A LARGE PORTION OF TROPICAL CYCLONES (TCS) EXPERIENCE ONE OR MORE RAPID INTENSIFICATION (RI) EVENTS DURING THEIR LIFE TIME. PREDICTING THESE EVENTS IS ONE OF THE MOST CHALLENGING ASPECTS FOR THE FORECASTING AND RESEARCH COMMUNITIES. RECENTLY A SERIES OF SATELLITE-BASED STATISTICAL STUDIES HAVE IDENTIFIED A GRADUAL INCREASE OF THE DEGREE OF SYMMETRY OF SHALLOW TO MODERATE PRECIPITATION AS A PRECURSOR AND INDICATOR OF RI. THIS KEY RESULT OF THE IDENTIFIED SYMMETRIC PROCESS IS CONTRADICTORY TO THE TRADITIONAL VIEWPOINT THAT ASYMMETRIC DEEP CONVECTION AND CONVECTIVE BURSTS ARE CRUCIAL PLAYERS IN THE RI PROCESS. HERE WE PROPOSE A 3-YEAR PROJECT WITH THE CENTRAL GOAL OF USING NASA SATELLITES AND AIRBORNE DATA TO CHARACTERIZE HOW THE SYMMETRIC PROCESS DICTATES THE EVOLUTION OF RI EVENTS. SPECIFICALLY WE WILL IDENTIFY THE ROLE OF DIFFERENT CLOUD AND PRECIPITATION TYPES (E.G. STRATIFORM VS. CONVECTIVE SHALLOW VS. DEEP CONVECTION) IN THE SYMMETRIC PROCESS OF DIFFERENT RI PATHWAYS THROUGH THEIR RELATIVE CONTRIBUTIONS TO AZIMUTHAL AREAL COVERAGE TOTAL RAIN AND LATENT HEATING. AN IMPROVED PREDICTION OF RI IS FUNDAMENTALLY DEPENDENT ON UNDERSTANDING THE ARRAY OF RI PATHWAYS POSSIBLE. THE FOUNDATION OF THE PROPOSED RESEARCH IS THUS TO DEVELOP A COMPREHENSIVE 18-YEAR GLOBAL DATABASE (1998-2015) OF RI AND SLOWLY INTENSIFYING (SI) STORMS. THE NEW RI/SI DATABASE WILL CONSIST OF PRECIPITATION PROPERTIES (INCLUDING CLOUD/PRECIPITATION TYPE) DERIVED FROM NASA TROPICAL RAINFALL MEASURING MISSION (TRMM) AND GLOBAL PRECIPITATION MEASUREMENT (GPM) RADAR REFLECTIVITY PROFILES TRMM/GPM MICROWAVE IMAGER BRIGHTNESS TEMPERATURES LIGHTNING STATISTICS FROM TRMM LIGHTNING IMAGING SENSOR (LIS) THERMODYNAMIC PROPERTIES (TEMPERATURE AND RELATIVE HUMIDITY PROFILES) FROM AIRS AMSU-A AND HSB INSTRUMENTS ON BOARD THE AQUA SATELLITE AS WELL AS ENVIRONMENTAL PARAMETERS (E.G. VERTICAL WIND SHEAR) DERIVED FROM THE NASA GMAO (GLOBAL MODELING AND ASSIMILATION OFFICE) MERRA (MODERN-ERA RETROSPECTIVE ANALYSIS FOR RESEARCH AND APPLICATIONS) REANALYSIS. AIRBORNE DOPPLER RADAR AND DROPSONDE DATA FROM NASA HURRICANE FIELD PROGRAMS FOR A FEW RI CASES WILL ALSO BE INCLUDED. ANALYSES FROM THE DATASET WILL IDENTIFY HOW DIFFERENT CLOUD/PRECIPITATION TYPES CONTRIBUTE DIFFERENTLY TO THE SYMMETRIC PROCESS OF RI AND WHETHER SYSTEMATIC DIFFERENCES EXIST BETWEEN RI AND SI STORMS FOR PRECIPITATION PROPERTIES IN TERMS OF THE EVOLUTION AND CONTRIBUTION OF CONVECTIVE AND STRATIFORM RAIN AND CONVECTION IN DIFFERENT DEPTH (SHALLOW MODERATE AND DEEP) AND INTENSITY. PARTICULAR ATTENTION WILL BE PLACED ON TEMPORAL EVOLUTION OF THESE PROPERTIES THROUGHOUT THE RI PROCESS (I.E. PRE-RI DURING RI AND AFTER RI) HOW THEY RELATE TO THE ENVIRONMENTAL SHEAR AND QUANTIFYING THE FEEDBACK OF PRECIPITATION PROCESSES ON INNER CORE THERMODYNAMIC PROPERTIES INCLUDING MOISTENING AND HUMIDIFICATION OF THE MID-TROPOSPHERE AND THE DEVELOPMENT OF THE UPPER-LEVEL WARM CORE.