Large-scale blowing dust event

April 10th, 2019 |

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

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

Strong winds — gusting as high as 77 mph in New Mexico and 88 mph in Texas — associated with a rapidly-intensifying midlatitude cyclone generated large plumes of blowing dust (originating from southeastern Arizona,southern New Mexico, northern Mexico and western Texas) on 10 April 2019. GOES-16 (GOES-East) Split Window (10.3-12.3 µm) images (above) helped to highlight the areas of blowing dust, which initially developed along and behind a cold front after 15 UTC.

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface winds and gusts [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface wind barbs and gusts [click to play animation | MP4]

GOES-16 Split Window images with hourly plots of surface wind barbs and gusts (above) showed the distribution of strong winds across the region, while plots of the surface visibility (below) showed decreases to 1/4 mile at Deming, New Mexico, 1/2 mile at Lubbock, Texas and 4 miles at Altus, Oklahoma.

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface visibility [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface visibility [click to play animation | MP4]

GOES-16 True Color Red-Green-Blue (RGB) images (below; courtesy of Rick Kohrs, SSEC) depicted the blowing dust as shades of tan to light brown. Willcox Playa was the source of the dust plume coming from southeastern Arizona. Note that the dust plume emanating from White Sands, New Mexico was lighter in appearance compared to the other tan/brown-colored areas of blowing dust — this is due to the white gypsum sand that comprises the surface of White Sands National Monument.

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

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

250-meter resolution MODIS True Color RGB images from the MODIS Today site (below) provided a more detailed view of the plume streaming northeastward from its White Sands source. On the later Aqua image, dense tan-colored areas of blowing dust had developed below the thin higher-altitude veil of brighter gypsum aerosols that had earlier been lofted from White Sands.

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

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

A NOAA-20 True Color RGB image viewed using RealEarth is shown below. 19 UTC surface observations at 3 sites near White Sands included Las Cruces KLRU (visibility 3 miles, wind gusting to 46 knots), Alamogordo KALM (visibility 3 miles, wind gusting to 43 knots) and Ruidoso KSRR (visibility 5 miles, wind gusting to 55 knots). The strong winds and dense areas of blowing dust reducing surface visibility not only impacted ground transportation but also posed a hazard to aviation.

NOAA-20 True Color RGB image at 1928 UTC [click to enlarge]

NOAA-20 True Color RGB image at 1928 UTC [click to enlarge]

===== 11 April Update =====

In a larger-scale view of GOES-16 Split Window images (below), the yellow dust signature could be followed during the subsequent overnight hours and into the following day on 11 April, as the aerosols were being transported northeastward across the Upper Midwest. There were widespread reports and photos of dust residue on vehicles and tan/brown-colored snow in parts of Nebraska, Iowa, Minnesota and Wisconsin.

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

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

IDEA forward trajectories (below) — initialized from a cluster of elevated Aura OMI Aerosol Index points over Mexico, New Mexico and Texas — passed directly over areas of model-derived precipitation across the Upper Midwest, providing further support of precipitation scavenging of dust aerosols. Interestingly, a similar event of long range dust transport occurred on 10-11 April 2008.

IDEA forward trajectories initialized from a cluster of elevated Aqua MODIS Aerosol Optical Depth points over NM/TX [click to play animation]

IDEA forward trajectories initialized from a cluster of elevated Aqua MODIS Aerosol Optical Depth points over NM/TX [click to play animation]

HYSPLIT model 24-hour forward trajectories initialized at 3 locations — El Paso, Lubbock and Amarillo in Texas — showed a few of the likely dust transport pathways toward the Upper Midwest at 3 different levels (below).

HYSPLIT model forward trajectories initialized at El Paso, Lubbock and Amarillo, Texas [click to enlarge]

HYSPLIT model 24-hour forward trajectories initialized at El Paso, Lubbock and Amarillo, Texas [click to enlarge]

GOES-16 True Color RGB images from the AOS site (below) showed that some clouds across the Upper Midwest exhibited a subtle light brown hue at times.

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

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

===== 12 April Update =====

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

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

GOES-16 Split Window (10.3-12.3 µm) images (above) showed that the yellow signature of dust aerosols aloft had wrapped all the way around the southern and eastern sectors of the occluded low on 12 April.

Ground-based lidar at the University of Wisconsin – Madison confirmed the presence of elevated levels of aerosol loading between the surface and 6 km.

Lidar aerosol class [click to enlarge]

Lidar aerosol class [click to enlarge]

Standing wave clouds over Virginia and North Carolina

March 7th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm), “Clean” Infrared Window (10.3 µm), Cloud Top Height, Cloud Particle Size Distribution, and Cloud Phase [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm), “Clean” Infrared Window (10.3 µm), Cloud Top Height, Cloud Particle Size Distribution, and Cloud Phase (above) helped to characterize standing wave clouds that developed to the lee of the Appalachian Mountains on 07 March 2019. The primary standing wave rotor clouds were composed of smaller supercooled water droplets,  with “banner clouds” composed of larger/colder ice crystals forming downwind of the rotor clouds. For example, at 1637 UTC cloud particle sizes associated with the rotor clouds were as small as 3-10 µm (darker shades of purple).

