Probability of precipitation

The chance of precipitation, rain or rain likely erroneously also called rain risk is the probability that there are at a given point in the forecast period, at least one rainfall event.

Does it mean in the weather forecast of a local radio station, could be expected with showers and the probability of precipitation for the period 6-12 clock amounts to 50 % percent for tomorrow, then there is a good chance to stay dry on the way to school, because showers are much shorter than six hours.

A chance of rain for an area is the average of the rain chances for his points. A holidaymaker who wants to climb the Brocken Harz on the following day, in a given for all of northern Germany Chance of rain 50% with significantly more likely to have rain at least once, see orographic rainfall.

For forecast periods that in the future much more than a few days, the probability of precipitation is the long-term average frequency of precipitation for this year and time of day. For very short-term predictions, a look to the sky, taking into account the wind direction. In between helping different methods: With knowledge of the current weather situation can be based on weather records indicate probabilities with which the weather is like change, and from this calculate the Niederschlagswahrscheinlicheit. The far more complex numerical weather prediction is meaningful for medium forecast periods and also loses so quickly in spatial resolution.

The benefit of the probability of precipitation depends on the application, though a short rain would disrupt about just before the grain harvest. To ask the farmer, however, whether it is to irrigate his field, he would be better off with the expected value of the rainfall.