Super Typhoon Lan in the West Pacific

October 21st, 2017 |

Advanced Dvorak Technique (ADT) plot for Typhoon Lan [click to enlarge]

Advanced Dvorak Technique (ADT) plot for Typhoon Lan [click to enlarge]

A plot of the Advanced Dvorak Technique for Typhoon Lan (above) showed that the tropical cyclone underwent a period of rapid intensification during the 00-12 UTC period on 20 October 2017.

A 24-hour animation of Himawari-8 rapid-scan (2.5 minute interval) Infrared Window (10.4 µm) images (below) revealed the development of a very large eye during the 20 October/06 UTC to 21 October/06 UTC period.

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1700 UTC or 2:00 AM kocal time (below; courtesy of William Straka, CIMSS/SSEC) provided a good visualization of the “stadium effect” — an eye that was more narrow at the surface, with a larger diameter at higher altitudes. A packet of mesospheric airglow waves (reference) was also evident on the Day/Night Band image, propagating south-southeastward away from the eye.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (10.4 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (10.4 µm) images [click to enlarge]

A 2-panel comparison of Himawari-8 Visible (0.64 µm) and Infrared Window (11.45 µm) images (below) showed the eye of Lan after it attained Super Typhoon status at 18 UTC on 20 October. Mesovortices could  be seen within the eye on the rapid-scan images.

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images [click to play MP4 animation]

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images [click to play MP4 animation]

A large amount of moisture was associated with this tropical cyclone, as depicted by hourly images of the MIMIC Total Precipitable Water product (below) — note the large area with TPW values of 70 mm or greater (light violet color enhancement).

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

A TPW value of 72.5 mm (2.87 inches) was derived from the Minamidaitojima, Japan rawinsonde data at 12 UTC on 21 October (below). Minamidaitojima is the largest island in the Daito Islands group southeast of Okinawa, Japan  — this station was just to the northeast of Lan around 12 UTC.

Rawinsonde data from Minamidaitojima, Japan [click to enlarge]

Rawinsonde data from Minamidaitojima, Japan [click to enlarge]

Wildfires in Northern California

October 9th, 2017 |

GOES-16 Shortwave Infrared (3.9 µm) images, with county outlines plotted in gray (dashed) and surface station identifiers plotted in white [click to play MP4 animation]

GOES-16 Shortwave Infrared (3.9 µm) images, with county outlines plotted in gray (dashed) and surface station identifiers plotted in white [click to play MP4 animation]

* 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).

GOES-16 Shortwave Infrared (3.9 µm, left) and Near-Infrared

GOES-16 Shortwave Infrared (3.9 µm, left) and Near-Infrared “Snow/Ice” (1.61 µm, right) images [click to play MP4 animation]

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.

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

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

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

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.

Suomi NPP VIIRS True-color and False-color RGB images [click to enlarge]

Suomi NPP VIIRS True-color and False-color RGB images [click to enlarge]

===== 10 October Update =====
Suomi NPP VIIRS true-color and false-color images [click to enlarge]

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

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 =====

Landsat-8 false-color RGB images, from 04 October (before the Tubbs Fire) and 11 October (after the Tubbs Fire) [click to enlarge]

Landsat-8 false-color RGB images, from 04 October (before the Tubbs Fire) and 11 October (after the Tubbs Fire) [click to enlarge]

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 =====
Suomi NPP VIIRS true-color RGB images, with VIIRS-detected fire locations [click to enlarge]

Suomi NPP VIIRS true-color RGB images, with VIIRS-detected fire locations [click to enlarge]

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).

Time series plot of surface observations at San Francisco International Airport [click to enlarge]

Time series plot of surface observations at San Francisco International Airport [click to enlarge]

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

Suomi NPP VIIRS true-color RGB image and Aerosol Optical Depth product [click to enlarge]

Suomi NPP VIIRS true-color RGB image and Aerosol Optical Depth product [click to enlarge]

Tropical Storm Nate forms near Nicaragua

October 5th, 2017 |

GOES-16 ABI Band 2 Visible (0.64 µm) Imagery, 1127 – 1324 UTC on 5 October 2017 (Click to animate)

GOES-16 Visible Imagery, above, shows convection (imagery at 1-minute intervals) surrounding Tropical Storm Nate, just onshore in northeastern Nicaragua.

