Blowing dust in southern Nevada

April 9th, 2019 |

GOES-17 Split Window (10.3-12.3 µm), Split Cloud Top Phase (11.2-8.4 µm) and

GOES-17 Split Window (10.3-12.3 µm), Split Cloud Top Phase (11.2-8.4 µm) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) Split Window (10.3-12.3 µm), Split Cloud Top Phase (11.2-8.4 µm) and “Red” Visible (0.64 µm) images (above) displayed a plume of blowing dust — whose source region was a dry lake bed along the California-Nevada border — which developed in advance of an approaching cold front (surface analyses) and moved northeastward across far southern Nevada on 09 April 2019. Wind gusts of 50-65 mph were reported across the region.

This dust plume was also apparent over far southern Nevada 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]

There are 5 airports located in the Las Vegas Valley, and GOES-17 images showed that the dust plume passed directly over Henderson (KHND) — time series plots of surface data from these sites (below) indicated that visibility was reduced to 3 miles at Henderson, with visibilities dropping to 8-9 miles at McCarran International Airport (KLAS) and Nellis Air Force Base (KLSV). The visibility was not impacted at the North Las Vegas Airport (KVGT), with its more northwest location being farther from the dust plume.

Time series plot of surface data at Henderson [click to enlarge]

Time series plot of surface data at Henderson [click to enlarge]

Time series plot of surface data at McCarran International Airport [click to enlarge]

Time series plot of surface data at McCarran International Airport [click to enlarge]

Time series plot of surface data at Nellis Air Force Base [click to enlarge]

Time series plot of surface data at Nellis Air Force Base [click to enlarge]

A notable exception was the Boulder City Municipal Airport (KBVU), which was downwind of a smaller local point source of blowing dust (Mursha Reservoir, another dry lake bed to the southwest) — the visibility at KBVU was restricted to 2 miles at times. With the 2-km spatial resolution (at satellite nadir) of the GOES-17 Infrared spectral bands, there was not a signature of this smaller-scale Boulder City dust plume in the 10.3-12.3 µm and 11.2-8.4 µm Brightness Temperature Difference products — however, this hazy plume was evident in the 0.5-km resolution (at satellite nadir) Visible imagery.

Time series plot of surface data at Boulder City Municipal Airport [click to enlarge]

Time series plot of surface data at Boulder City Municipal Airport [click to enlarge]

A comparison of 1-km resolution NOAA-19 AVHRR Visible (0.63 µm), Shortwave Infrared (3.8 µm) and Split Window (10.8-12.0 µm) images (below) provided a detailed view of the primary dust plume — and also exhibited a subtle signature of the smaller plume that reduced visibility at Boulder City KBVU. The small dust aerosols act as efficient reflectors of incoming solar radiation, therefore appearing warmer (darker) on the Shortwave Infrared image.

NOAA-19 AVHRR Visible (0.63 µm), Shortwave Infrared (3.8 µm) and Split Window (10.8-12.0 µm) images, with plots of 23 UTC surface reports [click to enlarge]

NOAA-19 AVHRR Visible (0.63 µm), Shortwave Infrared (3.8 µm) and Split Window (10.8-12.0 µm) images, with plots of 23 UTC surface reports [click to enlarge]

The GOES-17 and NOAA-19 images also showed that the larger dust plume moved across a section of Interstate 15 between Sloan and Jean; traffic cameras showed significant reductions in visibility along I-15 near Primm (along the California/Nevada border).

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.

===== 22 March Update =====

GOES-16 "Red" Visible (0.64 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]

There was a brief re-ignition of the fire that began at 2035 UTC on 22 March, as shown by 1-minute GOES-16 Visible, Near-Infrared and Shortwave Infrared images (above). The thermal anomaly of the fire was only apparent for about 50 minutes — reaching a peak infrared brightness temperature of 48.4ºC at 2044 UTC — while the dark smoke continued to spread to cover a north-south distance of over 10 miles in 90 minutes, moving over Interstate 10 and the cities of Channelview and Highlands.

Lake effect snow in Nevada

February 21st, 2019 |


GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Clean” Infrared Window (10.3 µm) images (above) showed an unusual lake effect snow feature downwind of Pyramid Lake in northwestern Nevada on 21 February 2019 — the surface visibility dropped to 0.5 mile with moderate snow as ihe lake effect cloud moved over Reno-Tahoe International Airport around 16 UTC. Prior to that, the lake effect snow also affected portions of Interstate 80 in the Patrick area.

