Look for more hot and oppressively humid conditions Tuesday and Wednesday along with the threat of thunderstorms and heavy rain as moisture from Tropical Depression Kilo lingers over the islands.
National Weather Service forecasters also say light winds will continue throughout the week before normal tradewinds possibly pick up over the weekend.
But more moisture could be on the way Sunday and into next week, as newly formed Tropical Depression 12-E was slowly approaching Hawaii from the east, meteorologist Ian Morrison said Monday.
Morrison said it appears 12-E will strengthen into a tropical storm Tuesday and bring more moisture to Hawaii. If it passes to the south, it could offer a potential replay of this week’s unstable weather, but it’s much too early to say, he added.
Kilo and Loke, which has strengthened into a hurricane, remained in the Central Pacific far to the west of the main Hawaiian Islands and are threatening the Northwest Hawaiian Islands.
Rainfall records were smashed on three islands Monday as thunderstorms struck heavy and hard early in the morning on Oahu, Kauai and Maui.
There was 3.53 inches of rain in Honolulu, breaking the old record of 0.46 inch for the date, set in 1966. Lihue saw 3.03 inches of rain, breaking its record of 0.26 inch set in 1970. And Kahului experienced 1.46 inches, breaking a record of 0.13 inch set in 1957.
The old records were much lower because summer is normally a dry season.
Morrison said extreme humidity with unusually high dew points — a measure of how much vapor is in the air — will remain over the islands Tuesday and likely Wednesday as a weak upper trough of low pressure north of Hawaii continues to destabilize the atmosphere, creating conditions that could generate heavy showers and lightning.
“But the exactly location (of the storms) in the islands is difficult to pin down,” he said. “In the next few days, it won’t be raining all the time. There will be clearing of clouds. But when it does rain, it should be a heavy downpour.”
A flash flood watch remains in effect for all islands through 6 p.m. Tuesday.
The weak trough should persist through the week, and light winds might stick around through Saturday. Moisture and the possibility of heavy showers and thunderstorms will remain through about Wednesday, Morrison said.
Humidity will back off slightly after Wednesday as drier air moves in from the east, he said, and light tradewinds might return with clouds and showers expected mostly in windward and mauka regions.
On Maui, Haleakala National Park will reopen its Kipahulu District on Tuesday following heavy rain Monday. The park is warning visitors to expect intermittent storm conditions, including heavy wind and rain, thunder, lightning, fog, extremely poor visibility and flooding.
Mariners might also encounter heavy showers or thunderstorms as a moist and unstable air mass lingers across the area through the next couple of days, forecasters said.
A west-by-northwest swell from a distant typhoon is expected to arrive Wednesday and then peak Thursday into Friday. The swell may be big enough to produce advisory-level surf along west-facing shores of Hawaii island, they said.
Tropical Depression Kilo — last week forecast to become a Category 2 hurricane and threaten Hawaii — remained disorganized east-northeast of Johnston Atoll on Monday, forecasters said.
