Hawaiian Islands weather details & Aloha paragraphs / April 16-17, 2010

April 16-17, 2010

Air Temperatures – The following maximum temperatures were recorded across the state of Hawaii Friday afternoon:

Lihue, Kauai – 72
Honolulu, Oahu – 74
Kaneohe, Oahu – 76
Kaunakakai, Molokai – 72
Kahului, Maui – 78
Hilo, Hawaii – 78
Kailua-kona – 81

Air Temperatures ranged between these warmest and coolest spots near sea level around the state – and on the highest mountains…at 4pm Friday afternoon:

Kailua-kona – 78F
Lihue, Kauai – 68

Haleakala Crater –    46 (near 10,000 feet on Maui)
Mauna Kea summit – 45 (near 14,000 feet on the Big Island)

Precipitation Totals – The following numbers represent the largest precipitation totals (inches) during the last 24 hours on each of the major islands, as of Friday afternoon:

0.33 Kokee, Kauai  
0.30 Makaha Stream, Oahu
0.00 Molokai 
0.00 Lanai
0.00 Kahoolawe
0.63 West Wailuaiki, Maui 
0.21 Kawainui Stream, Big Island

Marine Winds – Here’s the latest (automatically updated) weather map showing a 1034 millibar high pressure system located far to the northwest of the islands. At the same time, we have a 1004 millibar low pressure cell positioned to our northeast. This pressure configuration will keep our winds north to northeast through Saturday...becoming ENE Sunday.

Satellite and Radar Images: To view the cloud conditions we have here in Hawaii, please use the following satellite links, starting off with this Infrared Satellite Image of the islands to see all the clouds around the state during the day and night. This next image is one that gives close images of the islands only during the daytime hours, and is referred to as a Close-up visible image. This next image shows a larger view of the Pacific…giving perspective to the wider ranging cloud patterns in the Pacific Ocean. Finally, here’s a Looping IR satellite image, making viewable the clouds around the islands 24 hours a day. To help you keep track of where any showers may be around the islands, here’s the latest animated radar image.

Hawaii’s Mountains – Here’s a link to the live webcam on the summit of near 14,000 foot Mauna Kea on the Big Island of Hawaii. The tallest peak on the island of Maui is the Haleakala Crater, which is near 10,000 feet in elevation. These two webcams are available during the daylight hours here in the islands…and when there’s a big moon rising just after sunset for an hour or two! Plus, during the nights and early mornings you will be able to see stars, and the sunrise too…depending upon weather conditions.

Tropical Cyclone activity in the eastern and central Pacific – Here’s the latest weather information coming out of the National Hurricane Center, covering the eastern north Pacific. You can find the latest tropical cyclone information for the central north Pacific (where Hawaii is located) by clicking on this link to the Central Pacific Hurricane Center. Here’s a tracking map covering both the eastern and central Pacific Ocean. A satellite image, which shows the entire ocean area between Hawaii and the Mexican coast…can be found here.

 Aloha Paragraphs

  Windy cool weather

A cold front is dissipating, although may be able to make it down to the Big Island into Saturday morning. The latest weather map shows a strong high pressure system to the northwest of the islands, with a gale low pressure system to the northeast. This is keeping us in a northerly wind flow between these two weather features. Here’s a link to that weather map, so we can more easily visualize this pressure configuration. The cold front hasn’t been a big rainfall producer, by any means. The bulk of whatever showers that it brings have fallen along our north and northeast coasts and slopes. There may continue to be a few showers flying over into the leeward sides…carried there on the gusty north to north-northeast winds. In the wake of the frontal passage, drier air will flood into the state, with cool and breezy conditions prevailing through the weekend.

Just so we can keep up on how strong the winds are, these were the strongest gusts on each of the major islands around 5pm Friday:

Kauai –         31 mph
Oahu –         36 mph
Molokai –      30 mph
Lanai –         33 mph
Kahoolawe –  42 mph
Maui –          37 mph
Big Island –   44 mph

The cold front had passed over Kauai and Oahu during the day Friday, and was trying to pass over Maui…and down to the Big Island overnight. The front has slowed down its forward progress during the day, with only limited showers associated with it.  Here’s a satellite image showing the placement of the front as it is now crawling along. There are so many other clouds out there, that it’s not that easy to pick out the frontal band itself. If we look at this larger view, with this satellite image, we can more easily track this cold front down through the southern part of the island chain. At the same time, we can see that there are still some of those leftover high cirrus clouds around…down near the Big Island and the southeast from there.

The main thing that we’ll notice as we move into the weekend…will be the cool north winds. North winds of course come from further north in latitude, and remain chilled, as they rush over the colder sea water surface to our north as well. These winds will vary in direction between north and northeast actually, either of which will bring chilly weather to our islands. Most of the high temperatures remained anchored in the cooler 70F’s Friday, with two of the airport weather stations reaching only 72 degrees. This would definitely qualify as a winter-like day. As I suspected, the Kailua-kona area rose up to a perfectly warm 81F degrees, as it is for the most part out of the chilly north winds. Saturday should be another cool day, with daytime high temperatures remaining in the 70’s for the most part.









