Tracking Water Vapor with Multisensor Blended Products for Forecasters

Forecasters have been using the NOAA operational blended total precipitable water (TPW) product, developed by the Cooperative Institute for Research in the Atmosphere (CIRA), since 2009. TPW retrievals from polar orbiting passive microwave sensors are merged with ground-based Global Positioning System (GPS) measurements to create the product. Blended TPW has a wide variety of uses related to heavy precipitation and flooding, such as measuring the amount of moisture in an atmospheric river originating in the tropics. New blending techniques using the increased spatial and temporal resolution of GOES-16 data are expected to improve the depiction of TPW, especially over land. Advective blending, using model winds to advect the product to synoptic times, achieves a more useful product for forecasters.

Blended TPW conveys no information on the vertical distribution of moisture, which is relevant to a variety of forecast concerns. A blended seven-satellite, four-layer, layered water vapor product developed by CIRA allows forecasters to see the vertical distribution of water vapor in near real-time. This product is called blended Layered Precipitable Water (LPW) and consists of four tropospheric layers of water vapor. Blended LPW is created by using NOAA investments in polar orbiting satellite sounding retrievals from passive microwave radiances, in particular, the Microwave Integrated Retrieval System (MiRS). Data from the Suomi-NPP, NOAA-18 and -19, Metop-A and –B, and Defense Meteorological Program (DMSP) F17 and F18 spacecraft are merged to create the LPW product. The NOAA Joint Polar Satellite System Proving Ground and Risk Reduction program supports the development of advanced blending algorithms and the distribution of the product to NOAA national centers.

Examples of forecast usage and animations of the total and layered precipitable water products will be presented. Interactions with the National Hurricane Center (NHC) and the Weather Prediction Center (WPC) will be discussed.