It’s a three-day weekend, plans are made, and the forecast keeps changing its mind. Here’s why that huge cross-country storm is so frustratingly hard to nail down — and why it’s not anyone’s fault. The setup: a cross-country storm bringing rain, drama and very mixed signals. This is why storms are hard to track A big weather system is crossing the U.S. right now, loaded with Gulf moisture. Southeast : Finally getting rain in drought-stricken areas — but some spots could see