Steve Vasiloff, NOAA/NSSL
The major sources of information for a precipitation analysis of record are radar, rain and snow gauges, and satellite. Each sensor possesses strengths and weaknesses in regard to resolution and accuracy. For example, quantitative precipitation estimates (QPEs) from radar have been shown to have less skill in the Intermountain West as compared to east of the Rockies. This has led to the development of new multisensor QPE schemes that combine radar-based QPEs with satellite data and gauge observations. Advanced techniques for improving the accuracy of QPE include correcting for the range-dependency of radar QPEs through vertical profile of reflectivity adjustments, blending real-time estimates with climatological gauge analyses that take into account orographic precipitation enhancement (e.g., PRISMS climatology), satellite-radar regressions so satellite data can be used in areas of poor radar sampling, and utilization of mesoscale model analyses to identify precipitation phase.
This presentation will review these techniques and discuss their advantages as a function of geographic region, season, and precipitation type. New techniques and resources needed to develop and test them will also be presented. In addition, we will discuss challenges for analysis of precipitation at high temporal and spatial resolution. From a sensor availability standpoint, full-resolution radar reflectivity data from the WSR-88D network has been archived on a regular basis until only recently so historical analyses are not possible. Rain gauges, on the other hand, have been employed in the field for decades, but the density of observations is highly variable and is comparably coarse in the Intermountain West.