gov.noaa.nws:Observed_pcpn DOC/NOAA/National Weather Service Unknown https://water.noaa.gov/resources/downloads/precip/stageIV/ https://water.noaa.gov Observed precipitation is a byproduct of National Weather Service (NWS) operations at the 12 CONUS River Forecast Centers (RFCs), and is displayed as a gridded field with a spatial resolution of roughly 4x4 km. Observed precipitation estimates are created in order to simulate streamflow across the CONUS United States. 2005 Present ground condition In work Daily -125.0208333 -65 53 17 None Gridded Observed Precipitation Data Precipitation Observations None Continental United States CONUS Puerto Rico 2005 Present None This information is not certified and cannot be used in legal proceedings. Official, certified data is available exclusively through the National Climatic Data Center. DOC/NOAA/National Weather Service Precipitation Analysis Support Group Physical Scientist/Hydrologist mailing

National Weather Service - Office of Hydrologic Development 1325 East-West Hwy

Silver Spring Maryland 20910 USA 301-713-0640 301-713-0963 nws.hq.ohd.ahps.precip@noaa.gov "Studies have shown that algorithms which combine sensor inputs -- radar, gauge, satellite -- yield more accurate precipitation estimates than those which rely on a single sensor (i.e. radar-only, gauge-only, satellite-only). Although it is not perfect, this dataset is one of the best sources of timely, high resolution precipitation information available. Still, users should understand the inherent weaknesses of this dataset before using it in certain decision - making applications, especially those which require a high degree of accuracy. Radar Data Errors. These precipitation estimates are based substantially on radar which samples over a large area. Each grid value on the maps represents average precipitation over roughly 16 km2 (6¼ mi2). Radar values may not be comparable with one or more rain gauges within that area. Radar sampling errors that can create inaccuracies in the data include freezing or frozen precipitation, low topped convection, bright banding, accuracy of the reflectivity - rainfall relationship in use, calibration of the radar, radar location and elevation, range degradation (i.e., larger sampling area and effect of intervening precipitation), and the radar's effective coverage (e.g., physical obstructions such as mountains). Precipitation Gauge Errors. A rain gauge measures approximately 12 in2. There are over 10,000 precipitation gauges scattered through the country. Gauge sampling problems could include freezing precipitation, windy conditions, gauge siting (e.g., obstructions around the gauge), under-measurement by tipping bucket gauges in high intensity rainfall, and gauge maintenance. In places where NWS quality control efforts fail to resolve persistent problems, significant sampling errors will be noticable in longer-duration products (e.g. 30 days or more). Horizontal Accuracy. Horizontal accuracy errors may reach up to 5 km (3 mi). In other words, ""peaks"" in the precipitation data may actually have occurred miles away." "East of the Continental Divide, River Forecast Centers derive the ""Observed"" precipitation field using a multisensor approach. Hourly precipitation estimates from WSR-88D NEXRAD are compared to ground rainfall gauge reports, and a bias (correction factor) is calculated and applied to the radar field. The radar and gauge fields are combined into a ""multisensor field"", which is quality controlled on an hourly basis. In areas where there is limited or no radar coverage, satellite precipitation estimates (SPE) can be incorporated into this multisensor field. The SPE can also be biased against rain gauge reports. The following links provide additional information about the programs used to derive these multisensor fields: https://www.srh.noaa.gov/abrfc/?n=pcpn_methods https://water.weather.gov/precip/archive/AMS_Paper_Feb_2003.pdf In mountainous areas west of the Continental Divide, a different method is used to derive the ""Observed"" data. Gauge reports are plotted against long term climatologic precipitation (PRISM data), and derived amounts are interpolated between gauge locations. The following link provides more information about the process and program used to derived observed precipitation in the western U.S.: https://www.cnrfc.noaa.gov/products/rfcprismuse.pdf." Refer to: https://www.weather.gov/disclaimer.php Unknown Refer to: https://water.noaa.gov/resources/downloads/precip/stageIV/ Refer to: https://water.noaa.gov/resources/downloads/precip/stageIV/ DOC/NOAA/National Weather Service nwps.webmaster@noaa.gov Downloadable Data Refer to: https://www.weather.gov/disclaimer.php 20120719 DOC/NOAA/National Weather Service nwps.webmaster@noaa.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998