Because you might just get what you ask for and more!
When the Dollies were coming over, I had a look at the long range forecast, as you do, and was disappointed to see that we were likely to be in for a wet weekend. Not a problem as being crafters, I knew we would be able to find something to do, so when the first morning dawned clear and fine, I was happy. When the second day dawned, also clear and sunny I began to hope that it would stay fine till they had to go home, and thought to myself, if it will just hang on it can rain all it likes on Monday. Now here's the rub, be very careful what you ask for, hail, strong winds and driving rain was not exactly what I was thinking of when I said it could rain all it liked!