UPDATED (8:15 p.m. on 12/20/2017)

This is a Flash Flood Warning update for Wednesday night, December 20 at 8:15 p.m. by Hawaii County Civil Defense.

The National Weather Service has downgraded the Warning to a Flash Flood Watch. A Flash Flood Watch means flooding is still possible.

Rainy conditions are forecasted throughout tonight. Be on the alert for possible reoccurrence of heavy rains and flooding conditions.

Department of Public Works reports all roads are now open except Kukila Street in Hilo. Be aware that additional road closures may occur without notice.

For your additional information, a High Surf Advisory is in effect for the east-facing shores of Kohala, Hamakua, Hilo and Puna. A Winter Storm Warning also remains in effect for Hawaii Island Summits

UPDATED (6:15 p.m. on 12/20/2017)

The National Weather Service issued a Flash Flood Warning for Hawaii Island through tonight. A Flash Flood Warning means dangerous flooding is occurring or imminent; and may pose a threat to life and property. Heavy showers are expected to continue through tonight.

Due to the Flash Flood Warning, the following advisories are issued:

• Hawaii County Police and Public Works Departments report Kamehameha Avenue, Pauahi Street, Railroad Avenue and Kukila Street in Hilo are closed. Avoid these areas and use alternate routes.
• Due to occasional heavy downpours, driving conditions are poor. Be on the alert for additional possible road closures.
• Expect possible interruptions in your utility services.
• Be on the alert for malfunctioning traffic signals. Please treat flashing traffic lights as a four-way stop.
• Remember, if lightning does threaten your area, the safest place to be is indoors.

UPDATED (5:40 p.m. on 12/20/2017)

Flash Flood Warning for Hawaii Island

UPDATED (5:20 p.m. on 12/20/2017)

Police alert at 5:20 p.m.

• AVOID Kamehameha Avenue between Manono Street and Ponahawai Streets in Hilo due to flooding.
• Pauahi Street is closed at the Aupuni Street intersection.

Please use alternate routes and drive with caution.

Weather advisory map via National Weather Service/NOAA

Snowfall on the summit of Mauna Kea. Time-lapse images via the Gemini Telescope and UK Infrared Telescope cameras.

Winter Storm Warning

A winter storm warning remains in effect for the summits of Mauna Loa and Mauna Kea until 6 a.m. Thursday (Dec 21).

Heavy snow is occurring. Travel will be very difficult to impossible on the summit areas above 12,000 feet. Additional snow accumulations of 3-6 inches are expected.

Visibility will be reduced to zero as occasional heavy snow squalls impact the summit.

Flash Flood Watch (see update above)

A flash flood watch remains in effect for Hawaii Island through late tonight (Dec 20).

Abundant moisture associated with a cold front will combine with a developing low aloft to produce widespread heavy rain and a chance of thunderstorms.

Rain will be widespread, and will also affect urban areas in the lower elevations, which are more susceptible to flooding problems. Additionally, prolonged locally intense rainfall is expected, leading to flash flooding of streams and low-lying areas.

Campers and hikers should avoid low lying flood prone areas. People should stay away from streams, drainage ditches and low lying areas prone to flooding. The rainfall and runoff will cause hazardous driving conditions due to ponding, reduced visibility and poor braking action. Excessive runoff may cause rockslides and mudslides in steep terrain.

Debris in streams and gulches may clog bridges and culverts resulting in flooding outside normal water channels causing damage.

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

High Surf Advisory

A high surf advisory is in effect for north and east facing shores of Hawaii Island until 6 p.m. Thursday (Dec 21).

Surf along north facing shores of Niihau, Kauai, Oahu, Molokai, Maui and the Big Island, 15 to 20 feet. Along east facing shores of Kauai, Oahu, Molokai, Maui and the Big Island, 4 to 8 feet.

Small Craft Advisory

The National Weather Service in Honolulu has issued a small craft advisory for Hawaii Island windward waters.

Winds and seas will be from the northeast with winds 10 to 20 knots. Seas will be 8 to 12 feet.

Due to these advisories, the following are issued until further notice:

• Oceanfront residents and beachgoers along the affected shores are advised to be on the alert for high and dangerous surf.
• Boat owners and oceanfront residents should take action to secure their property before nightfall.
• Closures of roads and beaches may occur without notice.
• As in all severe weather conditions, expect possible interruptions in your utility services.
• Should power outages occur, be on the alert for malfunctioning traffic signals. Please treat flashing traffic lights as a four-way stop.
• Remember, if lightning does threaten your area, the safest place to be is indoors.

For links to the latest weather forecasts, reports, radar and satellite imagery visit our Weather Page at hawaii247.com/weather