Heathrow airport currently has one runway open and is accommodating both arrivals and departures, you can see a list of Heathrow Arrivals .
It is forecast to snow tonight – metcheck EGLL (Heathrow)
You can take a look at the snow/rain radar here – Rain Today
The airport is filling with stranded travellers, and the roads are busy and icy – therefore do not come to the airport until you have a confirmed flight. If you don’t have to fly, contact your airline to discuss cancelling the fligh – perhaps somebody who is stranded can get home if you don’t make your unnecessary journey.
Keep following @HeathrowAiport , @heathrowinfo for updates. Contact your airline, or find them on twitter for updates and news. @british_airways and @virginatlantic are key Heathrow airport users and their twitter updates are also very useful.