I don't know of any forecasts that go that far out. If I did, I wouldn't believe them.
Here's my thoughts of forecasts...
Forecast tomorrow. Get it right. Repeat 5 times and we'll talk about three days. Get it right. Repeat 5 times and we'll talk about 4 days. Lather rinse repeat with increasing amounts of days to look out. Any miss, continues the level at which the miss happened.
So far, I don't think we've hit 4 days, and are usually stuck repeating 2 day forecasts.
Present company excepted, of course.
