Plume of wildfire smoke from British Columbia

March 25th, 2019 |

GOES-17

GOES-17 “Red” Visible (0.64 µm) and Low-level Water Vapor (7.3 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) and Low-level Water Vapor (7.3 µm) images (above) showed a northeasterly flow (model analyses) off the coast of British Columbia, Canada on 25 March 2019. Contained within this offshore flow was a hazy plume moving over Haida Gwaii and out across the eastern Pacific Ocean.

This aerosol plume was more easily seen in GOES-17 True Color Red-Green-Blue (RGB) images from the AOS site (below).

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

In comparisons between VIIRS Visible (0.64 µm) and Day/Night Band (0.7 µm) from Suomi NPP at 2104 UTC and NOAA-20 at 2154 UTC (below), the portion of the plume where aerosols were most dense (and therefore more reflective) was better portrayed in the Day/Night Band images.

VIIRS Visible (0.64 µm) and Day/Night Band (0.7 µm) from Suomi NPP at 2104 UTC and NOAA-20 at 2154 UTC [click to enlarge]

VIIRS Visible (0.64 µm) and Day/Night Band (0.7 µm) from Suomi NPP at 2104 UTC and NOAA-20 at 2154 UTC [click to enlarge]

Similarly, the portion of this plume having a higher aerosol concentration was highlighted using Terra MODIS Near-Infrared “Cirrus” (1.61 µm) imagery (below). The corresponding MODIS Water Vapor (6.7 µm) image showed that while the plume was generally contained within a ribbon of drier air, a narrow tongue of moisture existed within the core of the band of dry air. Both the VIIRS and the MODIS imagery indicated that the plume was passing over Sandspit (surface identifier CYZP), where the surface visibility briefly dropped to 7 miles at 21 UTC during a short period of northwesterly winds.

Terra MODIS Visible (0.65 µm), Near-Infrared

Terra MODIS Visible (0.65 µm), Near-Infrared “Cirrus” (1.61 µm) and Water Vapor (6.7 µm) images at 1936 UTC [click to enlarge]

A toggle between the 2015 UTC Suomi NPP VIIRS True Color RGB image and Aerosol Optical Depth product as viewed using RealEarth (below) also showed the plume was passing over station CYZP on Haida Gwaii. Note that there were a few VIIRS fire detection points (red dots) in central British Columbia — which suggests that this aerosol plume was likely smoke from biomass burning.

Suomi NPP VIIRS True Color RGB image and Aerosol Optical Depth product at 2015 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB image and Aerosol Optical Depth product at 2015 UTC [click to enlarge]

Regarding the moisture gradient seen on the MODIS Water Vapor image, it is interesting to examine 3 adjacent closely-spaced NUCAPS soundings immediately south of CYZP (below). The Total Precipitable Water values increased from 0.18″ to 0.26″ within a distance of only 60 miles.

Suomi NPP VIIRS Visible (0.64 µm) image, with available NUCAPS locations [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image, with available NUCAPS locations [click to enlarge]

NUCAPS profiles at Points 1, 2 and 3 [click to enlarge]

NUCAPS profiles at Points 1, 2 and 3 [click to enlarge]

Tropical Storm Iba off the coast of Brazil

March 24th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with GLM Groups plotted in red [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) showed the formation of Tropical Storm Iba off the east coast of Brazil at 16 UTC on 24 March 2019 (surface analyses). Plots of GLM Groups revealed some intermittent lightning activity. Tropical cyclones in the South Atlantic basin are rare — the last was in 2010, and only one example (Catarina in March 2004) is known to have reached hurricane intensity.

GOES-16 "Clean" Infrared Window (10.3 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]

A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) from RealEarth (below) showed Iba at 1610 UTC.

