Himawari-8 imagery of Tropical Depression 24S / Cyclone Quang northwest of Australia

April 28th, 2015
Himawari-8 11.22 µm infrared imagery, 0000 - 1830 UTC on 28 April 2015 (click to play animation)

Himawari-8 11.22 µm infrared imagery, 0000 – 1830 UTC on 28 April 2015 (click to play animation)

The 10-minute full-disk imagery that is available from Himawari-8 captures the evolution of Tropical Depression 24S northwest of Australia. Convection is evolving on time-scales of 10 minutes or less, so the high temporal resolution is vital to describing the storm evolution. Of particular note are the development (and decay) of central dense overcast features near the storm center, which have a timescale of less than 30 minutes. Note also the well-developed outflow channel curving anticyclonically to the south and east of the storm.

Sea surface temperature fields (from this site) show very warm ocean waters (SSTs exceed 30º C). Wind shear over the system is small; strengthening is expected.

29 April Update: As anticipated, Tropical Depression 24S continued to intensify, becoming Tropical Storm Quang. A comparison of an MTSAT-2 visible image at 0132 UTC with an overlay of 0135 UTC ASCAT scatterometer winds, below, shows surface winds in the 40.0-45.9 knot range (yellow) in both the western and eastern hemispheres of the storm. A large convective burst (with overshooting tops) was apparent on the visible image, just south of the center of Quang.

MTSAT-2 visible image with ASCAT surface scatterometer winds

MTSAT-2 visible image with ASCAT surface scatterometer winds

Himawari-8 Infrared imagery on 29 April show eye development between 1600 and 1800 UTC. Quang was upgraded to a Cyclone at 1800 UTC. (Link)

Himawari-8 11.22 µm infrared imagery, 0000 - 1830 UTC on 29 April 2015 (click to play animation)

Himawari-8 11.22 µm infrared imagery, 0000 – 1830 UTC on 29 April 2015 (click to play animation)

The scanning strategy of the current operational MTSAT satellites is such that the Southern Hemisphere only receives 1 image per hour. The Himawari-8 satellite performs a Full Disk scan every 10 minutes — and as an MTSAT-2 10.8 µm IR vs Himawari-8 10.4 µm IR image comparison demonstrates (below; click image to play animation; also available as an MP4 movie file), the improved Himawari-8 spatial resolution (2 km vs 4 km) and more frequent scans allowed the formation of the eye of Quang to be more accurately followed as it rapidly intensified from a Tropical Storm to a Category 4 Severe Cyclone. A nighttime comparison of Suomi NPP VIIRS Day/Night Band and Infrared images on 29 April/1820 UTC (30 April/02:20 AM local time) can be seen here.

MTSAT-2 10.8 µm (top) and Himawari-8 10.4 µm (bottom) IR images  [click to play animation]

MTSAT-2 10.8 µm (top) and Himawari-8 10.4 µm (bottom) IR images [click to play animation]

The nighttime glow of Hawaii’s Kilauwea volcano

April 28th, 2015
Himawari-8 3.9 µm shortwave IR images (click to play animation)

Himawari-8 3.9 µm shortwave IR images (click to play animation)

The Kilauwea Volcano on the Big Island of Hawai’i began erupting in March 2008 (blog post | USGS reference), and has been in a nearly continuous phase of activity since then. During the pre-dawn hours of 28 April 2015, thermal signatures of the Kilauwea summit lava lake and nearby lava flows could be seen on McIDAS-V images of 10-minute interval Himawari-8 3.9 µm shortwave IR images (above; click image to play animation). The dark black pixels represent the hottest IR brightness temperatures.

On the corresponding Himawari-8 2.3 µm near-IR channel images (below; click image to play animation), the clusters of bright white pixels represent the glow of the hot lava features.

Himawari-8 2.3 µm near-IR channel images (click to play animation)

Himawari-8 2.3 µm near-IR channel images (click to play animation)

A different view is provided by the polar-orbiting Suomi NPP satellite — a comparison of AWIPS II images of VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR data (below) revealed the locations of the hottest lava features (black to yellow to red color enhancement) at 11:40 UTC (1:40 am local time).

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

A longer animation using GOES-15 (GOES-West) 3.9 µm shortwave IR images (below; click image to play animation) showed considerable temporal fluctuation in the location and intensity of the hot lava pixels (black to yellow to red color enhancement). For the latest information on the Kilauea eruption, visit the Hawaiian Volcano Observatory.

