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Strong cyclone near Antarctica

By Scott Bachmeier •

Composites of Infrared imagery (above) and Water Vapor imagery (below) from the AMRC site showed an anomalously strong (MSLP | 925 hPa winds | source) cyclone that was moving southeastward across the South Pacific Ocean toward the coast of Antarctica on 26 March 2019. These composites blend images from both geostationary and... Read More

Composites of geostationary and polar orbiter Infrared imagery [click to play animation]

Composites of geostationary and polar orbiter Infrared imagery [click to play animation]

Composites of Infrared imagery (above) and Water Vapor imagery (below) from the AMRC site showed an anomalously strong (MSLP | 925 hPa winds | source) cyclone that was moving southeastward across the South Pacific Ocean toward the coast of Antarctica on 26 March 2019. These composites blend images from both geostationary and polar orbiting satellites; the storm is located in the upper right quadrant of the images. On the Infrared imagery, brighter white shades over much of the middle of Antarctica indicated a very cold surface — in fact, surface air temperatures were as cold as -84ºF over the interior of the continent at 23 UTC.

Composites of geostationary and polar orbiter Water Vapor imagery [click to play animation]

Composites of geostationary and polar orbiter Water Vapor imagery [click to play animation]

The storm was evident along the southern limb of GOES-16 Full Disk scans, as seen on Mid-level Water Vapor (6.9 µm) and “Red” Visible (0.64 µm) images (below). The location of AMRC AWS station 8930 (Thurston Island) near the coast of Ellsworth Land in West Antarctica is indicated in red.

GOES-16 Mid-level Water Vapor images [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

This storm was also evident at the bottom center of a GOES-17 + GOES-16 composite of north-to-south True Color Red-Green-Blue (RGB) swaths of 15-minute illumination at local solar noon — beginning at 12 UTC in the east, and ending at 03 UTC in the west — combined and displayed in a Mollweide projection (below; courtesy of Rick Kohrs, SSEC).

GOES-17 + GOES-16 True Color RGB image [click to enlarge]

GOES-17 + GOES-16 True Color RGB image [click to enlarge]

A time series of surface observation data from AWS station 8930 on Thurston Island (below) showed that southeasterly winds peaked at 113 knots (58 m/s) late in the day on 26 March as the strong low pressure system approached. According to AMRC staff, this particular AWS is located on a nunatak near Parker Peak in the Walker Mountains (map) — such an exposure is prone to periods of strong winds, requiring a recent retrofitting of special instrumentation designed to withstand and measure higher wind speeds.

Tiime series of surface observation data from AWS station 8930 Thurston Island [click to enlarge]

Time series of surface observation data from AWS station 8930 Thurston Island [click to enlarge]

A closer look with GOES-16 Visible and Low-level Water Vapor (7.3 µm) images (below) revealed small wave perturbations in the cloud field and the eventual formation of a banner cloud as Peter I Island was acting as an obstacle to the strong boundary layer winds south of the storm center.

GOES-16 "Red" Visible (0.64 µm. left) and Low-level Water Vapor (7.3 µm, right) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm. left) and Low-level Water Vapor (7.3 µm, right) images [click to play animation | MP4]

A timely overpass of the Landsat-8 satellite provided a 30-meter resolution Landsat-8 False Color RGB image, viewed using RealEarth (below), of these orographically-induced cloud perturbations.

Landsat-8 False Color image [click to enlarge]

Landsat-8 False Color RGB image [click to enlarge]

The orographic wave clouds downwind of Peter I Island could also be seen on 375-meter resolution Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 19 UTC and 21 UTC (below).

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images 1t 19 UTC and 21 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 19 UTC and 21 UTC [click to enlarge]


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Plume of wildfire smoke from British Columbia

By Scott Bachmeier •

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... Read More

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]

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Tropical Storm Iba off the coast of Brazil

By Scott Bachmeier •

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... Read More

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]

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Severe Thunderstorms with Above-Anvil Cirrus Plumes over Texas

By Scott Bachmeier •

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images before sunset (above) and Infrared images after sunset (below) revealed Above-Anvil Cirrus Plume (AACP) features associated with severe thunderstorms that were producing large hail (SPC storm reports) over the Texas Panhandle on 22 March 2019.A plot of 00 UTC rawinsonde data from Amarillo, Texas (below) showed... Read More

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm replorts plotted in cyan [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images, with SPC storm reports plotted in red/cyan [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images before sunset (above) and Infrared images after sunset (below) revealed Above-Anvil Cirrus Plume (AACP) features associated with severe thunderstorms that were producing large hail (SPC storm reports) over the Texas Panhandle on 22 March 2019.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play animation | MP4]

A plot of 00 UTC rawinsonde data from Amarillo, Texas (below) showed that the Equilibrium Level (EL) and the tropopause was around 11 km — where the air temperature was near -60ºC, which is highlighted by a red enhancement on the Infrared imagery.  The calculated Maximum Parcel Level was around 13 km — where the air temperature was near -50ºC, which is highlighted by a yellow enhancement on the Infrared imagery; the MPL was the likely altitude of the AACP. Note on the 0245 UTC and 0258 UTC images that two of the hail reports were located near the colder (darker red to black) pixels of overshooting tops, which were close to the southern end of the warmer (brighter yellow) pixels of the AACP.

Plot of 00 UTC rawinsonde data from Amarillo, Texas [click to enlarge]

Plot of 00 UTC rawinsonde data from Amarillo, Texas [click to enlarge]

As pointed out on the Satellite Liaison Blog, some of the accumulating hail remained on the ground during the overnight hours — and the next morning, a hail swath signature was evident on GOES-16 Visible and Near-Infrared “Snow/Ice” (1.61 µm) imagery (below); the longest swath stretched for a distance of about 40 miles. The hail appeared as shades of white in the Visible imagery, and as darker shades of black in the Snow/Ice imagery (since ice is a strong absorber of radiation at the 1.61 µm wavelength). Note how the darker signature of wet soil (water is also a strong absorber at 1.61 µm) persisted on Near-Infrared  imagery even after the brighter signature of the melting hail swath disappeared on Visible imagery. Accumulating hail occurred over portions of Interstate 27 between Amarillo and Canyon, and Interstate 40 between Wildorado and Bushland; one trained storm spotter reported that the hail was several inches deep just northwest of Amarillo (Local Storm Reports).

GOES-16 "Red" Visible (0.64 µm) and Near-infrared "Snow/Ice" (1.61 µm) imagery [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Near-infrared “Snow/Ice” (1.61 µm) imagery [click to play animation | MP4]

As the morning sun was beginning to warm the soil, GOES-16 Land Surface Temperature images at 1402 and 1502 UTC or 9:02 and 10:02 AM local time (below) depicted temperatures up to 10ºF cooler within the hail swath compared to adjacent bare ground.

GOES-16 Land Surface Temperature product at 1402 and 1502 UTC [click to enlarge]

GOES-16 Land Surface Temperature product at 1402 and 1502 UTC [click to enlarge]

With ample illumination from the Moon (in the Waning Gibbous phase, at 92% of Full) a “visible image at night” was provided by the Suomi NPP VIIRS Day/Night Band (0.7 µm), which showed the hall swath at 0748 UTC or 2:48 AM local time — a toggle between that Day/Night Band image and an early morning GOES-16 Visible image is shown bellow.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0748 UTC and GOES-16 "Red" Visible (0.64 µm) image at 1427 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0748 UTC and GOES-16 “Red” Visible (0.64 µm) image at 1427 UTC [click to enlarge]

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