A sequence of GOES-16 (GOES-East) “Red” Visible (0.64 µm) images covering the 14 December – 26 December 2020 period (above) showed that after Iceberg A68a encountered the more shallow continental shelf waters southwest of South Georgia island earlier in the month (NOAA-20 True Color RGB images, 02-13 December), the large iceberg then began to move south-southeastward, shear apart and release 3 smaller orphan icebergs (in addition to widespread small ice floes).

A toggle between NOAA-20 VIIRS True Color RGB images on 23 December and 25 December viewed using RealEarth (below) provided a higher-resolution view of the numerous small ice floes that resulted from the iceberg fracturing process.

View only this post Read Less

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) indicated that a strong arctic cold front (surface analyses) had plunged southward across Mexico, through the Chivela Pass, and emerged as a Tehuano (or “Tehuantepecer“) gap wind into the Gulf of Tehuantepec on 24 December 2020. Along the Gulf of Mexico coast, a few sites in Mexico reported blowing dust and/or blowing sand with onshore winds gusting to 40 knots.

GOES-16 True Color RGB images created using Geo2Grid (below) showed the hazy signature of blowing dust/sand as it was transported off the south coast of Mexico and spread out across the Gulf of Tehuantepec.

===== 25 December Update =====

On the following day, GOES-16 Visible images (above) showed that the leading edge of the gap wind flow — marked by a broad arc cloud — was approaching the ITCZ / Monsoon Trough in the Pacific Ocean. Ship reports of 30-35 knot winds were seen within the offshore flow — and ASCAT surface scatterometer winds revealed speeds as high as 44 knots.

GOES-16 True Color RGB images (below) showed the hazy signature of blowing dust from Mexico as it spread out across the Pacific Ocean.

Aided by enhanced forward scattering during the morning hours, True Color RGB images from GOES-17 (GOES-West) showed the hazy signature of airborne dust from Mexico a bit better (below).

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Dust RGB images (above) displayed signatures of blowing dust (brighter shades of pink) moving southward across eastern Colorado and over the Oklahoma/Texas Panhandle region on 23 December 2020. The dust source region appeared to be eastern Colorado, where wind gusts in excess of 60 knots were observed during the morning hours.

GOES-16 True Color RGB images created using Geo2Grid (below) showed the lighter tan colored signature of these areas of blowing dust.

Additional details of this event are available on the Satellite Liaison Blog.

View only this post Read Less

Strong winds behind a storm moving along the United States/Canada border on 23 December 2020 led to blizzard warnings over much of the Northern Plains (link). How easily was the blowing snow detected by satellite?

The animation above shows the Day Snow Fog RGB from 1416 through 1751 UTC on 23 December 2020. During this time over North Dakota, low clouds (bright whitish/periwinkle) and mid/high-level clouds (transparent violet) masked the surface from the satellite view. However, blowing snow is suggested to the south of Lake Manitoba. The RGB has a slightly different, brighter color than the adjacent snow-cover — that is red — and the texture in the image, and the linear features aligned with the wind both suggest lofted blowing snow.

The VIIRS instruments on board Suomi-NPP and NOAA-20 also viewed this scene, once at 1759 UTC (from NOAA-20) and once at 1850 UTC (from Suomi-NPP), with much higher spatial resolution. There is a region of enhanced reflectance (i.e., whiter shades of grey) in the 1.61 µm imagery to the south-southeast of Lake Manitoba in the top center of the image.  These are lofted, fractured ice crystals that are more reflective of solar radiation than surrounding snow cover.  The signal shows up in the False Color imagery as well, but not in the true color imagery that does not incorporate information from the 1.61 µm channel.  A similar signal appears in extreme northeast North Dakota at 1759 UTC.  VIIRS imagery does not suggest widespread blowing snow.  Indeed, snow depths over North Dakota suggest little snow on the ground to blow around (snow depth analysis, from this site)!  Snow depths over Manitoba are a bit larger.

The animation from 1751 UTC to 2106 UTC on 23 December, below, which animation includes the times of the VIIRS overpasses above, also captures the snow plume downwind of Lake Manitoba, extending to the North Dakota/Minnesota border and, perhaps, into northwestern Minnesota. However, clouds over Minnesota (and the Red River of the North) make definitive blowing snow detection difficult. Traffic webcams as a supplement to the satellite data source will create a better feel for the horizontal extent of the blowing snow.

---

This 11-minute training video discusses this RGB’s abilities in blowing snow detection in a bit more depth.  You can view a longer presentation concerning othis RGB here.

View only this post Read Less