Strong July storm “Zeljko” affects parts of central Europe

July 25th, 2015

Meteosat-10 6.25  µm water vapor channel images [click to play animation]

Meteosat-10 6.25 µm water vapor channel images [click to play animation]

EUMETSAT Meteosat-10 6.25 µm water vapor channel images (above; click image to play animation; also available as an MP4 movie file) showed the well-defined circulation associated with an unusually strong (for July) storm centered just north of the Netherlands on 25 July 2015. Some locations experienced hurricane-force surface winds with this storm — which was given the name “Zeljko” by the Free University of Berlin (surface analyses) — and it was described as the most violent July storm on record for the Netherlands, where a wind gust of 121 km/hour (65 knots, or 75 mph) was reported. Peak wind gusts at major airports are plotted on the water vapor imagery above, which showed 55 knots or 63 mph at Amsterdam in the Netherlands at 13 UTC, and 47 knots or 54 mph at Münster-Osnabrück in northern Germany at 17 UTC. Strong winds disrupted both rail and air traffic in some areas; the winds made for some challenging landings at the Amsterdam Schiphol airport (one of which was documented in this YouTube video).

Meteosat-10 0.8 µm High Resolution Visible images (below; click image to play animation; also available as an MP4 movie file) displayed better detail of the center of the storm circulation when it was immediate off the coast of the Netherlands during the middle of the day.

Meteosat-10 0.8 µm visible channel images [click to play animation]

Meteosat-10 0.8 µm visible channel images [click to play animation]

A Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image visualized using the SSEC RealEarth web map server (below)  showed the center of the strong mid-latitude cyclone just off the coast of the Netherlands; at the time, winds were gusting to 50 knots at the Amsterdam Schiphol airport.

Suomi NPP VIIRS true-color image, with METAR surface reports

Suomi NPP VIIRS true-color image, with METAR surface reports

Wildfire smoke: from Alaska to Norway, via the Arctic and Atlantic Oceans

July 18th, 2015

Meteosat-10 0.8 µm visible channel images [click to play animation]

Meteosat-10 0.8 µm visible channel images [click to play animation]

EUMETSAT Meteosat-10 High Resolution Visible (0.8 µm) images (above; click to play animation; also available as an MP4 movie file) revealed the hazy signature of what appeared to be a ribbon of smoke aloft being transported eastward across the North Atlantic Ocean by the circulation of a large area of low pressure (surface | 500 hPa) on 17 July 2015. Early in the day, the smoke feature stretched from the east coast of Greenland to the central Atlantic Ocean; by the end of the day, the leading edge of the smoke had moved over the British Isles and was headed toward Scandinavia.

A portion of the smoke plume could be seen on Aqua MODIS and Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images (below) as it was approaching the southern portion of Great Britain.

Aqua MODIS and Suomi NPP VIIRS true-color images [click to enlarge]

Aqua MODIS and Suomi NPP VIIRS true-color images [click to enlarge]

On the following morning, Meteosat-10 visible images (below; click to play animation) showed that the leading edge of the smoke ribbon was moving over southern Norway.

Meteosat-10 0.8 µm visible channel images [click to play animation]

Meteosat-10 0.8 µm visible channel images [click to play animation]

The transport pathway of this smoke feature was rather interesting, as we shall explore with the following sets of images.

Suomi NPP VIIIRS 3.74 µm shortwave IR and 0.64 µm visible images on 06 July [click to enlarge]

Suomi NPP VIIIRS 3.74 µm shortwave IR and 0.64 µm visible images on 06 July [click to enlarge]

The 2015 wildfire season in Alaska had been very active — as of 17 July, it was rated as the 4th worst in terms of total acreage burned. In early July, numerous wildfires burning across the interior of Alaska were producing a large amount of smoke, as can be seen in a comparison of of Suomi NPP VIIRS 3.74 µm shortwave IR and 0.64 µm visible channel images at 2131 and 2312 UTC on 06 July (above). The thermal signature of the wildfire “hot spots” showed up as yellow to red to black pixels on the 2 shortwave IR images, while the widespread smoke plumes from the fires are evident on the 2 visible images; even in the relatively short 101 minutes separating the two sets of VIIRS images, notable changes in fire activity could be seen.

Looking a bit farther to the north and west, a sequence of VIIRS 0.64 µm visible images centered over Cape Lisburne (station identifier PALU) in northwestern Alaska covering a 2-day period from 06 to 08 July (below) showed the initial transport of large amounts of smoke from the interior of Alaska northwestward over the Chukchi Sea between Alaska and Russia.

