Typhoon Soulik in the northwest Pacific Ocean

August 20th, 2018 |

Himawari-8 AHI Band 13 Clean Window (10.4 µm) imagery, 0900-1400 UTC on 18 August 2018 (Click to animate)

Typhoon Soulik, south of Japan and moving westward, has acquired a very large eye — almost 100 miles across! Himawari-8 imagery, above (courtesy JMA), shows the evolution and enlargement of the eye between 0900 and 1400 UTC on 20 August 2018.

GCOM, Suomi NPP and NOAA-20 all passed over Soulik between 1600 and 1715 UTC on 18 August. The Infrared Toggle, below, from NOAA-20 (1608 UTC) and Suomi NPP (1658 UTC) also shows a large eye.

NOAA-20 (1608 UTC) and Suomi NPP (1658 UTC) 11.45 µm Infrared Imagery of Soulik on 18 August 2018 (Click to enlarge)

Day Night Band Imagery from Suomi NPP, below, also shows a large eye. There was little lunar illumination occurring at the time because the moon was below the horizon.

Suomi NPP Day Night Band Visible (0.70 µm) Imagery over Soulik, 1658 UTC on 18 August 2018 (Click to enlarge)

GCOM overflew Soulik at 1702 UTC, and the AMSR-2 instrument on board gave estimates of rain rate, both convective and a the surface. Those are toggled below.

GCOM AMSR-2 Microwave estimates of Precipitation over Soulik, 1702 UTC on 18 August 2018 (Click to enlarge)

(Suomi NPP, NOAA-20 and GCOM imagery courtesy William Straka, CIMSS)

Soulik’s eye was wide enough that a NUCAPS soundings retrieval (Click here for more information on NUCAPS soundings) could be made from data collected during a Suomi-NPP overpass at 0350 UTC on 21 August 2018.  Note the green sounding location within Soulik’s eye — Green dots denote regions where the infrared retrieval was successful.  The sounding at that point is shown below. (NUCAPS imagery courtesy Landon Aydlett, WFO Guam).

Suomi NPP NUCAPS sounding locations at 0350 UTC on 21 August 2018 on top of AHI 10.4 µm Clean Window imagery (Click to enlarge)

Suomi NPP NUCAPS Sounding within the eye of Soulik at 0350 UTC on 21 August 2018 (Click to enlarge)

You can use NUCAPS Soundings to diagnose the difference between the environment in the storm eye, and in the surrounding environment. The animation below shows locations of 5 soundings, one in the Eye, and one north, east, south and west of the CDO.  The five selected soundings are shown at the bottom, with insets showing which sounding is which.  The sounding in the eye shows remarkable warmth, as expected:  at 555 hPa, for example, eye temperatures are around 8º C;  values at the 4 outside points range from 0.4º to 2.9º C.  Sounding parameters as viewed in AWIPS can be seen here.

Suomi NPP NUCAPS Sounding Points overlain on a Day Night Band Image, ~0350 UTC on 21 August 2018 (Click to enlarge). Sounding locations are indicated.

NUCAPS Soundings in and around Typhoon Soulik at the locations indicated, ~0350 UTC on 21 August 2018 (Click to enlarge)

Soulik’s path is projected to remain south of Japan and approach the Korean Peninsula by mid-week. For more information on Soulik, consult the CIMSS/SSEC Tropical Weather Website, or the Joint Typhoon Warning Center.

Hurricane Lane in the eastern Pacific Ocean

August 17th, 2018 |

NOAA-20 VIIRS Imagery at 1023 UTC on 17 August 2018. Day Night Band Visible (0.7 µm) and I05 Infrared (11.45 µm) imagery are shown (Click to enlarge)

The active eastern Pacific Hurricane season continues, as Lane has formed. Suomi NPP and NOAA-20 overflew the system early on 17 August 2018. The toggle above, from NOAA-20’s VIIRS Instrument, shows both the Day Night Band 0.70 µm visible Image and the 11.45 µm infrared channels. Lack of lunar illumination means that only Earthglow is making clouds visible; a distinct eye is not present. The step animation below between the NOAA-20 11.45 µm infrared and, 50 minutes later, Suomi NPP’s 11.45 µm Infrared, right at the limb of the scan, also show no distinct eye.

VIIRS I05 11.45 µm Infrared Imagery from NOAA-20 (1023 UTC) and Suomi NPP (1113 UTC) on 17 August 2018 (Click to enlarge)

In fact, however, an eye was likely present at this time. As noted in the National Hurricane Center’s 0900 UTC Discussion (Link), “Recent microwave images show a well-defined low-level eye, but this feature is not yet apparent in geostationary satellite images.”  AMSR-2 (Advanced Microwave Scanning Radiometer 2) estimates of Convective Precipitation and Surface Rainfall in the toggle below (data from 1003 UTC) show a distinct eye.  AMSR-2 is a microwave instrument that flies on JAXA’s GCOM satellite;  microwave views of tropical cyclones are able to penetrate the cirrus shield that is commonly present, revealing important information about the low-level structure of a developing system.

GCOM AMSR-2 estimates of convective precipitation and surface rainfall rates at 1003 UTC on 17 August 2018 (Click to enlarge)

Polar Orbit tracks are available here. For the latest information on Hurricane Lane, refer to the National Hurricane Center or to the CIMSS/SSEC Tropical Weather Website. Imagery from Polar Orbiters are available at this site that shows data from an antenna in Honolulu.

Thank you to William Straka, CIMSS, for the imagery.

