GOES-17 (GOES-West) Mid-level Water Vapor (6.9 µm) images which included Pilot Reports (PIREPS) of turbulence (above) revealed a diverse variety of gravity waves across much of Northern California on 19 January 2021. Three types of waves were prevalent: (1) quasi-stationary mountain waves caused by strong northeasterly flow interacting with topography of the Sierra Nevada and Coastal Ranges, (2) long, narrow corridors of fast-moving waves flowing offshore, and (3) west-to-east oriented arcs of waves drifting slowly northward (against the ambient flow). With such disparate wave structures and the intersections of their wave fronts, the prospects for atmospheric turbulence were elevated — in fact, there were a few pilot reports of moderate to severe turbulence, at both low and high altitudes.

GOES-17 Mid-level Water Vapor images with plots of NAM40 model 500 hPa wind streamlines/isotachs at 18 UTC and 00 UTC (below) showed the strong northeasterly flow in the middle troposphere, with speeds as high as 100-110 knots.

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GOES-16 (GOES-East) “Red” Visible (0.64 µm) images created using Geo2Grid (above) revealed long trails of lee waves extending northeastward from many of the South Sandwich Islands on 16 January 2021. These lee waves were generated by strong southwesterly winds within the marine boundary layer interacting with the topography of the islands — wind speeds had increased across that portion of the South Atlantic Ocean, in response to the tight pressure gradient between high pressure north of the islands and a deepening area of low pressure southeast of the islands (MSLP analyses).

A toggle between two NOAA-20 VIIRS True Color RGB images as viewed using RealEarth (below) provided a higher-resolution view of the lee waves extending from the island chain.

Many of these islands contain active volcanoes, which frequently produce plumes (which are primarily comprised of steam). A closer look at the lee waves emanating from one of the northernmost islands (below) appeared to suggest that a brighter white volcanic plume existed within the train of waves.

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As discussed in this blog post, GOES-16 (GOES-East) Dust RGB images (above) displayed the distinct signature of a large blowing dust plume (brighter shades magenta/pink) that initially developed over drought-stricken areas of eastern Colorado and far western Kansas on 15 January 2021. Surface wind gusts in excess of 60 knots were seen in eastern Colorado near the source of the dust plume, with a peak gust of 63 knots or 72 mph — in fact, the anomalously-strong 925 hPa wind speeds were 5-6 sigma above the climatological mean (source). Pilot reports near the edges of the plume indicated visibility restrictions due to dust at altitudes of 5,000 feet over southwestern Kansas and 10,000 feet over northeastern New Mexico.

GOES-16 True Color RGB and Dust RGB images (created using Geo2Grid) are shown below.

Due to the presence of very dry throughout the lower/middle troposphere (Amarillo, Texas rawinsonde data), a signature of the dust plume was also evident in GOES-16 Near-Infrared “Cirrus” (1.37 µm) images (below).

After sunset, the plume signature persisted in GOES-16 Dust RGB images (below) as the blowing dust continued to move southeastward across Texas.

===== 16 January Update =====

On the following day, the dust plume began to flow off the Texas coast and over the Gulf of Mexico by 06 UTC — and although the plume signature began to diminish in the GOES-16 Dust RGB images after sunrise, it was very apparent in True Color RGB imagery (above). Note that the True Color images revealed some recirculation of dust which began to move inland toward the end of the day, as surface winds near the coast shifted to southeasterly (surface analyses).

GOES-16 Natural Color RGB images with plots of Ceiling and Visibility (below) showed that the dust reduced the visibility to 2.5 miles at a site located just off the Texas coast at 14 UTC, and to 5 miles at a site located about 100 miles offshore at 15 UTC.

In a toggle between VIIRS True Color and False Color RGB images from Suomi NPP (below), the dust plume was very evident over the Gulf of Mexico (where its lighter appearance stood out against the dark background of the water).

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The High Plains of Kansas, Colorado, Oklahoma and Texas experienced a significant dust storm (with Dust Storm Warnings issued) on 15 January 2021, (Click here for a blog post on the blowing dust with this storm on 14 January) associated with a strong jet streak and extratropical cyclone discussed here. The animation above (Here’s the same animation, but slower) shows visible imagery along with GOES-16 Mesoscale Sector Derived Motion Winds from the Visible Channel. These derived winds are available with a 5-minute cadence, and the dust was thick enough that features could be tracked. There aren’t a lot of derived winds; how well do these derived winds compare to surface winds?

The image above, from 1900 UTC, shows Derived Motion winds along with METAR observations. Derived Motion winds are stronger than surface winds, as expected; compare, for example, the observations at Limon CO (KLIC) with the nearby derived wind vectors. The levels of the derived motion winds are between 800-820 hPa, away from the effects of friction/surface roughness. However, they do give a nice estimate of what surface winds might be in regions without surface observations, as apparent in the animation at the top.

It can be difficult to view dust with just one ABI channel such as the visible, especially when the sun is high(ish) in the sky and there is little forward scattering. Multi-spectral RGB products, such as the GOES-16 Dust RGB, shown below in a toggle with a VIIRS True-Color image and the GOES-16 Fire RGB (there is a fire evident near KLHX, LaJunta, CO), are a valuable tool in identifying the horizontal extent of dust plumes.  Dust is highlighted in the Dust RGB by a vivid pink/magenta color.

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