Welcome to Sauna Island: Gilma, Hector no longer threats, but muggy times ahead for most of Labor Day Weekend

Enjoy basking in a sauna? Welcome to Sauna Island.

It was still 78 degrees at 7:48 p.m. Thursday night in Hilo. With a dew point of 76 degrees and relative humidity of 93%, it felt like it was still 81 degrees.

Needless to say, the air over the Big Island is more than moist.

That trend will continue for a good portion of the Labor Day Weekend as the remnants of what were 2 tropical cyclones — once-mighty Hurricane Gilma that at one time churned as a Category 4 storm in the Eastern Pacific and Tropical Storm Hector tailing behind — add their last breaths of tropical moisture to Hawai‘i’s forecast.

Neither are threats to the islands any longer as both dissipated — Hector at 2 a.m. Thursday before moving into the Central Pacific and Gilma at 5 p.m. Thursday.

The center of Gilma was still 185 miles east-northeast of Hilo when it fell apart.

What is left of Gilma was moving west-northwest at about 12 mph, which is expected to continue throughout the next couple of days. Winds of about 30 mph, with some stronger gusts, were also still embedded inside portions of the system.

Gilma actually dissipated sooner than forecasters expected. Originally, the storm was forecast to fall apart Saturday near Kaua‘i.

The Central Pacific Hurricane Center issued its last advisory for Gilma also at 5 p.m. Thursday, noting that moisture from the remnants of the former storm will help provide enhanced trade wind showers across the islands through tonight and possibly into Saturday, but no significant hazards are expected.

The center of what’s left of Gilma will pass north of the Big Island, putting the island on the weaker side of the former storm, meaning less of a chance for any of its remaining wind or rain.

However, the southern half of what’s left will scrape the islands during the next day or so which will increase the chances for widespread trade wind showers, some of which will be locally heavy, mainly windward and mauka, or toward the mountainside.

Widespread flooding is not expected, but localized flooding could happen. Heavy rain of 1 to 3 inches, with the potential for more in some places, is a possibility.

The highest rainfall amounts are expected over Kohala and Hāmākua on the Big Island and windward Maui.

“We just got out of our civil defense briefing for today, talking about Gilma and Hector,” said Hawai‘i County Mayor Mitch Roth in a reel posted at 9:42 a.m. Thursday on his official Facebook page. “It looks like they’re gonna pass by us, but that doesn’t mean we’re not going to get any rain. It appears that we’ll probably get some rain from North Hilo to North Kohala. Expecting a little bit more than usual.”

Because of that, Roth said the county is closing Waipi‘o Valley Road as a precaution.

The National Weather Service forecast office in Honolulu noted that South Hilo and Puna will remain pretty dry throughout the weekend.

Conditions will also be favorable for allowing showers to make it to the leeward side of the state as the center of Gilma’s remnants is forecast to become centered over the central part of the state tonight.

A more north trek, however, would cut off winds altogether and create drier conditions.

Winds should not be an issue and a moderate medium-period east swell caused by the former tropical cyclone should start to fade today and continue to do so through the weekend.

The real impact will be the the humidity.

“This weekend, we’re expecting to have some hot muggy weather throughout the whole island,” said Roth.

Dew points were in the mid to upper 70s in windward locations throughout the state Thursday afternoon, including 77 in Hilo and even at about 70 in some of the driest leeward places.

The dew point is the temperature at which the air needs to be cooled to achieve a relative humidity of 100%. The higher the dew point, the greater the amount of moisture in the air — it directly affects how comfortable it feels outside.

There was so much moisture in the air Thursday evening that there was no rain needed to produce a rainbow as the setting sun provided light at just the right angle to the cloud bank rolling in over the bay to get the full visible color spectrum for at least a quarter of a ’bow to appear.

Warm muggy conditions will persist through Sunday as the remnants of what was Tropical Storm Hector arrive, with overnight lows in the mid to upper 70s and dew points remaining in the 70s. Winds are expected to stay light as well, providing little aid.

A weak disturbance associated with the remnants of Hector will also bring another round of enhanced showers Saturday night into Sunday, with isolated thunderstorms possible along the northern slopes of Moloka‘i, Maui and the Big Island.

There is relief from the stifling steamy stickiness on the way though.

Harry Durgin, administrator and creator of the Puna Weather group on Facebook and citizen meteorologist, summed it up nicely in a post Thursday morning: “It’s all gone by late Sunday/early Monday.”

He said drier air works its way into the area by then, ushering in a return to a more typical northeast trade wind weather setup, with widely scattered showers mostly during the early mornings and night.

No matter the sauna-like weather, not having to deal with two more tropical cyclones is a relief for an island that was impacted by a Category 1 hurricane that skirted by just to its south last weekend.

“We can all breathe relief,” commented Jo Lani Shrinski on Durgin’s post, with Alita Acia agreeing in a later reply.

Maren Purves said she “can deal with more rain.”

Except for the mischievous Hone, which is a tropical depression now and is forecast to become a tropical storm again out in nowhere land west of the islands by itself after passing far south of Laysan Island, moving west-northwest toward the International Dateline, no other tropical cyclones are expected to develop in the next 7 days anywhere in the Central or Eastern Pacific.

The Central Pacific Hurricane Center in Honolulu also says there is a low chance for any tropical cyclones to form in the far Eastern Pacific through the week of Sept. 11-17.

Roth reminded those who experienced damages because of Hurricane Hone and haven’t reported them yet to do so at the Hawai‘i County Civil Defense website, where they can fill out a damage report form.

He added that while the island might not expect any tropical cyclones in the near future, it’s never too early to start preparing.

August and September are the most active months of the Central Pacific hurricane season, which runs June 1 through Nov. 30.

The mayor encouraged residents to take a look at all of the available resources on the Civil Defense website, which include preparation information, an all-hazards map, road closure updates and more.

“Other than that, wishing you an amazing weekend, on purpose,” the mayor said.