Bob Blog 21 Feb

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 21 Feb

The Cause of the cold in Texas
Texas has been breaking many records for cold during the past week---
Basically the polar jet stream has been weak and allowed a burst of polar
air to break southwards as far as Texas.
The Arctic Oscillation index is a parameter that is positive when the polar
vortex is well contained, and has spent much of the northern winter NEGATIVE
with a big dive in early February ,see
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index.
html
One reason for the blackouts is that the electricity grid could not cope
with the increased demand. The cold weather froze natural gas wells and
blocked pipes. It also froze some wind turbines, but the main problem was
with natural gas which is the state's primary energy source. The network
engineers managed to stop a state-wide blackout by controlled overloading.
Also, Texas has insisted on having its own grid and has little
interconnection to the USA western or eastern interconnections. (Source:
http://www.theguardian.com/us-news/2021/feb/20/texas-power-grid-explainer-wi
nter-weather)

The Tropics
TC DUJUAN is moving onto the Philippines and TC GUAMBE is tracking southeast
from Mozambique channel.
There is a moderate potential for a Tropical Cyclone to form between Vanuatu
and Samoa..

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is north of its normal position and from Papua New Guinea to
Samoa/Southern Cooks
A tropical low over the Southern Cooks is expected to travel southeast and
deepen in the subtropics from Monday to Wednesday local dates.
Another tropical low is expected to deepen near Vanuatu by Mon 1 March.

Subtropical ridge (STR)
HIGH 1026 east of North Island is south of Tasmania on Monday is expected to
travel across central Tasman Sea this week and onto central NZ on
Friday/Saturday.
Next HIGH is expected to travel east across Tasmania on Wednesday and then
go southeast around southern NZ on Thursday.

NZ/Tasman troughs
Low 990hpa between Coffs harbour and Lord Howe is travelling south-southeast
and expected to zip past the south of the South Island on Wednesday.
Another Low is expected to form east of Eden by Friday and travel southeast
past south end of NZ by Tuesday 2 March.

Panama to Galapagos/Marquesas
Good northerly winds for starters. There is likely to be a good tail current
near EQ 85W, and a head current near 5-6N 85W so good idea to go direct, or
if heading for Marquesas go via south of Galapagos.
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