CIMSS provides sectorized VIIRS true-color imagery for each of the five Great Lakes, and for the entire Great Lakes basin at the Direct Broadcast ftp site (ftp://ftp.ssec.wisc.edu/pub/eosdb/j01/viirs/ and ftp://ftp.ssec.wisc.edu/pub/eosdb/npp/viirs for NOAA-20 and Suomi-NPP, respectively). The imagery above shows NOAA-20 images saved from that site and merged together to make an animation (except for 12, 13, 14 November. Mea Culpa) over Lake Erie. Click here to view the animation as an mp4. (Additional animations for the other Great Lakes have also been created:  Lake Ontario in animated gif / mp4) Lake Huron in animated gif / mp4 ; Lake Michigan in animated gif / mp4; Lake Superior in animated gif ; mp4)

The daily views allow a user to view slow changes in the Lake’s circulation — when skies are clear. Such was the case on 8, 9 and 10 November, shown below. A slow anticyclonic motion in the widest part of central Lake Erie is apparent.

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Late November is a time when cold outbreaks can pass over relatively warm Great Lakes waters (click here for recent observations) and produce lake-effect snow. Gridded NUCAPS observations derived from NOAA-20 CrIS and ATMS data, above, shows a large area with temperatures colder than -12ºC over northwest Ontario and northern Minnesota, just upwind of the Great Lakes;  Lake Superior’s surface temperature at the time was around 5ºC —  a temperature difference that support lake-effect precipitation.  How well do the NUCAPS observations compare to model predictions of the environment?

Forecasts from the 1200 UTC run of the NAM, below, valid at 1800 UTC, and from the 1500 UTC run of the Rapid Refresh, valid at 1900 UTC, show -12ºC in bright magenta.  (Model analyses taken from this website)  NUCAPS analyses suggest the cold air is moving south faster than anticipated by the model.

 

This site can be used to view gridded NUCAPS fields outside of AWIPS.  The 850-mb analysis from the pass is shown below.  It’s important to recall that Gridded NUCAPS fields include data from all retrieved profiles — including profiles for which the infrared retrieval failed (usually in locations with thick clouds, and those from which the infrared and microwave retrievals both failed (usually in locations with rain). This mapping for the temperature gridding below shows where infrared retrievals failed (yellow) and where infrared and microwave retrievals both failed (red).

The ‘yellow’ points north and west of the Great Lakes were associated with clouds that are apparent in this VIIRS True Color image, taken from the UW-Madison Direct Broadcast ftp site (Link). The clouds were associated with a departing low pressure system (link).

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GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed a cutoff low that was moving slowly eastward across eastern New Mexico and the Oklahoma/Texas Panhandle on 28 November – 29 November 2020. This system was helping to produce rain and snow across parts of that region — and some elongated convective elements were evident across the OK/TX Panhandles. Snowfall totals included 2.5 inches in New Mexico and 3.0 inches in Texas, with 4.8 inches at Felt, Oklahoma (NOHRSC).

On the following day, a few north-to-south oriented mesoscale bands of snow cover were evident on GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (below). Since snow is a strong absorber of radiation at the 1.61 µm wavelength, it appeared as darker shades of black on those images. Swaths of lighter snow cover melted rather quickly during the day.

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JMA Himawari-8 True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) showed the volcanic clouds produced by an eruption of Lewotolok in Indonesia on 29 November 2020 — with one cloud plume moving to the northwest, and another moving more rapidly southeastward. This difference in volcanic cloud propagation was due to directional wind shear, as revealed by rawinsonde data from Kupang on the island of Timor (below), located about 250 km southeast of Lewotolok. A shift to northwesterly winds occurred at an altitude around 9 km (the 322 hPa pressure level).

Himawari-8 Ash RGB images (above) displayed an ash signature for both volcanic plumes, which became more diffuse after about 5 hours. Himawari-8 retrievals of Ash Height from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) showed maximum values in the 16-18 km range for the southeast-moving cloud (the  advisory issued by the Darwin VAAC listed maximum height values of 50,000 feet or 15 km).

Himawari-8 False Color images (below) indicated the presence of both SO2 (shades of yellow to green) and ash in the southeastward-moving volcanic cloud.

Explosive #eruption of #Lewotolo (#Lewotolok) #volcano, E. #Indonesia, at 01:50 UTC on Nov 29. Rapidly identified by the @NOAA/@UWCIMSS VOLCAT system due to strong thermal signal and vertical Cloud Growth Anomaly (#VolcanoCb) in #Himawari imagery. Max ash cloud height >12 km. pic.twitter.com/qoPcTlFJpz

— Simon Carn (@simoncarn) November 29, 2020

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