Weather forecasters are typically a curious sort. We run a forecast model out 16 days just for fun when we know pretty well that what's depicted out beyond a week is more a suggestion than a real shot at a forecast.
And then there's the most recent run which is a great illustration of why public forecasts don't go out that far.
This is the same model, 6 hours apart, each showing a forecast for the morning of August 30.
Of particular note is what appears to be a tropical storm or hurricane making landfall... somewhere.
The first model issued just before midnight Monday morning shows the storm making landfall around North Carolina:
Then, the model issued just six hours later for the same morning of Aug. 30 and has a "slightly" different track -- one that shows the storm in the Gulf of Mexico coming inland around New Orleans -- only off by about 770 miles.
You can see how this has a domino effect on the rest of the weather pattern depicted. The North Carolina version paints a cool, mostly cloudy day in Seattle for August 30th while the New Orleans version has a broiling heat wave over the West Coast with highs in the 90s for Seattle.
Suffice to say, don't ask what the weather will be like on Aug. 30 :)