The Great Lakes, viewed using GOES-16 and NOAA-20 imagery

January 21st, 2022 |

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) displayed mesovortices over southern Lake Michigan on 21 January 2022. The formation of these mesovortex features was aided by a mid-lake convergence of surface winds, which was suggested by RAP40 surface wind fields and shown n more detail by Metop-C ASCAT winds from this site (below).

Metop-C ASCAT surface scatterometer winds [click to enlarge]

Farther to the north, in spite of a cold night across northeast Wisconsin and Upper Michigan — with morning low temperatures of -30ºF at Laona, Wisconsin and -39ºF at Amasa, Michigan — GOES-16 Visible images (below) showed that southerly winds helped to open an ice lead near the center of Green Bay, with a slow northward drift of pack ice in the northern half of the bay. A lone ice floe was also seen moving northward near the western edge of the clouds in Lake Michigan.

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

A toggle between NOAA-20 VIIRS True Color and False Color RGB images (below) revealed a more detailed view of the ice structure — and also showed the narrow southwest-to-northeast oriented damage path that remained from a June 2007 EF-3 tornado that went through a portion of Menominee, Langlade and Oconto counties. The higher spatial resolution of the VIIRS imagery helped to highlight the aforementioned isolated ice floe in Lake Michigan (which appeared as cyan in the False Color RGB image).

NOAA-20 VIIRS True Color and False Color RGB images [click to enlarge]

To the east, mesovortices were also observed in Lake Huron – long with ice floes drifting away from the coast of Lower Michigan (below).

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

A was the case in Lake Michigan, these Lake Huron mesovortices were forming along an axis of surface wind convergence, seen in Metop-B ASCAT data (below).

Metop-B ASCAT surface scatterometer winds [click to enlarge]

A larger-scale toggle between NOAA-20 VIIRS True Color and False Color RGB images — created using data received from the SSEC/CIMSS Direct Broadcast ground station — provided a view of the entire Great Lakes region (below). 

NOAA-20 VIIRS True Color RGB and False Color RGB images (credit: Margaret Mooney, CIMSS) [click to play animation]

Atmospheric River affecting Alaska

January 21st, 2022 |
MIMIC Total Precipitable Water estimates, 1800 UTC on 20 January – 1700 UTC on 21 January 2022 (Click to enlarge)

MIMIC Total Precipitable Water fields for the 24 hours ending 1700 UTC on 21 January, above, show abundant moisture flowing into southern Alaska. Hourly GOES-17 infrared imagery (Band 13 clean window infrared imagery at 10.3 µm), below, shows a large cyclonic circulation to the south and west of Alaska that is helping to draw moisture towards the state. Level 2 Total Precipitable Water (TPW) is overlain on the imagery and two things stand out: because it is a clear-sky only product, and because the north Pacific Ocean is very cloudy on the 21st, there is little TPW information. Also, GOES-R Total Precipitable Water is not completely Full Disk; TPW is computed to a Local Zenith Angle of 67o (ATBD) and you can see the cut-off for the product in northwestern Canada. Those two things argue for the utility of microwave detection of moisture over Alaska, as shown above.

GOES-17 Clean Window (10.3 µm, Band 13), hourly from 1200 – 1700 UTC on 21 January 2022, overlain with GOES-17 Level 2 Total Precipitable Water (Click to enlarge)

Much of Alaska Southeast from Yakutat to Wrangell is under a Flood Watch. (Image, taken from this site)

Using CSPP Software to view Level 2 GOES-R Products

January 20th, 2022 |
Level 2 Cloudtop Phase product, 1401 UTC on 20 January 2022 (Click to enlarge)

The Community Satellite Processing Package (CSPP) Algorithm Integration Team (AIT) has released a new version of processing software that creates (using updated Enterprise algorithms) Level 2 GOES-R products from radiance products. It also includes processing to provide Quick Look imagery for those products; that is, if you have the processed Level 2 product files, you can display them. One example is shown above, Cloud Top Phase from 1401 UTC on 20 January 2022.

The processing package is available here (a quick easy registration may be required): Look for “AIT Framework V2.0beta4 Software for Linux” and download the gzipped tar file. Note also that documentation is also available (link). Per that documentation, I downloaded the software into a directory that I changed directories to, and I put that directory at the front of my unix PATH, i.e., export PATH=”$PWD:$PATH”. Then I used the aitf-ql (“ql” for quick-look) command:

aitf-ql /path/to/directory/holding/L2products/ACTPC/*s20220201401*.nc --image_size 2560.0 1920. -o /home/scottl/

I have specified both the image size, and the output directory. If you have access to L2 imagery (in NOAA CLASS, for example), this is an easy way to view the imagery. Note that this software will also create QuickLooks from ABI radiance files, as the GOES-17 example below shows. You can create imagery for computed brightness temperature (Bands 7-16) or reflectance (Bands 1-6).

GOES-17 Band 13 (Clean Window, 10.3 µm) at 1401 UTC on 20 January 2022 (Click to enlarge)

Standing wave clouds over northeastern Minnesota

January 19th, 2022 |

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animated GIF | MP4]

GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) revealed the formation of a standing wave cloud along the Minnesota shoreline of Lake Superior on 19 January 2022. This cloud feature was formed by a vertically-propagating internal gravity wave that resulted from the interaction of strong post-cold-frontal northwesterly winds with the topography of the shoreline — the terrain quickly drops from an elevation of about 2000 feet above sea level (over northeastern Minnesota) to about 600 feet above sea level (over Lake Superior) in a very short distance.

In a toggle between GOES-16 Water Vapor and Suomi-NPP VIIRS Infrared Window images at 1811 UTC (below), the coldest cloud-top infrared brightness temperatures were around -40ºC (lime green enhancement).

GOES-16 Mid-level Water Vapor (6.9 µm) and Suomi-NPP VIIRS Infrared Window (11.45 µm) images at 1811 UTC [click to enlarge]

A northwest-to-southeast oriented cross section of RAP40 model fields along line segment F-F’ (below) showed a deep pocket of positive Omega (upward vertical motion, yellow to red colors) that corresponded to the cloud band along Minnesota’s Lake Superior shoreline. Note that this Omega feature was vertically tilted in an “upshear” direction (toward the northwest), and extended upward to the 500 hPa pressure level. The depth and magnitude of this positive Omega decreased with time, leading to the dissipation of the standing wave cloud.

RAP40 model cross sections along Line F-F’ [click to play animated GIF | MP4]