Bob Blog 23 Oct

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 23 October 2022

The "SUCKER PUNCH" pattern
Friday 21 October, and a cold front went past Auckland in the morning
followed by showers in a southwest onshore flow from the Tasman Sea.

During the day locals watched the western horizon to time these showers.

By afternoon, the skies were clearing, and people started planning an
evening BBQ to celebrate the start of their only spring long weekend (thanks
to Labour Day Monday). Just as they gathered outside a sucker punch of wind
and rain arrived from the eastern horizon. How can this happen?

The "sucker punch" is a reasonably common Auckland weather pattern and is
explained by its position north of the main mountain ranges of Aotearoa.
At 7am the weather map shows the passing front is leading in a HIGH
crossing the south Tasman Sea.
At 1pm air is diverted northwards along the eastern side of the main
mountain ranges, and this creates a zone of falling pressure in the lee to
west of Taranaki
Then at 7pm the air that has freshly arrived in the Bay of Plenty and still
has the angular momentum it had when south of the mountains is finally free
of the mountains and gets kicked to the left by Coriolis and sucked in
towards that zone of falling pressure. The sucker punch.
TROPICS
The latest cyclone activity report is at zoom.earth and tropic.ssec.wisc.edu
and Tropical Cyclone Potential is from
www.ssd.noaa.gov/PS/TROP/TCFP/index.html

Depression Twentyfive is approaching Vietnam and Cyclone Roslyn is moving
on-to Mexico.

WEATHER ZONES
The SPCZ stretches from Coral Sea/ New Caledonia/ Vanuatu to Fiji then
across Tonga to Sothern Cooks. Tropical Low L1 is forming over Vanuatu and
expected to travel east across Fiji on Tues/Wed. Another tropical Low L2 is
forming between Southern Cooks and Austral islands and expected to travel
SE. Avoid these.
After L1 has cleared Fiji should be Ok to set sail for NZ.
HIGHS and LOWS
A southerly change travels northeast across NZ on Monday, followed by HIGH
H1 on Tuesday. H1 then is expected to travel off to the east along 35S.
Low L3 has formed offshore of Bundaberg and is expected to travel south
along the East Aus coast to Eden by mid-week and then southeast across the
south Tasman sea.

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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 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 64277762212
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