WEATHERGRAM
YOTREPS
Issued 3 July 2016
Bob McDavitt’s ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.
Back in the early 70s when I was a university student working at New Zealand Meteorological Service I was asked to help Edith Farkas with her study of observations of deplenishing amounts of ozone in the stratosphere. She was a good example of how it was possible to be a woman meteorologists in New Zealand even then— See www.iwonderweather.co.nz/taxonomy/term/188
Edith Farkas visiting Scott Base, Antarctica 1975.
These studies resulted in the Montreal protocol in 1987 whereby the UN banned the use of CFCs as a refrigerant. The Ozone hole peaked in 2000, and has had minor drops ever since, increasing briefly in October 2015. A news release this week announces that new studies of the data shows that increase was caused by the eruption of the Chilean Volcano Calbuco, and the hole is actually on “a path to heal”. The Montreal protocol is a beacon of hope for us humans on this planet, a sign that we can indeed terraform beneficially. See m.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11666732
How the hole in the ozone layer looked in 2000 when it was at its peak. Photo / NASA
This year is turning out to be the warmest on record— a good discussion on this and other weather topics is given by MetService Severe weather forecast Eric Brenstrum at www.radionz.co.nz/national/programmes/nights/audio/201806090/nights’-science-world-weather
Tropical cyclones are starting to form. AGATHA and BLAS are storms in the northeast Pacific that have formed on the Intertropical Convergence zone west of Mexico. These two storms are expected to go off to the northwest, but they may be followed by a third storm forming this weekend that may go westnorthwest all the way to Hawaii area by end of next week. And NEPARTAK is a storm in the NW pacific to south of Guam moving northwest towards Taiwan.
Last fortnight of weekly rain profiles shows how the Intertropical convergence zone is now intensifying over the eastern pacific. Also there is intense rain over south China and Southeast Asia.
Rain for the past fortnight from trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
WEATHER ZONES
Weather Zones (see text) as expected mid-week on Wednesday (GFS model) showing wind, isobars, current, swell black arrows / Sig wave height purple lines, SPCZ and STR.
SPCZ=South Pacific Convergence zone.
SPCZ is expected to remain draped from Coral Sea across northern Vanuatu to the Tuvalu/Tokelau area, then to Northern Cooks/Marquesas. There is also likely to be a developing trough near the end of the week over the Tahiti area.
This week’s SPCZ as seen on windyty.com
STR= Sub-tropical Ridge
STR is weak and well to the north.
The HIGH that is north east of NZ of Monday is expected to travel east along 30S. There may be a small squash zone of enhanced Se winds on its northern side near 18 to 19S between Palmerston Island and Tonga from Tues to Thursday UTC.
The next HIGH to exit Australia may be at 45S late this week, travelling east across southern and central NZ this weekend. It may indeed have a squash zone on its northern side, over or near northern NZ.
Voyage Outlooks:
Tahiti to the west
Looks OK for departure to the west between now and Tuesday local, albeit with light winds for starters. After that a developing trough is expected to bring some squalls and increase the SE winds to over 20 knots…. May have to wait until 20 July for next window of appropriate weather.
Since the SPCZ is expected to remain north of 15S, it appears that a voyage to the west should travel along the drier and more settled latitudes near 17S.
Weather may not remain settled all the way from Tahiti to Tonga, as a trough is expected to affect the Tongan area from 10 to 12 July local.
Between NZ and the tropics
MAYBE NOT this week (again), may as well stay put (again). A fast boat can possibly depart from Opua on Monday (after a passing low) but is likely to encounter strong + winds from a front on Thursday.
A LOW is crossing northern NZ on Thursday and Friday and is expected to linger to north of NZ until next week. The northerly winds ahead of this low are expected by Wednesday. So it’s another stay put week.
Between Australia and New Caledonia/Fiji
OK to depart from Coffs/Brisbane area on Monday (local), but otherwise stay put for a trough is expected there on Tuesday deepening into a LOW off Sydney rapidly on Tuesday night. Stay put Tuesday to Thursday local then it may be OK to go.
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See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website http://www.metbob.com for information on tailor-made voyage forecasts– Feedback to bob@metbob.com.
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