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Severe thunderstorms in North Carolina

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... Read More

GOES-16

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images, with plots of SPC storm reports [click to play animation | MP4]

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.

Terra MODIS Total Precipitable Water product [click to enlarge]

Terra MODIS Total Precipitable Water product [click to enlarge]

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Asian dust entrained into a midlatitude cyclone

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... Read More

True Color RGB images from MODIS (Terra) and VIIRS (NOAA-20 and Suomi NPP) [click to enlarge]

True Color RGB images from MODIS (Terra) and VIIRS (NOAA-20 and Suomi NPP) [click to enlarge]

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.

True Color RGB images from MODIS (Terra) and VIIRS (Suomi NPP) [click to enlarge]

True Color RGB images from MODIS (Terra) and VIIRS (Suomi NPP) [click to enlarge]

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.

Surface analyses at 3-hour intervals from 12 UTC on 11 May to 00 UTC on 13 May [click to enlarge]

Surface analyses at 3-hour intervals from 12 UTC on 11 May to 00 UTC on 13 May [click to enlarge]

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.

Himawari-8 Split Window Difference (10.4-12.3 µm) iimages [click to play animation |MP4]

Himawari-8 Split Window Difference (10.4-12.3 µm) images [click to play animation | MP4]

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Ash fall streak from the Sheveluch volcano in Kamchatka

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... Read More

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images, with topography [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images, with topography [click to enlarge]

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).

Himawari-8

Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

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.

Suomi NPP VIIRS True Color RGB images, 06-12 May 2019 [click to play animation | MP4]

Suomi NPP VIIRS True Color RGB images, 06-12 May 2019 [click to play animation | MP4]

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.

Suomi NPP False Color, Ash Probability, Height, Loading and Effective Radius [click to enlarge]

Suomi NPP False Color, Ash Probability, Height, Loading and Effective Radius [click to enlarge]

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.

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Record May snowfall in Duluth, Minnesota

Several snowfall records have already been broken for the Duluth area. The table in the image shows a list of these records. Stay tuned as the Monthly snowfall total and daily snowfall for today (5/9) are likely to change. #mnwx #mnclimate pic.twitter.com/nYbGyV6kZt — NWS Duluth (@NWSduluth) May 9, 2019 GOES-16 (GOES-East)... Read More


GOES-16 “Red” Visible (0.64 µm) images, with plots of surface weather type (yellow) and GLM Groups (red) [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the cloudiness associated with a midlatitude cyclone (surface analyses) that moved across the Upper Midwest on 08 May09 May 2019.  The system produced accumulating snowfall from extreme eastern South Dakota to central/northeastern Minnesota, northwestern Wisconsin and Upper Michigan — storm total accumulations were as high as 10.6 inches at Duluth, Minnesota (observations), 10.4 inches at Poplar, Wisconsin, 5.0 inches at Atlantic Mine, Michigan and 3.0 inches at Astoria, South Dakota (NOHRSC maps of snowfall/snowdepth). Note that the NW-SE oriented band of snowfall straddling the South Dakota/Minnesota border may have been enhanced by upslope flow as northeasterly surface winds encountered rising terrain of the Coteau des Prairies.

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) showed the formation of a SW-NE oriented deformation zone across Minnesota — forcing for ascent was further aided by a stretched lobe of 500 hPa vorticity and 310 K potential vorticity that moved northeastward across the region during this period, along with a favorably-coupled 250 hPa jet streak configuration. Cloud features within the deformation zone across eastern South Dakota into southern/central Minnesota had an appearance resembling convective elements/bands in both the Visible and Water Vapor imagery.

GOES-16 Mid-level Water Vapor (6.9 µm) images, with plots of surface weather type (yellow) and GLM Groups (red) [click to play animation | MP4]

Although lightning was not widespread — and thunder was not explicitly reported in any first-order station observations — there were isolated small clusters of GOES-16 GLM Groups detected, first over northeastern, then central and finally over southwestern Minnesota between 2256 and 0036 UTC (below), indicating the presence of thundersnow.

GOES-16 “Red” Visible (0.64 µm) images, with plots of surface weather type (yellow) and GLM Groups (red) [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with plots of surface weather type (yellow) and GLM Groups (red) [click to enlarge]




Through occasional breaks in the clouds later in the day on 09 May, GOES-16 Day Cloud Phase Distinction Red-Green-Blue (RGB) images (below) revealed the stationary signature of fresh snow cover (darker green) across central to northeastern Minnesota and far northwestern Wisconsin (glaciating cloud tops also appear as shades of green).

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

===== 10 May Update =====

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 Visible images (above) showed two swaths of snow cover remaining across northeastern Minnesota (where reported snow depths were 1-2 inches) and northwestern Wisconsin (where reported snow depths were 4-5 inches) on the morning of 10 May.

Comparisons of GOES-16 Land Surface Temperature (LST) and Visible images at 1401 UTC and 1501 UTC (below) indicated that LST values were as much as 10ºF colder within the areas of snow cover (brighter shades of cyan) compared to adjacent bare ground.

GOES-16 Land Surface Temperature and “Red” Visible (0.64 µm) images at 1401 UTC [click to enlarge]

GOES-16 Land Surface Temperature and “Red” Visible (0.64 µm) images at 1501 UTC [click to enlarge]

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