California Electricity-Supply Forecast for June Worsens.

Byline: Mike Taugher and Rick Jurgens

Jun. 5--An electricity supply forecast for gloom in June was based on overly optimistic assumptions about how many plants would be off-line.

The gloomy prediction was based on a historic average of 2,500 megawatts from power plants being unavailable because of maintenance or breakdowns.

In fact, plants producing 8,500 megawatts were off-line Friday, and that figure is not expected to get down to 3,000 megawatts until the end of June.

Whether the 6,000 megawatt difference will translate into more blackouts will depend on the weather and the availability of power from other states.

State grid managers in …