Residual winter ice in Lake Superior and Chequamegon Bay

April 27th, 2022 |

Landsat-8 False Color image [click to enlarge]

A 30-meter resolution Landsat-8 False Color image viewed using RealEarth (above) displayed thin filaments of ice (brighter shades of cyan) in far western Lake Superior, just off the northern coast of Wisconsin, on 27 April 2022. Chequamegon Bay in northern Wisconsin also had significant amounts of ice remaining from the winter months. Remnant snow cover (muted shades of cyan) was also apparent across much of northeastern Minnesota and parts of northern Wisconsin.

During the preceding overnight hours, a NOAA-20 VIIRS Advanced Clear-Sky Processing for Ocean (ACSPO) Sea Surface Temperature image around 0831 UTC (below) indicated that SST values were generally around 34oF (darker blue enhancement) in the portion of the lake north of the ice filaments. Farther to the east, the West Superior Buoy 45006 was reporting a SST value of 33oF at that time.

NOAA-20 VIIRS ACSPO Sea Surface Temperature image [click to enlarge]

GOES-16 (GOES-East) True Color RGB images displayed using CSPP GeoSphere (below) showed that (1) the thin ice filaments just off the coast of Wisconsin were moving southwestward during the day, and (2) within Chequamegon Bay, significant ice fracturing began during the afternoon hours.

GOES-16 True Color RGB images [click to play animated GIF | MP4]

This ice filament motion and ice fracturing was the result of persistent northeasterly surface winds during the day, which gusted to 29 knots at Duluth Sky Harbor Airport (below).

Plot of surface report data from Duluth Sky Harbor Airport [click to enlarge]

Grassland fire in Mongolia generates a pyrocumulonimbus cloud

April 19th, 2022 |

JMA Himawari-8 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.4 µm, bottom) images [click to play animated GIF | MP4]

JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.4 µm) images (above) showed signatures of a rapidly-spreading grassland fire in eastern Mongolia’s Numrug National Park (near the border with China) on 19 April 2022. The fast rate of northeastward growth of the dark burn scar in Visible imagery was particularly striking. Strong winds aided the rapid expansion of this fire, due to the tight pressure gradient between a high over central China and a deepening low that was moving from Siberia to northeastern China (surface analyses).

Consecutive NOAA-20 VIIRS Infrared image valid at 0401 UTC and 0541 UTC — viewed using RealEarth (below) — showed the eastward drift of individual small pyrocumulonimbus (pyroCb) clouds, which exhibited cloud-top infrared brightness temperatures of -40ºC and colder (brighter green color enhancement).

NOAA-20 VIIRS Infrared Window (11.45 µm) images at 0401 UTC and 0541 UTC [click to enlarge]

A toggle between NOAA-20 VIIRS True Color RGB and Infrared images at 0541 UTC (below) depicted the dark burn scar as well as the smoke plume with embedded pyroCb clouds.

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0541 UTC [click to enlarge]

30-meter resolution Landsat-8 False Color RGB imagery valid at 0252 UTC (below) provided an even more detailed view of the dark burn scar — in addition, the active fire front appeared as brighter shades of pink to red along the eastern and southeastern flanks.

Landsat-8 False Color image at 0252 UTC [click to enlarge]

After sunset, the northern flank of the fire continued to burn at an intense rate, judging from the thermal signature seen in Himawari-8 Shortwave Infrared images (below). Dense layered clouds began to move over the region before sunrise the next day, which then acted to mask the fire’s thermal signature.

JMA Himawari-8 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.4 µm, bottom) images [click to play animated GIF | MP4]

A toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images valid at 1757 UTC (below) showed the bright nighttime glow of active fires — especially along the aforementioned northern flank — in addition to the associated smoke plume that was moving eastward, as illuminated by the Moon (which was in the Waning Gibbous phase, at 90% of Full). This smoke did not exhibit a signature in the corresponding 11.45 µm Infrared image, since relatively thin smoke layers are generally transparent to upwelling surface radiation at longer wavelengths.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1742 UTC [click to enlarge]

Ice motion on the Great Lakes

February 19th, 2021 |

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

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) revealed the fracturing of land-fast ice in the far southern portion of Lake Michigan on 19 February 2021. Although the westerly wind speeds were not particularly strong — generally 15-20 knots over water, including Metop ASCAT winds early in the day — these winds in tandem with lake currents were enough to move some of this ice eastward.

Farther to the north over western Lake Superior, 5-minute CONUS sector GOES-16 Visible images (below) also showed a significant amount of ice motion during the day.

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

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

A 30-meter resolution Landsat-8 False Color RGB image viewed using RealEarth (below) provided a more detailed look at the ice structure over western Lake Superior at 1653 UTC. Ice and areas of vegetation-sparse snow cover (rivers, lakes and wildfire burn scars) appear as shades of cyan in the RGB image.

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

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

===== 20 February Update =====

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

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

On 20 February, another look at 1-minute GOES-16 Visible images over southern Lake Michigan (above) indicated that new ice leads were opening up within individual ice floes that had broken free a day earlier.

===== 21 February Update =====

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

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

On 21 February, GOES-16 Visible images (above) showed how southerly winds were shifting much the ice in Lake Erie to the north. However, the effects of lake currents on the ice motion were also evident. As mentioned in this blog post, ice coverage on Lake Erie was around 80%.

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]