A sequence of GOES-16 (GOES-East) Nighttime Microphysics RGB and Day Snow-Fog RGB images (above) showed the nocturnal development of lake effect fog/stratus plumes (lighter shades of yellow), which drifted northward from Lake Sakakawea in northwestern North Dakota on 26 October 2022. Two of the fog/stratus features moved across the Tioga and Stanley areas, where surface reports briefly indicated a drop in surface visibility to zero along with freezing fog. After sunrise, Day Snow-Fog RGB images revealed the dissipation of these lake effect fog/stratus features — and also displayed the areal coverage of early-season snow cover (shades of red) across the Montana/North Dakota border region.

The GOES-16 Nighttime Microphysics RGB image at 1001 UTC (below) includes an overlay of NOAA-20 VIIRS Sea Surface Temperature (SST) — the southerly flow of cold air (in the 20s F) across Lake Sakakawea’s SST values of 50-54ºF (shades of cyan) helped to create the lake effect fog/stratus features.

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Himawari-9 is slated to become operational (replacing Himawari-8, which has been operational at 140.7^o E Longitude since 2015!) on 13 December 2022 (Link). One change that users might observe arises from the slightly shorter central wavelength in the shortwave infrared band (Band 7). On Himawari-8, the central wavelength is 3.885 µm; on Himawari-9, the central wavelength is closer to 3.829 µm (see this link from JMA, or this one). The effect of the shorter wavelength on Himawari-9 is more noticeable during the daytime, when solar reflectance will lead to warmer observed brightness temperatures, especially over highly reflective convective updrafts (This presentation — see slide 19 — given at the CIRA RGB Workshop in October 2022, suggests daytime differences of up to 5 C.), and especially when compared to longwave infrared imagery as a brightness temperature difference.

The toggle above compares Himawari-8 visible imagery and Day Convection RGB imagery from Himawari-8 and -9 at 0200 UTC on 26 October 2022. in a region near Guam, without much intense convection. Subtle differences in the yellow shading over some convection are apparent (here’s a toggle just between Himawari-8 and -9 Day Convection RGB over Guam). It’s very hard to discern a difference in regions of no convection.

For strong convection, however, as shown below for a case over the south-central Equatorial Pacific, differences in yellow coloring over very strong convection are noteable; users might need to adjust the range of the RGB to draw out details in cloud tops, where, for Himawari-9 imagery, contrast is lost. (Here’s a toggle, over the strong convection, between Day Convection RGBs from Himawari-8 and Himawari-9).

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Spectral Response Functions for the infrared channels are available from Himawari-8 (here) and Himawari-9 (here). You will note that most infrared channels have similar functions; the outlier is band 7, shown below (and in this animated gif).

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Thanks to JMA for providing simultaneous image files for the different bands on Himawari-8 and Himawari-9!

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Day Cloud Phase Distinction RGB images (above) showed the compact exposed low-level circulation of Tropical Invest 94L as it moved northward away from Bermuda (station identifier TXKF) on 25 October 2022. In spite of Invest 94L moving through an environment of increasing deep-layer wind shear, bursts of deep convection did develop near the center of the disturbance around 17 UTC (with the convection just to the northeast eventually producing GLM-detected lightning activity for about an hour). The system was also moving across relatively cool water, with Sea Surface Temperature values of around 25ºC just north of Bermuda.

At the time that the lightning activity first began, the GOES-16 Day Cloud Phase Distinction RGB image at 1751 UTC which includes cursor output values of Cloud Top Height, Cloud Top Phase and RGB components is shown below. The coldest cloud-top infrared brightness temperature of -73ºC occurred about 24 minutes later, as the convective burst was producing an overshooting top at 1815 UTC.

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GOES-16 (GOES-East) Dust RGB images (above) highlighted large plumes of blowing dust (brighter shades of pink) — lofted by strong southwesterly winds (gusting in excess of 60 mph) ahead of an approaching cold front — across parts of the Central Plains on 23 October 2022. This blowing dust resulted in surface visibility values as low as 1 mile at locations such as Liberal KS and Burlington CO. The source region of the largest dust plume was western Kansas, an area experiencing exceptional to extreme drought conditions (according to the US Drought Monitor site).

GOES-16 True Color RGB and Nighttime Microphysics RGB images from the CSPP GeoSphere site (below) showed this blowing dust as lighter shades of tan during the daytime and varying shades of pink during the nighttime. Dust was transported as far northeastward as southern Minnesota and far western Wisconsin by 04 UTC on 24 October; dust briefly reduced the visibility to 4 miles at Sioux City IA and 6 miles at Yankton SD.

A NOAA-20 VIIRS True Color RGB image valid at 1904 UTC (below) indicated that this blowing dust likely affected travel along Interstate 70 across far eastern Colorado and western Kansas — with visibility restrictions to 2.5 miles and wind gusts of 54-55 knots (62-63 mph) at that particular time.

Highest wind speeds so far today. #kswx #nwsddc pic.twitter.com/JTeNIGylIq

— NWS Dodge City (@NWSDodgeCity) October 23, 2022

The Tri-State Area saw peak wind gusts up to 64 mph today with the strong winds. Let us know your wind reports as well as visibility reports due to blowing dust from today here! #COwx #KSwx #NEwx pic.twitter.com/VNzCzmosXC

— NWS Goodland (@NWSGoodland) October 24, 2022

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