How to pass url arguments (query string) to a HTTP request on Angular?

I would like to trigger HTTP request from an Angular component, but I do not know how to add URL arguments (query string) to it.

this.http.get(StaticSettings.BASE_URL).subscribe(
  (response) => this.onGetForecastResult(response.json()),
  (error) => this.onGetForecastError(error.json()),
  () => this.onGetForecastComplete()
)

Now my StaticSettings.BASE_URL is like a URL without query string like: http://atsomeplace.com/ but I want it to be like http://atsomeplace.com/?var1=val1&var2=val2

How to add var1, and var2 to my HTTP request object as an object?

{
  query: {
    var1: val1,
    var2: val2
  }
}

and then just the HTTP module does the job to parse it into URL query string.