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Alonsa, Manitoba EF-4 tornado

By Scott Bachmeier •

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... Read More

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]

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Transport of Saharan Air Layer dust across the Atlantic

By Scott Bachmeier •

The GOES-16 (GOES-East) Saharan Air Layer (SAL) infrared Split Window (12.3 µm – 10.3 µm) product (above) showed a large outbreak of SAL dust that emerged from the northwest coast of Africa on 30 July 2018, eventually moving over the Lesser Antilles and Puerto Rico late in the day on 03 August.During daylight hours,... Read More

GOES-16 Split Window (12.3 µm - 10.3 µm) Saharan Air Layer product [click to play MP4 animation]

GOES-16 Split Window (12.3 µm – 10.3 µm) Saharan Air Layer product [click to play MP4 animation]

The GOES-16 (GOES-East) Saharan Air Layer (SAL) infrared Split Window (12.3 µm – 10.3 µm) product (above) showed a large outbreak of SAL dust that emerged from the northwest coast of Africa on 30 July 2018, eventually moving over the Lesser Antilles and Puerto Rico late in the day on 03 August.

During daylight hours, the dust-laden SAL was also evident in GOES-16 Natural Color Red-Green-Blue (RGB) imagery (source) on 01, 02 and 03 August (below).

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

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

GOES-16 Split Window 10.3 µm - 12.3 µm) images [click to play animation | MP4]

GOES-16 Split Window (10.3 µm – 12.3 µm) images on 02 August [click to play animation | MP4]

The AWIPS version of GOES-16 Split Window (10.3 µm – 12.3 µm) imagery with a different color enhancement (above) showed the westward motion of the SAL dust (shades of cyan) on 02 August. The corresponding GOES-16 Dust Detection product (below) verified the presence of dust within the SAL plume. Since the Dust Detection product uses Visible and Near-Infrared bands, it is only available during daytime hours (and at solar zenith angles less than 60 degrees).

GOES-16 Dust derived product [click to play animation | MP4]

GOES-16 Dust Detection product on 02 August [click to play animation | MP4]

GOES-16 Split Window (10.3 µm - 12.3 µm) product [click to play animation | MP4]

GOES-16 Split Window (10.3 µm – 12.3 µm) product on 03 August [click to play animation | MP4]

GOES-16 Split Window (10.3 µm – 12.3 µm) imagery from 03 August (above) showed the continued westward motion of the SAL dust (shades of cyan). The corresponding GOES-16 Aerosol Optical Depth (AOD) product (below) provided a more quantitative measure of airborne dust. Like the Dust Detection product shown previously, the AOD product also uses Visible and Near-Infrared bands — so it too is only available during daytime hours (and at solar zenith angles less than 60 degrees). Additional information on GOES-R Aerosol Detection Products in AWIPS is available here and here.

GOES-16 Aerosol Optical Depth product [click to play animation | MP4]

GOES-16 Aerosol Optical Depth product on 03 August [click to play animation | MP4]

The 03 August GOES-16 imagery indicated that the leading edge of the SAL began to move over Puerto Rico late in the day. A comparison of morning and evening rawinsonde data from San Juan (below) revealed that the temperature inversion at the base of the SAL became more well-defined at 00 UTC on 04 August.

Plots of rawinsonde data from San Juan, Puerto Rico [click to enlarge]

Plots of rawinsonde data from San Juan, Puerto Rico [click to enlarge]

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Severe thunderstorms in Arizona

By Scott Bachmeier •

* GOES-17 images shown here are preliminary and non-operational *GOES-15 (GOES-West), GOES-17 and GOES-16 (GOES-East) Visible images (above) showed the development of thunderstorms which produced hail and damaging winds (SPC storm reports) in the Phoenix, Arizona area on 02 August 2018. The images are displayed in the native projection of each satellite (no re-mapping).... Read More

Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right), with SPC storm reports plotted in red [click to play animation | MP4]

Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right), with SPC storm reports plotted in red [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

GOES-15 (GOES-West), GOES-17 and GOES-16 (GOES-East) Visible images (above) showed the development of thunderstorms which produced hail and damaging winds (SPC storm reports) in the Phoenix, Arizona area on 02 August 2018. The images are displayed in the native projection of each satellite (no re-mapping). Due to a Full Disk scan, GOES-15 mages were only available every 30 minutes at the beginning of this particular time period; images from GOES-17 were every 5 minutes; a GOES-16 Mesoscale Domain Sector provided images at 1-minute intervals.

The strong thunderstorm winds also produced significant blowing dust — winds gusted to 47 knots (54 mph) and visibility was reduced to 1/2 mile at Phoenix KPHX (below). Winds gusted to 53 knots (61 mph) and visibility fell to 1/4 mile at Chandler KCHD.

Time series of surface observations for Phoenix, Arizona [click to enlarge]

Time series of surface observations for Phoenix, Arizona [click to enlarge]



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GOES-16 water vapor imagery over far northern Canada

By Scott Bachmeier •

Animations of GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed features moving eastward across Nunavut in northern Canada on 01 August 2018. These images covered the far northern portion of the GOES-16 Full Disk view in AWIPS, and depicted frontal wave disturbances within the polar jet stream... Read More

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

Animations of GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed features moving eastward across Nunavut in northern Canada on 01 August 2018. These images covered the far northern portion of the GOES-16 Full Disk view in AWIPS, and depicted frontal wave disturbances within the polar jet stream over that region.

Due to the large satellite viewing angle or “zenith angle”, the 2 km water vapor image pixel dimension (at satellite sub-point) increased to around 6.4 km or 4 miles (below).

Magnified view of GOES-16 Mid-level (6.9 µm) Water Vapor image, showing the pixel dimension over Nunavut, Canada [click to enlarge]

Magnified view of a GOES-16 Mid-level (6.9 µm) Water Vapor image, showing the pixel dimension over Nunavut, Canada [click to enlarge]

Another effect of the large satellite view angle was a shift of the Water Vapor weighting functions to higher altitudes — plots of the 7.3 µm, 6.9 µm and 6.2 µm weighting functions calculated using 12 UTC rawinsonde data from Baker Lake, Nunavut are shown below. These plots depict the layers of the atmosphere from which emitted radiation was detected by each of the 3 Water Vapor spectral bands on the ABI instrument.

GOES-16 Water Vapor weighting function plots calculated using 12 UTC rawinsonde data from Baker Lake, Nunavut [click to enlarge]

GOES-16 Water Vapor weighting function plots calculated using 12 UTC rawinsonde data from Baker Lake, Nunavut [click to enlarge]

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