PyroCumulonimbus cloud in Colorado

June 9th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.3 µm, right) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the formation of a small pyroCumulonimbus (pyroCb) cloud spawned by the 416 Fire in southwestern Colorado on 09 June 2018. A Mesoscale Domain Sector was positioned over the region, providing images at 1-minute intervals.

On Shortwave Infrared imagery, the thermal anomaly or “hot spot” appeared as a large cluster of red pixels — and the top of the pyroCb cloud took on a darker gray appearance than nearby high-altitude ice crystal clouds (due to enhanced solar reflectance off the smaller ice crystals of the pyroCb anvil). On 10.3 µm imagery, cloud-top infrared brightness temperatures cooled to around -50ºC (bright yellow enhancement) as the pyroCb drifted northeastward.

NOAA-19 AVHRR Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images, with plots of 22 UTC surface reports [click to enlarge]

NOAA-19 AVHRR Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images, with plots of 22 UTC surface reports [click to enlarge]

On 1-km resolution NOAA-19 AVHRR Infrared Window (10.8 µm) imagery at 22:07 UTC (above), the minimum cloud-top brightness temperature was -53ºC — this temperature roughly corresponded to an altitude of 11.6 km according to 00 UTC rawinsonde data from Grand Junction, Colorado (below).

Plots of rawinsonde data from Grand Junction, Colorado [click to enlarge]

Plots of rawinsonde data from Grand Junction, Colorado [click to enlarge]


Hurricane Aletta

June 7th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images [click to play MP4 animation]

Tropical Storm Aletta was upgraded to Hurricane Aletta at 21 UTC on 07 June 2018. As was the case on 06 June, a GOES-16 Mesoscale Domain Sector centered over the tropical cyclone provided 1-minute data — and an eye eventually became apparent on  “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) imagery (above).

DMSP-15, DMSP-17 and GPM GMI Microwave (85 GHz) imagery from the CIMSS Tropical Cyclones site (below) showed an increase in organization of the eye structure as the day progressed.

DMSP-15 SSMI Microwave image [click to enlarge]

DMSP-15 SSMI Microwave image [click to enlarge]

DMSP-17 SSMIS Microwave image [click to enlarge]

DMSP-17 SSMIS Microwave image [click to enlarge]

GPM GMI Microwave image [click to enlarge]

GPM GMI Microwave image [click to enlarge]

===== 08 June Update =====

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

Aletta went through a period of rapid intensification (ADT | SATCON), reaching Category 4 status by 15 UTC on 08 June. 1-minute GOES-16 Infrared (10.3 µm) images (above) showed the eye becoming more well-defined during the pre-dawn hours.

After sunrise, GOES-16 Visible images (below) initially hinted at the presence of mesovortices within the eye of Aletta.

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images [click to play MP4 animation]

Aletta had been moving over relatively warm water and within an environment characterized by low values of deep-layer wind shear (below) — both  of which were favorable factors for intensification. An animation of the deep-layer wind shear over the East Pacific Ocean during 06-07 June is available here.

Sea Surface Temperature and Deep-Layer Wind Shear products [click to enlarge]

Sea Surface Temperature and Deep-Layer Wind Shear products [click to enlarge]

Aletta peaked in intensity later in the day on 08 June (ADT | SATCON) — as pointed out by NHC “This is also consistent with GOES-16 measurements of increased inner-core lightning observed to be occurring to the east of the eastern eyewall, which some research suggests corresponds to a halting of the intensification process”. GOES-16 Infrared (10.3 µm) imagery with GLM Group Density counts are shown below.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) with GLM Group Density counts [click to play MP4 animation]

TransCanada pipeline explosion and fire in West Virginia

June 7th, 2018 |

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm, left), Near-Infrared “Cloud Particle Size” (2.24 µm, center) and Shortwave Infrared (3.9 µm, right) images; Interstate Highways are plotted in red, with State Highways in cyan [click to play animation | MP4]

An explosion and fire occurred along a TransCanada natural gas pipeline in the remote Nixon Ridge area of Marshall County, West Virginia on 07 June 2018. A thermal signature of the fire was seen in GOES-16 (GOES-East) Near-Infrared Snow/Ice (1.61 µm), Near-Infrared Cloud Particle Size (2.24 µm) and Shortwave Infrared (3.9 µm) images (above) beginning at 0817 UTC (4:17 am Eastern Time). The fire signature was no longer apparent after 0927 UTC (5:27 am Eastern Time).

Lava flow from Kilauea in Hawai’i

June 6th, 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]

The Kilauea volcano on the Big Island of Hawai’i continued to be active into early June 2018 — and GOES-15 (GOES-West) Shortwave Infrared (3.9 µm) imagery (above) showed the thermal anomaly or “hot spot” (black to yellow to red enhancement) associated with lava flows from active fissures in the East Rift Zone on 06 June.

GOES-15 Visible (0.63 µm) images (below) showed clouds of steam from the East Rift Zone drifting to the south-southwest; a hazy plume of volcanic fog or “vog” was also evident, which was being transported farther to the southwest by the northeasterly trade wind flow.

GOES-15 Visible (0.63 µm) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-15 Visible (0.63 µm) images, with hourly plots of surface reports [click to play MP4 animation]

A Suomi NPP VIIRS Visible (0.64 µm) image at 2307 UTC (below) showed clear skies over Kapoho on the eastern tip of the Big Island, with steam plumes from the active East Rift Zone fissures flowing southwestward.

Suomi NPP VIIRS Visible (0.64 µm) image [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image [click to enlarge]

The corresponding VIIRS Shortwave Infrared (3.74 µm) image (below) helped to discriminate between the hot brightness temperatures of recent (and old) lava flows and the cooler brightness temperatures exhibited by regions of vegetation.

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

A closer look at the Kilauea East Rift Zone (below) provided a detailed view of the recent lava flow and active fissures, including the lava field that entered and covered Kapoho Bay a few days earlier. Note the appearance of numerous multi-colored pixels in the center of the lava field — the 3.74 µm I04 band detectors on the VIIRS instrument saturate around 385 K, so the hottest lava features which exceeded that brightness temperature threshold ended up being displayed as cold pixels (the so-called “wrap-around” effect). There is a Moderate-resolution M13 band (4.05 µm) on VIIRS which saturates at a much hotter 700 K; while it is a lower spatial resolution (750 meters, vs 375 meters for the I04 band), the M13 band can be useful for sampling the actual temperature of very hot features such as lava flows or wildfires.

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

Thanks to Jordan Gerth (CIMSS) and Eric Lau (NWS Pacific Region Headquarters) for providing the VIIRS imagery for this case.

Update: This link shows Landsat-8 and Sentinel-2 imagery before and after the Kapoho Bay lava flow.