EUMETSAT Meteosat-11 Water Vapor (6.25 µm) images (above) showed the large field of strong surface winds associated with Storm Jorge as it approached the British Isles on 29 February – 01 March 2020. Peak wind gusts of 70 knots were recorded in Ireland.

Surface analyses from the Ocean Prediction Center (below) indicated that the Hurricane Force occluded low reached a minimum pressure of 952 hPa at 06 UTC on 29 February.

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GOES-16 (GOES-East) Visible (0.64 µm) images (above) revealed a cloud arc which marked the leading edge of a Tehuano wind event — air behind a cold front plunged southward across the Gulf of Mexico during the previous day, crossed the mountains of Mexico through Chivela Pass (topography) , and emerged over the Pacific Ocean on 27 February 2020. Within the western portion of the gap wind flow, ASCAT winds speeds were as high as 32 knots at 1540 UTC — but closer to the coast the Ocean Prediction Center was initially forecasting an area of Storm Force winds (downgraded to Gale Force winds later in the day).

On a GOES-16 Visible image with plots of available NOAA-20 NUCAPS profiles (below), the location of one profile immediately offshore (Point 1) and another just ahead of the Tehauno cloud arc (Point 2) are highlighted.

A toggle between the NUCAPS profile immediately offshore (Point 1, at 15.39 N latitude 94.55 W longitude) and the profile just ahead of the Tehauno cloud arc (Point 2, at 7.29 N latitude 93.95 W longitude) is show below. Note that Total Precipitable Water values were 1.78 inches ahead of the cloud arc, compared to 1.16 inches immediately off the coast of Mexico where the dry gap winds were entering the Gulf of Tehuantepec.

In a comparison of Visible images from GOES-17 (GOES-West) and GOES-16 (GOES-East), haziness in the Gulf of Tehuantepec (best seen with GOES-16, due to a larger forward scattering angle) highlighted blowing dust that was being carried offshore by the strong gap winds.

GOES-16 True Color Red-Green-Blue (RGB) images created using Geo2Grid (below) provided a clearer view of the blowing dust plumes in the Gulf of Tehuantepec.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 as viewed using RealEarth are shown below.

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Gridded NUCAPS fields include 850-mb dewpoint temperature fields, and this blog post compares the NUCAPS fields to model fields, and this is part of an ongoing series of blog posts on these horizontal fields.  The imagery above compares NUCAPS fields at 850 mb with NAM40 and RAP40 data over the southeastern part of the United States.  Very dry air is indicated over the western Atlantic Ocean north and west of the Gulf Stream.  There is generally good agreement between the NUCAPS and model fields. Model fields appear dryer (or NUCAPS fields are more moist).  Model fields show a pronounced gradient over the upper midwest that, at this scan time, were too far west to be viewed by NUCAPS.  (Click here to view the NUCAPS points — green, yellow and red — for this time, to show something about the data that has been input into the gridded fields).

However, the following pass from NOAA-20 (click here to view NOAA-20 orbit paths) included midwestern data.  Again, the general good agreement is obvious, especially with regard to the placement of the gradient. Is the atmosphere as dry as the model suggests at 850 mb? That’s a hard question to answer given 1200 UTC Soundings at Omaha, Minneapolis/Chanhassen, and Green Bay.  Note that NAM12 and RAP13 data are being shown in this example;  they gave mostly the same answer as NAM40/RAP40 used above.

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GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the onset of a 2-day event of dense plumes of blowing sand/dust (known locally as a Calima) — with Western Sahara and Morocco being the primary source regions — which moved across the Canary Islands and the adjacent East Atlantic Ocean on 22 February 2020. Along the coast of Morocco, surface visibility was reduced to 1/8 mile at Tan-Tan (GMAT); over the Canary Islands, visibility dropped to 1/4 mile at Gran Canaria (GCLP).

GOES-16 Dust Red-Green-Blue (RGB) images spanning the period 0800 UTC on 22 February to 2100 UTC on 23 February (below) provided a continuous day/night visualization of the first dust plume (shades of pink/magenta). During the day on 23 February, a second dust plume could be seen emerging from below a patch of mid/high-altitude clouds. The RGB images were created using Geo2Grid.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) revealed orographic waves in the airborne sand/dust downwind (northwest) of some of the Canary Islands on 23 February.

This sand/dust was being lofted by anomalously strong lower-tropospheric winds — which were up to 5 standard deviations above the mean at the 925 hPa pressure level (below).

===== 24 February Update =====

GOES-16 Dust RGB images on 24 February (above) showed the second major pulse of sand/dust curling around the northern periphery of the offshore cutoff low pressure system. Toward the end of the animation, another minor pulse could be seen streaming northwestward off the coast of Western Sahara. A longer Dust RGB animation from 08 UTC on 22 February to 18 UTC on 24 February is available here.

In addition to the Dust RGB, signatures of the airborne sand/dust were also evident in GOES-16 Split Window Difference (10.3-12.3 µm) and Split Cloud Top Phase (11.2-8.4 µm) imagery (below). This arises from the fact that silicates (sand/dust particles) have different energy absorption characteristics at varying wavelengths.

A comparison of TROPOMI Aerosol Index, TROPOMI Aerosol layer height (meters), Meteosat-11 Natural Color RGB and Meteosat-11 Dust RGB images at 1515 UTC is shown below (credit: Bob Carp, SSEC). Note that the height of the center of the aerosol layer near the western tip of the plume was generally in the 500-1000 meter range (shades of blue to cyan).

A GOES-16 Split Window Difference (10.3-12.3 µm) image with plots of available NUCAPS profile points at 1600 UTC (above) denoted the locations of a sequence of 9 consecutive north-to-south sounding points through the western tip of the dust plume. Profiles of NUCAPS temperature and dew point data for those 9 points are shown below — the strong temperature inversion and dry air below 1 km at Points 6, 7 and 8 showed the presence of this dry, dust-laden air (and the Total Precipitable Water value dropped to a minimum value of 0.34 inch at Point 7).

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