Bob Blog 8 Oct 23

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 8 Oct 2023

Island Climate Update

NIWA have issued their October edition of the Island Climate Update
available online as a pdf at niwa.co.nz/climate/island-climate-update.
Now that we are having El Nino this page gives us a look at what that may
mean for rainfall and drought/water stress over the next few months.

On this page there is also access to a selection of maps for various
locations the recent conditions, and Outlooks for various periods.

Amongst these I found the following to be most interesting:

During the past month there was less than 40mm of rain over Tonga ,, and
this has resulted in an area of severe water stress there as shown in the
recent water stress map.

Interestingly this region is expected to quickly recover during October:

The prospects for rain between now and December show only a narrow zone of
"near normal", a very wet equatorial zone and a tendency for dryness away
from the equator.

The "normal" pattern needs to be considered along with this map to turn it
into a rainfall map. However, this map gives an indication to what is
physically different. the Hadley cell is being distorted by an extra boost
of upward motion mainly along equator near the dateline and as this air
lifts to the top f the troposphere it is deflected away from the equator and
descends/dries out until it find =s the surface again around 25 north or
south.

TROPICS

KOINU (Japanese for "puppy") produced a measured wind of 213mph and then
destroyed the anemometer at Lanyu Island - that's the third highest
land-based measured wind gust. BOLAVEN is expected to stay out to sea east
of Japan. LIDIA and 16E are fading.

WEATHER ZONES
The South Pacific Convergence zone is expected to stay north from Solomons
to northern Vanuatu to Samoa/Northern Tonga. There is expected to be a
passing trough over Southern Cooks and Austral Islands after mid-week.

HIGHS and LOWS
LOW L1 east of NZ has some large southerly swells as far north as Fiji on
Monday. It is expected to move off to the SE allowing HIGH H1 to spread
slowly into Tasman Sea and then along 30S past the north of NZ on Friday
13th This HIGH has brought a squash zone in the Coral Sea for a few days and
is bringing good conditions for sailing from tropics to NZ or Aus this week.

The next Low following H1 is expected to bring a warm front and northerly
winds to Northland early next week and then to travel east along 30S
followed by a burst of large southerly swells mid next week. Avoid arriving
in Northland around 18/19 Oct.

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If you would like more details about 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 text 64277762212.
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