The GOES (Geostationary Operational Environmental Satellites) constellation of weather satellites has been the backbone of weather forecasting for North America since the mid-1970s.  

The vast majority of the satellite imagery you see on KIRO 7 Eyewitness News comes from GOES-West, which is parked over the equatorial Pacific at 135 degrees west longitude and at an altitude of 22,240 miles.  

(Why so high?  That exact altitude is the point at which the satellite can stay above one point on the Earth's surface at all times as the planet revolves below.  That's called geosychronous orbit.   The vast majority of communications satellites are also in geosynchronous orbit, which is why that little TV dish on your roof never has to move!)

So what's with this "new" satellite?  

The current occupant of the name "GOES-West" is a satellite called GOES-11.

It was launched in 2000 with a planned operational life of five years.  It has lasted more than a decade.

While GOES-11 was at the cutting edge of technology at the turn of the milennium, obviously things have changed in ten years time!

Come on or about December 6, GOES-15 will take over the name GOES-West.   The newer satellite is presently in a slow crawl from where it has been in storage on-orbit since its launch in March of last year to its new home over the Pacific.  

When it arrives at its final destination, the older satellite will be moved to another orbit and decommissioned. 

Improvement in clarity and resolution for some products will aid forecasters

As image sensor technology has improved in ten years time, we can expect some minor improvement to the clarity of visual and infrared images.  Those are the "satellite pictures" you see every day in weathercasts and on the Internet.  We'll also get another one to two image scans per hour from the new satellite, keeping our satellite animations "fresher" than they are now.

There is also a satellite imagery product that senses the amount of water vapor in the mid-levels of the atmosphere.  While it doesn't show clouds per se, and neither does it depict what's happening at ground level, water vapor imagery is extremely useful for determining large-scale storm motion, how moisture laden a column of the atmosphere is, and also helps us pick out areas where large-scale storm systems might be intensifying or weakening.

With GOES-15, our water vapor imagery will go from a resolution of eight kilometers down to four.  That's a doubling in resolution, and a big deal!  

The image at the top of this story demonstrates this improvement.  At left is a water vapor image of a storm centered over northern Arizona from the current western U.S. satellite, and at right is the same storm from GOES-15.  You can see the difference in clarity and the absence of large pixels.  A movie of this storm can be found here, courtesy of CIMSS at the University of Wisconsin.

The current GOES-West satellite was under construction just prior to the turn of the century, so when GOES-15 takes up that mantle on December 6, the Pacific Northwest will get a weather satellite that is true 21st Century technology!

Here's a short Wikipedia article that includes an image of GOES-15 while it was still under construction and a video of the spectacular night launch aboard a Delta IV rocket last year.