In the last few weeks I have run across two new methods for estimating precipitation amounts in places where no rain gauge is present (which is most of the US). These methods incorporate new techniques for filling in the gaps between surface rain gauges using radar data.
NOAA’s National Centers for Environmental Information posted a story earlier this week on their new Climate Data Record at https://www.ncei.noaa.gov/news/precipitation-record-helps-forecasting. The improvement uses a combination of radar and conventional rain gauge data to provide rainfall estimates that are now able to get down to a 1×1 kilometer grid, a big improvement from the older 4×4 kilometer grid.
The University of Missouri posted a story earlier this month on their news site which describes a different method of improving rainfall estimates by incorporating humidity information to account for evaporation of rain from the time it leaves the cloud at radar-beam height until it hits the ground. When the air below the raining cloud is dry, a lot of the rain evaporates and does not fall on the surface, which means that the radar alone is overestimating the amount of precipitation that reaches the ground. You can read that story at https://nbsubscribe.missouri.edu/news-releases/2018/0611-new-method-makes-weather-forecasts-right-as-rain/.