By NICK STANEK
Capital News Service
LANSING — The polar vortex has Michigan wine producers worried about their crops. Cold weather is nothing new for Michigan but its vineyards are not used to recent record-breaking lows. The polar vortex in December raised concerns but cold temperatures in late-January have Michigan growers worried that their vineyards may be destroyed. Some grapes can survive temperatures as low as the negative 30s but for certain varieties that grow in Southern Michigan, temperatures even as low as 5 degrees can be dangerous. Southern Michigan was hit the hardest with temperatures as low as minus 15.