According to the National Weather Service in Honolulu, all of the Hawaiian Islands could be faced with massive levels of flooding. The source is from a storm system that could keep those flooding conditions up until Tuesday.
About one foot of rain has dropped in Kula on Maui in the past day which makes the prediction more accurate. This is on top of the rainfall storm totals moving forward predicted to be about 10 to 15 inches, with isolated areas facing 20 to 25 inches.
Heavy Rain Is Still An Issue Even As It's Dying Down
The Big Island itself didn't face as much during the story with only 8 inches of rain falling in the past day in multiple locations. Early this morning the amount of rainfall decreased too.
But residents can't rest easy as heavy rain is still forecasted in Maui, Oahu, and Kauai over the course of today (December 6th). Furthermore, a flash flood warning was issued for Molokai and Maui. It's reasonable to issue those warnings as NWS Honolulu stated that:
"2 to 3 inches of rainfall per hour will exacerbate the ongoing flooding from the rainfall from earlier. Already, Maui has gotten over 6 inches of rain in the past 6 hours and runoff is still high."
There is also another issue that stems from the rainfall too: landslides.
Landslides are to be expected and can even result in closing highways and cutting off communities in the process.
A flood watch is expected to remain in effect until Tuesday afternoon local time.
The Dangers Of These Rain Events
In the past, rain events of this level cause a lot of flooding and can affect areas that aren't used to flooding at all. There are also low spots in the roads that can also become dangerous or even impassable because of the risk of severe runoff.
These rainfalls also are able to move debris which creates another layer of problems as the debris can clog streams, gulches, bridges and culverts that cause more flooding.
The NWS cautions people about the numerous landslides that could happen in areas where there is steep terrain. This means urban areas - especially on Oahu - could be faced with severe flooding. There is also isolated highways - like the Belt Highway in Big Island's Kau District and Pilani Highwat on Maul - that could be closed in several locations. If taking those highways, prepare for long detours or having your community totally isolated.