On April 15th, 2018 a singular weather event occurred on the island of Kauai Hawaii. In a 24 hour period 49.69 inches of rain dropped from the sky breaking the record for total precipitation ever recorded in the USA. The TB4 Tipping Bucket Rain Gauge from HyQuest Solutions’ partner Hydrological Services America was the instrument that recorded the historic rainfall, reliably and precisely when it really mattered.
After considering the observation and the various surrounding factors, the NCEC determined the observation to be valid, and it now stands as the 24-hour record precipitation for the United States. This value supersedes the previous record of 43.00” occurring 25-26 July 1979 at Alvin, Texas during Tropical Storm Claudette. The Kauai event shattered this record without the involvement of a tropical cyclone - just historically high moisture levels over the Pacific colliding with unstable air masses streaming down from the north.
Three large bursts
Though Kauai is the rainiest place on Earth - receiving some 400 inches per year with rain on most days - this single day rainfall was far in excess of even that soggy norm. In total, it amounted to about one and a half months of precipitation for the world’s wettest location falling in just one day. Although some precipitation occurred through most of the period, the primary contributors to the very large 24-hour total occurred in three bursts.
After the event, the TB4 and data logger were put through several calibration tests using equipment designed or adapted for the purpose of analyzing gauge performance under high rainfall rates. The tests showed that the gauge performed within expected tolerances.