Tropical Rainfall Product Description
The National Hurricane Center's (NHC) Tropical Analysis and Forecast Branch (TAFB) is providing on an operational basis an event-driven satellite-based 6-hour Quantitative Precipitation Estimates (QPE) text product for tropical cyclones and tropical disturbances affecting areas within the National Hurricane Center (NHC) and Central Pacific Hurricane Center (CPHC) areas of responsibility (AOR).
2. Product Description
The Satellite Quantitative Precipitation Estimate (QPE) Webpage hosts event-driven satellite-based 6-hour QPEs in text form for tropical cyclones and tropical disturbances. The satellite QPE product is a text product that provides 6-hour estimates of the amount of rain that has fallen from a tropical cyclone or disturbance impacting land and the distribution of that rain. The product is generated when model guidance is initiated by the U.S. National Hurricane Center (NHC) or the Central Pacific Hurricane Center (CPHC) for a tropical disturbance or cyclone in the North Atlantic, eastern North Pacific or central North Pacific basins. The product may also be generated for tropical disturbances that are heavy rainfall producers over land but are not anticipated to become tropical cyclones in the next few days. The product consists of Satellite-based Rainfall Estimates (SREs) valid over the same 6-hour period from the U.S. Naval Research Laboratory (NRL) and NOAA's Climate Prediction Center (CPC) as well as a recent forecast from the Global Forecast System (GFS) model in a text table. The bottom of the webpage displays a number of links to rainfall analysis and guidance products from U.S. weather services that may be helpful to our partners.
The NHC satellite QPE text product offers six-hour QPEs derived from both the NRL-Blend Satellite Rainfall Estimate (SRE) technique provided by the U.S. Naval Research Laboratory and the QMORPH SRE technique provided by NOAA's Climate Prediction Center. These SRE techniques incorporate both geostationary and microwave satellite imagery to generate precipitation estimates within a few hours of real-time. This is seen as an improvement over the Griffith-Woodley technique used to generate the current NHC Satellite Rainfall Estimate Product. Descriptions of these three SRE techniques can be found here. In addition, the text product provides a rainfall forecast from a recent run of the Global Forecast (GFS) model that spans the same 6-hour period as the satellite-based estimates. The initialization time of the GFS run is specified in the text product. Information on the GFS model can be found here. The location of the tropical cyclone or disturbance at the most recent synoptic time is provided by NHC or CPHC forecasters and is used as the center point for 6° latitude by 6° longitude tables created for each of the rainfall estimate methods. A range of precipitation values is specified in millimeters for each 1° bin within each table. In addition to the tables, the text product provides the amount and location of the 6-hour and 24-hour precipitation maxima determined by each of the three methods. These values are rounded to the nearest 10 millimeters. Differences between the estimates provided by the three methods indicate uncertainty in the amount of rain received.
The NHC 6-hour QPE text product is available four times a day when there are active tropical cyclones and/or tropical disturbances. They are posted to the web at approximately 0400, 1000 1600 and 2200 UTC. URL for satellite rainfall QPEs: http://www.nhc.noaa.gov/marine/rainfall
Examples of the NHC 6-hour satellite QPE text product are provided below.
Figure 1. An example of the 6-hour satellite QPE text product. Each of the tables in the product describes the distribution of rainfall over the 6-hr period ending at the date/time noted at the top of the product based on a different method of rainfall estimation. In addition, the text product provides the amount and location of the 6-hour and 24-hour precipitation maxima determined by each of the three methods. The first table in the product is derived from the QMORPH SRE technique, the second table is derived from the NRL-Blend technique, and the third table is derived from the rainfall forecast from a recent run of the GFS forecast models.
6. Feedback and CommentsThe NHC Tropical Analysis and Forecast Branch is requesting your comments and feedback about the NHC/TAFB QPE and QPF webpage.
Comments may also be mailed to the following address:
National Hurricane Center/Tropical Analysis and Forecast Branch
11691 SW 17th Street
Miami, Florida 33165