An unusually strong solar storm headed toward Earth could produce northern lights in the U.S. and potentially disrupt communications this weekend. The National Oceanic and Atmospheric Administration issued a rare geomagnetic storm watch _ the first in nearly 20 years. The watch starts Friday and lasts all weekend. The agency says the sun is producing strong solar flares and has hurled at least five outbursts of plasma our way. Each ejection can contain billions of tons of solar plasma. NOAA says the latest storm could produce northern lights as far south in the U.S. as Alabama and Northern California.