A morning overpass of the NOAA-19 satellite provided a 1-km resolution Infrared Window (10.8 µm) image of the lake effect cloud at 1254 UTC (below). The coldest cloud-top infrared brightness temperature on that image was -46ºC.

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

GOES-17 cloud-top infrared brightness temperatures associated with this feature were as cold as -47ºC just after 15 UTC, which were very close to the tropopause temperature of -47.9ºC on 12 UTC rawinsonde data from Reno (below).

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Although clouds often prevented a good view of Lake Pyramid, Terra MODIS Sea Surface Temperature values of 42º and 43ºF were sampled on 11 and 16 February (below). With a northerly flow of air having temperatures around 20ºF across such warm water, significant boundary layer instability was generated to aid the growth of the lake effect cloud feature.

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Although the view angle from GOES-16 (GOES-East) was rather large, a Land Surface Temperature pixel mapped to the northern portion of the lake had a value of 39.3ºF at 1701 UTC (below).

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]

Rope cloud in the East Pacific Ocean

January 16th, 2019 |
GOES-17

GOES-17 “Red” Visible (0.64 µm) image, with an overlay of the 12 UTC surface analysis [click to enlarge]

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

An 1802 UTC GOES-17 “Red” Visible (0.64 µm) image with an overlay of the 12 UTC surface analysis (above) revealed a well-defined rope cloud which stretched for nearly 1000 miles, marking the cold front position at the time of the image. Rope clouds can therefore be used to diagnose the exact location of the leading edge of a cold frontal boundary between times when surface analyses are available. In this case, the cold front was associated with a Hurricane Force low over the East Pacific Ocean on 16 January 2019 (surface analyses).

GOES-17 "Red" Visible (0.64 µm) images [click to play animation]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation]

An animation of GOES-17 Visible images is shown above, with a zoomed-in version closer to the rope cloud displayed below.

GOES-17 "Red" Visible (0.64 µm) images [click to play animation]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation]

An even closer look (below) showed that the rope cloud was only about 2-3 miles wide.

GOES-17 "Red" Visible (0.64 µm) images [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) images [click to enlarge]

When the 18 UTC surface analysis later became available, a close-up comparison with the 1802 UTC GOES-17 Visible image (below) indicated that the northern portion of the cold front (as indicated by the rope cloud) was slightly ahead of — and the southern portion slightly behind — the smoothed cold frontal position of the surface analysis product.

1802 UTC GOES-17 "Red" Visible (0.64 µm) image, with an overlay of the 18 UTC surface analysis [click to enlarge]

1802 UTC GOES-17 “Red” Visible (0.64 µm) image, with an overlay of the 18 UTC surface analysis [click to enlarge]

NOAA-15 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1617 UTC [click to enlarge]

NOAA-15 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1617 UTC [click to enlarge]

1-km resolution AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images of the rope cloud were captured by NOAA-15 at 1617 UTC (above) and by NOAA-18 at 1710 UTC (below). Along the northeastern portion of the rope cloud, there were a few convective clouds which exhibited cloud-top infrared brightness temperatures as cold as -55 to -60ºC (darker shades of red) and were tall enough to be casting shadows due to the low morning sun angle.

NOAA-18 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images [click to enlarge]

NOAA-18 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1710 UTC [click to enlarge]


===== 17 January Update =====

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

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

On the following day, another rope cloud (one that was more fractured) was seen moving across Hawai’i as a cold front passed the island of Kaua’i — the southeastward progression of the rope cloud was evident on GOES-17 True Color Red-Green-Blue (RGB) images (above)  from the UW AOS site.

Surface observations plotted on GOES-17 Visible images (below) showed the wind shift from southwest to north as the cold front moved through Lihue on Kauwa’i around 00 UTC.

GOES-17

GOES-17 “Red” Visible (0.64 µm) images, with plots of surface reports [click to play animation | MP4]

===== 18 January Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with and without buoy observations [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with and without buoy observations [click to enlarge]

Not all rope clouds are associated with cold fronts; with ample illumination from the Moon — in the Waxing Gibbous phase, at 90% of Full — a Suomi NPP VIIRS Day/Night Band (0.7 µm) image (above) provided a “visible image at night” of a rope cloud in the northern Gulf of Mexico which highlighted a surface wind shift axis.

A sequence of VIIRS Day/Night Band images from NOAA-20 and Suomi NPP (below) showed the movement of the rope cloud during a time span of about 1.5 hours.

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]