Why Issue An "Unreliable" Long Range Weather Forecast?
Long term weather forecast products exist primarily because there is a strong demand for them. The fact that they are produced to satisfy that demand does not mean that they can! Not by any stretch of the imagination.
You as a consumer do not necessarily know that, because the "disclaimer" is usually tucked in the fine print somewhere deep in the organization's Web site.
I conducted a survey recently to find out just how easy (or hard) it is for you to find out if you should actually plan any significant activity on these so-called forecasts.
I found the "disclaimers" (see excerpts above) after many hours of searching through the government Web sites of each country!
The UK MetOffice calls its 14 day extended forecast a "forecast" but Canada, the US and Australia use the more appropriate terms "trend" or "outlook".
The latter two terms are much closer to what these products can actually deliver: a general idea of the trend or tendency.
Even as such, they can only be relied upon to give a general idea of the tendencies such as...
Meteorology as a science cannot produce a reliable detailed forecast much beyond 72 hours. Beyond that, "forecasting" rapidly becomes statistically less reliable than flipping a coin!
Conclusion And Recommendation
It would be wise to consider the 14 day weather forecast as an experimental product to which you are being given access. You should not use it to support critical weather-dependant decisions or activities.