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 1610 UTC [click to enlarge]

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 1610 UTC [click to enlarge]

GOES-16 Infrared images with an overlay of deep-layer wind shear valid at 18 UTC from the CIMSS Tropical Cyclones site (below) revealed a very tight gradient of shear over Iba. However, the shear gradient began to relax somewhat by 21 UTC.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with an overlay of 18 UTC deep-layer wind shear [click to enlarge]

In a sequence of GOES-16 “Clean” Infrared Window (10.3 µm) and Infrared-Water Vapor (10.3-6.9µm) brightness temperature difference (BTD) images (below), the clusters of deep convection propagating southward — east of Iba’s center of circulation, denoted by “I” — exhibited large negative BTD values (darker shades of red) suggestive of significant cloud-top penetration into the lower stratosphere (reference).

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) and Infrared-Water Vapor (10.3-6.9µm) BTD images [click to enlarge]

GOES-16 Visible images with an overlay of 1138 UTC ASCAT surface scatterometer winds from the Metop-A satellite (below) showed speeds in the 40-49 knot range (yellow barbs).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with Metop-A ASCAT winds at 1137 UTC [click to enlarge]

The MIMIC Total Precipitable Water product (below) showed that Iba was embedded within a plume of moisture that extended southeastward off the coast of Brazil.

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

Sea Surface Temperature values (below) were around 30ºC in the waters where Iba intensified.

Sea Surface Temperature analysis at 2230 UTC on 23 March [click to enlarge]

Sea Surface Temperature analysis at 2230 UTC on 23 March [click to enlarge]

===== 25 March Update =====

GOES-16

GOES-16 “Red” Visible (0.64 µm) with GLM Groups (left) and “Clean” Infrared Window (10.3 µm, right) images [click to play animation | MP4]

A comparison of GOES-16 Visible and Infrared images (above) showed that increasing deep-layer wind shear had exposed the low-level circulation center of Iba. However, GLM Groups plotted on the Visible images revealed an increasing amount of lightning activity associated with a convective burst that began to wrap around the southern edge of the storm center after 15 UTC — and a brief cloud-top infrared brightness temperature of -90ºC (yellow pixel embedded with darker purple shades) was seen at 1635 UTC.

A timely overpass of the Suomi NPP satellite at 1639 UTC provided 375-meter resolution VIIRS True Color RGB and Infrared Window (11.45 µm) images (below), which showed a large overshooting top that exhibited infrared brightness temperatures of -90ºC and colder (yellow), with a warmer ring of compensating subsidence immediately surrounding it. The coldest pixel had a brightness temperature of -103.7ºC — which is almost 1ºC colder than the -102.96ºC value noted over Australia in 2008.

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

The explosive growth of that convective burst was very apparent in a toggle between VIIRS Infrared images from NOAA-20 at 1549 UTC and Suomi NPP at 1639 UTC (below, courtesy of William Straka, CIMSS). Note that the images use a slightly different variant of the color enhancement. A comparison of VIIRS True Color and Infrared images from NOAA-20 and Suomi NPP viewed using RealEarth is available here.

VIIRS Infrared (11.45 µm) images from NOAA-20 at 1549 UTC and Suomi NPP at 1639 UTC [click to enlarge]

VIIRS Infrared (11.45 µm) images from NOAA-20 at 1549 UTC and Suomi NPP at 1639 UTC [click to enlarge]

Flooding in South Dakota, Nebraska and Iowa

March 15th, 2019 |

GOES-16 Near-Infrared

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

GOES-16 (GOES-East) Near-Infrared “Vegetation” (0.86 µm) and “Snow/Ice” (1.61 µm) images (above) revealed widespread river flooding (in the wake of rapid snow melt and heavy rainfall) across parts of southeastern South Dakota, eastern Nebraska and western/central Iowa on 15 March 2019. Water and flooded land appear as darkest shades of gray to black on both sets of images —  remaining snow cover also appeared as darker shades on the 1.61 µm imagery. Additional information regarding the flooding is available from NWS Sioux Falls

In a toggle between Suomi NPP VIIRS Visible (0.64 µm) and “Snow/Ice” (1.61 µm) images at 1821 UTC (below),1.61 µm imagery showed the darker shades of flooding over a north/south portion of Interstate 29 that was closed from State Highway 34 (west of Glenwood, Iowa) to the Iowa/Missouri border (south of Hamburg, Iowa).

