Bob blog 2 June

WEATHERGRAM

YOTREPS

Compiled Sun 02 June 2019

 

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.

 

REVIEW of MAY

Sea Surface temperature anomalies as at end of April may be seen at

www.weatherzone.com.au/climate/indicator_sst.jsp?lt=global&lc=global&c=ssta

 

The main pattern changes are a slight warming around New Caledonia and slight reduction in the warmth of the Tasman Sea, a warming in the India Ocean, warming in the Humboldt current off western South America, and a reduction in the warmth of the North Atlantic. The Caspian Sea and Black Sea are outstandingly warmer than normal.

Another month that has been mostly warm, with the main cool areas being melt water around the Arctic or Antarctic.

 

To see how the annual weather cycle and the seasons are working out, we csn check the average isobar maps for past 30 days and their anomaly from www.esrl.noaa.gov/psd/map/images/fnl/slp_30b.fnl.html

The subtropical ridge has started its northern shift in both hemispheres. This has allowed troughs to develop in the South Tasman Sea. The near equatorial trough has also drifted north, especially over India. But the Indian Monsoon is only now starting and is about a week late, as seen at

www.imd.gov.in/pages/monsoon_main.php. A late monsoon encourages a heat wave over northern India, and sure enough today’s high is 45C

 

Zooming into the NZ area, and comparing monthly anomalies for end of May with end of April, shows that the subtropical ridge STR has moved north as shown by the northern 1015 isobar over Queensland. Also, the STR has weakened in the South Tasman Sea with the 1015 isobar shifting from 50S to 40S. The westerly winds over NZ are increasing.

 

THE TROPICS

There are no cyclones at present, but there is a tropical depression off the central American east coast. The latest cyclone activity report is at tropic.ssec.wisc.edu and TCFP tropical Cyclone Formation Potential at www.ssd.noaa.gov/PS/TROP/TCFP/index.html

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is rather weak and mainly from Solomons to the Tokelau area this week, north of Samoa.

There is also an active convergence zone lurking to southeast of Tahiti around the Gambier Islands.

 

Subtropical ridge (STR)

HIGH at 30S to north of NZ on Monday is expected to travel quickly off to east.

Next HIGH is expected to enter from the west into the south Tasman Sea on Friday and travel across central NZ on Sun/Mon 9/10 June.

 

Australia to Noumea

Travelling Tasman Trough expected to break the trade winds and reach Noumea around Wednesday, followed by southwest/South winds and big swells  on Thursday, then the trade winds return.

 

NZ to tropics:

Stay put until Friday or Saturday.

A Low is expected to develop off Sydney on Monday and deepen into a large system with a Low of 986hPa on Tuesday, then cross the North Island on Wednesday, followed by a cold and vigorous SW flow from the Antarctic over NZ on Thursday, slowly easing on Friday.

Departures to the north from NZ may be possible on Saturday (perhaps for some from late Friday).

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

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Weathergram archive (with translator) is at weathergram.blogspot.co.nz.

Contact is bob@metbob.com or txt 6427 7762212

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