Suomi NPP VIIRS 0.64 µm visible channel images covering the 06-08 July period [click to enlarge]

Suomi NPP VIIRS 0.64 µm visible channel images covering the 06-08 July period [click to enlarge]

Daily composites of Suomi NPP OMPS Aerosol Index covering the period of 04-17 July (below; courtesy of Colin Seftor; see his OMPS Blog post) showed the strong signal of this dense Alaskan smoke (denoted by the red arrows) as it moved from east to west over the far southern Arctic Ocean and along the far northern coast of Russia from 06-10 July. The Aerosol Index signal seemed to stall north of Scandinavia on 12-13 July, but then a small portion began to move toward Iceland and Greenland on 13-15 July around the periphery of a large upper-level low (500 hPa analyses). Finally, some of this smoke was then transported eastward across the Atlantic Ocean around the southern periphery of this upper-level low on 17 July, as was seen on the Meteosat-10 visible images at the beginning of this blog post.

Suomi NPP OMPS Aerosol Index images, covering the period 04-17 July [click to enlarge]

Suomi NPP OMPS Aerosol Index images, covering the period 04-17 July [click to enlarge]

CALIOP lidar data from the CALIPSO satellite (below) showed the vertical distribution of the Alaskan smoke over and off the coast of northern Norway on 11 July. The signal of the smoke was located in the center portion of the images; while there appeared to be some smoke at various altitudes within the middle to upper troposphere, a significant amount of smoke was seen in the lower stratosphere in the 10-12 km altitude range.

CALIPSO CALIOP lidar data showing the smoke over northern Norway on 11 July [click to enlarge]

CALIPSO CALIOP lidar data showing the smoke over northern Norway on 11 July [click to enlarge]

Wildfires in Greece

July 17th, 2015
Suomi NPP VIIRS true-color image (actual satellite overpass time 1112 UTC)

Suomi NPP VIIRS true-color image (actual satellite overpass time 1112 UTC)

Suomi NPP VIIRS (above; toggle with Google maps) and Aqua MODIS (below; toggle with Google maps) true-color Red/Green/Blue (RGB) images visualized using SSEC RealEarth showed 2 smoke plumes from wildfires burning in Greece on 17 July 2015. These fires were causing evacuations in some areas, according to the Wildfire Today site.

Aqua MODIS true-color image composite (actual satellite overpass times 1102 UTC and 1240 UTC)

Aqua MODIS true-color image composite (actual satellite overpass times 1102 UTC and 1240 UTC)

Surface observations around the time of the images (below) indicated that air temperatures were in the 90-100º F (32.2-37.8º C) range at many sites across the region. Winds at Athens were from the northeast at 26 knots, with gusts to 36 knots (time series plot of surface data). Near the edge of the larger smoke plume to the southwest, the surface visibility was restricted to 5 miles at Kithira (but was as low as 3 miles at 10 UTC: time series plot of surface data).

Aqua MODIS true-color image, with Athens, Greece surface observation (click to enlarge)

Aqua MODIS true-color image, with Athens, Greece surface observation (click to enlarge)

Aqua MODIS true-color image, with Kithira, Greece surface observation (click to enlarge)

Aqua MODIS true-color image, with Kithira, Greece surface observation (click to enlarge)

EUMETSAT Meteosat-10 High Resolution Visible (0.8 µm) and shortwave IR (3.92 µm) images (below; click to play animation; also available as an MP4 movie file) showed thee temporal evolution of the smoke plume and the associated fire hot spots (dark black to red pixels). Athens is located within the cyan circle on the images.

Meteosat-10 visible and shortwave IR images (click to play animation)

Meteosat-10 visible and shortwave IR images (click to play animation)

Tornado-producing severe thunderstorm in northern Italy

July 8th, 2015
Metoesat-10 High Resolution Visible (0.8 µm) images (click to play animation)

Metoesat-10 High Resolution Visible (0.8 µm) images (click to play animation)

EUMETSAT Meteosat-10 SEVIRI High Resolution Visible (0.8 µm) images (above; click to play animation) showed the development of an isolated supercell thunderstorm that produced large hail and a violent tornado (1 fatality; estimated EF3 damage) near Venice, Italy (station identifier LIPZ) around 1530 UTC on 08 July 2015. Additional information and imagery is available from meteonetwork.

The corresponding Meteosat-10 Infrared (10.8 µm) images (below; click to play animation) revealed the development of a very cold overshooting top prior to the development of the tornado (1430-1500 UTC) — the minimum cloud-top IR brightness temperature was -70º C (darker black enhancement) on the 1445 UTC image. The overshooting top then rapidly collapsed, as seen by the warming cloud-top IR brightness temperatures on the 1515 and 1530 UTC images. Such an overshooting top collapse sometimes occurs prior to tornado formation in a supercell thunderstorm.

Meteosat-10 Infrared (10.8 µm) images (click to play animation)

Meteosat-10 Infrared (10.8 µm) images (click to play animation)

A close-up view of the 1500 UTC Metosat-10 Infrared (10.8 µm) image is shown below, as displayed using SSEC RealEarth.

Meteosat-10 Infrared (10.8 µm) image, displayed using RealEarth

Meteosat-10 Infrared (10.8 µm) image, displayed using RealEarth