The day-to-day inconsistency

• Forecasts have to change
• Consistency-skill?
• Beware of consistent forecasts!
• Instead of complaining about jumpiness - make use of it!

Closely related to the dynamic activity and accuracy is the problem if "inconsistent" or "jumpy" forecasts: the re-occurring problem that today's medium-range forecast is quite different to yesterday's. There is a wide spread (mis)conception that "jumpy" forecasts are of lower reliability than "consistent" forecasts.

1. An example of forecast "jumpiness" from the end of January 2001. Over a period of two days, the D+4 to D+6 are quite consistent, only with the exception of the D+5 from 27 January.