After reaching Category 3 intensity over the eastern Atlantic Ocean on 14 October, Hurricane Ophelia (storm track) rapidly underwent transition to an extratropical storm which eventually spread high winds across much of Ireland and the United Kingdom on 16 October 2017. EUMETSAT Meteosat-10 upper-level Water Vapor (6.25 µm) (above) and lower-level Water Vapor (7.35 µm) images (below) revealed the familiar “scorpion tail” signature of a sting jet (reference). Hourly wind gusts (in knots) from primary reporting stations are plotted in red.

Two sites with notable wind gusts were Cork, Ireland (67 knots at 0930 UTC) and Valley, UK (70 knots at 1500 UT), shown below. In fact, a wind gust of 103 knots (119 mph or 191 km/hour) was reported at the Fastnet Rock Lighthouse off the southwest coast of Ireland.

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In a toggle between Terra MODIS (overpass time around 1159 UTC) and Aqua MODIS (overpass time around 1345 UTC) true-color Red-Green-Blue (RGB) imagery (above), a somewhat hazy appearance was seen over the Irish Sea on the Terra MODIS image. This was due to an airborne plume of sand from the Sahara Desert (UK Met Office story).

In fact, blowing sand was observed about 3 hours later at Isle of Man, from 1520-1620 UTC — during that time period their surface winds gusted to 68 knots (78 mph), and surface visibility was reduced to 2.2 miles (below).

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Hurricane Ophelia — the record-tying 10th consecutive Atlantic basin hurricane of the 2017 season — reached a satellite-estimated Category 3 intensity at 15 UTC on 14 October 2017. GOES-13 (GOES-East) Visible (0.63 µm) and Infrared Window (10.7 µm) images (above) showed a well-defined circular eye as the storm moved well south of the Azores. The tweet below underscores the unusual nature of the intensity and location of Ophelia (which also occurred over unusually-cold waters).

#Ophelia has shattered the record for northeastern-most forming Cat 3 in the Atlantic and is the easternmost overall. League of its own. pic.twitter.com/sZrHap5z1f

— Brenden Moses (@Cyclonebiskit) October 14, 2017

A DMSP-17 SSMIS Microwave (85 GHz) image (below) also revealed a circular eye structure.

One factor that might have aided this increase of intensity was the recent passage of Ophelia through an environment of higher Maximum Potential Intensity (reference), where maximum wind speed values of 100 knots resided (below).

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GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing.

GOES-16 provides many tools to the Operational Meteorologist, and to National Weather Service Incident Meteorologists (IMETs), to monitor fires when they occur, such as those over Napa and Sonoma Counties in California (Blog Post). Visible (0.64 µm) and Shortwave Infrared (3.9 µm) channels, above and below, respectively, are available routinely at 5-minute intervals over the Continental United States. During daytime, the Visible Imagery is useful for highlighting smoke palls and for alerting meteorologists to any wind changes. The Shortwave Infrared has long been used to detect fires; the shortwave infrared channel on GOES-16 can detect hotter and smaller fires than previous GOES Satellites because of improved spatial resolution and improved bit depth in the imagery.

GOES-16 Channels can be combined to create Red Green Blue (RGB) Composites that also help identify fires qualitatively. The Fire RGB, below, combines the shortwave IR (3.9 µm) with the 2.2 µm and 1.6 µm channels; as fires get warmer, radiation is emitted at shorter and shorter wavelengths. When this RGB shows white values, you can be certain that the fire is very hot. At some times in the RGB animation, the 3.9 µm imagery is missing where the fire is exceptionally hot, meaning the ‘red’ component of the RGB has no value, and the RGB acquires a blue and green hue.

The Fire Temperature RGB like the visible imagery shown above offer qualitative information about fire. More quantitative information is available in GOES-16 Baseline Products that are an extension and refinement of the WF-ABBA products available for GOES-13 and GOES-15 (and other satellites). Fire-related products for GOES-16 include Fire Area and Fire Temperature, shown below. The products give the size of the fire within the pixel, and its temperature. These products are valuable in quickly evolving fires to monitor how things change, and the products are available every 5 minutes.

Finally, GOES-16 has 1-minute Mesoscale Sectors that can be used to closely monitor quickly-evolving fire situations. The 3.9 µm shortwave infrared and Fire RGB images are shown below for a two-hour period. There can be significant changes to a fire in 1 minute, as was seen in this Blog Post! Note again that missing points in the 3.9 µm imagery will show up as green or blue regions in the RGB.

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* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

GOES-16 Shortwave Infrared (3.9 µm) images (above) showed the “hot spot” signatures (black to yellow to red pixels) associated with numerous wildfires that began to burn in Northern California’s Napa County around 0442 UTC on 09 October 2017 (9:42 PM local time on 08 October). A strong easterly to northeasterly Diablo wind (gusts) along with dry fuels led to extreme fire behavior, with many of the fires quickly exhibiting very hot infrared brightness temperature values and growing in size at an explosive rate (reportedly burning 80,000 acres in 18 hours).

A comparison of nighttime GOES-16 Shortwave Infrared (3.9 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (below) offered another example of nocturnal fire signature identification — the bright glow of the fires showed up well on the 1-km resolution 1.61 µm imagery. Especially noteworthy was the very rapid southwestward run of the Tubbs Fire, which eventually moved just south of station identifier KSTS (Santa Rosa Sonoma County Airport; the city of Santa Rosa is located about 5 miles southeast of the airport). These Northern California fires have resulted in numerous fatalities, destroyed at least 3500 homes and businesses, and forced large-scale evacuations (media story).

A toggle between 1007 UTC (3:07 AM local time) Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images (below) provided a view of the fires at an even higher spatial resolution. Since the Moon was in the Waning Gibbous phase (at 82% of Full), it provided ample illumination to highlight the dense smoke plumes drifting west-southwestward over the adjacent offshore waters of the Pacific Ocean.

A closer VIIRS image comparison (with county outlines) is shown below.

A comparison of Suomi NPP VIIRS true-color and false-color Red-Green-Blue (RGB) images from RealEarth (below) helped to discriminate between smoke and cloud features offshore over the Pacific Ocean.

===== 10 October Update =====With the switch to southwesterly surface winds on 10 October, smoke plumes could be seen moving northeastward on RealEarth VIIRS true-color imagery, while the burn scars of a number of the larger fires became apparent on VIIRS false-color RGB imagery (above).

===== 11 October Update =====

A toggle (above)  between 30-meter resolution Landsat-8 false-color RGB images from 04 October (before the Tubbs Fire) and 11 October (after the Tubbs Fire) showed the size of the fire burn scar (shades of brown) which extended southwestward from the fire source region into Santa Rosa.

===== 12 October Update =====A transition back to northerly winds on 12 October helped to transport the wildfire smoke far southward over the Pacific Ocean (above). Smoke was reducing surface visibility and adversely affecting air quality at locations such as San Francisco (below).

Suomi NPP VIIRS Aerosol Optical Depth values were very high — at or near 1.0 — within portions of the dense smoke plume (below).

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