Tehuano gap wind event

By Scott Bachmeier • 27 February 2020

GOES-16 Visible (0.64 µm) images, with plots of surface reports (yellow), ASCAT winds (violet) and surface analyses (cyan) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with plots of surface reports (yellow), ASCAT winds (violet) and surface analyses (cyan) [click to play animation | MP4]

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.

GOES-16 Visible (0.64 µm) image, with plots of available NOAA-20 NUCAPS profiles [click to enlarge]

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.

NOAA-20 NUCAPS Temperature (red) and dewpoint (green) profiles for Point 1 and Point 2 [click to enlarge]

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.

“Red” Visible (0.64 µm) images from GOES-17 (left) and GOES-16 (right) [click to play animation | MP4]

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.