Near Real-time Storm Precipitation Analytics Using Dual-pol Radar Data

A systematic means of providing an accurate, detailed analysis of precipitation associated with a recently occurring storm has historically been difficult to attain given the lack of reliable data. However, real-time precipitation gauge data and radar-estimated precipitation data make near real-time, systematic storm analyses possible. MetStorm™, an analysis system developed by MetStat, integrates quality-controlled precipitation gauge data, dual-pol radar-estimated precipitation data, satellite-estimated precipitation data and innovative algorithms for computing precipitation analytics. If available, storm analyses of this nature support media inquiries, hydrologic modeling calibration and validation, flood responses, forensic cases, insurance claims, emergency management, situational awareness, and help build a storm database for use in engineering design applications.

Radar estimated precipitation data is produced through a polarimetric technique developed at Weather Decision Technologies. Within radar echoes, hydrometeors are classified by the Polarimetric Radar Identification System (POLARIS), which is a technique largely based on the classification algorithm developed by the National Severe Storms Laboratory. POLARIS contains 3 non-hydrometeor (including tornadic debris) and 10 precipitation classifications with multiple hail size categories. A POLARIS Quantitative Precipitation Estimation (PQPE) system uses a suite of rain rate relationships dependent on reflectivity, differential reflectivity and/or specific differential phase. The hydrometeor type and location relative to freezing level determine which rain rate relationship is applied for each radar bin.

MetStorm™ is a new Geographic Information System (GIS) based analysis system that produces gridded precipitation at 5-minute and/or 1-hour intervals over a specified domain. The relative spatial precipitation patterns are largely governed by PQPE mosaics containing a spatial resolution of 1-km and updated every 2.5 minutes. Meanwhile, the precipitation magnitudes of MetStorm™ precipitation grids are influenced by quality-controlled rain gauge data from our strategic partner, Synoptic Data Corp. MetStorm™ has the ability to integrate both hourly- and daily-reported precipitation data, thereby providing a high degree of gauge density for “ground truthing.” Satellite data, though at a coarser spatial resolution (4-km), influences areas void of rain gauge and/or radar data. Innovative algorithms blend the precipitation estimates from the different sources into a seamless GIS grid, which provides the basis for summary statistics, maps, tables and plots.

MetStorm™ generates a unique set of storm precipitation analytics, including a depth-area-duration (DAD) table and plot, average recurrence interval map, and mass curve table/plot for the storms' center and a complete station catalog. A free subset of storm analytics are posted on the web for significant storms, while more in-depth analytics are available upon request. This presentation will include a synopsis of the PQPE system and brief overview of MetStorm™ with examples of recent storms.