Long-track Tornado over southwestern Manitoba

July 27th, 2015

Color-enhanced Infrared (10.7 µm) imagery from GOES-15 (left) and GOES-13 (right), times as indicated  [click to play animation]

Color-enhanced Infrared (10.7 µm) imagery from GOES-15 (left) and GOES-13 (right), times as indicated [click to play animation]

A strong tornado (rated a high-end EF-2) touched down near Pierson, Manitoba at around 0130 UTC on 28 July or 8:30 pm local time on 27 July (Press Report) and persisted until about 0355 UTC or 10:55 pm local time (near Virden Manitoba). The animation above shows GOES-15 (left) and GOES-13 (right) Infrared imagery from 0000 UTC through 0430 UTC. The strong storm lifting northward over southwestern Manitoba is apparent, with an enhanced-V signature especially noticeable in the GOES-13 imagery.

A closer view of the tornadic supercell is shown below, with overlays of surface reports (metric units). The pulsing nature of the overshooting tops is evident in the fluctuation of the coldest cloud-top IR brightness temperatures (the coldest of which was -69º C, darker black color enhancement, on the 0300 UTC GOES-15 and 0315 UTC GOES-13 images). There are different apparent positions of the storms based on the satellite that views them because of parallax shifts. Such shifts are especially pronounced at higher latitudes with very tall storms.

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images, with surface reports [click to play animation]

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images, with surface reports [click to play animation]

A 1-km resolution Terra MODIS 11.0 µm Infrared image at 0331 UTC is shown below; the minimum cloud-top IR brightness temperature was -73º C.

Terra MODIS 11.0 µm Infrared image [click to enlarge]

Terra MODIS 11.0 µm Infrared image [click to enlarge]

GOES-13 Visible (0.63 µm) imagery, times as indicated  [click to play animation]

GOES-13 Visible (0.63 µm) imagery, times as indicated [click to play animation]

Visible imagery from GOES-13 (above) and GOES-15 (below) showed the overshooting tops associated with the tornadic thunderstorm, as well as the rapidly expanding cirrus shield.

GOES-15 Visible (0.62 µm) imagery, times as indicated  [click to play animation]

GOES-15 Visible (0.62 µm) imagery, times as indicated [click to play animation]

A closer view of the tornadic supercell from GOES-15 vs GOES-13 is shown below, with overlays of surface reports (metric units). The overshooting tops are again apparent on the images, along with an above-anvil plume (which is easier seen on the GOES-13 images, due to a more favorable forward-scattering viewing geometry). The robust convective development was first seen on the 2030 UTC images, in the vicinity of the Saskatchewan/Manitoba/North Dakota border region.

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images, with surface reports [click to play animation]

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images, with surface reports [click to play animation]

As an area of low pressure was deepening over eastern Montana, warm and humid air was surging northward into far southern Saskatchewan and Manitoba (surface analyses). GOES sounder derived product images (available from this site) of Convective Available Potential Energy (CAPE), Lifted Index, and Total Precipitable Water (below) showed that the environment across southern Manitoba was becoming increasingly unstable and moist leading up to the time of convective initiation.

GOES sounder CAPE derived product images [click to play animation]

GOES sounder CAPE derived product images [click to play animation]

GOES sounder Lifted Index derived product images [click to play animation]

GOES sounder Lifted Index derived product images [click to play animation]

GOES sounder Total Precipitable Water derived product images [click to play animation]

GOES sounder Total Precipitable Water derived product images [click to play animation]

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

How long can Tornado Scars last?

July 22nd, 2015
MODIS True-Color Image,  June 9, 2007 (left) and  July 15, 2015 (right) (click to enlarge)

MODIS True-Color Image, June 9, 2007 (left) and July 15, 2015 (right) (click to enlarge)

On 07 June 2007, severe thunderstorms moved through the Upper Midwest (blog post on that event), spawning strong tornadoes; from the SPC Storm Reports comments:

HUNDREDS OF TREES DOWN NORTH OF ZOAR. (GRB)

NUMEROUS TREES DOWN OF 1 FOOT DIAMETER AND GREATER. TRACK WAS APPROXIMATELY 1/4 MILE IN LENGTH AND 125 YARDS WIDE (MQT)

Terra MODIS data on 09 June 2007 (in the image above, at left) showed a tornado scar (much longer than 1/4 mile in length) running southwest-to-northeast through heavily forested Menominee County into Langlade County and then Oconto County in northeast Wisconsin. Terra MODIS True-Color imagery from 15 July 2015 (also in the image above, at right) (cropped from imagery at the MODIS Today website), shows that a scar persists more than 8 years later! (This persistent scar has been mentioned before on this blog here in 2009 and here in 2011).

Landsat-8 overflew northeast Wisconsin on 15 July 2015, at nearly the same time as the Terra MODIS imagery above, and those views, captured via SSEC‘s RealEarth are shown below. The scar is more evident in the shortwave infrared (Band 6, 1.61 µm) than the visible (Band 3, 0.56 µm) because the shortwave infrared channel is more sensitive to changes in vegetation. Lakes are also far more apparent in the 1.61 µm imagery because water absorbs 1.61 µm radiation; little is scattered back to the satellite for detection and water therefore appears black.

Landsat-8 band 3 (0.56 µm) and Band 6 (1.61 µm) imagery, ~1640 UTC July 15, 2015 (click to enlarge)

Landsat-8 band 3 and Band 6 imagery, ~1640 UTC July 15, 2015 (click to enlarge)


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In April 2011, an historic tornadic event occurred over the Deep South that spawned numerous strong long-tracked tornadoes (blog post). The tornado paths from this event were also visible from both MODIS and GOES imagery (Link). The animation below shows MODIS true color imagery from before the tornadoes, from several days after, and from early May this year. Three distinct tornado scars remain in Alabama: One runs from Tuscaloosa to Birmingham, a second is south of Tuscaloosa, and a third is north of Tuscaloosa.

MODIS True-Color Imagery over Alabama, 13 April and 29 April in 2011 and 01 May in 2015 (click to enlarge)

MODIS True-Color Imagery over Alabama, 13 April and 29 April in 2011 and 01 May in 2015 (click to enlarge)

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]