Wildfire smoke across the Midwestern US

August 11th, 2018 |

GOES-16 Natural Color RGB images [click to play MP4 animation]

GOES-16 Natural Color RGB images, 09-11 August [click to play MP4 animation]

Numerous wildfires burning in southwestern Canada (primarily British Columbia: NOAA HMS fire/smoke product) produced large amounts of smoke, which was subsequently transported eastward across southern Canada and then southward across the Midwestern US during the 09 August11 August 2018 period. GOES-16 (GOES-East) Natural Color Red-Green-Blue (RGB) images from the AOS site (above) showed this smoke, portions of which were optically very thick at times (and were able to cast shadows owing to its significant vertical depth).

On 09 August the smoke was most highly concentrated over the Dakotas, as shown in a comparison of GOES-16 Aerosol Optical Depth (AOD), Smoke Detection, “Blue” Visible (0.47 µm) and “Red” Visible (0.64 µm) images (below). While much of the smoke was likely aloft within the middle troposphere, some had been mixed downward into the boundary layer and was restricting the surface visibility to 3-5 miles at many locations.

Note that the hazy signature of the widespread smoke was a bit more apparent in the 0.47 µm Visible imagery than the 0.64 µm Visible imagery, especially during mid-day when the sun-satellite “forward scattering angle” was at a minimum. The AOD and Smoke Detection derived products use data from Visible and Near-Infrared bands — so it they are only available during daytime hours (and only at solar zenith angles less than 60 degrees). The Smoke Detection product was more effective during times of enhanced forward scattering (early and late in the day) — but it also was susceptible to false alarms due to solar reflectance off water surfaces. Additional information on GOES-R Aerosol Detection Products in AWIPS is available here and here.

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right).

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right). “Blue” Visible (0.47 µm, bottom left) and “Red” Visible (0.64 µm, bottom right) [click to play animation | MP4]

On 10 August, the smoke was most dense across the eastern Dakotas and Minnesota (below) — and once again, surface visibilities were restricted to 3-5 miles at some locations. On this day pilot reports mentioned flight visibility being restricted to 3 miles at altitudes as high as 12,000 feet.

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right). "Blue" Visible (0.47 µm, bottom left) and "Red" Visible (0.64 µm, bottom right) [click to play animation | MP4]

GOES-16 Aerosol Optical Depth (top left), Smoke Detection product (top right). “Blue” Visible (0.47 µm, bottom left) and “Red” Visible (0.64 µm, bottom right) [click to play animation | MP4]

Finally, on 11 August a north-to-south plume of particularly dense smoke drifted southward across Minnesota and Iowa, as seen in a comparison of GOES-16 Aerosol Optical Depth, “Red” Visible (0.64 µm). Near-Infrared “Cirrus” (1.37 µm) and “Clean” Infrared Window (10.3 µm) images (below). In this case the AOD values were quite high (in excess of 3.0 in northwestern Minnesota), beyond the range of values scaled for display in AWIPS — this led to the swath of black “No Data” values where the smoke was most dense. This plume of thick smoke also exhibited a signature in Near-Infrared “Cirrus” images; higher concentrations of airborne particles that are effective scatterers of light at the 1.37 µm wavelength (such as ice crystals, smoke, volcanic ash, or dust) will be detected using this imagery. Note the lack of a well defined signature on the 10.3 µm imagery — smoke is effectively transparent to radiation at these longer infrared wavelengths.

GOES-16 Aerosol Optical Depth (top left), "Red" Visible (0.64 µm, top right). Near-Infrared "Cirrus" (1.37 µm, bottom left) and "Clean" Infrared Window (10.3 µm, bottom right) [click to play animation | MP4]

GOES-16 Aerosol Optical Depth (top left), “Red” Visible (0.64 µm, top right). Near-Infrared “Cirrus” (1.37 µm, bottom left) and “Clean” Infrared Window (10.3 µm, bottom right) [click to play animation | MP4]

On a side note, the north-south plume of dense smoke over southcentral Canada and the Midwest US on 11 August was also very apparent from a distance of 983,269 miles (1,582,418.07 km) — 44 times the distance of the GOES-16 satellite — in EPIC Natural Color imagery from the DSCOVR satellite (below).

DSCOVR EPIC Natural Color images [click to enlarge]

DSCOVR EPIC Natural Color images [click to enlarge]

Alonsa, Manitoba EF-4 tornado

August 3rd, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface reports; yellow * denotes the town of Alonsa [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development of a thunderstorm which produced an EF-4 tornado near Alonsa, Manitoba during the early evening hours on 03 August 2018. The cell began to develop southwest of Alonsa around 0020 UTC, and as the thunderstorm matured a series of pulsing overshooting tops could be seen. The haziness evident in the Visible imagery was due to smoke from wildfires in the western US and Canada.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed that the coldest cloud-top infrared brightness temperature of around -70ºC occurred at 0123 UTC (just prior to the time of the tornado).

GOES-16 "Clean" Infrared Window (10.3 µm) images, with hourly plots of surface reports; black * denotes the town of Alonsa [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of surface reports; black * denotes the town of Alonsa [click to play MP4 animation]


The tornado damage path could also be seen in a comparison of ESA Sentinel-2 False Color, Normalized Difference Vegetation Index (NDVI) and Moisture Index Red-Green-Blue (RGB) images (below).

ESA Sentinel-2B False Color, Normalized Difference Vegetattion Index (NDVI) and Moisture Index RGB images [click to enlarge]

ESA Sentinel-2 False Color, Normalized Difference Vegetation Index (NDVI) and Moisture Index RGB images [click to enlarge]