Suomi NPP VIIRS Near-Infrared "Vegetation" (0.86 µm) and "Snow/Ice" (1.61 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and “Snow/Ice” (1.61 µm) images; Interstate Highways are plotted in red, while State Highways are plotted in gray [click to enlarge]

Comparisons of Terra MODIS True Color and False Color Red-Green-Blue (RGB) images at 1720 UTC viewed using RealEarth are shown below. In the False color imagery, snow cover appears as lighter shades of cyan, while water appears as darker shades of blue.

Terra MODIS True Color and False Color RGB images [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered over eastern Nebraska [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Vermillion, South Dakota [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Vermillion, South Dakota [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Ames, Iowa [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Ames, Iowa [click to enlarge]

===== 16 March Update =====

Landsat-8 False Color image. centered to the east of Sioux City, Iowa [click to enlarge]

Landsat-8 False Color image centered to the east of Sioux City, Iowa [click to enlarge]

An overpass of the Landsat-8 satellite at 1706 UTC on 16 March provided 30-meter resolution False Color imagery — 2 sections of the swath are shown above and below. The RealEarth link to interactively view the image is here.

Landsat-8 False Color image. centered to the south of Omaha, Nebraska [click to enlarge]

Landsat-8 False Color image centered to the south of Omaha, Nebraska [click to enlarge]

Closer views centered at the NWS Omaha forecast office (which had to be evacuated due to flooding) and just west of Offutt Air Force Base (about one-third of which was under water) are shown below.

Landsat-8 False Color image. centered at the NWS forecast office in Valley, Nebraska [click to enlarge]

Landsat-8 False Color image centered at the NWS forecast office in Valley, Nebraska [click to enlarge]

Landsat-8 False Color image. centered near Offutt Air Force Base, Nebraska [click to enlarge]

Landsat-8 False Color image centered just west of Offutt Air Force Base, Nebraska [click to enlarge]



Cyclone Idai makes landfall in Mozambique

March 14th, 2019 |

Meteosat-8 Infrared (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Cyclone Idai — which had been slowly intensifying over warm water within the Mozambique Channel since 09 March — made landfall as a Category 2 storm along the coast of Mozambique on 14 March 2019 (storm track). A toggle between Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (above) revealed a large and well-defined eye and eyewall structure at 1630 UTC. Idai had been rated at Category 3 intensity during 3 periods of time during its life cycle, most recently at 12 UTC on the day of landfall.

At 1911 UTC, Metop-A ASCAT winds in excess of 60  knots were sampled just west of the eyewall region (below).

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

A comparison of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, visualized using RealEarth, is shown below.

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

Idai had been moving through an environment of very low deep-layer wind shear — a favorable factor for maintaining its intensity — as shown in an animation of Meteosat-8 Infrared Window (10.8 µm) images (below).

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

The MIMIC TC product (below) suggested that Idai might have been in the early stage of an eyewall replacement cycle (ERC) just prior to making landfall. This, after completing a separate ERC during the preceding 48 hours.

MIMIC TC morphed microwave imagery [click to enlarge]

MIMIC TC morphed microwave image product [click to enlarge]

The eye of Idal was becoming cloud-filled as it approached the Mozambique coast, as seen on EUMETSAT Meteosat-8 High Resolution Visible (0.8 µm) images (below).

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

A time series of surface data from the port city of Beira FQBR (below) showed deteriorating conditions before observations ceased at 15 UTC.

Surface observation data from Beira, Mozambique [click to enlarge]

Surface observation data from Beira, Mozambique [click to enlarge]


Incidentally, an overpass of the Landsat-8 satellite on 11 March provided a 30-meter resolution view of the eye (below), soon after Idai’s first period of rapid intensification to Category 3 strength (SATCON). Surface mesovortices were apparent within the eye.

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Flooding from Idai led to hundreds of fatalities in Mozambique and Zimbabwe.