Tropical Cyclone Veronica north of Australia

March 21st, 2019 |

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (1145 µm) images at 1716 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1716 UTC [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above) showed Category 4 Cyclone Veronica off the northern coast of Western Australia at 1716 UTC on 21 March 2019. Ample illumination from a Full Moon maximized the “visible image at night” capability of the Day/Night Band.

In a comparison of Microwave images from Suomi NPP ATMS at 1716 UTC and from GCOM-W1 AMSR2 at 1732 UTC (below), an eyewall that was nearly completely closed was apparent. Suomi NPP and GCOM-W1 images courtesy of William Straka, CIMSS.

Microwave images from Suomi NPP ATMS at 1716 UTC and from GCOM-W1 AMSR2 at 1732 UTC [click to enlarge]

Microwave images from Suomi NPP ATMS at 1716 UTC and from GCOM-W1 AMSR2 at 1732 UTC [click to enlarge]

A DMSP-17 SSMIS Microwave (85 GHz) image at 2246 UTC from the CIMSS Tropical Cyclones site is shown below. The deep-layer Wind Shear at 21 UTC was low (green contours), and Sea Surface Temperature values were quite high — both factors favorable for continued intensification as Veronica moved slowly toward the coast.

DMSP-17 SSMIS Microwave (85 GHz) image at 2246 UTC, with an overlay of 21 UTC deep-layer Wind Shear, and Sea Surface Temperature [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 2246 UTC, with an overlay of 21 UTC deep-layer Wind Shear, and Sea Surface Temperature [click to enlarge]

2.5-minute interval rapid scan Himawari-8 Infrared Window (10.4 µm) images (below) showed increasing organization to the eyewall structure. At times the cloud-top infrared brightness temperatures were -90ºC and colder (yellow pixels embedded within darker purple). Note: the rapid scan sector was re-poositioned eastward at 0100 UTC (to monitor Cyclone Trevor), so 10-minute imaging resumed after that time.

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

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

After sunrise, rapid scan Himawari-8 “Red” Visible (0.64 µm) images (below) revealed that the large eye was completely cloud-filled.

Himawari-8 "Red" Visible (0.64 µm) images [click to play animation | MP4]

Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Record warmth in Alaska and Canada

March 19th, 2019 |

GOES-17

GOES-17 “Red” Visible (0.64 µm) images, with hourly surface temperatures plotted in cyan [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) showed that it was generally cloud-free across much of eastern Alaska and northwestern Canada on 19 March 2019 — the abundant solar insolation help to warm surface temperatures to record levels for the month of March at locations such as Sitka (high=67ºF) and Yakutat (high=60ºF) along the Alaska Panhandle, and at Yohin Lake (high=71ºF) in the Canadian Northwest Territories. The 70ºF at Klawock was the earliest occurrence of 70ºF on record for the state of Alaska, and the 71ºF at Yohin Lake was the earliest 70ºF on record for the Northwest Territores. In the eastern Interior of Alaska, daily temperature records for 19 March were set at Eagle (high=55ºF) and Northway (high=50ºF).

GOES-17 Air Mass RGB images from the AOS site (below) helped to highlight the anomalous mid-tropospheric ridge and warm lower-tropospheric temperatures over western North America — note the northwestward surge of green hues that are more characteristic of warm subtropical air masses south of the polar jet stream over the central Pacific Ocean. Note that GOES-17 was conducting a test of the Mode 6 scan schedule, so Full Disk images were available every 10 minutes.

GOES-17 Air Mass RGB images [click to play animation | MP4]

GOES-17 Air Mass RGB images [click to play animation | MP4]



Chemical plant fire near Houston, Texas

March 18th, 2019 |

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images (above) revealed the thermal anomaly or “hot spot” of a fire burning at the Intercontinental Terminals Company petrochemical plant in Deer Park, Texas on 18 March 2019. Although the thermal signature was often partially masked by the passage of high clouds overhead, it was still evident for much of the time period (0202-1457 UTC, or 9:02pm-9:57am CDT). The fire started around 1530 UTC (10:30am CDT) on 17 March.

Comparisons of 2-km resolution (at satellite subpoint) GOES-16 Shortwave Infrared and 375-meter resolution VIIRS Shortwave Infrared (3.74 µm) imagery from Suomi NPP (at 0741 UTC) and NOAA-20 (at 0835 UTC) are shown below. The thermal signature is better defined and more accurately located using the higher-resolution VIIRS imagery.

Shortwave Infrared images from Suomi NPP VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0741 UTC [click to enlarge]

Shortwave Infrared images from Suomi NPP VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0741 UTC [click to enlarge]

Shortwave Infrared images from NOAA-20 VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0835 UTC [click to enlarge]

Shortwave Infrared images from NOAA-20 VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0835 UTC [click to enlarge]

A comparison of 1-km resolution NOAA-19 AVHRR and 2-km resolution GOES-16 Shortwave Infrared images at 1132 UTC is shown below. This happened to be at a time when the GOES-16 thermal signature was being masked by high clouds overhead. The fire was located northeast of the Houston Hobby (station identifier KHOU) and Ellington (station identifier KEFD) airports.

Shortwave Infrared images from NOAA-19 (3.7 µm) and GOES-16 (3.9 µm) at 1132 UTC [click to enlarge]

Shortwave Infrared images from NOAA-19 (3.7 µm) and GOES-16 (3.9 µm) at 1132 UTC [click to enlarge]

In a sequence of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (below), the dark-colored smoke plume was most obvious in the Near-Infrared imagery — this is due to the fact that vegetation is more reflective at those wavelengths, helping to enhance the smoke/surface contrast. The smoke had drifted as far westward as Austin and Kerrville, a distance of over 100 miles.

GOES-16 "Red" Visible (0.64 µm), Near-Infrared "Vegetation" (0.86 µm) and Near-Infrared "Snow/Ice" (1.61 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

===== 19 March Update =====

GOES-16 "Red" Visible (0.64 µm), Near-Infrared "Vegetation" (0.86 µm), and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

The Deer Park Fire continued to burn uncontrolled on 19 March — 1-minute Mesoscale Domain Sector GOES-16 Visible, Near-Infrared and Shortwave Infrared images (above) showed that while the passage of mid/upper-level clouds often obscured the dark-colored smoke plume, a signature of the hot thermal anomaly was seen almost continuously. Note that the color enhancement applied to the Shortwave Infrared imagery is different from the one used in the 18 March examples.

Signatures of fresh snowfall in the Dakotas

March 17th, 2019 |

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) Near-Infrared “Snow/Ice” (1.61 µm) images (above) depicted the signature of northwest-to-southeast oriented swaths of fresh snowfall (lighter gray shades) which had recently fallen on top of the aged snow pack across North Dakota on 17 March 2019. As discussed here, the surface of the preexisting snow cover had experienced rapid melting several days earlier, which increased its “water to ice crystal” ratio — making it appear darker, since water is a stronger absorber of radiation at the 1.61 µm wavelength.

A similar (albeit broader and more continuous) northwest-southeast swath of fresh snowfall was seen across South Dakota (below).

GOES-16 Near-Infrared "Snow/Ice" (1.61 µm) images [click to play animation | MP4]

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

The radar-derived 24 hour precipitation ending at 12 UTC on 17 March is shown below.

24-hour precipitation ending at 12 UTC on 17 March [click to enlarge]

24-hour precipitation ending at 12 UTC on 17 March [click to enlarge]