MODIS-derived (from Terra and Aqua satellites) Bidirectional Reflectance Distribution Function (BRDF), above, (as noted in this blog post), shows the (meager) snow distribution as of early December. How many counties (or parishes) in the United States (out of more than 3000!) are clearly delineated in Satellite Imagery such as what is shown above? Counties that are primarily islands (or peninsulas) — Dare County in North Carolina, for example — show up well (False Color image shown here, in an image taken from VIIRS Today), but the inland borders do not.

For a county to be recognizable from Space, its landcover must differ significantly from adjacent counties. In the zooming-in animation below (from RealEarth, click the image to zoom in), users will note that Menominee County in northeast Wisconsin becomes apparent. Menominee County is almost entirely forest (unlike its neighbors) and as such has a much different signal in the (for example) 0.87 µm channel on VIIRS (or 0.86 µm on GOES-16). When it is zoomed in, the outlines of the County are obvious.

The county also shows up well in the VIIRS True Color/False Color toggle below, from 30 November. The southern edge of the snow at that time was just southeast of Menominee County, and the land-use change across the county border is apparent. Snow in the county (cyan in the False Color enhancement) is difficult to view from the imagery — because of the pine forests!

Menominee County has been on this blog before! In 2007, a tornado tracked through Menominee County and left a visible scar in satellite imagery (link). Eight years later (link), the scar was still apparent! November 6 2021 was a clear day over the upper Midwest. Suomi-NPP True Color imagery, below (link to original large image), still shows vestiges of the scar!

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NOAA-20 True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 True Color RGB and Infrared Window (11.45 µm) images viewed using RealEarth (above) showed a large convective burst south of the center of Tropical Storm Nahtoh — located in the Philippine Sea — at 0356 UTC on 01 December 2021. A robust overshooting top near the center of the convective burst exhibited a cluster of cloud-top infrared brightness temperatures of -100ºC and colder (red pixels embedded within purple-to-yellow-to-black enhancement).

2.5-minute rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (below) displayed the evolution of Nyatoh as it transitioned from a Tropical Storm to a Category 1 Typhoon at 1200 UTC. The coldest cloud-top infrared brightness temperatures of convective overshooting tops were in the -90 to -98ºC range, but did not quite reach the -100ºC threshold that was seen in the VIIRS imagery.

JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animated GIF | MP4]

Himawari-8 Infrared images with contours of 18 UTC deep-layer wind shear from the CIMSS Tropical Cyclones site (below) showed that Nyatoh was moving through an environment of low to moderate shear.

Himawari-8 Infrared images, with contours of 18 UTC deep-layer wind shear [click to enlarge]

Himawari-8 Infrared – Water Vapor Difference images (below) indicated that much of the deep convection associated with Typhoon Nyatoh was likely penetrating the local tropopause. This product is discussed here.

Himawari-8 Infrared – Water Vapor Difference images [click to enlarge]

DMSP SSMIS Microwave (85 GHz) images at 1905 UTC and 2148 UTC are shown below. A completely closed eyewall had not yet formed at those times.

DMSP-18 SSMIS Microwave (85 GHz) image at 1905 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 2148 UTC [click to enlarge]

===== 02 December Update =====

JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animated GIF | MP4]

Typhoon Nyatoh rapidly intensified to a Category 3 storm by 1200 UTC, and then Category 4 by 1800 on 02 December (ADT | SATCON) — 2.5-minute rapid scan Himawari-8 Infrared images (above) showed the storm during this intensification period. During the 1200-1800 UTC time frame, subtle waves could be seen propagating south-southwestward across the cold central dense overcast, away from the center of Nyatoh. Energy from those waves was apparently propagating vertically, such that mesospheric airglow waves (reference) were evident in a Suomi-NPP VIIRS Day/Night Band (0.7 µm) image around 1650 UTC (below). Other examples of mesospheric airglow waves — caused by tropical cyclones, deep convection or jet streams — are available here .

Suomi-NPP VIIRS Day/Night Band (0.7 µm) image at 1650 UTC [click to enlarge]

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RealEarth has added GOES-17 IFR Probability Fields to its product suite (GOES-16 IFR Probability fields have been available in RealEarth for some time). They can be accessed most simply by entering ‘IFR Probabilty’ in the RealEarth search box. At present only the ‘PACUS’ domain (the GOES-17 equivalent of the GOES-16 ‘CONUS’ domain) is available, at 5-minute time-steps. An example over western Washington and offshore waters is shown above.

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The GOES-17 Air Mass RGB, above, shows a distinct jet in the northwestern quadrant of the image. Derived Motion winds are as strong as 170 knots between 250-350 mb (they’re almost as strong from 350-450 mb!) In contrast, winds from 450-600 mb are closer to 70 knots just to the northwest of that upper-level jet. As you might expect, Turbulence Probability fields have a maximum along that very strong jet, as shown below. High Probabilities of turbulence also exist northeast of Hawaii (in the lower left corner of the image), and near the upper-level low at 33 N, 134 W. Turbulence Probablities are derived from GOES-17 infrared data and from GFS estimates of upper level stability. (Training on this product is available here under ‘Machine-Learning for Turbulence Detection by Satellite’).

In addition to their availability in AWIPS, as shown above (via an LDM feed from CIMSS), Turbulence Probabilities are also available on line at https://cimss.ssec.wisc.edu/turbulence. Values from 2000 UTC are shown below in the GOES-17 ‘Gulf of Alaska’ and ‘Vancouver’ domains.

Turbulence probability fields from 2120 UTC, below, show that most of the Pilot Reports of turbulence align with the axis of higher probabilities. But not all of them: Severe turbulence (denoted in red) is noted near Oahu in a region of small (but not zero!) probability.

The strong jet obvious in the Air Mass RGB is associated with strong transport of moisture towards the Pacific Northwest. MIMIC Total Precipitable Water (TPW) fields, below, show abundant moisture traveling across most of the Pacific. OSPO’s TPW Percent of Normal fields show values exceeding 200% in this moist airstream (image from 1500 UTC on 30 November).

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