The price you pay for fresh vegetables is going up maybe double or even triple in the coming weeks.    This is happening after the worst freeze in 60 years damaged and wiped out entire crops in northern Mexico and the southwestern U.S.  The problem started about a week ago when we were focusing on the Superbowl and sheets of ice falling from Texas Stadium.  Farmers throughout northern Mexico and the Southwest experienced unprecedented crop losses.  Now devastation that seemed so far away, is going to be hitting us in the pocketbooks.  As an example, Roma tomatoes have more than doubled in price since Thursday and very soon they may not be available at all.  About the only produce not impacted by the freeze in the coming weeks are things grown right here in the Northwest like potatoes, onions and apples.  The situation is so dire, some stores can't honor certain advertised prices, which were ordered in local newspapers long before the freeze.  Some grocers are saying this is the worst produce situation they have seen seen in a quarter century.   Normal prices likely won't return until new crops in Mexico start producing again in late March and early April.