Now-Tropical Storm Olivia is now reaching the Hawaiian Islands, and is expected to bring pounding rain, strong winds and flash floods.
This morning, Sept. 12, the National Weather Service said, “Tropical Storm Olivia will bring strong winds, heavy rainfall, and high surf to much of the state today into tonight, with the potential for additional heavy rainfall continuing through Thursday night. Winds have increased to minimal tropical storm force near 40 mph with gusts to 50 mph over parts of Maui County during the night. Tropical-storm-force winds are expected to continue across Maui County and spread across Oahu later today. The mountainous terrain of the islands will produce localized areas of highly enhanced winds away from the center of Olivia, which can cause damage before the onset of more widespread tropical-storm-force winds.”
Floods remain a major concern for the NWS. “Showers and areas of moderate to heavy rain will continue to increase today, with flooding rainfall a significant threat through Thursday night. Expect storm rainfall totals of 5 to 10 inches, with isolated areas reaching up to 15 inches. Much of this rainfall will be focused on windward areas of the islands, especially from Kauai through Maui. However, flooding is still a significant threat for all areas, particularly as Olivia moves through the islands.”
This morning at 7 a.m. local time, the Honolulu Star-Advertiser wrote that “Rain and wind from Tropical Storm Olivia continue to pass slowly over Maui, where up to 15 inches of forecast rain could create life-threatening conditions.”
About 6 inches of rain had already fallen on Maui this morning, Sept. 12, reported the Central Pacific Hurricane Center.
Flash flooding is also expected from the second cyclone to strike the islands in 2018 after Hurricane Lane brought over 50 inches of rain in August.
School closures may be expected for midweek, similar to what happened with Hurricane Gordon in the southeast U.S., given the potential for another foot or more of rain.
On Monday morning, Sept. 10, the National Weather Service said the “impacts of Hurricane Olivia are expected to reach Hawaii on Tuesday; and Hurricane Florence is now a major hurricane, and should be closely monitored by residents in the southeast and mid-Atlantic. Flood threats continue in the northeast, due to the remnants of Gordon and in the western Gulf Coast.”
In particular, “tropical storm conditions are expected over parts of Hawaii starting late Tuesday…. Olivia is forecast to be a strong tropical storm when it reaches the Hawaiian Islands…. Olivia is expected to produce total rainfall accumulations of 10 to 15 inches. Isolated maximum amounts of 20 inches are possible, especially over windward sections of Maui County and the Big Island. This rainfall may produce life-threatening flash flooding.”
Monday morning, the NWS detailed, “The chance for flooding rainfall will increase rapidly late Tuesday and will remain a significant threat through at least Wednesday. Preliminary storm total rainfall amounts are in the 10 to 15-inch range, with isolated areas up to 20 inches. Much of this rainfall will be focused on windward areas, many of which already received substantial amounts of rain from recent Hurricane Lane. However, flooding will be a significant threat for all areas.”
Meanwhile, on the U.S. east coast, the National Hurricane Center said on Monday afternoon that Hurricane Florence has become a Category 4 hurricane, “has continued to rapidly strengthen and has maximum sustained winds near 130 mph.” North and South Carolina then, plus Virginia, are squarely in its path.
NHC warned today that, “A life-threatening storm surge is likely” there, along with life-threatening freshwater flooding, combined with a “prolonged and exceptionally heavy rainfall event.” There are also likely “damaging hurricane-force winds” along the coast, with damaging winds reaching well-inland in those states.