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Bob McDavitt's ideas for sailing weather around the South pacific

02 February 2020

Bob Blog 2 Feb

WEATHERGRAM

YOTREPS

Compiled Sun 02 Feb 2020

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.

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REVIEW OF THE LAST MONTH (January 2020)

Sea Surface temperature anomalies as at start of January compared with the start of Feb may be seen at https://www.weatherzone.com.au/climate/indicator_sst.jsp?lt=global&lc=global&c=ssta

The main changes are in the South Pacific Ocean, with the hot pool east of NZ fading, and the hot pool in the Tasman Sea intensifying

According to BoM (Australia) the Indian Ocean is going neutral – and since ENSO is also neutral, there are no major climate drivers active at present. That means that it is the short-term drivers (such as MJO) and ocean temperature that we need to watch to work out weather changes in advance.

During January there have also been some small changes in the pattern around South America, but anomolies in the North Pacific remain much the same.

To see how the annual weather cycle and the seasons are working out, we can 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 in much the same place. The area below 1010hPa in the equatorial area has expanded around Indonesia and the Coral Sea but not advanced much further southwards.

There remains higher than normal air pressure over the Antarctic, but this is now retreating. In the Arctic, high anomolies have been replaced by low anomolies. High-anomaly zones have shifted all over the planet, and the one that was over SE-Australia a month ago is now in east Tasma Sea. maintaining a weak southerly anomaly flow over the North Island.

 

Zooming into the NZ area, and comparing monthly anomalies from last month with now, shows that the subtropical ridge STR has strengthened in the east of the South Pacific but weakened around and west of Australia--- and remains about the same in the Tasman Sea.

The 1010 isobar in the tropics has drifted south especially in the Coral Sea, and the 1010 isobar near NZ has also drifted south.

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The Tropics

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 (but not this week).

At present there is  no  cyclone in any basin.

There is a tropical depression in the Coral Sea near 10S 155E and its central pressure MAY deepen to 1000 h Pa as it travels south to just northwest of New Caledonia on Tue 4 Feb then west across the Coral Sea, slowly fading.

 

WATHER ZONES

SPCZ=South Pacific Convergence zone.

The SPCZ is active this week from the Coral Sea across northern Vanuatu to Tuvalu and Samoa.

The low tonight over Southern cook is expected to move off to Se next few days.

Another weaker low is expected to travel south from Tuvalu to Fiji /Tonga from 6 to 8 February.

The outlook for next week is a possible tropical Cyclone developing for Vanuatu from 13 Feb, this will be reviewed next weekend.

SO,  if you are planning to Island hopping next few weeks, keep up to date and stay alert.

 

Subtropical ridge (STR)

HIGH is crossing northern NZ and moving off the east along 27S.

Another High from Bass strait on Tuesday is expected to travel east across Tasma Sea at 40S then skirt around south of the South Island on Friday then go NE across Chathams.

Third High is expected to move from wet into south Tasman at 45S on Saturday.

 

Tasman Sea /NZ/Aus

Active trough is expected to cross the South Island on Monday and weaken over the North Island on Tuesday and be followed by a brief slightly cooler SW flow.

As for Noumea to Australia: Mainly SE/E winds, so OK.

As for Sydney to NZ: will need to go SE to 40S to get a round Highs in the Tasman.

 

From Panama to Galapagos/Marquesas:

Northerly winds to around 4N. Then an active ITCZ and variable winds from 4N to 2N (will need some waypoints), and a good west -going current near 3N 83 to 85W, then S /SE winds as far as Galapagos area, As for getting to Marquesas, not enough data for entire voyage but what data we have is looking OK and goes past the north end of the Galapagos. .

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

Or Facebook at /www.facebook.com/metbobnz/

Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom).

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

Contact is bob@metbob.com or txt 6427 7762212

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