Re-suspended ash from the Katmai volcano in Alaska

February 28th, 2021 |

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

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

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) showed the hazy signature of a plume of re-suspended ash from the 1912 Katmai volcanic eruption. Strong surface winds gusting to 50-55 knots — caused by a strong pressure gradient along the western periphery of a Storm Force low in the Gulf of Alaska (surface analyses) — lofted some of the thick layer of ash that has remained on the ground in the vicinity of the volcano. The most dense portion of the aerosol plume was  moving across the Barren Islands (between Kodiak Island to the south and the Kenai Peninsula to the north); near the northern edge of the aerosol plume, surface visibility was reduced to 5 miles at Homer and 7 miles at Seldovia.

A sequence of Suomi NPP VIIRS Day/Night Band (0.7 µm) images (below) showed that the plume had formed before sunrise — ample illumination from a Full Moon provided vivid “visible mages at night” (at 1131 UTC and 1311 UTC).

Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

ASCAT winds from Metop-C at 0743 UTC and 2124 UTC (source) are shown below — they indicated a dramatic increase in surface wind speeds  of 50 knots or greater emerging from the Barren Islands into the Gulf of Alaska later in the day.

ASCAT winds from Metop-C, at 0743 UTC and 2124 UTC [click to enlarge]

ASCAT winds from Metop-C, at 0743 UTC and 2124 UTC [click to enlarge]

GOES-17 True Color RGB images created using Geo2Grid (below) provided a clearer view of the re-suspended ash plume. North of the plume, note the tidal ebb and flow of ice within Cook Inlet and Turnagain Arm leading into the Anchorage area.

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

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

Ice formation in southern Lake Michigan

February 7th, 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]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) revealed an increasing amount of ice coverage within the nearshore waters of southern Lake Michigan on 07 February 2021 — this was due to a recent influx of arctic air across the Upper Midwest and western Great Lakes.

A sequence of VIIRS True Color RGB and False Color RGB images from Suomi-NPP and NOAA-20 (below) provided 375-meter resolution views of the lake ice.

VIIRS True Color RGB and False Color RGB images [click to enlarge]

VIIRS True Color RGB and False Color RGB images [click to enlarge]

The MIRS Sea Ice Concentration product derived from Suomi-NPP ATMS data (below) depicted maximum values of 60-63% (lighter green), which was fairly consistent with the Ice Concentration analysis from GLERL.

MIRS Sea Ice Concentration product derived from Suomi-NPP ATMS data [click to enlarge]

MIRS Sea Ice Concentration product derived from Suomi-NPP ATMS data [click to enlarge]

The Suomi-NPP VIIRS Sea Surface Temperature product (below) revealed values of 34-39ºF along the leading edge of widespread lake effect cloud bands that were producing snowfall in Lower Michigan.

Suomi-NPP VIIRS Sa Surface Temperature product [click to enlarge]

Suomi-NPP VIIRS Sea Surface Temperature product [click to enlarge]

A 250-meter resolution Aqua MODIS True Color RGB image of the ice at 1917 UTC (from the MODIS Today site) is shown below.

Aqua MODIS True Color RGB image [click to enlarge]

Aqua MODIS True Color RGB image [click to enlarge]

Finally, an overpass of Landsat-8 offered a 30-meter resolution view of a portion of the lake ice near Chicago, as visualized using RealEarth (below).

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

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

South Atlantic cyclone off the coast of Uruguay

February 5th, 2021 |

GOES-16

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

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a cyclone (surface analyses) moving off the coast of Uruguay on 05 February 2021. What appeared to be an eye-like feature developed at the storm center toward the end of the day.

A toggle between VIIRS True Color RGB images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) provided a larger scale perspective of the cyclone.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

Cold temperatures across the North Slope of Alaska

February 4th, 2021 |

Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) images (above) revealed a large area of cold surface infrared brightness temperatures across much of the North Slope of Alaska on 04 February 2021 — with the coldest IR temperature being -56ºC (darker shades of violet) about 30 miles south-southeast of Umiat (PAUM) on the 1221 UTC image. The surface air temperature at the nearby Umiat RAWS site around that time was -55ºF (-48.3ºC). Narrow fingers of cold air drainage into some of the river valleys along the northern slopes of the Brooks Range (topography) were also apparent.

The corresponding GOES-17 “Clean” Infrared Window (10.35 µm) images (below) also showed the large area of cold surface IR brightness temperatures, but the temperatures were not as cold (in the -40 to -50ºC range), and the small-scale signatures of various topographical features were not depicted.

GOES-17 "Clean" Infrared Window (10.35 µm) images [click to enlarge]

GOES-17 “Clean” Infrared Window (10.35 µm) images [click to enlarge]

A toggle between Infrared Window images from Suomi NPP VIIRS and GOES-17 (10.35 µm) at 1223 UTC is shown below.

Infrared Window images from Suomi NPP VIIRS and GOES-17 (10.35 µm) at 1223 UTC [click to enlarge]

Infrared Window images from Suomi NPP VIIRS (11.45 µm) and GOES-17 (10.35 µm) at 1223 UTC [click to enlarge]