Lake Michigan Mesovortex

December 31st, 2017 |

1-minute GOES-16

1-minute GOES-16 “Red” Visible (0.64 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a well-defined mesoscale vortex (or “mesovortex”) moving southward across southern Lake Michigan on 31 December 2017. The default western GOES-16 Mesoscale Sector provided images at 1-minute intervals. This feature was responsible for brief periods of heavy snow at locations such as South Haven, Michigan KLWA (beginning at 1455 UTC), Benton Harbor, Michigan KBEH (beginning at 1625 UTC) and La Porte, Indiana KPPO (from 2055 to 2115 UTC).

Comparisons of POES AVHRR/Terra MODIS/Suomi NPP Infrared (10.8 µm/11.0 µm/11.45 µm) and Visible (0.86 µm/0.65 µm/0.64 µm) images along with an overlay of the corresponding Real-Time Mesoscale Analysis (RTMA) surface winds (below) provided views of the mesovortex at 1522 UTC, 1714 UTC and 1852 UTC, respectively.

POES AVHRR Infrared (10.8 µm) and Visible (0.86 µm) images at 1522 UTC, with 15 UTC RTMA surface winds [click to enlarge]

POES AVHRR Infrared (10.8 µm) and Visible (0.86 µm) images at 1522 UTC, with 15 UTC RTMA surface winds [click to enlarge]

Terra MODIS Infrared (11.0 µm) and Visible (0.65 µm) images at 1714 UTC, with 17 UTC RTMA surface winds [click to enlarge]

Terra MODIS Infrared (11.0 µm) and Visible (0.65 µm) images at 1714 UTC, with 17 UTC RTMA surface winds [click to enlarge]

Suomi NPP Infrared (11.45 µm) and Visible (0.64 µm) images at 1852 UTC, with 19 UTC RTMA surface winds [click to enlarge]

Suomi NPP Infrared (11.45 µm) and Visible (0.64 µm) images at 1852 UTC, with 19 UTC RTMA surface winds [click to enlarge]

During the preceding nighttime hours, a comparison of Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 0729 UTC along with an overlay of 07 UTC RTMA surface winds (below) showed in spite of patchy thin cirrus clouds over the region, ample illumination from the Moon (which was in the Waxing Gibbous phase, at 96% of Full) enabled a signature of the early stage of mesovortex formation to be seen on the Day/Night Band (DNB) image. Ice crystals within the thin cirrus clouds were responsible for the significant scattering city light signatures on the DNB image.

Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 0729 UTC, with 07 UTC RTMA surface winds [click to enlarge]

Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 0729 UTC, with 07 UTC RTMA surface winds [click to enlarge]

As an aside, it is interesting to note that ice could be seen in the nearshore waters of Lake Michigan — both in the western part of the lake, off the coast of Wisconsin and Illinois, and in the eastern part of the lake off the coast of Lower Michigan. The lake ice appeared as darker shades of cyan in the 250-meter resolution Terra MODIS false-color (Band 7-2-1 combination) Red-Green-Blue (RGB) image from the MODIS Today site (below).

Terra MODIS true-color and false-color images over southern Lake Michigan [click to enlarge]

Terra MODIS true-color and false-color images over southern Lake Michigan [click to enlarge]

Aircraft hole punch and cloud dissipation features over Illinois, Indiana and Ohio

December 21st, 2017 |

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

Terra MODIS True-color and False-color RGB images [click to enlarge]

A toggle between 250-meter resolution Terra MODIS True-color and False-color Red-Green-Blue (RGB) images from the MODIS Today site (above) revealed numerous aircraft “hole punch” and dissipation trail or “distrail” features over Illinois, Indiana and Ohio on 21 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 causes the small supercooled water droplets to turn into larger ice crystals (many of which then fall from the cloud layer, creating “fall streak holes“). The ice crystal clouds appear as darker shades of cyan on the false-color image.

GOES-16 "Red" Visible (0.64 µm) and Near-Infrared "Snow/Ice" (1.61 µm) images over Illinois/Indiana [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images over Illinois/Indiana [click to play MP4 animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images showed the hole punch and distrail features over Illinois/Indiana (above) and over Indiana/Ohio (below). The glaciated (ice crystal) hole punch and distrail clouds appeared dark gray on the Snow/Ice images (since ice is a strong absorber of radiation at the 1.61 µm wavelength).

GOES-16 "Red" Visible (0.64 µm) and Near-Infrared "Snow/Ice" (1.61 µm) images over Indiana/Ohio [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images over Indiana/Ohio [click to play MP4 animation]

RealEarth is used to display Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.9 µm), Near-Infrared (1.61 µm), True-color and False-color RGB images at 1841 UTC (below). O ne the Shortwave Infrared images, the hole punch and distrail features are colder (brighter white) than the surrounding supercooled water droplet cloud deck — since water droplet are effective absorbers of incoming solar radiation, such clouds appear warmer (darker gray) in 3.9 µm images.

Suomi NPP VIIRS

Suomi NPP VIIRS “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), Near-Infrared “Snow/Ice” (1.61 µm), True-color and False-color RGB images [click to enlarge]

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]