Over the past month, Hawaii has been locked into a pattern of persistent storminess that lead to heavy rains, flooding, and severe weather. A series of upper-level low pressure centers north and west of the state helped to draw moisture up from the deep Tropics. This southerly flow also interacted with the topography of the islands to enhance rainfall amounts. The net result was numerous record-setting rainfall totals across the state for the month of March. On Kauai, Mount Waialeale (one of the wettest places on earth) set an all-time monthly record of 93.71 inches of rain. Part of the reason for all of the rainfall is the current La Niña. During La Niña conditions, Hawaii is expected to have above average rain.

The Tropical Rainfall Measuring Mission satellite, better known as TRMM, was launched into service in November of 1997 to measure rainfall over the Tropics. It is equipped with both passive and active sensors, including the first and only precipitation radar in space. The TRMM-based, near-real time Multi- satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center monitors rainfall over the global Tropics. MPA rainfall anomalies are shown here for the period 19 February to 1 April 2006 for the northern East Pacific. It shows that Hawaii and the surrounding area had higher-than-average rainfall (green areas) for the period with the western half of the state having a lot higher than average (blue areas). The image also shows a coherent pattern of above-average-rainfall anomalies that extend to the West Coast (green streaks) and culminate in well-above-average rainfall (blue areas) over northern California, which is consistent with a La Niña pattern.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Image produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC).