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Last Updated: 9:54 PM GMT on March 08, 2012
— Last Comment: 9:03 AM GMT on January 09, 2013
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How does Wunderground forecast precipitation? |
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When we talk about precipitation forecasting, we classify it into two categories, PoP(Probability of Precipitation) and QPF(Quantitative Precipitation Forecast). PoP and QPF have very little to do with each other. A high PoP does not represent high QPF. However, high QPF sometimes relates to a high PoP.
First, let's look at PoP. PoP is the probability that precipitation will be reported at a certain location during a specified period of time. Wunderground takes various numerical weather prediction models, such as GFS(Global Forecast System), GEM(Global Environmental Multiscale) and other regional models, and makes a consensus forecast for Pop. If numerous models predict precipitation, the higher the PoP will be.
Next, what is QPF? A spatial and temporal precipitation forecast that will predict the potential amount of future precipitation for a specified region, or area. Currently, Wunderground uses NDFD(National Digital Forecast Database ) for US cities and GFS for international cities. We don't have any data for the measure precision at this point
The quality of the forecast is usually good during the first 72 hours. The error gets larger farther into the future. Both radar and satellite data are integrated into the model data assimilation to improve its analysis and forecasts. Also, convection effect is taken into account by the model.
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Copyright © 2013 Weather Underground, Inc.
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Copyright © 2013 Weather Underground, Inc.
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