Lake Effect snow moved over Chicago on 28 January 2022. Along-lake winds, as shown below in scatterometry from this site, produced a single snow band that released on Chicago. The image above shows Nighttime microphysics with and without radar displayed. Once the relationship between the radar and the RGB is established, it is not difficult to monitor the stationarity of the band.

After sunrise, other ABI bands are available to highlight precipitating lake-effect snowbands. RGB combinations that include Band 5 (1.6 µm) are of particular use because they can highlight glaciation in the cloud. Consider the examples below showing two RGBs and visible imagery with and without radar overlain. Which one would you choose and use to highlight the precipitating snow band? Will that choice change with sun angle, do you think?

The Day Cloud Phase Distinction RGB, below, animated from 1426 to 1921 UTC (click here to see the animation without observations), highlights the narrow nature of the band as it moves inland over Chicago.

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Microwave-derived estimates of Total Precipitable Water (TPW), above, from MIMIC TPW, show an increase in moisture around the Samoan Islands to the west of 170^o W. Percent of Normal mappings of blended TPW in this region, as shown below (taken from this site), show values at >150% of normal.

In anticipation of heavy rains, the National Weather Service Pacific Region requested a Mesoscale Domain (a complete list of messages is here) centered on Tutuila, the main island of American Samoa, through 1100 UTC on 28 January. An animation of GOES-17 Band 13, below, (every 5 minutes, rather than the 1-minute cadence of Mesoscale domains) overlain on top of the Level 2 Total Precipitable Water product (a product that is computed hourly for the Full Disk domain), shows a focus of convection moving westward over American Samoa and Samoa. Note the degradation of the Level 2 Product TPW that is associated with the poor functionality of the Loop Heat Pipe on GOES-17 that occurs at night. Magenta values in the TPW enhancement signify values exceeding 2″. Samoa and American Samoa are within a ribbon of exceptional moisture.

GOES-17 Visible Imagery, below, during the daytime, also show widespread convection moving into the Samoan waters. A benefit of the visible imagery is that surface lines of convergence that may initiate convection are apparent with the 5-minute cadence shown below; those lines are even more apparent in 1-minute imagery (shown here from 1825 – 2234 UTC)

Added, 28 January: the two final hours of the mesoscale domain are shown below. The axis of the deepest moisture has shifted westward through the mesoscale domain from the previous day; showers continue to develop.

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US Space Force EWS-G1 Infrared Window (10.7 µm) images [click to play animated GIF | MP4]

US Space Force EWS-G1 (formerly GOES-13) Infrared Window (10.7 µm) images (above) showed Cyclone Batsirai in the South Indian Ocean as it rapidly intensified from a Tropical Storm at 06 UTC to Category 2 storm (at 12 UTC on 27 January) and briefly exhibited a pinhole eye — and then rapidly collapsed back to Tropical Storm intensity by 00 UTC on 28 January 2022 (SATCON).

EWS-G1 Visible (0.63 µm) images  (below) also displayed the rapid formation of a pinhole eye.

US Space Force EWS-G1 Visible (0.63 µm) images [click to play animated GIF | MP4]

A map of Sea Surface Temperature from the CIMSS Tropical Cyclones site (below) showed that Batsirai had been moving over relatively warm water during its period of rapid intensification. 

Sea Surface Temperature, with the track of Cyclone Batsirai [click to enlarge]

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

GOES-16 (GOES-East) True Color RGB images created using Geo2Grid (above) displayed the areal extent of snow cover across parts of North Carolina, Virginia, Maryland and Delaware — resulting from a 21-22 January winter storm (NWS Newport/Morehead City NC | NWS Wakefield VA) — that still remained on 24 January 2022.

A Suomi-NPP VIIRS True Color RGB image along with the corresponding GOES-16 Land Surface Temperature (LST) derived product at 1800 UTC or Noon EDT  (below) showed that LST values over deeper snow cover near the Virginia/North Carolina border were held to the upper 30s and low 40s F (shades of blue), in contrast to upper 50s and low 60s F (shades of orange) over bare ground not far to the south and west. The closest reporting station to the coldest LST value of 37ºF was Elizabeth City, NC (where the morning snow depth was 3.0 inches).

Suomi-NPP VIIRS True Color RGB image and GOES-16 Land Surface Temperature product [click to enlarge]

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