Hawaiian Islands Weather Details & Aloha Paragraphs / April 27-28, 2018

Air Temperatures – The following high temperatures (F) were recorded across the state of Hawaii Friday…along with the low temperatures Friday:

80 – 71  Lihue, Kauai
79 – 70  Honolulu, Oahu
76 – 68  Molokai AP
79 – 70  Kahului AP, Maui
81 – 73  Kailua Kona
81 – 67  Hilo AP, Hawaii

Here are the latest 24-hour precipitation totals (inches) for each of the islands Friday evening:

2.43  Mount Waialeale, Kauai
4.40  Luluku, Oahu
0.94   Molokai
0.44  Lanai
0.00  Kahoolawe
1.11  Kepuni, Maui
1.46  Saddle Quarry, Big Island

The following numbers represent the strongest wind gusts (mph) Friday evening:

18  Port Allen, Kauai
16  Kii, Oahu
07  Molokai
10  Lanai
20  Kahoolawe
23  Kula 1, Maui
21  South Point, Big Island

Hawaii’s Mountains – Here’s a link to the live webcam on the summit of our tallest mountain Mauna Kea (nearly 13,800 feet high) on the Big Island of Hawaii. Here’s the webcam for the Haleakala Crater on Maui. These webcams are available during the daylight hours here in the islands, and at night whenever there’s a big moon shining down. Also, at night you will be able to see the stars — and the sunrise and sunset too — depending upon weather conditions.

