Year-to-year weather differences affect every winery. But when you only make a single wine, like say merlot, each year, it has an even larger impact on your business. Take Medolla Vineyards for example. Owned by John and Denise Medolla, this new procucer snuck up on me last spring their first release — a 2002 merlot. 2002 is considered by many to be an above average years for Long Island merlot and that wine is a classic North Fork merlot that, at $22, is one of the best deals in local vino. It straddles the line between Old and New World…