1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible and Infrared images (above) showed the WNW motion of the eye of Hurricane Erin during a 7-hour period as the tropical cyclone rapidly intensified from a Category 4  storm at 0950 UTC to a Category 5 storm at 1520 UTC, north of the Leeward Islands on 16 August 2025. Erin was the earliest Category 5 hurricane on record in the Atlantic Ocean, as well as one of the Atlantic’s fastest-intensifying tropical cyclones on record (SATCON). Plots of 1-minute GOES-19 GLM Flash Points displayed abundant lightning activity within the inner eyewall of Erin’s pinhole eye. In addition, the eye exhibited a notable stadium effect — with a very small low-altitude eye seen in visible imagery, broadening to a larger high-altitude eye in infrared imagery (for example, at 1657 UTC). The coldest cloud-top infrared brightness temperatures within the eyewall were around -80 C.

A closer view of 1-minute GOES-19 Visible imagery (below) revealed the presence of low-altitude mesovortices within the eye. A pinhole eye and mesovortices within the eye are 2 satellite-observed characteristics often associated with intense Category 5 tropical cyclones. In addition, Erin was moving though an environment of weak deep-layer wind shear and traversing warm sea surface temperatures — 2 factors that favored intensification.

A GOES-19 Visible image at 1424 UTC (below) included plots of ASCAT ocean surface winds valid at that time; hurricane-force winds only extended about 10-15 miles from the center of Erin. However, significant rainfall contamination within portions of the eyewall adversely affected the quality of a few of the scatterometer winds (with 3 erroneous wind directions seen near the eye).

A Synthetic Aperture Radar (SAR) image from RCM-3 at 2229 UTC on 16 August (below) depicted a peak radial wind velocity of 123 kts in the SE quadrant of Erin (source) — this was around the time that the hurricane was undergoing an eyewall replacement cycle, and decreasing in intensity from a Category 5 at 2100 UTC to a Category 4 at 0000 UTC.

Later that evening, 1-minute GOES-19 Infrared images (below) showed that the eye of Category 4 Hurricane Erin passed about 40 miles south of Buoy 41043 — which reported hourly wind gusts of 64 kts at 0200 UTC and 0300 UTC on 17 August (the highest 10-minute wind gust was 66.1 kts at 0250 UTC).

Plots of wind speed / wind gusts / atmospheric pressure and wave height at Buoy 41043 (below) indicated that their maximum (or minimum, in terms of pressure) values occurred around 0300 UTC on 17 August (just as the eye of Erin was passing south of the Buoy).

The maximum wave height of 29 ft measured at Buoy 41043 was commensurate with the 25.32 ft significant wave height sensed by Sentinel-3A (and the 39.52 ft sensed by SWOT) farther to the south, near the northern Leeward Islands, during the morning hours (1237 UTC and 1428 UTC) on 16 August (below).

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10-minute Full Disk scan GOES-18 (GOES-West) daytime True Color RGB and nighttime Dust RGB images created using Geo2Grid (above) showed a plume of resuspended volcanic ash (hazy shades of tan in True Color RGB, and subtle shades of violet in Dust RGB images) from the 1912 Novarupta-Katmai eruption in Alaska — which was being transported offshore across the Shelikof Strait and Kodiak Island, emerging over the Gulf of Alaska during 15-16 August 2025. Surface volcanic ash within the Valley Of Ten Thousand Smokes was being lofted by strong northwesterly winds (surface analyses) that were being channeled through the valley.

According to this USGS Volcano Notice, the National Weather Service issued a SIGMET advising that the maximum height of this resuspended ash was 6000 ft.

Other similar resuspended ash events have been documented here on this blog.

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Today at 16:55 UTC, NOAA decommissioned NOAA-19, the most recently launched of the remaining legacy NOAA POES spacecraft. NOAA-19 launched on February 6th, 2009 and become operational on June 2nd, 2009. For the last 16 years, NOAA-19 has provided routine weather observations of the entire globe from low-earth orbit.

The AVHRR visible/IR imager and AMSU-A/MHS set of microwave sounders were both functioning well on NOAA-19 in its final days. However, due to a spacecraft battery failure on August 9th, the decision was made to accelerate the decommissioning timeline by about 6 days. The HRPT direct broadcast system on the spacecraft started to falter on August 11th, so the final daytime overpass of Wisconsin by NOAA-19 (with valid science data) was received by SSEC’s Madison antenna at 15:56 UTC on August 10th. Below is a selection of the AVHRR Level 1 imagery from that pass, along with AVHRR Level 2 Sea Surface Temperature retrievals from CSPP ACSPO, and AMSU-A/MHS Level 2 Total Precipitable Water and Rain Rate products from CSPP MiRS.

		[Inactive]
AVHRR Band 1: “Red Visible” [0.63 µm]	AVHRR Band 2: “Vegetation Near-IR” [0.86 µm]	AVHRR Band 3A: “Snow/Ice Near-IR” [1.61 µm]
AVHRR Band 3B: “Shortwave IR Window” [3.74 µm]	AVHRR Band 4: “Legacy IR Window” [10.8 µm]	AVHRR Band 5: “Dirty IR Window” [12.0 µm]
ACSPO AVHRR Sea Surface Temperature	MiRS AMSU-A/MHS Total Precipitable Water	MiRS AMSU-A/MHS Rain Rate

Today’s activity follows NOAA-18’s decommissioning on June 6th. NOAA-15, the last operating spacecraft in the POES series, is slated to be turned off during the week of August 18th.

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10-minute Full Disk scan GOES-19 (GOES-East) Nighttime Microphyscics RGB images from the CSPP GeoSphere site (above) showed a signature of the Ariane-62 rocket condensation cloud (darker shades of blue) following the launch of EUMETSAT Metop-SGA1 from Europe’s Spaceport (Guyana Space Center) at Kourou, French Guyana about 3 hours after sunset on 12 August 2025 (the launch time was 0037 UTC on 13 August). The ascending rocket booster condensation cloud was initially apparent in the 0040 UTC image, followed by the lower-altitude condensation cloud originating from near the launch site (which spread out along and near the coast).

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