A comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed plumes of blowing snow originating over northern Lake Winnipeg and southern Lake Manitoba, lofted by strong northerly winds in the wake of a cold frontal passage. The blowing snow originating over the southern portion of Lake Manitoba was then then channeled southward into the Red River Valley (topography), with horizontal convective roll clouds eventually developing.

In a sequence of MODIS Visible (0.65 µm) and Snow/Ice (1.61 µm) images from Terra and Aqua in addition to VIIRS Visible (0.64 µm) and Snow/Ice (1.61 µm) from NOAA-20 and Suomi NPP (below), the plumes of blowing snow were also easier to detect in the Snow/Ice images (due to better contrast against the existing snow cover).

A closer view of the Lake Manitoba plume is shown below; surface observations indicated that visibility was reduced to 1/4 statute mile at locations such as Calilier ND (plot | text) and Hallock MN (plot | text).

An Aqua MODIS True Color Red-Green-Blue (RGB) image centered on Winnipeg, Manitoba (source)  is shown below.

Toggles between 250-meter resolution Terra/Aqua MODIS True Color and False Color RGB images (centered between Lake Manitoba and the North Dakota border) from the MODIS Today site (below) provided a more detailed view of the blowing snow streaming southeastward from Lake Manitoba into far northeastern North Dakota and far northwestern Minnesota.

View only this post Read Less

GOES-17 images shown here are preliminary and non-operational

When GOES-17 was in the test position at 89.5 degrees W Longitude, GOES-16 and GOES-17 in satellite projections could be used to create stereoscopic imagery (example 1; example 2; example 3); the human brain could correct for any projection differences to create 3-dimensional imagery (as explained here, for example). Because GOES-17 is now in its operational position at 137.2 degrees W Longitude, the perspective differences are too great. However, a simple remap of the imagery to the same native projection (Mercator in this case) allows for the construction of animations that show three dimensions, as shown above for the storm making landfall over southern California on 14 January 2019. The coastlines of Washington and Oregon are apparent in the imagery, as is Baja California. Multiple cloud layers become apparent in the imagery.

View only this post Read Less

* GOES-17 images shown here are preliminary and non-operational *

A GOES-17 Mid-level (6.9 µm) Water Vapor image with contours of NAM40 model 500 hPa geopotential height (above) showed an arc of dry air aloft over the far western US at 1202 UTC on 13 January 2019. This was a classic example of an “inside blocking” boundary as described by Weldon and Holmes, 1991 (page 75) — following middle/upper-tropospheric anticyclogenesis, an easterly flow of dry (via a period of synoptic-scale sinking) air on the equatorward side of the high pressure eventually becomes elongated within a deformation zone, acting to either completely block or slow the arrival of an upstream flow of moisture from the west. The arrival of a dry easterly flow aloft was very evident in a sequence of plots of rawinsonde data from Reno, Nevada during the period 12 January/12 UTC to 13 January/12 UTC (below). At 12 UTC on 13 January the Total Precipitable Water at Reno was 3.3 mm or 0.13 inch (their mean value for that day/time is 7.9 mm or 0.31 inch).

Since air within the middle and upper troposphere was becoming increasingly dry, the weighting functions for the three GOES-17 Water Vapor spectral bands were shifted to lower altitudes — weighting functions calculated using rawinsonde data from Reno, Nevada (12 January/12 UTC to 13 January/12 UTC) are shown below. This downward shift in weighting functions allowed radiation from the surface of higher-terrain features to reach the satellite with minimal absorption and re-radiation from water vapor aloft.

An animation of GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor imagery (below) revealed a clear signature of the higher terrain of the Sierra Nevada and other mountain ranges in California and Nevada.

Another ABI spectral band affected by absorption of tropospheric water vapor is the Near-Infrared “Cirrus” (1.37 µm) — after sunrise, a comparison of Cirrus and “Red” Visible (0.64 µm) images (below) also showed a clear signature of the highest terrain in the 1.37 µm imagery.

View only this post Read Less

* GOES-17 images shown here are preliminary and non-operational *

A comparison of GOES-17 (soon to become GOES-West) and GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) revealed a plume of lake effect clouds streaming south of Fort Peck Lake in northeastern Montana on 11 January 2019. As a cold front moved south-southwestward across the region (surface analyses), surface winds shifted to northerly at Glasgow KGGW which brought a flow of colder air across the still-unfrozen lake. Note that before sunrise the initial formation of the lake effect clouds could be seen on Shortwave Infrared imagery — and after sunrise, the feature appeared progressively warmer (shades of orange) on 3.9 µm images as the supercooled water droplets at the cloud top reflected increasing amounts of incoming solar radiation.

An Aqua MODIS Sea Surface Temperature product at 1942 UTC (below) showed that mid-lake water temperatures south of Glasgow were as warm as 36ºF (lighter shades of blue) — significantly warmer than Glasgow’s early morning surface air temperatures that were as cold as 17ºF at 14 UTC.

A comparison of the Sea Surface Temperature product with the corresponding Aqua MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.9 µm) and Infrared Window (11.0 µm) images at 1942 UTC (below) showed the lake effect cloud plume as well as a patch of snow cover northeast of the lake — snow absorbs radiation at the 1.61 µm wavelength, making it appear dark on the “Snow/Ice” image.

Terra and Aqua MODIS True Color and False Color Red-Green-Blue (RGB) images viewed using RealEarth (below) showed that parts of the Missouri River upstream (to the west of) of Fort Peck Lake — in the area of the UL Bend National Wildlife Refuge — were beginning to freeze (ice and snow appear as shades of cyan on the False Color RGB images).

View only this post Read Less