Samwood, What do you mean by local sources, the Russian Hydrometeorological Center? Local weather stations built-in global weather monitoring, almost all sources - both Russian and international use the same data, usually with stations at airports. The difference may be in the interpretation of these data, the frequency of updates and proper in the forecast for the future. Weather Underground (it is in Climendo) - receives data from private portable weather stations, if any in your town in the next street it will be the most accurate information.
In general, there is some kind of exclusive local weather information, all in the public domain. Rivaled only algorithms and ways of presenting forecasts.