Air Temperatures – The following maximum temperatures (F) were recorded across the state of Hawaii Friday…along with the minimums Friday:
81 – 72 Lihue, Kauai
86 – 73 Honolulu, Oahu
85 – 71 Molokai AP
87 – 65 Kahului AP, Maui
87 – 75 Kailua Kona
84 – 68 Hilo AP, Hawaii
Here are the latest 24-hour precipitation totals (inches) for each of the islands…as of Friday evening:
3.12 Mount Waialeale, Kauai
0.57 Poamoho RG 1, Oahu
0.21 Puu Alii, Molokai
0.00 Lanai
0.00 Kahoolawe
0.30 West Wailuaiki, Maui
0.18 Saddle Quarry, Big Island
The following numbers represent the strongest wind gusts (mph)…as of Friday evening:
20 Port Allen, Kauai – NE
31 Oahu Forest NWR, Oahu – SW
24 Molokai – ENE
25 Lanai – NE
18 Kahoolawe – NE
08 Kaupo Gap, Maui – NW
24 Kealakomo, Big Island – NNE
Hawaii’s Mountains – Here’s a link to the live web cam on the summit of near 13,800 foot Mauna Kea on the Big Island of Hawaii. This web cam is available during the daylight hours here in the islands…and when there’s a big moon shining down during the night at times. Plus, during the nights you will be able to see stars, and the sunrise and sunset too…depending upon weather conditions.
Aloha Paragraphs
Low pressure systems over the ocean far to the north…along
with their trailing cold fronts – high clouds southwest
Scattered clouds…thunderstorms well southwest
Clear to partly cloudy…a few cloudy areas locally
Showers falling locally…mostly offshore
looping radar image
High Surf Advisory…for north and west shores of Kauai,
Oahu and Molokai, and for the north shore of Maui
~~~ Hawaii Weather Narrative ~~~
Gusty trades turning slightly lighter…strengthening again during the second half of the weekend. Here’s the latest weather map, showing the Hawaiian Islands, and the rest of the North Pacific Ocean. We find high pressure systems offshore to the northwest and northeast of the islands…with their associated ridges of high pressure well north of Hawaii. At the same time, we see low pressure systems far north in the Gulf of Alaska, along with the tail-end of an associated cold front northwest of the islands. The trade winds will continue, with a slight reduction in strength over the next day or two…before they strengthen again Sunday. It looks like moderately strong trade winds will be blowing all of next week, strongest during the days and lighter at night.
Here’s a wind profile…of the offshore waters around the islands – with a closer view
Here’s the Hawaiian Islands Sulfate Aerosol animated graphic – showing vog forecast
Off and on showers falling over the windward sides…although not exclusively. The trade winds will keep active showers focused along the windward sides for the most part, although stretching over into the leeward sides at times…carried by the gusty trades. We should continue to see showers remaining quite numerous, particularly along the windward and mountain slopes at night. The models go on to show the tail-end of a cold front slipping down over the state Sunday…keeping our shower activity going into Monday. A fairly typical trade wind weather pattern will occur next week, with most showers landing on the windward coasts and slopes.
Marine environment details: A high surf advisory for most north and west facing shores is in effect through Saturday. The combination of the long period swell, and upstream generated wind swell waves, will lead to seas near small craft advisory /SCA/ levels Saturday. Although the swell will slowly diminish over the weekend, winds will start to come up again near Kauai Saturday night and across the state on Sunday. Will likely need a SCA at least for the normally windy areas including the channels during that time.
Lowering surf along north
and west shores
Here on Maui – Just after sunrise, we find generally clear skies, with some clouds along the windward sides, and stretching up over the West Maui Mountains as usual. The trade winds are blowing, although somewhat lighter than they have been earlier this week. Here in upcountry Kula, it’s clear and calm, with an air temperature at my weather tower of 50F degrees at 630am.
– Early Friday afternoon, under clear to partly cloudy skies, with more compacted cumulus clouds evident over the mountain slopes as usual. Radar doesn’t really show any showers falling, although if there are, they are very minor. The trade winds are blowing, although at their weakest point this week so far.
– Early evening, with partly cloudy skies in general, with a mix of cloudy and clear areas as well.
Friday Evening Film: My film buff friend Jeff is in Germany this week, visiting and working with his friend Svetlana. So I’ll be heading down to Kahului this evening to catch one of the new films. This time I’ll see one called Criminal, starring a rather impressive cast, including Kevin Costner, Gary Oldman, Tommy Lee Jones, Ryan Reynolds, Jordi Molla, and Gal Gadot…among many others. The synopsis: the memories and skills of a CIA agent are implanted into the brain of a dangerous criminal, in order to stop an international terrorist. The critics aren’t very enthused about this film, despite the top notch caste, as a matter of fact…they are rather negative about it across the board. Oh well, I saw it anyway, and can’t give such a dreadful review. It was full of action, and I guess because of its R rating, it allowed Kevin Costner to really bear down with some pretty heavy violence. As far as a grade goes, I’ll give it a strong B, although not as far as a B+ I’m afraid. Here’s the trailer in case you want to take a quick peek what I sat through.
World-wide tropical cyclone activity:
>>> Atlantic Ocean: The last regularly scheduled Tropical Weather Outlook of the 2015 Atlantic hurricane season…has occurred. Routine issuance of the Tropical Weather Outlook will resume on June 1, 2016. During the off-season, Special Tropical Weather Outlooks will be issued if conditions warrant. Here’s the 2015 hurricane season summary
Here’s a satellite image of the Atlantic Ocean
>>> Caribbean Sea: The last regularly scheduled Tropical Weather Outlook of the 2015 Atlantic hurricane season…has occurred. Routine issuance of the Tropical Weather Outlook will resume on June 1, 2016. During the off-season, Special Tropical Weather Outlooks will be issued if conditions warrant.
