When I run "npm outdated", it doesn't show anything for "Latest". All of the @angular packages should have a latest version of at least 4.4.6, and I expect most of the other ones should have newer versions as well. What is listed under "Current" is what is in my package.json file.
I had the same problem with latest windows 10 version using powershell.
A quick workaround is to just use the regular CMD window.
Windows Key + R ---> cmd