Hawaiian Islands weather details & Aloha paragraphs / July 21-22, 2008

Aloha Paragraphs



Baldwin Beach, Maui
Photo Credit: Flickr.com

Our local trade winds will surge in strength Tuesday and Wednesday. The fairly normal trade winds we saw Monday, will pick up Tuesday, becoming rather strong and gusty into Thursday. The passage of a tropical vortex, the remains of former tropical cyclone Elida, as it passes to the south of the islands, combined with strengthening high pressure to the north of Hawaii… will be the source of our stronger trade wind flow. The NWS has issued a small craft wind advisory for those windiest marine waters in the southern part of the state. Later in the week, by Friday into the weekend, our local winds will drop down into the more moderately strong realms.

The remnant moisture from a now retired eastern Pacific hurricane, will bring increased showers to our islands. The leading edge of this tropical moisture will arrive over the Big Island Tuesday, moving up the island chain to Maui during the day…and may bring showers to the other islands Tuesday night into Wednesday morning. The most generous showers will fall along the windward sides of the Big Island, and perhaps Maui. There are still some strands of high cirrus here and there, but it will generally be quite thin…perhaps just enough to provide some nice sunset colors Monday evening. We will see off and on showers reaching the windward sides of the islands Monday night into Tuesday morning. Here’s a looping radar image, so we can begin to monitor the incoming showers that will be around for the next several days.

~~~ It’s early Monday evening here in Kihei, Maui, as I begin updating this last section of today’s narrative. The most interesting weather feature, or at least will be soon, is what’s left of Elida, approaching our general area from the east-southeast of the Big Island. If you click on this looping satellite image, you will see what’s left of Elida, to the lower right of the Hawaiian Islands…as it spins westward. Elida was a hurricane earlier in her life while in the eastern Pacific, but is now simply a low level swirl of clouds, with an occasional towering cumulus cloud, or a couple of thunderstorms popping-up near the center of this tropical disturbance. As this counterclockwise rotating vortex (area of low pressure) moves away to the west later Wednesday into Thursday, our trade winds will slow down, and our shower activity will fade.

~~~ Just so that everyone is clear, former Elida poses no danger to the Hawaiian Islands. We will see our local winds increasing Tuesday, as high pressure strengthens to our north, and the tropical vortex of former Elida passes by to our south Wednesday. This won’t be anything radical by any means, but it will be gustier than normal for a couple of days. The fringe moisture from this area of disturbed weather should extend far enough northward to bring an increase in showers, falling mostly along the windward sides. As we move through the second half of the week, our weather will snap back into what we call a normal trade wind weather pattern. I’ll be back very early Tuesday morning with your next new weather narrative, I hope you have a great Monday night until then! Aloha for now…Glenn.

Interesting: The town of Cherrapunjee, in the north-eastern Indian state of Meghalaya, is reputed to be the wettest place in the world.  But there are signs that its weather patterns may be being hit by global climate change. "Not without reason has Cherrapunjee achieved fame as being the place with the heaviest rainfall on earth," wrote German missionary Christopher Becker more than 100 years ago. "One must experience it to have an idea of the immense quantity of rain which comes down from the skies, at times day and night without a stop. It is enough to go a few steps from the house to be drenched from head to foot. An umbrella serves no purpose."  But according to Cherrapunjee’s most renowned weather-watcher, Denis Rayen, the climate of the town is changing fast. "In the days of the Raj, the British used to come here to the the Khasi hills to escape the heat – we are 4,823ft (1,484m) above sea level," he says.

"But today I am not sure they would be able to do that, because it is getting a lot hotter here and the monsoon is arriving later." Official figures compiled by the Indian Meteorological Office in the nearby city of Guwahati back up Mr Rayen’s arguments that north-east India as a whole is getting hotter. "The average temperature for Guwahati at this time of the year should be around 32C – but this year the temperature has been as high as 38C," said weather expert Harendas Das. It’s too early yet to say precisely what is happening, but the evidence suggests that higher temperatures mean the whole area is experiencing less rainfall."

Interesting2:

Half of Beijing‘s drivers left their cars at home and took public transportation instead on Monday, the first workday under new restrictions meant to clear this city’s notoriously polluted skies before next month’s Olympics. Under a two-month plan that started Sunday, half of the capital’s 3.3 million cars will be removed from city streets on alternate days, depending on whether the license plate ends in an odd or even number. Those caught driving on days they shouldn’t will be fined $14, a pricey penalty even for China‘s capital. Drivers with even-numbered plates were forced Monday to take public transportation, where crowds remained surprisingly manageable.

That’s likely because employers have been asked to stagger work schedules, and public institutions will open an hour later than normal. "It seems that the subway isn’t as busy as I expected. There are fans and air conditioning, so you don’t feel very hot," said Chen Songde, who normally drives to work in Beijing. Traffic still snaked along main thoroughfares and highways Monday, but it moved at a steady pace. "Before we would be at a dead standstill," said a taxi driver who would give only his surname, Zhang, as he steered around cars. "Now it’s better."

Interesting3: The Arctic may get some temporary relief from global warming if the annual North American wildfire season intensifies, according to a new study by researchers at the University of Colorado and NOAA. Smoke transported to the Arctic from northern forest fires may cool the surface for several weeks to months at a time, according to the most detailed analysis yet of how smoke influences the Arctic climate relative to the amount of snow and ice cover. "Smoke in the atmosphere temporarily reduces the amount of solar radiation reaching the surface. This transitory effect could partly offset some of the warming caused by the buildup of greenhouse gases and other pollutants," said Robert Stone, an atmospheric scientist with the university and NOAA Cooperative Institute for Research in Environmental Sciences (CIRES) and lead author of the study, which appears this week in the Journal of Geophysical Research. How much solar energy is prevented from reaching the surface depends on the smoke’s opacity, the elevation of the sun above the horizon, and the brightness of the surface, according to the study.

Stone and his research colleagues analyzed the short-term climate impact of numerous wildfires that swept through Alaska and western Canada in 2004. That summer, fires burned a record 10,000 square miles of Alaska‘s interior and another 12,000 square miles in western Canada.  A NOAA climate observatory near Barrow, Alaska, provided the data for the study. Smoke observed at Barrow was so thick that at times visibility dropped to just over one mile. The aerosol optical depth (AOD), a measure of the total absorption and scattering of solar radiation by smoke particles, rose a hundredfold from typical summer values. Smoke in the atmosphere tends to cool the snow-free tundra while warming the smoke layer itself, the authors found. Smoke has an even greater cooling effect over the darker, ice-free ocean and less over bright snow.