Satellite winds « CIMSS Satellite Blog

Contrails over Wisconsin, and a mesovortex moving across Indiana

March 31st, 2020 | Scott Bachmeier

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Cirrus” (1.37 µm), Near-Infrared “Snow/Ice” (1.61 µm), Upper-level Water Vapor (6.2 µm), Mid-level Water Vapor (6.9 µm), Low-level Water Vapor (7.3 µm), “Clean” Infrared Window (10.35 µm) and Day Cloud Phase Distinction RGB images [click to play animation | MP4]

A sequence of GOES-16 (GOES-East) “Red” Visible (0.64 µm), Near-Infrared “Cirrus” (1.37 µm), Near-Infrared “Snow/Ice” (1.61 µm), Upper-level Water Vapor (6.2 µm), Mid-level Water Vapor (6.9 µm), Low-level Water Vapor (7.3 µm), “Clean” Infrared Window (10.35 µm) and Day Cloud Phase Distinction Red-Green-Blue (RGB) images (above) showed both circular and linear contrails over southern Wisconsin on 31 March 2020. The circular contrail was likely created by military aircraft (Wisconsin Air National Guard) performing training operations.

A toggle between GOES-16 Visible and Cirrus images at 1601 UTC (below) indicated that the darker signature seen in Visible imagery was actually the shadow from the high-altitude contrails being cast upon the top of the low-level stratus clouds.

GOES-16 “Red” Visible (0.64 µm), and Near-Infrared “Cirrus” (1.37 µm) images [click to enlarge]

Another feature of interest was revealed by 1-minute Mesoscale Domain Sector GOES-16 Visible images — a mesovortex that was moving southwestward from southwest Michigan across northwestern Indiana (below). However, the small-scale circulation of the vortex was not captured by 1-minute GOES-16 Derived Motion Winds.

GOES-16 "Red" Visible (0.64 µm) images with plots of Derived Motion Winds (yellow) [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) images, with Derived Motion Winds plotted in yellow [click to play animation | MP4]

Posted in GOES-16, Red-Green-Blue (RGB) images, Satellite winds | No Comments »

Anomalously-strong jet stream winds over Colorado

March 25th, 2020 | Scott Bachmeier

GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds and contours of RUC40 model maximum wind speeds [click to play animation | MP4]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of 6.2 µm Derived Motion Winds and contours of RUC40 model maximum wind speeds [click to play animation | MP4]

An anomalously-strong upper tropospheric jet stream was moving over northern Colorado on 25 March 2020 — GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds and contours of RUC40 model maximum wind speeds (above) revealed that the highest satellite-tracked Derived Motion Wind speeds just northeast of Grand Junction, Colorado (KGJT) were 165 knots. RUC40 model Maximum Wind Speed values were also around 165 knots across that area. The strongest wind speeds in 00 UTC rawinsonde data from Grand Junction were 160 knots (below).

Plot of rawinsonde data from Grand Junction, Colorado at 00 UTC on 26 March [click to enlarge]

The 250 hPa GFS model wind speed anomalies (below) were 3-4 sigma above normal over northern Colorado at 00 UTC on 26 March (source).

250 hPa wind speed anomalies at 00 UTC on 26 March [click to enlarge]

Posted in GOES-16, Satellite winds | No Comments »

Lake Erie mesovortex, and an undular bore over the Dakotas

March 24th, 2020 | Scott Bachmeier

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

Two interesting small-scale features were seen in GOES-16 (GOES-East) imagery on 24 March 2020. First of all, 1-minute Mesoscale Domain Sector “Red” Visible (0.64 µm) images (above) showed a mesovortex that was migrating west-northwestward across Lake Erie during the day. This feature had a diameter of around 10 miles — such a small-scale circulation was not captured by Metop-A ASCAT surface scatterometer data.

During the preceding overnight hours, an early signature of the mesovortex was evident in Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and “Fog product” Brightness Temperature Difference (BTD) images at 0806 UTC (below).

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and “Fog product” Brightness Temperature Difference (BTD) images [click to enlarge]

The second feature of interest was a pre-cold-frontal undular bore that was moving eastward across the Dakotas, as seen in Day Cloud Phase Distinction Red-Green-Blue (RGB) images (below).

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

Posted in GOES-16, Metop, Red-Green-Blue (RGB) images, Satellite winds, Suomi NPP, VIIRS | No Comments »

Tehuano gap wind event

February 27th, 2020 | Scott Bachmeier

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.