Local gas prices are slowly rising, with a double digit jump seen in the Bay area. Average retail gasoline prices in Modesto have risen 6.3 cents per gallon in the past week, averaging $3.09/gallon Sunday, according to GasBuddy’s daily survey of 201 gas outlets in Modesto. This compares with the national average that has increased 1.9 cents per gallon in the last week to $2.60/gallon, according to gasoline price website GasBuddy.com.