The highest peaks of the Big Island of Hawai’i are under Blizzard warnings as of early 3 December 2021, as shown in the screen capture below from the National Weather Service in Honolulu.

The image above shows NUCAPS Sounding Availability in AWIPS over the central Pacific. A long swath of profiles was available from a NOAA-20 overpass near 1200 UTC. Each of the dots represents a profile of temperature and moisture over the Pacific, a large region with little observational data. These retrieved profiles can give useful information about the structure of the atmosphere in advance of a storm. In this case, moisture is apparent, and so is mid-tropospheric drying; thus, evaporational cooling from precipitation might be important. The freezing level of the profiles is also shown, and most values are near 12500′. (Mauna Loa and Mauna Kea top out at 13,679′ and 13,803′, respectively). Note that the relatively low freezing levels extend far to the south, as shown in this NUCAPS profile at 17.3N, 160 W, at the southern edge of the domain above!

Two of the NUCAPS soundings in the animation above are near upper-air radiosondes at Hilo and at Lihue. A toggle between the Hilo sounding and NUCAPS profile is just below; underneath that profile is the toggle between the Lihue soundings and the adjacent NUCAPS profile. Keep in mind with these comparisons that the radiosonde is a sensor at one point moving up through the atmosphere whereas the NUCAPS profile represents a large volume of air. Gross aspects of the two soundings agree: moisture in the levels, dry air aloft.

Individual NUCAPS profiles can be aggregated into gridded fields to depict values along horizontal surfaces. These can be found at this website, for example, from SPoRT. The 850-mb field (a level far below the peaks!) shows temperatures near freezing not too far north of Hawai’i.

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AWIPS tip: It can be tedious to load up individual soundings. PopUp SkewTs can be used in AWIPS to quickly scan through the profiles to identify any threshold values. PopUp SkewTs can be accessed under the Volume Browser.

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Added, 8 December 2021: The NUCAPS Sounding Availability plot, above, shows a swath several days after the snow, and after warmer air has moved in from the east. The easternmost sounding just south of 20 N, below, shows a freezing level closer to 14600′!

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GOES-17 (GOES-West) “Red” Visible (0.64 µm) images, with and without plots of Visible Derived Motion Winds (above) showed a lower-tropospheric vortex propagating west-northwestward to the north of Hawai’i on 02 December 2021. There were no ship or buoy reports in the vicinity of the vortex, but Derived Motion Wind speeds were 20-25 knots or less during this time period.

Convergence near the center of the vortex was aiding in the development of some shallow convection — and GOES-17 Day Cloud Phase Distinction RGB images (below) indicated that the tops of many cloud features comprising the vortex were glaciating (exhibiting shades of green to yellow),

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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!

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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 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.

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 – 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.

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.

 

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

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 .

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