ForWarn is a satellite-based mapping system for monitoring drought and forest stress.
ForWarn is updated every eight days about changes in forests and vegetation in the US. You can see where greenery is being lost or gained, and why.
The interactive map provides tools for attributing changes in forest condition to insects, disease, etc. Show or hide layers of graphical data to see where wildfire, storms, human development or unusual weather have reduced the greenness of forests.
One set of layers is the "Normalized Difference Vegetation Index," or NDVI, shown in the image in this post. It uses colors to convey changes in the condition of vegetation over a period of 1, 3, 5 or 8 years.
The ForWarn map lets you zoom in on your property of favorite hiking destination. Some layers are extremely detailed.
A few of the layers, like current drought and pest proximity, are fairly easy to understand. Most of the layer descriptions defy comprehension by a layman like myself.
Disturbance tracking data is archived for the Lower 48 since 2000.
This blog post explains more about the origins of the ForWarn tool and how it can be used: "US Forest Service and NASA Team up on Climate Change Early Warning System for Forests"