Heavy rainfall in Hawai’i

March 8th, 2021 |

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) revealed 2 bursts of back-building thunderstorms that produced heavy rainfall (as much as 19.21 inches) and flooding along the northern coast of the Hawaiian island of Maui on 08 March 2021. This heavy rain caused rockslides that closed some roads, and prompted evacuations of a few communities downstream of the Kaupakulua Dam (which began to experience over-topping).

The coldest 10.35 µm infrared brightness temperatures were around -48ºC — for example, at 0000 UTC on 09 March (below).

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images at 0000 UTC on 09 March [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images at 0000 UTC on 09 March [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

In closer views of GOES-17 Visible and Infrared images (above), USGS river and rain gauge locations are plotted in large yellow text — the abrupt rise in flow of the Honopau Stream near Huelo (HPOH1) and the rapid accumulation of 17 inches of rainfall at the Wailuaiki rain gauge near Keanae (WWKH1) are shown below.

Hydrograph for the Honopau Stream near Huelo [click to enlarge]

Hydrograph for the Honopau Stream near Huelo [click to enlarge]

Graph of West Wailuaiki rain gauge accumulation [click to enlarge]

Graph of West Wailuaiki rain gauge accumulation [click to enlarge]

GOES-17 Water Vapor images, with plots of mid-upper level Derived Motion Winds [click to enlarge]

GOES-17 Water Vapor images, with plots of mid-upper level Derived Motion Winds [click to enlarge]

GOES-17 Water Vapor images with plots of mid-upper level Derived Motion Winds (above) showed the circulation of an upper level low west of the Hawaiian Islands — and with an increase in southwesterly upper-tropospheric wind speeds (as shown in Lihue rawinsonde data). the corresponding upper-level divergence (below) was seen to increase across the island chain by 00 UTC on 09 March (providing a more favorable environment for the development of deep convection).

GOES-17 Water Vapor images, with contours of upper level divergence [click to enlarge]

GOES-17 Water Vapor images, with contours of upper level divergence [click to enlarge]

The MIMIC Total Precipitable Water product spanning the 2 day period leading up to the heavy rainfall (below) showed an axis of higher tropical moisture — with TPW values of 1.50 to 1.75 inches — moving westward across Hawai’i.

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

The TPW value calculated from Hilo, Hawai’i rawinsonde data increased from 37.8 mm to 42.3 mm (1.49 inches to 1.67 inches) during the day as the lobe of enhanced moisture began to move westward over the Big Island (below).

Plots of rawinsonde data from Hilo, Hawai'i [click to enlarge]

Plots of rawinsonde data from Hilo, Hawai’i [click to enlarge]

Leave a Reply