Bob Blog 27 Aug 2017

WEATHERGRAM

YOTREPS

Compiled Sun 27 Aug 2017

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.

LISA BLAIR arrived back in Sydney yesterday—the first woman to circumnavigate Antarctica solo in a yacht.

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Here is S/v CLIMATE ACTION NOW closing in on Sydney heads.

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And a Video of this is available at tinyurl.com/y8zytx6h

I have been helping Lisa with some weather information during this fantastic adventure.

TROPICS

Both HARVEY (Texas) and PAKHAR (Hong Kong) have moved inland and turned into wet tropical depressions. There are two tropical depressions at present, one is east of PAKHAR and is forecast to go north and stay east of Japan. T’other is in the Atlantic and is forecast to go N/NE and may sideswipe the Eastern seaboard of United States with some northerly winds on its western side.

We can see these track possibilities at ruc.noaa.gov/

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Last week’s rain map, compared with the week before, shows the most intense rain is still around Southeast Asia in the monsoon. This is affecting 41 million people, and there have been 1200 recent deaths, see http://www.aljazeera.com/news/2017/08/floods-kill-1200-india-nepal-bangladesh-170826230610924.html.

In the tropical South Pacific, the rain map shows a general decrease in activity.

Rain for the past fortnight from trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

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WEATHER ZONES

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Weather Zones (see text) as expected mid-week on Wednesday (GFS model) showing wind, isobars, current, lightning, Sig wave height purple lines, SPCZ and STR.

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to stay put his week and linger across east Solomon Islands and Tuvalu slowly spread southwards towards Fiji and Samoa this week.

A trough is travelling east off NZ tonight and is expected to travel east and is expected to affect the region between NZ and south of Tonga during the next few days. bring some rain to the Tonga and Niue area early this week and then fade away.

Another trough is expected to travel east across the Society Islands and Tahiti from mid-to-late week, but since this region is at the northern end of this trough, its impact is minor.

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Accumulated rainfall from windyty.com

Subtropical ridge (STR)

HIGH 1033hPa east of NZ is expected to travel east along 40S and build to 1036hPa during Monday /Tuesday/Wednesday and then slowly ease and travel off to the southeast. Although this is 25degrees of latitude away from the tropics, this HIGH is expected to squeeze the isobars near 15S closer together forming a squash zone of strong trade winds and swells rising to 3 to 4 metres mid-week between Borabora and Samoa. Avoid.

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Close up of the squash zone of strong winds (in green) and 3-4metre swells (in purple) on Wed 30 Aug 2017 UTC. Avoid.

French Polynesia to the west:

Not this week. We should wait a while until after this squash zone.

Between NZ and the tropics:

A Low is expected to travel east across North island on Wednesday UTC and another on Friday UTC.

If in NZ, may as well stay put this week.

If travelling to NZ, arrange arrival after Sat 2 Sep.

Between Australia and the tropics:

Weak subtropical ridge is expected to linger over northern Tasman Sea between Queensland and south of New Caledonia. Southwest winds are likely south of 30S.

If you would like more detail for your voyage, then check metbob.com to see what I offer.

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See my website http://www.metbob.com for more information

Feedback to bob@metbob.com or txt 6427 7762212

Weathergram text only (and translator) is at weathergram.blogspot.co.nz.

Weathergram with graphics is at metbob.wordpress.com,

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