Extreme rainfall has wreaked havoc on Hawaii's Big Island and Maui over the past few days, as a Kona storm, or strong low-pressure system, passed northwest of the island chain. Radar estimates reveal that rainfall exceeded 15 inches on three Hawaiian islands, resulting in widespread flooding and pollution concerns in the southeastern part of Hilo on the Big Island.

Responding to the situation, the Hawaii State Department of Health issued a brown water advisory, urging the public to avoid floodwaters and storm water runoff due to the presence of potentially hazardous materials. The floodwaters were found to contain overflowing cesspools, sewer systems, manholes, pesticides, animal fecal matter, dead animals, pathogens, chemicals, and flood debris.

The severity of the current weather conditions only underlines the desperate need for water in the Aloha State. Recent data from the federal drought monitor reveals that approximately 94 percent of the state is facing some level of drought, with about 12 percent experiencing extreme drought conditions. This marks a Level 3 out of 4 on the drought scale.

In addition to the heavy rainfall, the Kona storm system brought unexpected snowfall to the summit of Mauna Kea on the Big Island. Freezing temperatures accompanied 5 inches of heavy, wet snow on the peak, which stands at an elevation of 13,803 feet. The occurrence of both flooding rain and high-elevation snow follows the devastating Maui fire disaster four months ago, which claimed nearly 100 lives, destroyed over 2,000 structures, and burned more than 17,000 acres.

Kona storms, which affect Hawaii a few times each winter, are low-pressure systems originating from the mid-latitudes that intensify over the central tropical Pacific Ocean. As they pass northwest of Hawaii, they usher tropical moisture northward, resulting in torrential rainfall across the islands. Some Kona storms also bring severe weather, with recent warnings issued for potential waterspouts west of Kauai.

Although Kona storms are not tropical storms themselves, their impacts can be similar. In rare occurrences, they can even transition into subtropical or tropical systems. One notable case took place in December 2010, when a Kona storm transformed into Subtropical Storm Omeka, making it the latest-forming tropical storm on record in the eastern tropical Pacific.

Over the past 72 hours, rainfall on the eastern parts of the Big Island reached nearly 10 inches, with some areas experiencing pockets of rainfall approaching 15 inches. This disparity in rain totals is typical during intense thunderstorm activity, which tends to be irregular and highly localized in intensity. Doppler radar estimates also suggest that certain neighborhoods received significant precipitation, ranging from 15 to 17.5 inches.

As a result of the extreme rainfall, the National Weather Service in Honolulu issued four flash flood warnings, including two for the Big Island. Rainfall rates of 2 to 3 inches per hour were reported during downpours, causing certain roads, such as Wood Valley Road near Pahala, Highway 132 near Four Corners, and Pohaku Drive in Orchidland Estates, to be temporarily closed.

The brown water advisory remains in effect, with a flood watch extending into the evening. Additional rain showers and downpours are expected as the Kona storm gradually weakens its grip on the Hawaiian archipelago.

In addition to the flooding, the Kona low-pressure system resulted in moderate snowfall at the summit of Mauna Kea. Data from weather balloons indicate that the freezing level was around 8,500 feet on Wednesday night, rising to approximately 15,400 feet on Thursday afternoon. This led to heavy snow accumulation, blanketing the peak.

As Hawaii continues to battle the effects of extreme weather, residents remain vigilant, prepared for further rainfall, flooding, and the possible long-term consequences of the ongoing drought conditions.