GOES-15 3.9 µm shortwave IR images (click to play animation)

GOES-15 3.9 µm shortwave IR images (click to play animation)

NOAA/CIMSS ProbSevere Product and storms over Texas

April 24th, 2015
NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1902, 1908, 1912, 1930, 1938, 1944, 1948, 1950, 1954 and 1958 UTC (click to play animation)

NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1902, 1908, 1912, 1930, 1938, 1944, 1948, 1950, 1954 and 1958 UTC (click to play animation)

Severe thunderstorms moved across central Texas on April 24th (Link). The NOAA/CIMSS ProbSevere product can be used with storms like this to alert a forecaster to when severe weather will develop. ProbSevere output tells you the probability that a given storm cell will first produce severe weather in the next 60 minutes. (The type of severe weather — hail, high winds or tornado) are not specified by the product. In the animation, a strong thunderstorm is just entering Coke county from Sterling county to the north of Tom Green county. The list below shows ProbSevere values with the three storms shown in the animation above.

  1. 1902 UTC  (Northern Cell)  ProbSevere 46%
  2. 1908 UTC (Northern Cell) ProbSevere 50%
  3. 1912 UTC (Northern Cell) ProbSevere 85%
  4. 1930 UTC (Northern Cell) ProbSevere 95%
  5. 1932 UTC (Northern Cell) ProbSevere 95% (Severe Thunderstorm Warning active)
  6. 1948 UTC (Southern Cell) ProbSevere 23%
  7. 1950 UTC (Southern Cell) ProbSevere 50%
  8. 1954 UTC (Middle Cell) ProbSevere 57%
  9. 1956 UTC (Middle Cell) ProbSevere 70%

So, the northern cell crossed the 50% ProbSevere threshold at 1908 UTC, the southern cell crossed the 50% ProbSevere threshold at 1950 UTC, and the small middle cell had a >50% ProbSevere from the start, at 1954 UTC.

Severe hail (1.25″ in diameter) was reported at 1928 UTC (20 minutes after ProbSevere crossed the 50% threshold) 8 miles west (31.89 N, 100.62 W)of Robert Lee, TX (the county seat of Coke County). At 1957 UTC, 1.75″ Hail was reported four miles north (31.94 N, 100.30 W) of Bronte, TX (also in Coke County).

The middle cell in the animation above eventually merged with the southern cell, and intensified. The animation from 1958 through 2014 UTC is below. ProbSevere with the middle storm (that merges with the southern cell) is 70%, rising to 98% at 2014 UTC.

NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1958, 2000, 2008, 2010, 2012, 2014 UTC (click to play animation)

NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1958, 2000, 2008, 2010, 2012, 2014 UTC (click to play animation)

At 2015 UTC, the National Weather Service issued a Severe Thunderstorm Warning. At this time, 2.75″ Hail was falling five miles northwest of Tennyson in Coke County. (31.79N, 100.35W). The 2016 UTC ProbSevere output is here.

The ProbSevere product is something that distills many bytes of information: model output that describes the environmental conditions, satellite data that describes the initial growth of convection, and MRMS radar data that captures the present state of a storm. The distilled data can be used to increase the confidence that a severe event will occur within the next 60 minutes.

An animation of the 10.7 µm imagery from 1800 through 2015 UTC is shown below. The locations of the severe hail reports noted above are included on the relevant images.

GOES-13 10.7 Brightness Temperature 1800-2015 UTC on 24 April 2015;  Coke County is highlighted (click to play animation)

GOES-13 10.7 Brightness Temperature 1800-2015 UTC on 24 April 2015; Coke County is highlighted (click to play animation)

Gravity Waves Associated with Calbuco Volcanic Eruption

April 23rd, 2015
I05_04315_0509_Calbuco_VolGW_zoom

Suomi NPP VIIRS 11.45 µm imagery, 0509 UTC 23 April 2015 (Click to enlarge)

Suomi NPP overflew the erupting Calbuco Volcano in southern Chile around 0509 UTC or 2:09 am local time on 23 April 2015. The image above is the VIIRS 11.45 µm infrared imagery (click here for a similar view).

The shock of the volcanic eruption generated mesospheric gravity waves (or “mesospheric airglow waves”) that were evident in the Day/Night Band, shown in the toggle below between the 11.45 µm and the night-time visible imagery. No lunar illumination was present, so the waves were apparent via the Earth’s airglow as the primary light source; this “night glow” is emitted from a variety of high-altitude (80-105 km) gases located near the mesopause (reference).

IO5_DNB_04315_0509_Calbuco_VolGW

Toggle between VIIRS 11.45 µm infrared image and 0.70 µm Day/Night Band image, 0509 UTC 23 April 2015 (Click to enlarge)

(VIIRS images courtesy of William Straka, SSEC)