What is already known:
What this study adds:
Four radar-based quantitative precipitation estimation (QPE) products from the Multi-Radar Multi-Sensor (MRMS) system are evaluated against hourly and daily gauge-based rainfall amounts over Alaska, Hawaii, and Puerto Rico. Three products are 1) Radar-Only QPE (Q3RAD), the initial version of MRMS QPE that is reflectivity-based, 2) Dual-Polarization QPE (Q3DP), a version of Q3RAD which uses dual-polarization variables in its calculations, 3) Dual-Polarization QPE with Evaporation Correction (Q3EVAP), a product which adds an evaporation correction to Q3DP, and 4) Multi-Sensor QPE (Q3MS), which utilizes gauge- based correction and terrain data and is evaluated daily. The evaluation of QPE data takes place from June 2019 to June 2021. Both the Alaska and Puerto Rico domains exhibited spatial error trends corresponding to the quality of radar coverage, with larger errors in regions of poor coverage. The Hawaii domain was characterized by underestimation throughout the region. Puerto Rico was prone to overestimates in the west, but did not have a problem with underestimation. The results of the study are useful to those who wish to learn more about the present limitations and challenges of radar-based QPE in domains outside the continental United States.