Bob Blog 1 Aug 2021

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.
Compiled Sunday 1 August 2021

REVIEW OF THE LAST MONTH (July 2021)

Sea Surface temperature anomalies from https://www.weatherzone.com.au/climate/indicator_sst.jsp?lt=global&lc=global&c=ssta

Extraordinary warming took place during July in the Sea of Japan and along 40N across the North Pacific. Warming has also increased around north Australia leading to record breaking heat for north and interior of Australia.

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 psl.noaa.gov/map/clim/glbcir.quick.shtml

The northern subtropical ridge has intensified in the Pacific and Atlantic. In the southern hemisphere the subtropical ridge has intensified in the South Atlantic and between Africa and Australia but wakened over South Australia and New Zealand. Pressures have dropped over northern India in line with the Indian monsoon.
The anomaly map shows an intense area of lower than normal pressure across South Australia to southern New Zealand.

Zooming into the NZ area shows how much the westerly winds have spread north in the past month, a sign that NZ waters are in for a windy spring.

TROPICS
The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

There are still some areas of high potential for formation around Japan. TC NINE and HILDA are travelling westwards across the North Pacific.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is expected to be thin and weak and north of its normal position stretching from Solomon Islands to Samoa to Southern Cooks.
Passing trough1 with light winds is expected to be over Samoa tonight and travel slowly east stalling over southern Cooks by end of the week.
Passing trough2 is expected to travel east offshore Queensland coast on early Wednesday and New Caledonia/Vanuatu on Thursday/ Friday.

HIGHS and LOWS
L1 Active trough/Low1 east of NZ tonight with low centre that is expected to go south to 46S by mid-week. This is expected to combine with a front that travels east over South Island on Monday and North Island on Tuesday. Avoid.
H2 High is expected to move off Australia around 35/37S on Monday then cross Tasman Sea and be north of North Island on Wednesday, providing the lull of the week.
L3 An active trough and Low is expected to cross Tasmania on Tuesday and then travel NE to reach North Island by Friday. 2 LOW traveling east along 30S south of Southern Cooks early this week bringing light winds to French Polynesia FP.
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Contact is bob@metbob.com or txt 64277762212
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