Two cold weather systems from the Gulf of Alaska are forecasted to bring rain, wind, lightning and low snow to Northern California, continuing through Friday. These adverse weather conditions could result in falling trees or lightning strikes taking down power lines and interrupting electric service. To prepare for such storms and minimize outages, Pacific Gas and Electric Co. has extensive training, preventive maintenance and tree pruning programs. Each year, the utility inspects every mile of line in its service area — more than 130,000 miles total — and spends more than $180 million to reduce the hazards from trees. When …