Hawaiian Islands Weather Details & Aloha Paragraphs / April 25-26, 2018

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

75 – 72  Lihue, Kauai
84 – 72  Honolulu, Oahu
81 – 72  Molokai AP
83 – 69  Kahului AP, Maui
83 – 73  Kailua Kona
82 – 68  Hilo AP, Hawaii

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

2.02  Kilohana, Kauai
0.28  Manoa Lyon Arboretum, Oahu
0.23  Molokai
0.00  Lanai
0.00  Kahoolawe
1.20  Puu Kukui, Maui
1.64  Saddle Quarry, Big Island

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

36  Port Allen, Kauai
35  Kuaokala, Oahu
28  Molokai
31  Lanai
35  Kahoolawe
31  Maalaea Bay, Maui
35  PTA Keamuku, 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

High pressure north-northeast of the state…a cold front northwest

The high and middle clouds…clipping the Big Island

Clear to partly…cloudy some windward areas

Showers locally – Looping image

 

~~~ Hawaii Weather Narrative ~~~

 

Small Craft Advisory – windiest coasts and channels around Maui County and the Big Island

 

Broad Brush Overview: The robust high pressure system located well north-northeast of the state, will continue the gusty trade wind flow over the islands, along with bringing off and on windward showers. The trades will gradually weaken tonight through early Thursday, then veer to the southeast late Thursday ahead of a late season cold front…potentially bringing volcanic haze (vog). The front will affect the western end of the state Friday and Friday night, then move to the eastern end of the island chain Saturday. A band of clouds and showers associated with the front will likely bring wet and unsettled weather to portions of the state starting late Thursday or Friday…continuing into the weekend.

Details: Look for moderate to locally strong trade winds across the island chain for the time being. Meanwhile, a mid-level ridge west of the state is providing a northwesterly flow aloft above the island chain. This is maintaining stable atmospheric conditions over the islands. The latest precipitable water values are 1.0-1.1 inches, with isolated pockets of up to 1.3 inches, in the vicinity of the state.

The surface high will remain north-northeast of the area, however, since it will be gradually weakening, the pressure gradient will relax slightly starting tonight. This will likely bring trade wind speeds down a notch in turn. The mid-level ridge will also remain in place, which will keep the stable atmospheric conditions across the region. The slightly drier conditions upstream of the islands will continue to spread westward. This will likely reduce the coverage of low clouds and showers over many areas…at least compared to the recent past.

Looking Ahead: Look for some changes in our local weather pattern Thursday. The models show the mid-level ridge will weaken due to an upper-level trough shifting down from the northwest toward the state. This will result in some destabilization of the atmosphere, especially by late Thursday. The trough aloft will also likely cause the development of a deep surface low well north of the islands. This feature will push a cold front down toward Kauai late Thursday night, which will cause the trade winds to weaken…and eventually shift to a southeast direction.

The models also show an area of slightly enhanced low-level moisture moving in from the east Thursday. Assuming this pocket of increased moisture arrives in the islands as expected, we could see an increase in low clouds and showers, especially over windward areas. The models also continue to suggest that a surface trough may develop near the western islands. This feature may become the focus for prefrontal showers Thursday night and Friday morning, especially over Kauai and Oahu…with the potential for heavy downpours, mainly over the western islands.

As we push into Friday, the winds will continue to shift to a south to southwest Kona direction, ahead of the approaching front. This front is forecast to reach Kauai Friday afternoon, and eventually push down across Oahu to Maui County Friday evening through early Saturday. At the same time, the upper-level trough is forecast to pass over the area. Assuming these features develop in this manner, it would greatly increase the likelihood of heavy rainfall, and possibly localized flooding, ahead of and along the front as it moves down the western end of the island chain…especially from Kauai to Molokai.

The potential for wet and unsettled weather shifts to the central and eastern islands, as the front continues to push eastward this weekend. The front may stall near the Big Island, or eventually push east of the state. If it stalls, there’s a good chance enhanced moisture will be drawn up over the eastern islands. This could lead to flooding rainfall for the eastern end of the state starting some time this weekend. However, the latest guidance is leaning toward the front eventually pushing just east of the Big Island.