Aloha Paragraphs

A cold front to the northwest…is approaching the state

Multi-level clouds…coming up from the southwest

Mostly cloudy skies…lots of high cirrus

Showers locally…some are locally heavy – Looping image

 

~~~ Hawaii Weather Narrative ~~~

 

Wind Advisory…Big Island summits / 35-50 with gusts to over 60 mph

Small Craft Advisory…waters around Kauai, Oahu, and windward  Maui County

High Surf Warning…north and west shores of Kauai and Niihau

High Surf Advisory…Kauai northwest, windward and leeward waters

 

>>> My friend Hans Rosendal, who lives on Oahu, recently sent out this message: “The various models show an interesting case of a strong cutoff Low centered to the north of Hawaii, potentially inducing tropical cyclone development to the south of the islands. This area to the south of Hawaii is unusually warm this spring in spite of lingering La Nino along the equator. A broad east /west strip of well above normal sea surface temperatures is located south of Hawaii…extending almost as far east as Mexico.

Moderately strong southwest winds (29 to 46 mph) associated with the Low to the north of Hawaii, is forecast to persist in a deep layer at low and mid-levels. This in turn could potentially generate the cyclonic vorticity over this warm water region…to spin up a tropical cyclone within the models. We shall see if this will happen, and how long this small tropical vortex will last, as it moves northeast in the coming days passing well east of the Big Island of Hawaii.

This type of brief tropical cyclone genesis has been occurring several times this winter/spring season, during the very wet off and on situations we’ve seen this year so far. This brings to mind the similarly very wet  2006 spring in Hawaii, and the stormy March 1951 with its out of season tropical cyclone vortex…which affected particularly Oahu with flooding rains.”

Broad Brush Overview: A cold front currently located to the northwest of the state, will approach and move down the island chain through Saturday…then come to halt somewhere over the eastern islands Saturday night into early next week. This late season cold front will bring clouds and showers along and ahead of it, a few of which may be heavy at times. A cooler and drier air mass will move over the smaller islands after the front passes, although the stalled front will keep wet weather over the Big Island, and perhaps Maui for several days into next week.

Details: The models show this cold front pushing down across Kauai first, then on to Oahu and Maui County, before arriving over the Big Island late tonight. This cloud band will probably stall near the Big Island Saturday night, acting as a focus for cloud and shower development. This late April front is expected to produce clouds and showers that will affect both windward and leeward portions of the islands. Thunderstorms aren’t expected, although brief heavy showers are possible along and ahead of the front…with the outside chance of a few flakes of snow over the Big Island summits.

North to northwest breezes will arrive over the smaller islands in the wake of the front’s passage. This should bring cool and mostly dry weather Saturday into Sunday, although a trough of low pressure aloft may bring more low clouds to the area late Sunday and Sunday night. However, a shortage of moisture should limit the coverage and intensity of these showers, with north to northwest winds focusing this moisture along north facing coasts and slopes. As this trough passes over the islands, strong winds will likely occur over the summits of the Big Island…where warning level wind speeds are possible Sunday and Monday.

Looking Ahead: High pressure will build to the northwest of the islands next week, supporting more common northeast trade winds, which will carry a few windward showers our way. In addition, we’ll find a relatively cool air mass remaining in place…tropically speaking of course. Remnant moisture associated with the front, will continue to linger near the Big Island and perhaps parts of Maui County for most of next week, where an usually prolonged period of cloudy and showery weather appears more and more likely. The word unusual keeps cropping in our local weather circumstances this year…as you know!

Here’s a wind profile of the Pacific Ocean – Closer view of the islands / Here’s the vog forecast animation / Here’s the latest weather map

Marine environment details: A developing low north of the islands will bring a front over the island chain through the next couple of days, with a trough forming ahead of the front. The trough will develop near Oahu and Maui County first, bringing heavier showers through tonight. The front is expected to stall near the Big Island Saturday night and Sunday, with moisture lingering there during the first part of the week. Northerly winds behind the front will approach small craft advisory criteria…as winds accelerate around the terrain. The low will send a mix of swells and seas toward the islands this weekend into next week, with associated seas rising late Sunday into Monday.

A moderate north-northwest swell will peak Friday, with surf heights remaining below advisory levels. The low that develops north of the islands will remain in place until early next week. The amount of swell and surf that arrives in the islands is somewhat uncertain, and will depend on the evolution of the low and associated fetch. Current indications are that a fairly significant swell will produce advisory level surf along exposed north and west facing shores, with the peak of the swell around Sunday.

Several pulses of small south swells are expected over the next week or so, with a peak in swell energy Sunday. Rough and choppy surf along east facing shores will diminish as the trades weaken.

 

World-wide Tropical Cyclone activity

Here’s the latest Pacific Disaster Center (PDC) Weather Wall Presentation…covering a tropical disturbance being referred to as Invest 98S

>>> Atlantic Ocean:

>>> Caribbean Sea:

>>> Gulf of Mexico:

Here’s a satellite image of the Caribbean Sea…and the Gulf of Mexico

Here’s the link to the National Hurricane Center (NHC)

>>> Eastern Pacific:

Here’s a wide satellite image that covers the entire area between Mexico, out through the central Pacific…to the International Dateline.

Here’s the link to the National Hurricane Center (NHC)

>>> Central Pacific:

Here’s a link to the Central Pacific Hurricane Center (CPHC)

>>> Northwest Pacific Ocean: No active tropical cyclones

>>> North and South Indian Oceans / Arabian Sea: No active tropical cyclones

Here’s a link to the Joint Typhoon Warning Center (JTWC)


Interesting: The Origin Story of Rosetta Comet Is Weird, and Ends with a Rubber Ducky – The Rosetta space probe’s “rubber ducky” comet seems likely to have emerged from a gentle kiss in the cold black of outer space. And the comet might have a secret to tell about Neptune.

Comet 67P, where the European Space Agency (ESA) landed its Rosetta probe back in the summer of 2016, has a strange shape. It is fairly small, just about 2.5 miles at its widest point, and consists of two bulging lobes linked together by a narrow neck. In an unpublished paper awaiting peer review that appeared in the preprint journal arXiv, astronomers detailed how the comet may have formed and migrated into the orbit of Jupiter. And that history has important implications for the early history of the solar system, particularly for the planet Neptune, the researchers said.

Astronomers don’t have time machines; they can’t travel to the past and see how 67P formed. But they can use the information they do have about the comet and our solar system to model the object’s history. And that model has led to some fascinating conclusions about what the solar system looked like eons ago, when 67P likely formed.

The solar system is a roiling field of orbiting objects, tugging on one another with gravity. So, there are limits to how precisely astronomers can track 67P backward through time. Researchers already knew that the comet passed near Jupiter on Feb. 4, 1959, and Oct. 2, 1923. Peering further into the past, though, is much more difficult, the scientists said.

But by modeling dozens of paths that could have pointed the comet to its current position, the researchers concluded that the object likely moved into the inner solar system more than 1,000 years ago. That was after it formed and spent eons orbiting the sun 20 to 30 times farther away than planet Earth is located, in a giant cloud of rubble.

But that trajectory poses a problem, because unless 67P broke off from a larger comet, it almost certainly wouldn’t have survived the version of the early solar system that scientists have long imagined, the researchers in the new study said.

Most histories of the early solar system have a disk of dust and rubble orbiting at 20 to 30 times Earth’s current distance from the sun. In this cloud of material, billions of years ago, little clumps of dirt formed and banged into one another, sometimes clumping together into larger objects and sometimes falling apart.

In the most common version of this story, that cloud lasted about 400 million years. But the astronomers in the new study found that if that were true, 67P almost certainly wouldn’t have survived. Over all that time, the comet would have smashed into other objects and fallen apart, the researchers said.

So 67P’s survival lends credence to another hypothesis: Perhaps Neptune, which once orbited much closer to the sun, drifted out through that disk of matter soon after the disk formed 4.5 billion years ago. Neptune’s drifting could have caused the disk to disperse, saving 67P from collisions in the rough and tumble environment of the rubble disk that spawned the comet, the new study said.

If Neptune’s bulk absorbed or dispersed most of the rubble just 10 million years after the disk formed, that might explain how 67P survived to the present, the study said. Four-hundred million years? Deadly. But 10 million? That’s a short enough span of time spent in the dirt cloud for 67P to have survived intact, the researchers wrote in their study.

Cosmic kiss

The astronomers didn’t offer a firm answer on how 67P itself was formed. It’s possible, they wrote, that a mound of rubble just formed in its current, rubber-ducky shape from the beginning, though there are reasons to doubt that hypothesis.

The two lobes could also have resulted from two smaller comets orbiting one another, called a binary, coming together, and there are two possibilities for how that might have happened, the study said. Maybe a slowly orbiting binary brushed past a planet and got nudged into forming a single comet. Or maybe tiny collisions with other rocks pushed the two lobes together until they met.

A brush with a planet pushing the binary together, the researchers found, is unlikely. Such a close encounter with a planet would likely destroy most comets.

But maybe, out in that rubble cloud, pebbles bashed into the two orbiting chunks of 67P over and over. Each of those collisions would have sapped a bit of energy from the binary orbit, slowing the orbiting chunks down, the study said.

The pieces would have already been moving pretty slowly, the authors wrote. The lightweight lobes of 67P would have orbited one another at just a few feet per second back then. As the chunks experienced collisions, that speed would have dropped over time, until the pieces came together relatively gently.

It seems very likely, then, that Rosetta’s comet formed in this billions-of-years-old kiss, the two lobes locking together and drifting a long way through space before arriving in a spot where humans could reach out and touch them.