Heavy rainfall over the Hawaiian island of Kauai
A series of back-building thunderstorms produced very heavy rainfall and flash flooding (Public Information Statement | Local Storm Reports | CoCoRaHS) over the northern and eastern portion of Kauai on 14-15 April 2018. GOES-15 (GOES-West) Water Vapor (6.5 µm) and Infrared Window (10.7 µm) images (above) showed these deep convective storms, which exhibited cloud-top infrared brightness temperatures in the -60 to -70 ºC range (red to black enhancement). December 2018 Update: a new US record for 24-hour precipitation (49.69 inches) was confirmed by the National Climate Extremes Committee.Even though the JMA Himawari-8 AHI instrument provides more frequent Water Vapor and Infrared Window images (every 10 minutes, compared to every 15-30 minutes with GOES-15) at a higher spatial resolution (2-km at satellite sub-point, vs 4-km with GOES-15), Hawai’i is located near the limb of the Himawari-8 view — so parallax was playing a major role in the apparent location of the important convective features. Note how the primary thunderstorms were displayed to the east of Kauai on the Himawari-8 images, in contrast to directly over the island on GOES-15 images.
The MIMIC Total Precipitable Water product (above) showed that high amounts of tropical moisture were drawn northward across Hawai’i by the circulation of an upper-level trough — depicted by mid/upper-level atmospheric motion vectors — that was situated west/northwest of the islands (below).