]

A toggle between 05 December Aqua MODIS and 17 December Terra MODIS false-color images (below) showed the northward and northwestward growth of the Thomas Fire burn scar.

Aqua MODIS (05 December) and Terra MODIS (17 December) false-color RGB images [click to enlarge]

Aqua MODIS (05 December) and Terra MODIS (17 December) false-color RGB images [click to enlarge]

Day 7 of the Thomas Fire in Southern California

December 10th, 2017 |

GOES-15 Shortwave Infrared (3.9 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

GOES-15 Shortwave Infrared (3.9 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

The Thomas fire began burning in Southern California around 6:30 PM local time on 04 December (blog post) — and on 10 December 2017, GOES-15 (GOES-West) Shortwave Infrared (3.9 µm) images (above) revealed that the fire showed little signs of diminishing during the nighttime hours, and in fact began to exhibit a trend of intensification around 05 UTC or 9 PM local time. However, toward the end of the day on 10 December, bands of  thick cirrus clouds moving over the fire region acted to dramatically attenuate the satellite-detected thermal signature of the fire complex. Although the Santa Ana winds were not as intense as they had been during the previous week, some strong wind gusts were still observed.

A sequence of 4 Shortwave Infrared images from Terra MODIS and Suomi NPP VIIRS (below) showed the westward and northwestward expansion of the fire during the 0637 to 2032 UTC period. The Thomas fire has now burned 230,000 acres, making it the fifth largest wildfire on record in California.

Terra MODIS and Suomi NPP VIIRS Shortwave Infrared images, with corresponding surface reports plotted in cyan [click to enlarge]

Terra MODIS and Suomi NPP VIIRS Shortwave Infrared images, with corresponding surface reports plotted in cyan [click to enlarge]

In a toggle between Terra MODIS true-color and false-color Red-Green-Blue (RGB) images at 1846 UTC (below; source) the true-color image revealed a broad plume of thick smoke being transported westward and northwestward from the fire source region, while the false-color image showed the areal coverage of the burn scar (which appeared as reddish-brown hues beneath the clouds) as well as locations of the larger and more intense active fires (brighter pink to white) that were burning along the northern to western perimeter of the burn scar.

Terra MODIS true-color and false-color images [click to enlarge]

Terra MODIS true-color and false-color images [click to enlarge]

A comparison of Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 2032 UTC or 12:32 PM  local time (below) showed a well-defined thermal signature before the thicker cirrus clouds moved overhead from the south. A small cloud cluster (located just northwest of the fire thermal signature) exhibited a minimum infrared brightness temperature of -43ºC — if this cloud feature was indeed generated by the fire complex, it meets the -40ºC criteria of a pyrocumulonimbus cloud.

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images, with surface reports plotted in cyan [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images, with surface reports plotted in cyan [click to enlarge]

The fire was producing very thick smoke, in addition to deep pyrocumulus clouds (top photo taken around 1945 UTC or 11:45 AM local time):

Shown below is a photo taken at 2045 UTC or 12:45 PM local time, from a commercial jet flying into Santa Barbara (courtesy of Henry Dubroff/www.pacbiztimes.com).

Photo of Thomas Fire pyrocumulus [click to enlarge]

Photo of Thomas Fire pyrocumulus [click to enlarge]

===== 11 December Update =====
 

Suomi NPP VIIRS Day/Night Band (0.7 µm), Near-Infrared (1.61 and 2.25 µm), Shortwave Infrared (3.75 and 4.05 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm), Near-Infrared (1.61 and 2.25 µm), Shortwave Infrared (3.75 and 4.05 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm), Near-Infrared (1.61 and 2.25 µm), Shortwave Infrared (3.75 and 4.05 µm) and Infrared Window (11.45 µm) images at 1035 UTC or 2:35 AM local time (above; courtesy of William Straka, CIMSS) demonstrated how different spectral bands can be used to detect nighttime fire signatures. The maximum infrared brightness temperature on the 4.05 µm image was 389 K (115.9ºC or 240.5ºF). Note that the recently-launched JPSS-1/NOAA-20 satellite also carries a VIIRS instrument.

