SAB Areal Tropical Rainfall Potential
The Satellite Analysis Branch (SAB) of NOAA's
Satellites and Information Service
produces a graphical representation of the forecast Tropical
Rainfall Potential (TRaP) for any tropical system in the Western Hemisphere
and many in the Eastern Hemisphere. This is an objective analysis done by
taking the latest microwave rain rate data from the Defense Meteorological
Satellite Program's (DMSP) Special Sensor Microwave Imager (SSM/I), the NOAA
Advanced Microwave Sounder Unit (AMSU), or the NASA Tropical Rainfall
Measuring Mission (TRMM) Microwave Imager (TMI) and performing an
extrapolation of the rain rate values based on the latest forecast track and
speed of the storm.
Rain Rates depicted below are areal averages on the order of 15 KM for AMSU, 13x15 KM for SSM/I,
and 5 KM for TRMM (at nadir).
Therefore, the rain rates may seem lower than what is intuitive for a tropical cyclone.
Official forecast bulletins issued by NOAA's
National Center for Environmental Prediction (NCEP)
Tropical Prediction Center (TPC)
and the National Weather Service
Central Pacific Hurricane Center
for the Western Hemisphere are used in the extrapolation. In
addition to performing the extrapolations for Eastern Hemisphere storms using
Joint Typhoon Warning Center (JTWC)
forecasts of storm speed and direction, TRaPs are now generated using forecasts from the
Regional Specialized Meteorological Centers (RSMC) of Tokyo,
La Reunion, Perth, Darwin, Brisbane, and Nadi. This can be done for tropical cyclones of an intensity of
35 knots (T2.5 on the Dvorak classification scale) or greater.
Read about limitations of the Microwave TRaP technique.
View archived Areal-TRaPs and Rain Rate images.
View 2004 Archived TRaPs and Rain Rate Images.