GOES-16 ABI “Clean Window” Infrared (10.3 µm) Imagery, 4 October 2017 at 2300 UTC through 1130 UTC on 5 October 2017 (Click to animate)

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

The Tropical Depression (#16) in the western Caribbean Sea has strengthened to become a minimal Tropical Storm, acquiring the name Nate. The animation from GOES-16, above, shows disorganized convection over the entire basin, stretching into the Pacific Ocean south of central America. (The sheared remains of Pacific Tropical Storm Ramon are also present south of Mexico). The animation below, from 0000-1300 UTC on 5 October 2017, shows the mid-level Water Vapor Infrared Imagery (6.95 µm) from GOES-16. Convection develops over the center of Nate, over Nicaragua, at the end of the animation.

GOES-16 ABI “Mid-Level Water Vapor” Infrared (6.95 µm) Imagery, 0000-1300 UTC on 5 October 2017 (Click to animate)

Microwave Imagery, below, from SSMI/S at around 1000 UTC on 5 October, (from this site) suggests that Nate is centered very near the coast of Nicaragua. Nate is forecast to move north into the Gulf of Mexico; its path through the northwest Caribbean suggests strengthening is possible if Nate remains far enough from land. Very warm water is present in the northwest Caribbean; that warmth extends to great depth as shown by this plot of Oceanic Heat Content; that warmth extends into the central Gulf of Mexico.

85 GHz Brightness Temperatures, 1000 UTC on 5 October 2017 (Click to enlarge)

Nate formed at a time when the Moon was Full. Thus, Suomi NPP Day Night Band Visible Imagery showed excellent illumination. The image below is from 0627 UTC on 5 October.

Suomi NPP Day Night Band Visible (0.7 µm) Imagery, 0627 UTC on 5 October 2017 (Click to enlarge)

Total Precipitable Water in advance of Nate is plentiful, as shown in the loop below (from this site). There is dry air over the continental United States, however, associated with a strong High Pressure System. Easterly winds south of that system are apparent in Scatterometer winds from early in the morning on 5 October.

MIMIC Morphed Total Precipitable Water, 1200 UTC 4 October – 1100 UTC 5 October 2017 (Click to enlarge)

Mostly Clear Skies over Puerto Rico

September 25th, 2017 |

Suomi NPP Day Night Band Visible (0.7 µm) Imagery, 0619 UTC on 25 September 2017 (Click to enlarge)

Mostly clear skies over Puerto Rico early on 25 September 2017 allowed the Day Night Band on Suomi NPP to observe man-made sources of light on that island as shown in the image above (Courtesy of William Straka, CIMSS).  (A previous example on this blog showed lights through clouds).  A similar view is available at NASA’s Worldview site, or at Real Earth. The Lunar Phase on 25 September 2017 is Waxing Crescent with 26% illumination; similar illumination occurred on 24 August, and a link to the Day Night Band imagery at NASA Worldview on that day is here. The differences are stark.

A RealEarth examination of two Suomi NPP VIIRS Day/Night Band (0.7 µm) images — an archived “clear sky” view from 31 December 2015, and an “after-Maria” image from 26 September 2017 (below) — provides a good before/after comparison showing a reduction in the amount of city light illumination following the passage of the hurricane.

Suomi NPP VIIRS Day/Night Band (0.7 µm) images: an  archived

Suomi NPP VIIRS Day/Night Band (0.7 µm) images: an archived “clear sky’ view from 31 December 2015, and a “after-Maria” image from 26 September 2017 [click to enlarge]

The Infrared Imagery, below, suggests a few clouds over northwest Puerto Rico. Such clouds could alter the perception of light sources in that region.

Suomi NPP VIIRS Infrared (11.45 µm) Imagery, 0619 UTC on 25 September 2017 (Click to enlarge)