npm outdated doesn't tell me I can upgrade a version

gistfile1.txt

/* package.json */
{
        "name": "test",
        "version": "0.0.1",
        "dependencies": {
                "semver": "1.1.1"
        }
}

/*
$ npm outdated
npm WARN package.json test@0.0.1 No README.md file found!
npm http GET https://registry.npmjs.org/semver/1.1.1
npm http 304 https://registry.npmjs.org/semver/1.1.1
*/

/* package.json */
{
        "name": "test",
        "version": "0.0.1",
        "dependencies": {
                "semver": "~1.1"
        }
}

/*
$ npm outdated
npm WARN package.json test@0.0.1 No README.md file found!
npm http GET https://registry.npmjs.org/semver
npm http 304 https://registry.npmjs.org/semver
semver@1.1.2 node_modules\semver current=1.1.1
*/