The satellite imagery below shows how the once well-defined eye wall of Hilary has now collapsed. In addition, Hilary has broadened and looks more ragged on the edges. These are all signs of a rapidly weakening hurricane.
Regardless, this system is still headed our way and the pace has accelerated. Most computer forecasts (shown below) have the storm weakening to a Tropical Storm by the time to passes overhead midday on Sunday. The real threat from Hilary will be the heavy rain and potential for flash flooding.
Showers will develop to the east in the desert and mountains this evening and tonight. Those showers will migrate westward early Sunday morning. Periods of rain and downpours will then arrive midday as the core of Hilary passes overhead. This will occur between 12-5 PM.
Lingering showers an isolated downpours will still be possible Sunday evening and Sunday night as the storm exits the region. Most rain will be gone Monday morning.
I've posted the official track from the National Hurricane Center and also the computer projected rain totals from Hilary. San Diego should see 1.5 to 2.5", though in the mountains, totals will range from 4" to 7" (isolated areas could get more).
As always, check with the National Weather Service San Diego for all the latest warnings and advisories.