GOES-16 Day Cloud Phase Distinction Red-Green-Blue (RGB) images from the AOS site (below) also identified the rotor clouds as supercooled water droplet features (brighter shades of white), with the banner clouds being identified as high-level ice (shades of pink) or glaciating (shades of green) features. An unrelated phenomena was the brief brightening of the bare ground across much of the Southeast US midway through the animation — a result of transient solar reflectance that is seen around the Spring and Autumn equinox.

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

In a comparison of 1-km resolution Terra MODIS Visible (0.65 µm), Near-Infrared “Cirrus” (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images at 1631 UTC (below), note that the standing wave rotor clouds appeared much warmer (darker gray) in the Shortwave Infrared images — this is due to the fact that small supercooled water droplets are very efficient reflectors of incoming solar radiation.

Terra MODIS Visible (0.65 µm), Near-Infrared

Terra MODIS Visible (0.65 µm), Near-Infrared “Cirrus” (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images [click to enlarge]

There were a few pilot reports of light to moderate turbulence in the general vicinity of the standing waves, especially around 14 UTC (below).

Terra MODIS Visible (0.65 µm) image, with pilot reports of turbulence [click to enlarge]

Terra MODIS Visible (0.65 µm) image, with pilot reports of turbulence [click to enlarge]

Turbulence over the western United States

February 13th, 2019 |

GOES-17 Low-Level Water Vapor Imagery (7.3 µm) on 13 February 2019, 1932-2012 UTC (Click to animate)

A strong storm system affecting the western third of the United States on 13 February 2019 was responsible for turbulence that caused damage and injuries and forced an ERJ-170 aircraft flying from John Wayne Airport (in Orange County CA) to Seattle WA to make an unscheduled stop in Reno NV (News report). (Flight Aware information on the flight) Three passengers were hospitalized.

The water vapor imagery animation above, annotated so that the departure airport (SNA) and Reno (RNO) are shown in the first frame. During the second run-through of the animation, the approximate location of the turbulence is noted with a red square (Flight Aware data suggests it occurred very near 2030 UTC — Flight Aware times are EST), and the animation slows. Water Vapor imagery suggests that the aircraft encountered a convective element that likely was associated with the Sierra Nevada. A stepped animation between 2027 and 2032 UTC is shown below.

GOES-17 Low-Level Water Vapor Imagery (7.3 µm) on 13 February 2019, 2027 and 2032 UTC (Click to enlarge)

Cloud-top waves producing turbulence north of Hawai’i

February 6th, 2019 |
GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play MP4 animation]

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play MP4 animation]

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

Transient pockets of cloud-top waves were evident on GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) north of Hawai’i on 06 February 2019. Some of the waves were located along the tops of convective cloud features, while others appeared to be randomly distributed.

Plots of rawinsonde data from Lihue, Hawai’i (below) showed that winds within the middle to upper troposphere had a general westerly component — so these mesoscale cloud-top wave features were oriented perpendicular to the flow.

Plots of rawinsonde data from Lihue, Hawai'i [click to enlarge]

Plots of rawinsonde data from Lihue, Hawai’i [click to enlarge]

There was only 1 pilot report of turbulence within the broad region exhibiting these waves, occurring at 2304 UTC at an altitude of 33,000 feet — and this appeared to coincide with a discrete wave packet that was propagating eastward (below).

GOES-17 Upper-level Water Vapor (6.2 µm) images within 30 minutes of the 2304 UTC pilot report of turbulence [click to enlarge]

GOES-17 Upper-level Water Vapor (6.2 µm) images within 30 minutes of the 2304 UTC pilot report of turbulence [click to enlarge]

While the more robust wave packets could also be seen in GOES-17 “Clean” Infrared Window (10.3 µm) images (below), their complete areal coverage was more obvious in the Water Vapor imagery — particularly where the wave features were more subtle.

GOES-17 Upper-level Water Vapor (6.2 µm) and “Clean” Infrared Window (10.3 µm) images at 2302 UTC [click to enlarge]

Aviation advisories for Significant Weather (SIGWX) had been issued for that region (below), which included a Moderate risk for Clear Air Turbulence (CAT) from 28,000-39,000 feet and the possibility of isolated/embedded Cumulonimbus (CB) clouds with tops to 38,000 feet, along with a west-northwest high-level jet stream from 290º at 90 knots. The pilot report of turbulence at 33,000 feet included winds from 261º at 81 knots.

GOES-17 Upper-level Water Vapor (6.2 µm) image, with plots of aviation Significant Weather advisories [click to enlarge]

GOES-17 Upper-level Water Vapor (6.2 µm) image, with plots of aviation Significant Weather advisories that were in effect at that time [click to enlarge]

The cloud-top waves were also seen in a sequence of VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, viewed using RealEarth (below).

VIIRS Infrared Window (11.45 µm) images from NOAA-20 (at 2230 and 0030 UTC) and Suomi NPP (at 2320 UTC) [click to enlarge]

VIIRS Infrared Window (11.45 µm) images from NOAA-20 (at 2230 and 0030 UTC) and Suomi NPP (at 2320 UTC) [click to enlarge]