GOES-15 Shortwave Infrared (3.9 µm) images (below) showed that once the thicker bands of cirrus clouds moved northwestward away from the region, a more well-defined thermal signature became apparent.

GOES-15 Shortwave Infrared (3.9 µm) images, with hourly surface reports plotted in yellow [click to play animation]

GOES-15 Shortwave Infrared (3.9 µm) images, with hourly surface reports plotted in yellow [click to play animation]

A 7-day sequence Nighttime and Daytime composites of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images (source: RealEarth) is shown below — it illustrates the spread of the Thomas Fire from 05 December to 11 December. Hot infrared pixels are black, with saturated pixels appearing bright white.

7-day sequence Nighttime and Daytime composites of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images [click to play animation]

7-day sequence Nighttime and Daytime composites of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images [click to play animation]

Snowfall across the Deep South

December 9th, 2017 |

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 (GOES-East) Visible (0.63 µm) images (above) showed a broad swath of snow cover from Louisiana to Virginia on 09 December 2017. Some notable storm total accumulations included 6.5 inches at Kentwood, Louisiana, 7.0 inches at Bay Springs, Mississippi, 12.0 inches at Jacksonville, Alabama, 2.0 inches at Century, Florida, 18.0 inches at Mountain City, Georgia, 7.0 inches near Roan Mountain, Tennessee, and 25 inches at Mt. Mitchell State Park, North Carolina. Daily record snowfall accumulations included a Trace at New Orleans, Louisiana, 5.1 inches at Jackson, Mississippi and 1 inch at Mobile, Alabama.

A closer view of GOES-13 visible images (below) showed the band of snow cover across Louisiana, Mississippi and Alabama. Much of the the snow melted quickly, due to warm ground temperatures and a full day of sun.

GOES-13 Visible (0.63 µm) images, with station identifiers plotted in yellow [click to play animation]

GOES-13 Visible (0.63 µm) images, with hourly surface reports plotted in yellow [click to play animation]

A more detailed view of the snow cover was provided by 250-meter resolution Terra and Aqua MODIS true-color Red-Green-Blue (RGB) images from the SSEC MODIS Direct Broadcast site (below). Note that snow cover was evident all the way to the Gulf Coast at Atchafalaya Bay, Louisiana early in the day.

Terra and Aqua MODIS true-color RGB images of the central Gulf Coast region [click to enlarge]

Terra and Aqua MODIS true-color images of the central Gulf Coast region [click to enlarge]

Terra and Aqua MODIS true-color RGB images, centered over Atchafalaya Bay, Louisiana [click to enlarge]

Terra and Aqua MODIS true-color RGB images, centered over Atchafalaya Bay, Louisiana [click to enlarge]

Terra and Aqua MODIS true-color images, centered over New Orleans, Louisiana [click to enlarge]

Terra and Aqua MODIS true-color images, centered over New Orleans, Louisiana [click to enlarge]

Terra MODIS true-color image, centered over Atlanta, Georgia [click to enlarge]

Terra MODIS true-color image, centered over Atlanta, Georgia [click to enlarge]

It is interesting to note that with the aid of reflected moonlight — the Moon was in the Waning Gibbous phase, at 59% of Full — the Suomi NPP VIIRS Day/Night Band (0.7 µm) was able to detect the area of deeper snow cover across southeastern Louisiana and southern Mississippi at 0741 UTC or 1:41 AM local time; this snow cover was then seen during the following morning on GOES-13 Visible (0.63 µm) imagery at 1440 UTC or 8:40 AM local time (below). A VIIRS instrument is part of the payload on the recently-launched JPSS-1/NOAA-20 satellite.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and GOES-13 Visible (0.63 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and GOES-13 Visible (0.63 µm) images [click to enlarge]