1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images, with 5-minute plots of Derived Motion Winds (above) revealed a cumulus cloud field that beautifully outlined the flow around an area of high pressure that was centered over Louisiana on 15 May 2019. Subsidence within the dome of high pressure prevented significant vertical development of these cumulus clouds.

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GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed clusters of severe thunderstorms that produced tornadoes and large hail (SPC storm reports) across parts of central and eastern North Carolina on 13 May 2019.

A west-to-east oriented quasi-stationary frontal boundary was acting as a focusing mechanism for many of these thunderstorms — the Terra MODIS Total Precipitable Water product at 1525 UTC (below) showed TPW values around 28 mm or 1.1 inch (lighter green enhancement) pooled immediately south of this frontal boundary.

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True Color Red-Green-Blue (RGB) images from the MODIS instrument (on the Terra satellite) and the VIIRS instrument (on the NOAA-20 and Suomii NPP satellites) as viewed using RealEarth (above) revealed a tan-colored swirl of dust that had been lofted from the surface and entrained into the circulation of a midlatitude cyclone along the Mongolia/China border on 12 May 2019.

A sequence of MODIS/VIIRS True Color RGB images from Terra and Suomi NPP on 10, 11 and 12 May (below) showed the initial signature of surface-based blowing dust appearing in the Kumul and Jiuquan areas of northwestern China on 11 May, before it became wrapped into the circulation of the aforementioned midlatitude cyclone on 12 May.

Surface analyses at 3-hour intervals (source), from 12 UTC on 11 May to 00 UTC on 13 May (below) illustrated the strong pressure gradient between a large dome of high pressure over Mongolia and a developing midlatitude cyclone along the Mongolia/China border on 11 May — strong surface winds generated by this pressure gradient initially caused the blowing dust to begin in northwestern China.

JMA Himawari-8 Split Window Difference (10.4-12.3 µm) images (below) showed the signature of dust (yellow to cyan enhancement) moving eastward from the desert source region in northwestern China and becoming wrapped into the circulation of the midlatitude cyclone along the Mongolia/China border.

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In a comparison of Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images on 12 May 2019 (above), a dark volcanic ash fall streak was evident in the Visible image, which extended over 100 miles southward from the Sheveluch volcano on the Kamchatka Peninsula of Russia. This feature was a layer of volcanic ash that had been deposited on top of existing snow cover — note that most of the dark ash fall streak exhibited much cooler infrared brightness temperatures compared to the bare ground of the interior valley to the west (since the ash streak existed on top of a higher-altitude area of snow cover).

This ash fall streak was a result of an explosive eruption of the volcano over a month earlier, on 10 April — the volcanic ash plume could be seen moving southward in Himawari-8 Visible (0.64 µm) images (below).

An interesting aspect of this long-lived ash fall streak was that a portion of it was apparently covered by a layer of fresh snowfall at some point after the eruption — and a 7-day sequence of Suomi NPP VIIRS True Color Red-Green-Blue (RGB) images viewed using RealEarth (below) suggested that this layer of new snow was melting with the aid of the high May sun angle, gradually revealing more of the original length of the ash fall streak.

Note that there was another small volcanic plume moving south-southwestward from Sheveluch in the 09 May VIIRS True Color image — retrieved quantities of ash probability, height, loading and effective radius for this volcanic plume (source) are shown below.

This type of volcanic ash fall streak frequently occurs on the snow-covered Kamchatka Peninsula — here is an example from March 2013.

Thanks go out to Santiago Gassó for bringing this interesting feature to our attention.

In #Kamchatka today, this feature caught my attention. A long dark streak , it is not atmospheric, it appears lack of snow on the ground, it is there the previous days. I am not super familiar with the topo but I do not recall seeing it before. Any guess? some ground heating? pic.twitter.com/ShVbWCPJhF

— Santiago Gassó (@SanGasso) May 12, 2019

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