It’s Friday evening as I begin writing this last section of today’s narrative. The cold front has slowed down considerably during the day Friday, and will have to really stretch to make it through the entire state. It was overlying Maui County Friday evening, with clouds generally hung up along the windward sides. As we can see by glancing at this looping radar image, there’s little more than a few light showers over parts of Maui and the Big Island. ~~~ Interestingly enough, the high temperature at the Honolulu airport reached only 74F degrees Friday afternoon. The prior record low maximum temperature was 77 degrees, back in both 1949 and 1962. This then broke the record for the date by a full 3 degrees! The record low maximum air temperature at the airport in Honolulu on Saturday is 77 degrees again…it will be interesting to see if we have two broken records in a row. ~~~ Here in Kula, Maui, we are right on the edge of the clouds to our north, as we have been all day. The light mist has been flying over here off and on Friday, which has been a nice treat. The winds are very gusty and on the cool side. I must admit, after working at home all day, that my nerves are slightly on edge, after hearing my wind chimes clanging around right outside my weather tower! It’s a well known fact that windy weather is the most irritating to human beings. The air temperature at 525pm was a cool 60.6 degrees. ~~~ I’ll be back Saturday morning with your next new weather narrative. I hope you have a great Friday night wherever you happen to be hanging your hat! Aloha for now…Glenn.

Interesting: As an Icelandic volcano spewed more ash on Friday, disrupting air travel in Europe for a second day, the big question for scientists was how long the eruption might continue. The answer will go a long way toward determining any lasting impact on air travel, climate and health. But experts said that, for now, the question was essentially unanswerable.

“This may have been it,” said Colin Macpherson, a professor in the department of earth science at the University of Durham in England. “Alternatively it may be that we’re seeing the beginning of prolonged activity.” Jennie Gilbert, a professor at the University of Lancaster in England who has studied Icelandic volcanoes, said: “I don’t think there’s any general feeling for how this volcano will operate.

My best guess is that it will be explosive for a few days and then might continue at a reduced level.” Dr. Macpherson said that volcanologists in Iceland would be monitoring the volcano for indications that the eruption was continuing or starting to taper off. Small-scale seismic activity, for example, would be a sign that hot magma was still coming up through the volcano, cracking the ground as it moved through.

Slight changes in the slope of the volcano’s flanks, as measured by a device called a tilt-meter, would suggest that gases were continuing to build up below as they bubbled out of the magma, causing the surface to bulge, or were dissipating. “As long as the tilt is increasing, it’s still erupting,” Dr. Macpherson said. One complicating factor is that the eruption is occurring under an ice sheet, the Eyjafjallajokull glacier.

Melting of the underside of the ice has caused flooding, forcing evacuations of some communities near the volcano in southern Iceland. But of more concern for Europe is how the water being produced might be affecting the volcano and the ash it is generating. “Certainly the fact that the eruption is going on underneath the ice sheet is likely to have an effect on the explosivity of the volcano,” Dr. Macpherson said.

He likened the situation to putting a hot pan under the kitchen faucet — as the hot magma hits the cold water it rapidly creates steam. If the steam is contained by rock, the pressure can build up and a localized explosion can occur. Dr. Macpherson said that the magma also contained gases of its own that bubble out and build up. The explosivity of the volcano is a function of both these gases and the steam, he said, and the precise contribution of each is unknown.

But if the eruption continues at some point there will be no more ice to melt near the eruption site, which might reduce the explosivity. Dr. Gilbert said the presence of water can also affect the characteristics of the sand like ash that is produced. As the molten rock hits the cold water it is rapidly quenched, fusing into a glassy material. Then when the pressure builds up and the volcano explodes, this material breaks up into very fine particles. “It’s like this sort of shattering effect,” she said.

Interesting2: We’re not quite back to the pre-plane era, but air travel over and around the north Atlantic might get a lot more disrupted in the coming years. Volcanologists say the fireworks exploding from the Eyjafjallajökull volcano on Iceland, which is responsible for the ash cloud that is grounding all commercial flights across northern Europe, may become a familiar sight. Increased rumblings under Iceland over the past decade suggest that the area is entering a more active phase, with more eruptions and the potential for some very large bangs.

"Volcanic activity on Iceland appears to follow a periodicity of around 50 to 80 years. The increase in activity over the past 10 years suggests we might be entering a more active phase with more eruptions," says Thorvaldur Thordarson, an expert on Icelandic volcanoes at the University of Edinburgh, UK. By contrast, the latter half of the 20th century was unusually quiet. Along with increased volcanism, more seismic activity has been recorded around Iceland, including the magnitude-6.1 quake that rocked Reykjavik in May 2008.

In 1998 Gudrún Larsen from the University of Iceland in Reykjavik and colleagues used 800 years’ worth of data from lava layers, ice cores and historical records to show that Iceland’s volcanism goes through cycles of high and low activity. The peaks of these cycles seem to be strongly linked to bursts of earthquakes, which release the build-up of strain on tectonic faults near Iceland caused by the rifting of the Atlantic Ocean. In addition, the periodicity may be linked to pulses of magma coming from the mantle and pressure fluctuations at the surface caused by glaciers melting and geothermal activity.

Larsen and colleagues showed that the Vatnajökull ice cap region – which includes the highly active Grímsvötn and Bárdarbunga volcanoes – experienced between 6 and 11 eruptions every 40 years during phases of high activity, compared with no more than three eruptions per 40 years during low-activity phases. Other regions of Iceland appear to follow a similar pattern to Vatnajökull. As well as becoming more frequent, eruptions seem to get more intense during the high-activity phases.

A number of Iceland’s most devastating eruptions – including that of the volcano Laki in 1783 that killed over half of Iceland’s livestock and led to a famine that wiped out about a quarter of the human population – have occurred when the Atlantic rift system has been active. "If we are entering a more active phase, these bigger eruptions will become more likely," says Thordarson. Judging by recent volcanic and earthquake activity, Thordarson and his colleagues believe that Iceland is entering its next active phase and estimate it will last for 60 years or so, peaking between 2030 and 2040.