NWS Precipitation Analysis Product Victor Murphy NWS Southern

NWS Precipitation Analysis Product Victor Murphy NWS Southern Region Climate Service Program Mgr. 5 th US Drought Monitor Forum Portland, OR October 11, 2007

NWS Southern Region Drought Monitor Forum Overview n Data Collection n Data Mosaic n The Webpage n Controls n Products n Future Plans n Current Feedback http: //water. weather. gov

NWS Southern Region Data Collection – 2 Processes n East of the Continental Divide 3. Radar, and Rain Gauges (and satellite) Most effective in areas with good radar coverage and dense gauge network. “MPE” Multisensor Precipitation Estimator n West of the Continental Divide 1. Statistical relationship between precip at known stations and normal precipitation Most effective in areas with poor radar coverage. ” “Daily QC/Mountain Mapper” 1. 2. 3. http: //water. weather. gov

NWS Southern Region Mosaic Data into One Dataset n n n Each NWS RFC is in unique position to create gridded precipitation estimates as part of the core function of their duties. Hourly Digital Precip (HDP) is computed for each radar within an RFCs area. This is merged with hourly observed rain gauge reports. Bias field created based on the difference between radar value and gauge value. Where no gauges exist, bias is computed using triangular grid and distance from nearest gauge site. http: //water. weather. gov

NWS Southern Region Drought Monitor Forum Bias field then used to create the final precipitation product. n Hydrologic Rainfall Analysis Project (HRAP) grids are created. n Resolution is 4 km x 4 km. n Grids available daily for download by customers to create their own value added products. n http: //water. weather. gov

NWS Southern Region Drought Monitor Forum Hourly Quality Control • Hail Contamination/Bright Banding • Beam Blockage/AP • Poor Z-R Relationships • Rain gauge errors n Hourly gauge data supplemented with Co. Op Network data at 12 Z daily. n Supplemental data (i. e. Co. Ra. HS, local alert gauges, etc. ) also used. n http: //water. weather. gov

NWS Southern Region Drought Monitor Forum n • • Derived Gridded Products Observed Precipitation Normal Precipitation (Monthly PRISM data used…and weighted for daily values). Departure from Normal. Percentage of Normal. http: //water. weather. gov

NWS Southern Region Drought Monitor Forum n • • Observed Data Expressed as a 24 hour total ending at 1200 Z. Usually available at approx 1500 Z. Western data usually available at approx 1700 Z. http: //water. weather. gov

NWS Southern Region Observed Precipitation http: //water. weather. gov

NWS Southern Region Easy to use Controls http: //water. weather. gov

NWS Southern Regional/State Choices http: //water. weather. gov

NWS Southern Region Time Interval Selections http: //water. weather. gov

NWS Southern Region Normal Values Available http: //water. weather. gov

NWS Southern Region Departure from Normal http: //water. weather. gov

NWS Southern Region Percent of Normal http: //water. weather. gov

NWS Southern Region Individual States Selected http: //water. weather. gov

NWS Southern Region Individual States Selected http: //water. weather. gov

NWS Southern Region Other Website Features. . Survey and Feedback Section---PLEASE! http: //water. weather. gov

NWS Southern Region Future Plans Enable dynamically created websites to easily download a graphic of the product that is currently being viewed. n Extend archive back to 2001. n User selectable time intervals. n NEW! Product now nationally supported by OH AHPS program with regard to web presentation. n http: //water. weather. gov

NWS Southern Region Drought Monitor Forum Questions? ? http: //water. weather. gov