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

83 – 73  Lihue, Kauai
85 – 73  Honolulu, Oahu
84 – 69  Molokai
85 – 66  Kahului AP, Maui
83 – 73  Kona Int’l AP
82 – 67  Hilo AP, Hawaii

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

0.79  Mount Waialeale, Kauai
1.08  Poamoho RG 1, Oahu
 0.08  Molokai
0.00  Lanai
0.00  Kahoolawe
3.97  Puu Kukui, Maui
1.94  Waiaha, Big Island

The following numbers represent the strongest wind gusts (mph) as of Tuesday evening:

23  Port Allen, Kauai
20  Kahuku Trng, Oahu
27  Molokai
 27  Lanai
37  Kahoolawe
30  Kahului AP, Maui
24  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. This webcam is 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

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A gale low pressure system northeast…has a trailing cold front north of Kauai

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The cold front won’t reach the state

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Partly to mostly cloudy, some clear areas…thunderstorms north of Kauai

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Showers…some are locally heavy – Looping radar image

~~~ Hawaii Weather Narrative ~~~

 

Broad brush overview: Moderate trade winds will persist through much of this week, as areas of high pressure pass by well north of the state. An upper level trough of low pressure will linger just west of the islands during the next few days, producing somewhat unstable conditions…and possibly triggering briefly heavy showers. Rainfall will remain focused over windward slopes, though isolated showers will develop over leeward areas each afternoon locally. Increasingly stable trade wind weather is expected during the weekend.

Details: An unstable trade flow is currently active over the islands. These winds are driven by a high pressure system passing north of Kauai. A high of this magnitude would typically generate stronger trade winds, although with a stalled cold front sitting not far north of the islands, its helping to limit wind speeds. An upper trough several hundred miles west of the state, is causing thunderstorms along the front, and is producing instability over the islands. Moisture moving in on the trade wind flow is unimpressive. The result is a somewhat unstable trade flow, with shower-bearing cumulus clouds along the windward sides.

This somewhat unstable, easterly trade wind flow will persist through at least Thursday, and possibly Friday. The upper level trough will drift closer to the islands during the next 24 hours. As pockets of moisture move along the trade wind flow, the increased instability will likely trigger a few heavy showers. This rainfall will be focused over windward slopes, though spotty afternoon showers, some briefly heavy, are possible over sheltered leeward areas where sea breezes develop. In addition, there’s a slight chance of thunderstorms over the next few days.

Looking ahead: A more stable trade wind weather pattern is expected by Saturday. The upper trough will fill overhead, allowing a weak low level inversion to rebuild. The above mentioned stalled frontal boundary will merge with another front, and may be driven southward, as another area of high pressure sets up north of the state. The models diverge on the handling of these features Sunday into next Monday. One of the reliable models develops a breezy and wet trade wind weather pattern over the western of the the island chain, while another holds the moisture to the north…resulting in a weaker trade wind flow.

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: The surface high pressure system currently north of the state will move eastward, while the pressure gradient south of this high continues to produce locally strong easterly trade winds. A Small Craft Advisory (SCA) is in effect for waters around the Big Island and the Pailolo Channel. Winds are expected to drop below SCA levels tonight, as the high moves farther away…and the pressure gradient around the state relaxes. Moderate to locally strong trade winds are expected through the rest of the week.

Surf is expected to remain below advisory levels through the weekend. The current north-northwest swell will gradually lower today. A new moderate northwest swell will arrive later today, and then peak Wednesday…well below the advisory threshold. A northwest swell arriving Thursday night will be larger, although surf from this swell is expected to remain below the advisory threshold when it peaks Friday. Another northwest swell may arrive next Monday. A north swell building tonight will shift to the northeast Wednesday then fade Thursday. A swell from the southern hemisphere is expected to arrive Thursday night, peak Saturday, then slowly Sunday.

 

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Becoming more shower prone…some may be locally heavy

Southern California weather summary: A few weak disturbances will bring cooler temperatures, periods of light rain…and gusty winds to areas north of Point Conception through Wednesday. Rain chances will spread south of Point Conception Wednesday night into Thursday. A chance of rain is expected for the area Sunday into Monday.

 

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Clearing skies over Southern California

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Mostly clear…with more clouds offshore to the west



World-wide tropical cyclone activity


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>>> Atlantic Ocean: The 2017 hurricane season begins June 1st

Here’s a satellite image of the Atlantic Ocean

>>> Caribbean: The 2017 hurricane season begins June 1st

>>> Gulf of Mexico: The 2017 hurricane season begins June 1st

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: The 2017 hurricane season begins May 15th

