TypeScript output file doesn't get updated after transpilation

I downloaded this seed for an Angular & TypeScript project. I updated the ts files and then transpiled it with no errors, but the output file doesn't get updated.

tsconfig:

{
    "compilerOptions": {
        "module": "commonjs",
        "target": "es5",
        "noImplicitAny": true,
        "sourceMap": true,
         "outFile": "dist/app.js"
    },
    "exclude": [
        "node_modules"
    ],
    "files": [        
        "app/initialize.ts",
        "app/welcome/welcome.ts"
    ]
}

Please let me know if you need any other information.

via Alon