Mesoscale Convective System in the Plains

June 11th, 2018 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with plots of SPC storm reports [click to play MP4 animation]

A Mesoscale Convective System (MCS) developed over eastern Nebraska early in the evening on 11 June 2018, then propagated southward across the Plains during the subsequent overnight hours. GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with plots of SPC storm reports are shown above; a Mesoscale Sector was positioned over the region, providing images at 1-minute intervals.

A closer look over Kansas using Infrared imagery from polar-orbiting satellites (below) revealed some very cold cloud-top infrared brightness temperatures, which included -87ºC on MODIS, -90ºC on VIIRS and -92ºC on AVHRR.

POES AVHRR, Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images, with plots of SPC storm reports [click to enlarge]

Metop-B AVHRR, Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images, with plots of SPC storm reports [click to enlarge]

The coldest air temperature on 00 UTC rawinsonde data from Dodge City and Topeka, Kansas (below) was -69.5ºC (at altitudes of 14.6 km/49,900 feet at Dodge City, and 17.6 km/57,700 feet at Topeka) — so in theory air parcels and cloud material within a vigorous overshooting top could have ascended a few km (or thousands of feet) beyond those altitudes to exhibit an infrared brightness temperature of -92ºC.

Plots of rawinsonde data from Dodge City and Topeka, Kansas [click to enlarge]

Plots of rawinsonde data from Dodge City and Topeka, Kansas [click to enlarge]

A toggle between re-mapped versions of the GOES-16 ABI and Metop-B AVHRR Infrared imagery over Kansas at the time of the very cold cloud-top infrared brightness temperature (below) revealed 2 important points: (1) with improved spatial resolution (1 km for AVHRR, vs 2 km *at satellite sub-point* for ABI) the instrument detectors sensed much colder temperatures (-92.6ºC with AVHRR vs -81.2ºC with ABI), and (2) due to parallax. the GOES-16 image features are displaced to the northwest. In addition to the isolated cold overshooting top in south-central Kansas, note the pronounced “Enhanced-V” storm top signature in far northeastern Kansas.

Comparison of GOES-16 ABI and Metop-B AVHRR Infrared images [click to enlarge]

Comparison of GOES-16 ABI and Metop-B AVHRR Infrared images [click to enlarge]

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Cape Newenham, Alaska bow shock waves

June 10th, 2018 |

GOES-15 Visible (0.63 µm) images, with hourly plots of wind barbs [click to play animation]

GOES-15 Visible (0.63 µm) images, with hourly plots of wind barbs [click to play animation]

GOES-15 (GOES-West) Visible (0.63 µm) images (above) showed patches of fog and low stratus moving southwestward off Southwest Alaska and across the adjacent offshore waters of the Bering Sea on 10 June 2018.

A closer look using 250-meter resolution Terra/Aqua MODIS and 375-meter resolution Suomi NPP VIIRS true-color Red-Green-Blue (RGB) images from RealEarth (below) revealed a packet of “bow shock waves” created as the shallow fog/stratus interacted with the relatively rugged terrain of the narrow Cape Newenham land feature (Google Maps). Other examples of similar bow shock wave cloud features have been documented here, here and here.

Terra MODIS, Aqua MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

Terra MODIS, Aqua MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

A 30-meter resolution Landsat-8 false-color RGB image (below) provided a more detailed view of the bow shock wave structure. Snow cover (cyan) could be seen on some of the higher-elevation land features.

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

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

A time series plot of Cape Newenham surface observations (below) showed the fluctuations in visibility as northerly winds brought patches of fog over the site.

Time series plot of Cape Newenham surface observations [click to enlarge]

Time series plot of Cape Newenham surface observations [click to enlarge]

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]

Eruptions of Kilauea in Hawai’i

May 5th, 2018 |

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

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

Heightened seismic activity of the Kilauea volcano on the Big Island of Hawai’i had been ongoing since April 2018, but increased further in early May leading to a series of minor eruptions (Hawaiian Volcano Observatory | USGS) — and GOES-15 (GOES-West) Shortwave Infrared (3.9 µm) images (above) showed the nearly persistent thermal anomaly or “hot spot” (dark black to red enhancement) during the 03-05 May period. Among the numerous earthquakes, the strongest was an M6.9 which occurred at 2233 UTC on 04 May.

A nighttime image of Suomi NPP VIIRS Day/Night Band (0.7 µm) data viewed using RealEarth (below) revealed the bright glow from Kilauea, and also from the Leilani Estates subdivision where several fissure vents had opened (forcing some evacuations).

Suomi NPP VIIRS Day.Night Band (0.7 µm) images, with island boundary and Google Maps labels [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) images, with the island boundary and Google Maps labels [click to enlarge]

A comparison of Suomi NPP VIIRS Day/Night Band images from 03 May and 04 May (below) showed the before/after difference in the bright signal emitted by the fissure vents near Leilani Estates.

Suomi NPP VIIRS Day/Night Band (0.7 µm) images from 03 May and 04 May [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) images from 03 May and 04 May [click to enlarge]

===== 06 May Update =====

Eruptions of fissure vents became more continuous in the Leilani Estates subdivision on 06 May. A comparison of GOES-15 Visible and Shortwave Infrared images (below) showed a long volcanic plume streaming southwestward, with robust thermal anomaly activity at the plume source.

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2018/05/G15_VIS_SWIR_HI_06MAY2018_960x640_B12_2018126_201500_0002PANELS_00002.GIF

GOES-15 Visible (0.63 µm, left) and Shortwave Infrared (3.9 µm, right) images, with hourly plots of surface reports [click to play animation | MP4]

An Aqua MODIS True-color Red-Green-Blue (RGB) image (below) provided a more detailed view of the volcanic plume at 0007 UTC on 07 May. Note the cluster of red thermal anomalies in the vicinity of the Leilani Estates subdivision (the source of the plume).

Aqua MODIS True-color RGB image [click to enlarge]

Aqua MODIS True-color RGB image, with VIIRS thermal anomalies plotted in red [click to enlarge]