Here’s the NOAA 2016 Hurricane Season Summary for the Eastern Pacific Basin

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: The 2017 hurricane season begins June 1st

Here’s the NOAA 2016 Hurricane Season Summary for the Central Pacific Basin

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

>>> Northwest Pacific Ocean: No active tropical cyclones

>>> South 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: North America’s freshwater lakes are getting saltier – North America’s freshwater lakes are getting saltier due to development and exposure to road salt. A study of 371 lakes published today in the Proceedings of the National Academy of Sciences reports that many Midwestern and Northeastern lakes are experiencing increasing chloride trends, with some 44% of lakes sampled in these regions undergoing long-term salinization.

The study is the first large-scale analysis of chloride trends in freshwater lakes. It was conducted by a team of fifteen researchers as part of the Global Lake Ecological Observatory Network (GLEON) Fellowship Program, an initiative that seeks to train the next generation of freshwater scientists and practitioners.

Lead author Hilary Dugan, a limnologist at the University of Wisconsin-Madison and former Cary Institute of Ecosystem Studies Postdoctoral Fellow, explains, “We compiled long-term data, and compared chloride concentrations in North American lakes and reservoirs to climate and land use patterns, with the goal of revealing whether, how, and why salinization is changing across broad geographic scales. The picture is sobering. For lakes, small amounts of shoreline development translate into big salinization risks.”

Chloride trends in 371 freshwater lakes were analyzed. Each lake was larger than 4 hectares in size with at least 10 years of recorded chloride data. The majority of the lakes (284) were located in a North American Lakes Region that includes Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New York, Ontario, Rhode Island, Vermont, and Wisconsin.

Since the 1940s, the use of road salt to keep winter roads navigable has been escalating. Each year, some 23 million metric tons of sodium chloride-based deicer is applied to North America’s roads to melt away snow and ice. Much of this road salt washes into nearby water bodies, where it is recognized as a major source of chloride pollution to groundwater, streams, rivers, and lakes.

To gauge road salt exposure, the research team assessed road density and land cover within a 100- to 1500-meter buffer around each of the 371 study lakes. Roadways and impervious surfaces such as parking lots and sidewalks are reliable proxies for road salt application because as developed areas, they are susceptible to high levels of salting and runoff.

Results were clear: roads and other impervious surfaces within 500 meters of a lake’s shoreline were a strong predictor of elevated chloride concentrations. In the North American Lakes Region, 70% (94 out of 134) of lakes with more than 1% impervious land cover in their 500-meter buffer zone had increasing chloride trends. When results are extrapolated to all lakes in the North American Lakes Region, some 7,770 lakes may be at risk of rising salinity.

If current salinization trends continue, many North American lakes will surpass EPA-recommended chloride levels in 50 years. Within this study, 14 North American Lakes Region lakes are expected to exceed the EPA’s aquatic life criterion concentration of 230 mg/L by 2050, and 47 are on track to reach chloride concentrations of 100 mg/L during the same time period.

Co-author Sarah Bartlett, a graduate student at the University of Wisconsin-Milwaukee, explains, “These results are likely an underestimation of the salinization problem, as a number of regions with heavy road salt application, such as Quebec or the Maritime Provinces of Canada, had no long-term lake data available.” Co-author Flora Krivak-Tetley, a graduate student at Dartmouth College, added, “It is also extremely difficult to obtain rates of road salt application both through time and across regions. Better application data would allow us to more accurately forecast ecosystem health.”

In lakes, elevated chloride levels have been shown to alter the composition of fish, invertebrates, and the plankton that form the base of the aquatic food web. Aquatic species richness and abundance can decline, and in extreme cases salinization can prevent lakes from mixing – causing low oxygen conditions that smother aquatic life and reduce water quality.

The study’s authors recommend that best lake management practices recognize that shoreline management extends well beyond a lake’s perimeter. While many states and municipalities acknowledge the importance of shoreline management, they note that zoning regulations are often only enforced within 300 meters, and many lakes lack the monitoring programs needed to adequately track lake health.

Coauthor and Fellowship advisor Kathleen Weathers, an ecosystem scientist at the Cary Institute of Ecosystem Studies and co-chair of GLEON, comments, “In the North American Lakes Region – where road salt is a reality – roads and other impervious surfaces within 500 meters of a lake’s shoreline are a recipe for salinization. We need to manage and monitor lakes to ensure they are kept ‘fresh’ and protect the myriad of services they provide, from fisheries and recreation to drinking water supplies.”

A lake’s chloride status may also provide a window into the ecological health of its watershed. Co-author Samantha Burke, a graduate student at the University of Waterloo, adds, “Unlike flowing streams and rivers, water resides in lakes for long periods of time. This makes them vulnerable to pollution from their watersheds and good early warning indicators of environmental disruption.”