>>> Gulf of Mexico: The last regularly scheduled Tropical Weather Outlook of the 2015 Atlantic hurricane season…has occurred. Routine issuance of the Tropical Weather Outlook will resume on June 1, 2016. During the off-season, Special Tropical Weather Outlooks will be issued if conditions warrant.
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 last regularly scheduled Tropical Weather Outlook of the 2015 North Pacific hurricane season…has occurred. Routine issuance of the Tropical Weather Outlook will resume on May 15, 2016. During the off-season, Special Tropical Weather Outlooks will be issued if conditions warrant. Here’s the 2015 hurricane season summary
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 central north Pacific hurricane season has officially ended. Routine issuance of the tropical weather outlook will resume on June 1, 2016. During the off-season, special tropical weather outlooks will be issued if conditions warrant. Here’s the 2015 hurricane season summary
Here’s a link to the Central Pacific Hurricane Center (CPHC)
>>> South Pacific Ocean: No active tropical cyclones
>>> North and South Indian Oceans / Arabian Sea:
Tropical Cyclone 19S (Fantala) remains active in the South Indian Ocean…here’s the JTWC graphical track map, a satellite image, and what the computer forecast models are showing
Here’s a link to the Joint Typhoon Warning Center (JTWC)
Interesting: Study shows most US roofs can support a solar system – Most U.S. rooftops in good repair can take the weight of solar photovoltaic (PV) systems. That’s the conclusion of a three-year study by a research team led by Sandia National Laboratories.
“There is a mis-perception in the building industry that existing residential rooftops lack the strength to carry the weight load of rooftop solar photovoltaic installations,” said Sandia structural engineer Steve Dwyer. “Most existing well-built wooden rooftops can support PV system loads.”
Sandia took on the job of analyzing rooftop structural strength to address concerns raised in the U.S. Department of Energy’s (DOE) Solar America Cities program. The agency named 25 cities to promote adoption of solar technology at a comprehensive, local level through photovoltaics.
At least one city reported the primary barrier to solar was the difficulty and cost of obtaining construction permits for rooftop solar installations because of structural issues. “I couldn’t believe it was a problem,” said Dwyer, who led the Sandia test team. “Solar PV systems represent little additional weight and roofs are very strong.”
He said many code officials aren’t familiar with solar technology and lack the training to evaluate how a solar PV system might affect roof structure. So they bring structural engineers into the permitting process, adding time and money for the system owner and the solar contractor. Often, they then deny engineering certification for solar PV installations on wood roofs, declaring the structures too weak.
Load-bearing capacity is several times higher
In two, first-of-their-kind studies funded by DOE’s SunShot Initiative — which seeks to make solar energy cost competitive with other energy sources by the end of the decade — and conducted in partnership with the University of New Mexico (UNM), Sandia stressed wood rooftop structures to the point of failure and compared the data with allowable loads identified in the International Residential Code and the National Design Standard.
They concluded the actual load-bearing capacity for residential rooftop structural systems is several times higher than the calculated values.
Sandia hopes engineers and permitting officials will use the results when they make decisions about rooftop strength and solar PV applications, increasing the number of safe, cost-effective rooftop solar PV installations.
“Safety is a crucial factor in building codes and must be considered when there is any change to a structure,” Dwyer said. “Understanding how weight loads affect the structural integrity of a roof is important to homeowners, code officials, solar installers and builders. These results provide a new tool and set of data for consideration in evaluating rooftops for solar PV installations.”
The roof acts as a whole
Dwyer said engineers doing rooftop structural analysis often calculate stresses on the basis of an individual beam, rafter or truss. That approach assumes each component of the structure acts alone. “It fails to consider the rooftop system as a whole or consider the load-sharing or load redistribution effects of a roof system,” he said. “The result is a conservative analysis that does not accurately represent the roof’s ability to support a PV installation. It’s not a fair assessment.”
And he said engineering evaluations are not universally applied across cities and states. “Some do them and some don’t,” he said. “Local governments pick and choose what they accept. Not everybody uses the same method, so it can be difficult for solar installers and residents to know what to expect. All these issues have posed serious challenges to the solar industry.”
Dwyer said the Sandia team realized building codes won’t change, so they tackled the problem by building some roofs, breaking them and showing the permitting community just how strong a roof is. Starting about three years ago, the team built different roof sizes in a UNM lab.
“We did a lot of testing,” Dwyer said. “First we wanted to be sure we were on the right track. We thought, ‘OK, the engineers are not giving credit for load sharing, so we tested a two-by-four, broke it in half, then nailed a piece of sheeting to it to see if it added strength. It did, 35 percent with nailing and 74 with gluing. We were on the right track.”
They built scaled versions of roofs in different lengths with five rafters or trusses 8 to 20 feet long and applied a uniform load over the whole thing. “We used air as the load,” Dwyer said. “We built bladders of different sizes and used them to put pressure on top of the roof by filling them with air at up to 144 pounds per square foot. We broke every size rafter and the more commonly used trusses, five sets of each.”
On average, the rafter-based tests demonstrated a 330 percent excess load-bearing capacity compared to values computed in the National Design Standard. “This suggests that current rooftop structural evaluations are overly conservative in evaluating the ability of roofs to support additional loading from solar PV installations,” Dwyer said. “A well-built home that meets local building standards and has not been adversely modified or damaged should have enough load-bearing capacity to support a roof-mounted PV system.”
Email Glenn James: 
