tornado

Snapsat Beta for Landsat imagery

May 4, 2016

We have previously had a look at how to get Landsat imagery into Google Earth. We have used a number of different techniques over time, but in all cases, obtaining high quality Landsat imagery required a large download (typically over 700 Mb) and several stages of image processing to combine multiple bands into a full colour image.

We recently discovered Snapsat, a website dedicated to making it easier to obtain processed Landsat imagery. In March last year, Amazon announced the availability of Landsat data on Amazon Web Services (AWS). Snapsat builds on the AWS, offering to provide easy access and processing of the Landsat data. It appears to have been set up mid last year not long after the Landsat data was made available on AWS but not much work appears to have been done on it since then. However, it still works well and makes obtaining processed Landsat imagery remarkably easy. Learn how to use it here.

As we mentioned in this post there was a Tornado which struck Dallas, Texas in December last year. There is no imagery yet in Google Earth showing the main path of destruction. So we tried out Snapsat by downloading a Landsat image of Dallas from January 12th. The process was straight forward and only required a download of 107 Mb as opposed to the 772 Mb required to download the same imagery from Earth Explorer. And we can see the track of the tornado.

Tornado track, Dallas, Texas, as seen in Landsat imagery. Ends of the track marked with arrows.

There are, however, a few disadvantages to using Snapsat. The website does not do pansharpening, a process whereby a higher resolution grey-scale image is used in combination with the three colour bands to create a higher resolution image overall. This means that the imagery obtained via Snapsat is not the highest quality possible. Another issue is that the downloaded file does not include Geo-coding information so it cannot be automatically imported into Google Earth Pro. However, since we usually have to crop the imagery anyway, manual positioning is often necessary and not very difficult.

We got the same image from Earth Explorer and used GIMP to process the imagery (very inexpertly) and the result is noticeably sharper because of the pansharpening.

Tornado track, Dallas, Texas, as seen in Landsat imagery, with basic pansharpening via GIMP

To see the two overlays in Google Earth download this KML file.

Seeing a tornado track with Landsat imagery

December 28, 2015

We have looked at the paths of destruction caused by tornadoes in Google Earth imagery a number of times before. Nearly every one of the tornadoes we have looked at in the US occurred in the months of April or May, which appears to be peak tornado season in the US. Tornadoes can, however, occur at any time of year and due to the unseasonably warm weather the US has been having recently there were several tornadoes just before Christmas.

We came across this story, which says that one of the tornadoes had a record long track for the month of December. Google has not yet released any December imagery so we wondered if it would be visible in Landsat imagery. We used the technique described in this post to get a relatively low resolution Landsat image of the area captured on December 24th, the day after the tornado struck and found we were able to just make out the path of the tornado. We also downloaded the higher resolution version of the Landsat data and processed it with software from GeoSage as described in this post.

We were able to trace out the path of the tornado a distance of around 92 km (57 miles). News reports, however, mention damage to property quite some distance from both ends of the visible track (from Clarksdale, Mississippi to Lutts, Arkansas) reaching at least double that distance.

A section of the track as seen in Landsat 8 imagery. Can you see it?

Keep in mind that Landsat imagery has a resolution of about 30m per pixel. The visible track of the tornado is over a kilometre wide in places.

Shown above is only a part of the visible track. For the full track and two different versions of the Landsat imagery (cropped and compressed to keep the file sizes down) download this KML file. The KML also includes markers relating to some news stories and links to YouTube videos of the tornado or other tornadoes in the vicinity.

Rochelle/Fairdale Tornado Damage now Visible in Google Earth

May 28, 2015

We have looked at tornado damage in Google Earth a number of times before, including tornado’s that struck the US towns of:
Pilger, Nebraska and Wessington Springs, South Dakota
Mayflower, Arkansas – May 2014
Moore, Oklahoma – May, 2013
Joplin, Missouri – May 2011
Tuscaloosa and Jefferson County, Alabama – April 2011
Yazoo City, Mississippi – April 2010
Greensburg, Kansas – May 2007

On April 9th, 2015 a tornado struck near the town of Rochelle, Illinois. For ground level videos and photos see this story. Considering the amount of damage visible in Google Earth, it is amazing that only two people lost their lives.

The image from April 11th, 2015 was captured just two days after the tornado struck and clearly shows the scar left by the tornado right across the image, over 30km.

About half the town of Fairdale, Illinois was completely destroyed.

Some houses near the town of Rochelle, Illinois. Notice all the cars lining the roads. Presumably a mix of rescue workers making sure there is nobody still trapped in the debris, news reporters and curious onlookers.

To see the above imagery in Google Earth, you will need to look in ‘historical imagery’. You can also download this KML file which shows the locations of all the tornado’s we have covered in the past including this one.

Tornado damage in Google Earth

January 12, 2015

We recently came across this article featuring Google Earth imagery showing the town of Pilger, Nebraska, before and after a tornado. After a bit of research, it appears that the newly added image is from October 14th, 2014 and shows the town in the early stages of reconstruction. There are, however, images in Google Earth’s historical imagery that show the town just days after the tornado hit. It also turns out that the tornado that hit Pilger was just one of an outbreak of tornadoes from June 16-18 of 77 tornadoes that caused two fatalities, numerous injuries and widespread damage over several states.

Looking around in Google Earth’s historical imagery we discovered more images from soon after the tornados, including some showing tornado damage in the town of Wessington Springs, South Dakota. In addition, there is also imagery from Madison, Wisconsin which was also struck by a tornado, but we were unable to identify any tornado damage.

Pilger in September 2011.

Pilger on June 21st, 2014, just days after the tornado

Pilger on October 14th 2014, showing the debris has been cleared.

Wessington Springs on June 21st, 2014

You can see some footage of the tornado from security cameras in this news report and from a distance in this YouTube video, and in depth analysis of the tornado here. It is also worth having a look at the Street View in Pilger, which is from August 2012 and gives an idea of what buildings were destroyed.

To view the locations mentioned in this post in Google Earth, download this KML file

See here for past articles about the destruction caused by tornados seen in Google Earth.

The tornado damage in Mayflower, Arkansas

May 6, 2014

The NASA Earth Observatory site brings us amazing images from time to time (such as some of these), and they’re back with some fresh imagery from the tornadoes that have ripped across the central United States in recent weeks.

The Mayflower tornado hit on April 27 and was rated an EF4. It left a path nearly 41 miles long and destroyed between 400-500 homes. From the Earth Observatory site:

At MODIS resolution, the entire town of Mayflower is barely distinguishable; but at ALI’s top resolution of 10 meters per pixel, it is possible to distinguish between individual buildings. In this ALI image, a trail of damaged trees and homes is visible near Interstate 40. The storm moved in a northeasterly direction, hitting the southern part of Mayflower first, then crossing I-40, and flattening neighborhoods along the shore of Lake Taylor.

You can read more on the NASA Earth Observatory site or download this KML file to view it for yourself in Google Earth.