Arctic outbreak with snow cover extending to South Texas

February 15th, 2021 |

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

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

In the wake of a southward surge of arctic air across the central US — which produced surface temperatures as cold as -50ºF in Minnesota on 13 February — GOES-16 (GOES-East) Day Cloud Phase Distinction RGB images (above) showed the large areal extent of snow cover (brighter shades of green) across Oklahoma, New Mexico and Texas on 15 February 2021. In the RGB images, low-level supercooled water droplet clouds appear as pale shades of white.


A closer view of GOES-16 Day Cloud Phase Distinction RGB images (below) showed the far southern extent of snow cover across northern Mexico and southern Texas. Precipitation briefly transitioned from rain to snow as far south as Brownsville, but there was no accumulation at that site.

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

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

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images (below) revealed a number of lake effect cloud plumes across northern and eastern Texas, as cold air moved across the warmer waters of small lakes.

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images, with and without plots of surface reports [click to play animation | MP4]

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images, with and without plots of surface reports [click to play animation | MP4]

Farther north over the Texas Panhandle, GOES-16 “Snow/Ice” images (below) showed a small cloud plume originating at the Xcel Energy Harrington Station power plant just north-northwest of Amarillo (KAMA). Note the drop in surface visibility to 5 miles at 17 UTC — this was likely due to snow flurries as the cloud plume drifted over the airport.

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

A timely overpass of Landsat-8 provided a 30-meter resolution False Color RGB image at 1721 UTC, as viewed using RealEarth (below) — as the cloud plume drifted over the KAMA airport, the 17 UTC METAR surface report indicated that the cloud base was at 1000 feet.

Landsat-8 False Color RGB image [click to enlarge]

Landsat-8 False Color RGB image [click to enlarge]

===== 16 February Update =====

GOES-16 CIMSS Natural Color RGB images, with plots of Metop-A ASCAT winds and surface/ship reports [click to play animation | MP4]

GOES-16 CIMSS Natural Color RGB images, with plots of Metop-A ASCAT winds and surface/ship reports [click to play animation | MP4]

On the following day, GOES-16 CIMSS Natural Color RGB images with plots of Metop-A ASCAT winds (above) showed how Tehuano gap winds had moved through Chivela Pass in southern Mexico (topography) and were spreading out across the Gulf of Tehuantepec (south of Ixtepec, station identifier MMIT). The highest surface scatterometer wind speeds were 24 knots near the coast.

With a low sun angle maximizing forward scattering, a plume of blowing dust could be seen right after sunrise in GOES-17 (GOES-West) True Color RGB images created using Geo2Grid (below), moving southward across the Gulf of Tehuantepec.

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

Comparing SAR wind data to GOES-16 ABI imagery

February 15th, 2021 |

Sentinel-1A wind information over northern Lake Michigan, 2342 UTC on 14 February 2021 (Click to enlarge)

Synthetic Aperture Radar (SAR) imagery can be used to produce very high resolution mapping of winds. Imagery is available in selected domains at this NOAA/OSPO website; OSPO is the Office of Satellite Product Observations. Data are available from three different satellites: Sentinel-1/Sentinel-2 (managed by the European Space Agency) and RADARSAT (managed by the Canadian Space Agency). These space-borne radars can operate in a mode that provides very small-scale wind information, as shown above.  Note the fine detail in the winds — elongated regions of winds in excess of 20 knots from north of Green Bay southeastward across Lake Michigan to North and South Manitou islands.  What does the ABI Imagery look like at the same time?

GOES-16 Band 7 (3.9 µm) imagery, below, similarly shows three parallel lines of colder cloud tops (the greyscale enhancement used is such that colder values are whiter). SAR data shows that convective bands over the lake have stronger surface winds than regions in between the convective bands.

GOES-16 Band 7 Shortwave Infrared (3.9 µm) imagery, 2341 UTC on 14 February 2021