As the BBC's five day forecast so succinctly puts it: "Thursday's predominant weather is forecast to be sleet."
If you want to be a bit more precise then tomorrow is very likely to go something like this: rain, sleet, snow, cold, ice, hail, rain, snow, cold, more rain.
With a bit of luck it will be more 'slushy' then 'deep' and the whole of the capital won't grind to a shuddering halt, however if the rain forecast for tomorrow evening does materialise the stupidly cold night we're due for leading into Friday means that there'll be a few drivers doing their best car-curling impressions down the M25 come the Friday morning rush hour.
The BBC has a page of RAC icy conditions advice for those wanting to prepare themselves. Or you could just watch the following 'educational video' from another BBC source instead: