Hurricane Gert

August 15th, 2017 |

GOES-16 imagery (all 16 ABI Bands) from 1912-2132 UTC, 15 August 2017 [click to play animation]

GOES-16 imagery (all 16 ABI Bands) from 1912-2132 UTC, 15 August 2017 [click to play animation]

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

Hurricane Gert, a Category-1 storm on the Saffir-Simpson scale, is over the open Atlantic Ocean east of Cape Hatteras. It is close enough to the USA, however, that it is within GOES-16’s CONUS domain where 5-minute sampling is routine. The animation above shows all 16 channels from GOES-16 ABI, every five minutes from 1912-2132 UTC on 15 August 2017. A distinct eye is not apparent in the visible or infrared satellite imagery, but microwave data (from here) suggests an eye is present, at least at times. A comparison of 2035 UTC DMSP-16 SSMIS Microwave (85 GHz) and 2045 UTC GOES-13 Infrared Window (10.7 µm) images can be seen here.

The low-level Water Vapor imagery, below, shows that Gert is south and east of a front along the East Coast. This front should steer the storm to the north and east. Swells from the storm will affect the East Coast however.

GOES-16 imagery Low-Level Water Vapor (7.34 µm) Infrared Imagery from 1832-2137 UTC, 15 August 2017 [click to play animation]

GOES-16 Low-Level Water Vapor (7.34 µm) Infrared Imagery from 1832-2137 UTC, 15 August 2017 [click to play animation]

For more information on Gert, consult the website of the National Hurricane Center, or the CIMSS Tropical Weather Website.

GOES-16 ABI Imagery from the morning of 16 August 2017, below, shows that an eye has appeared in visible and infrared imagery.

GOES-16 imagery (all 16 ABI Bands) from 1117-1337 UTC, 16 August 2017 [click to play animation]

GOES-16 imagery (all 16 ABI Bands) from 1117-1337 UTC, 16 August 2017 [click to play animation]

A closer view using 1-minute interval GOES-16 Mesoscale Sector “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images, below, showed that  the most vigorous areas of deep convection were generally confined to the northern semicircle of the eyewall region — cloud-top infrared brightness temperatures were as cold as -80º C (violet color enhancement) at times.

GOES-16 Visible (0,64 µm, top) and Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

Hail damage swath in South Dakota and Minnesota

July 4th, 2017 |

SPC storm report plots, from 12 UTC on 21 June to 12 UTC on 22 June 2017 [click to go to SPC storm reports list]

SPC storm report plots, from 12 UTC on 21 June to 12 UTC on 22 June 2017 [click to go to SPC storm reports list]

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

As seen on the map of SPC storm reports from 21 June 2017 (above), nighttime thunderstorms (during the pre-dawn hours of 22 June) produced a swath of hail (as large as 2.0 inches in diameter) that damaged emerging crops at some locations across eastern South Dakota and southwestern Minnesota (NWS Aberdeen summary).

Nearly 2 weeks later, on 04 July, the hail damage swath was still apparent on GOES-16 imagery. In a comparison of “Blue” Visible (0.47 µm), “Red” Visible (0.64 µm) and Near-Infrared “Vegetation” (0.86 µm ) images (below), the northwest-to-southeast oriented hail damage swath was best seen on the 0.64 µm imagery (in part due to its higher spatial resolution, which is 0.5 km at satellite sub-point); healthy vegetation is more reflective at 0.86 µm, so the crop-damaged hail swath appears slightly darker in those images.

GOES-16

GOES-16 “Blue” Visible (0.47 µm, top), “Red” Visible (0.64 µm, middle) and Near-Infrared “Vegetation” (0.86 µm, bottom) images [click to play animation]

A signature of the hail damage swath was also seen in Near-Infrared “Snow/Ice” (1.61 µm) and Shortwave Infrared (3.9 µm) images (below). The hail damage swath warmed more quickly on the 3.9 µm imagery — exhibiting a darker black appearance with time — compared to the adjacent fields of healthy crops.

GOES-16

GOES-16 “Red” Visible (0.64 µm, top), Snow/Ice (1.61 µm, middle) and Shortwave Infrared (3.9 µm, bottom) images [click to play animation]

Why was the hail damage swath also seen on the 1.61 µm “Snow/Ice” (Band 5) imagery? A look at the Spectral Response Functions for GOES-16 ABI  bands 3, 4, 5 and 6 — plotted with the reflectance of asphalt, dirt, grass and snow (below) — show that the 1.61 µm Band 5 happens to cover a portion of the radiation spectrum where there is a minor peak in grass relectance (denoted by the green plot).