Thus, wet conditions remain in the forecast through Sunday over the eastern end of the state, although there is a chance things could improve, especially over Maui County, later this weekend. To the west of the front, a drier and more stable northerly flow will fill in over Kauai and Oahu. Therefore, while there’s still some uncertainty in where the front will move to, Kauai and Oahu have the greatest chance of experiencing drier conditions starting as early as Saturday.

Heading into early next week, a return to typical trade wind weather appears to be unlikely. The upper-level trough will remain over the region, while a surface low is forecast to meander several hundred miles north of the state. As a result, surface winds will likely remain relatively light. In addition, the models are hinting that the remnant moisture from the frontal band may push back westward over the state some time early next week. If so, expect a wet weather pattern to return to portions of the state then.

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 high north-northeast of the islands is producing moderate to locally strong trade winds over the area. The high will weaken as it moves southwestward through Thursday, causing the trades to become light and variable Thursday night.

A low is forecast to form rapidly north of the islands Thursday night and Friday, with a cold front reaching Kauai early Friday evening. The front stalls near the Big Island Saturday afternoon, and lingers there for the rest of the weekend. Initially, in the wake of the front, northerly winds may briefly reach small craft advisory criteria within some of the marine zones.

The low north of the islands will be generating a rough swell toward the islands this weekend into next week. Preceding this swell, a moderate northwest swell is due to arrive late Thursday…peaking early Friday.

This swell is forecast to be reinforced by a series of potentially larger north-northwest swells later in the week. The current indications are that a fairly significant swell will produce high end advisory level surf along exposed north and west facing shores, with the peak of the swell around Sunday.

The weather pattern in the southern hemisphere has become more conducive for south swells to arrive in the islands, and a series of relatively small southwest to south swells are expected over the next week or so. Finally, the rough and choppy surf along windward shores brought on by the breezy trades, will begin lowering Thursday…along with the diminishing trades.

 

World-wide Tropical Cyclone activity

Here’s the latest Pacific Disaster Center (PDC) Weather Wall Presentation

>>> 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 Truth Behind This Amazing Video from the Surface of a Comet – That snowy-looking scene wasn’t captured on Mount Everest, or in some canyon in Antarctica. That’s the view from a lander on the surface of a comet.

Remember Rosetta? That comet-chasing European Space Agency (ESA) probe that deployed (and accidentally bounced) its lander Philae on the surface of Comet 67P? This GIF is made up of images Rosetta beamed back to Earth, which have been freely available online for a while. But it took Twitter user landru79 processing and assembling them into this short, looped clip to reveal the drama they contained.

As several astronomers and casual observers pointed out in the replies to landru79’s original tweet, the “snowstorm” depicted almost certainly isn’t a true snowfall of the sort experienced on Earth and other planets. Instead, there are likely two or three different phenomena creating the snowy effect.

Up close to the camera, dust particles backlit by the sun are likely moving around, mimicking the look of snow on Earth. Cosmic rays may also be creating snow-like artifacts on the images. And those dots in the background, that appear to be falling straight down and disappearing behind the cliff? Those appear to be stars, which look like they’re falling because the comet is rotating as it orbits the sun every 6.5 years.

The clip has also been sped up a great deal, enhancing the drama.

According to the creator, the first frame of the GIF is an image shot June 1, 2016, at 3.981 seconds past 5 p.m. UTC (1 p.m. Eastern). The last frame is an image shot at 17.017 seconds past 5:25 p.m. (1:25 p.m. Eastern) on the same day. That means that a bit more than 25 minutes worth of action is compressed into this short clip, so everything appears to be moving much faster than it did in reality.

But none of that is to detract from what landru79 pulled off here, which captures something close to the drama of standing on the surface of a far-away comet (though we’ve never tried that).

Landru79 said that in their next project they will use the color information Rosetta beamed home to make a full-color version of the GIF.