(BIVN) – A Flood Advisory was posted for the entire island of Hawaiʻi on Sunday morning, while a Blizzard Warning remained in effect for the summits of Maunakea and Mauna Loa, as widespread heavy rainfall and thunderstorms, “capable of producing catastrophic flooding”, threatened the State of Hawaiʻi.

At 9:27 a.m. HST, radar indicated heavy rain mainly over southeast and west Big Island. The National Weather Service in Honolulu said rain was falling at a rate of 1 to 2 inches per hour, with additional, heavy rainfall expected throughout the day today.

A kona low is responsible for the weather, which will include strong south to southwest winds through the first half of the week. “Expect a prolonged period of heavy rainfall, capable of producing extreme rainfall rates, potentially continuing into Wednesday,” a National Weather Service discussion on Sunday stated. “These rainfall rates for long durations combined with rivers and streams quickly rising will support the potential for catastrophic flooding. In addition to the threat of flash flooding, thunderstorms capable of generating strong straight-line winds will become a possibility, especially Monday through Tuesday when the deep layer shear, instability, and moisture axis could come into phase.”

Blizzard conditions are occurring on Hawaiʻi island summits. Additional snow accumulations of up to 8 inches, and winds gusting as high as 125 mph, are expected.

A High Surf Warning has also been issued for north facing shores of the Big Island, where surf heights could reach 20 to 30 feet. Surf of 8 to 12 feet will be possible along the west facing shore of the Big island north of Kua Bay, forecasters say.

From the Hawaiʻi County Civil Defense:

The National Weather Service forecasts this to be a Catastrophic Flooding Event with 20 to 25 inches of rainfall in isolated areas of Hawaii Island. Know that rain events of this magnitude can affect areas that do not usually flood.

Due to the Flood Watch, conditions are favorable for flash flooding and the following are in effect:

All Residents in flood prone areas are asked to remain alert for flooding conditions.

Be prepared for sudden road closures, possible landslides, downed trees, and utility disruptions.

Do not cross fast flowing water in your vehicle or on foot. Turn around don’t drown.

If lightning threatens your area, the safest place to be is indoors.

Due to the possible severity of weather forecast for today, Civil Defense encourages all non-essential outdoor activity and travel be suspended until conditions improve.

A Wind Advisory for Hawaii Island remains in effect through Monday for winds from the southerly direction up to 50mph. Winds this strong can bring down trees and cause road closures and utility disruptions. Secure outdoor items before the winds begin.

A High Surf Warning for west and north facing shores of Hawaii Island continues through Monday for surf up to 30 feet. Surf of this size is extremely life threatening and may cause damage to boats and shoreline property.

Due to the High Surf Warnings all beach parks are closed today.

The National Weather Service Blizzard Warning continues for the summits of Hawaii Island through today and the High Wind Warning for the summits through Monday. Know that summit roads are closed to the public at this time.