Spectral Response Functions for GOES-16 ABI Bands 3, 4, 5 and 6, along with the reflectance of asphalt, dirt, grass and snow [click to enlarge]

Spectral Response Functions for GOES-16 ABI Bands 3, 4, 5 and 6, along with the reflectance of asphalt, dirt, grass and snow [click to enlarge]

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Aqua MODIS Land Surface Temperature product {click to enlarge]

Aqua MODIS Land Surface Temperature product {click to enlarge]

Regarding the warmer temperatures seen on GOES-16 Shortwave Infrared images, the 1-km resolution Aqua MODIS Land Surface Temperature product at 1738 UTC (above) revealed a 10º F difference between the warmer hail damage swath (which appeared to be about 100 miles in length) and adjacent fields of undamaged crops. A similar result was noted on 03 July by NWS Aberdeen (below).

A comparison of before (21 June) and after (02 July) Aqua MODIS true-color Red/Green/Blue (RGB) images from the SSEC MODIS Direct Broadcast site (below) clearly shows the hail damage path.

Aqua MODIS true-color RGB images, before (21 June) and after (02 July) the hail event [click to enlarge]

Aqua MODIS true-color RGB images, before (21 June) and after (02 July) the hail event [click to enlarge]

On 05 July a closer view of the hail scar was seen using a Suomi NPP VIIRS true-color RGB image from RealEarth (below).

Suomi NPP VIIRS true-color RGB image [click to enlarge]

Suomi NPP VIIRS true-color RGB image [click to enlarge]

Incidentally, on 02 July the Sentinel-2A satellite provided 10-meter resolution true-color imagery of the hail swath:

===== 07 July Update =====

The hail damage swath was also evident on a 30-meter resolution Landsat-8 false-color RGB image from 07 July:

Landsat-8 false-color RGB image [click to enlarge]

Landsat-8 false-color RGB image [click to enlarge]

Landsat-8 false-color RGB image, zoomed in on Castlewood, South Dakota [click to enlarge]

Landsat-8 false-color RGB image, zoomed in on Castlewood, South Dakota [click to enlarge]

Other examples of satellite-observed hail damage swaths can be seen here and here.

 

Eruption of Bogoslof in Alaska’s Aleutian Islands

May 28th, 2017 |

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images, with hourly surface and ship reports plotted in yellow [click to play animation]

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images, with hourly surface and ship reports plotted in yellow [click to play animation]

The Bogoslof volcano in Alaska’s Aleutian Islands erupted around 2216 UTC on 29 May 2017. A comparison of Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images (above; MP4) showed the volcanic cloud as it drifted north/northeastward.

A very oblique view of the volcanic cloud was captured by Korean COMS-1 satellite at 2315 UTC (below).

COMS-1 Visible (0.67 µm) images, with surface observations plotted in yellow [click to enlarge]

COMS-1 Visible (0.67 µm) images, with surface observations plotted in yellow [click to enlarge]

Himawaari-8 false-color images from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) revealed the initial signature of a volcanic cloud — however, this signature became less distinct after about 02 UTC on 29 May.

Himawari-8 false-color RGB images [click to play animation]

Himawari-8 false-color RGB images [click to play animation]

A different type of Himawari-8 false-color imagery (below) makes use of the 8.5 µm spectral band, which can help to infer the presence of sulfur dioxide within a volcanic cloud feature. A similar 8.4 µm band is available from the ABI instrument on the GOES-R series of satellites.

Himawari-8 false-color images [click to play animation]

3Himawari-8 false-color images [click to play animation]

A blend of Himawari-8 Infrared Window (10.4 µm) and radiometrically-retrieved Ash Cloud Height is shown below; the maximum ash cloud height was generally in the 10-12 km (33,000-39,000 feet above sea level) range (dark blue color enhancement). A volcanic ash signal was no longer apparent after 2320 UTC — this was likely due to enhanced ash particle removal via water (both liquid and ice) related processes.

Himawari-8 Infrared Window (10.4 µm) images and Ash Cloud Height retrievals [click to play animation]

Himawari-8 Infrared Window (10.4 µm) images and Ash Cloud Height retrievals [click to play animation]

A DigitalGlobe WorldView image at 2234 UTC (below) provided remarkable detail of the Bogoslof volcanic cloud shortly after the eruption began.


Cyclone Donna in the South Pacific Ocean

May 7th, 2017 |

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]

Cyclone Donna (18P) formed in the South Pacific Ocean (northeast of Vanuatu) on 02 May 2017. Himawari-8 Infrared Window (10.4 µm) images during the 03-06 May period (above) revealed the formation of multiple convective bursts, many exhibiting cloud-top IR brightness temperatures of -90º C and colder.

On 07 May, Cyclone Donna rapidly intensified from a Category 2 to a Category 4 storm (SATCON | ADT) — and Himawari-8 Infrared Window images (below) showed the presence of a large eye for a few hours. Environmental factors favoring rapid intensification included warm sea surface temperatures and light vertical wind shear.

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 comparison of GMI Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images from the CIMSS Tropical Cyclones site (below) showed that the actual diameter of the eye was much larger on microwave imagery around 1400 UTC on 07 May.

GMI Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]

GMI Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]