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.

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

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.

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.

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.

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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).

This is drone footage from @MarshallCoWVOEM Director Tom Hart says this is at the end of Nixon Ridge near Fish Creek. The explosion left a crater. The DEP estimates 10 acres are affected @WTRF7News pic.twitter.com/QXTOsWBvNg

— Tessa DiTirro (@TDiTirroWTRF) June 7, 2018

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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.

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.

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.

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.

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.

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The first Tropical Storm, Aletta, of the eastern Pacific Ocean basin has been named. One-minute imagery from a moveable Mesoscale Sector, above as an animated gif (or here as an mp4), shows a distinct low-or mid-level circulation center moving out from under higher clouds in the northeast quadrant of the storm at about 1621 UTC, being even more obvious at 1636 UTC.

The GOES-16 CONUS Sector scans at 5-minute intervals. The southern boundary of the CONUS sector (15º N Latitude), however, bisects this tropical storm, as shown at this link, and is therefore unhelpful for center diagnostics. Full Disk imagery captures the storm evolution at a 15-minute time step that is too coarse to provide a smooth animation. (Just two years ago, the time resolution for this storm formation would have been every 3 hours, as that was the time cadence for a Full Disk from GOES-13! GOES-16 really is life-changing for those who view satellite animations.)

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