If you already use Google Webmaster Tools (If not, you should be!), then you’ve probably seen the Search Queries Feature, but Google has now added alerts for Search Queries data. So now you can be notified when something changes with the search queries where your site is showing.
The Search Queries feature gives insight into how your site is performing. It shows things such as impressions, average position and clicks to your top pages. Usually these metric follow a pattern. With the new service you can be notified when something out of the ordinary happens, such as a spike or a drop.
Here’s an example alert:
This way you’ll be on top of things if there is a technical problem with your site or to better understand if there is a send change in the trends in the demand for your content. Sometimes these changes can be a result of a database failure that causes errors in some of your content, or a mention of your site on a social network, blog or another site. All of these scenarios would warrant a closer look.
Also, don’t forget to turn on your email notifications:
Read the announcement over the Official Google Webmaster Central Blog