Bobgram

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 Sun 31 January 2021
TC ANA is expected to have peaked as Category 2 over Suva local noon Sunday
and then weaken and travel southwards across Kadavu area tonight and then
off to southeast on Monday.
See Fiji Met Service official track map as at http://www.met.gov.fj/
If you only have access to email then you can download the latest by sending
an email to mailto:query@saildocs.com , no subject needed, with the message:

SEND https://www.met.gov.fj/aifs_prods/20032.txt
Note that the gale winds are in a ring around the centre, Observations of 33
knots (peak 46 knots) at Rakiraki and 38 knots at Undu point at local noon
as seen on windy.com

And the scatterometer (taken when ANA was over Yasawa Islands) shows how the
squall bands spiral not the low centre (see
manati.star.nesdis.noaa.gov/datasets/SSCATData.php) Black data has been
affected by rain.

TC ANA is part of a broad band of lows that stretches all the way across
northern Australia into the Indian Ocean. This monsoonal trough has a zone
of near equatorial westerly winds on its northern side and is a classical
tropical feature brought about as a burst of energy extends eastwards thanks
to a positive phase of the MJO (Madden Julian Oscillation). It will dominate
the South Pacific for next few weeks and is likely to trigger a few more
cyclones, some affecting Fiji.

Monsoonal trough is seen at satview.bom.gov.au/
The Tropics
The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical
Cyclone Potential is from http://www.ssd.noaa.gov/PS/TROP/TCFP/index.html
TC ANA is travelling south over Fiji. There is a Tropical depression
northeast of Espirito Santo which may visit Fiji on Monday, and a tropical
low in the Coral Sea which may visit Vanuatu by Tuesday and New Caledonia on
Wednesday. These systems my briefly become cyclones. And there is a high
potential of tropical cyclone formation along a monsoonal trough from
northern Australia to Fiji. However they are all "feeding from the same
pool" and this means that none of them are likely to reach the higher
categories of wind speed or area coverage. It does mean that heavy rain may
be encountered in many places along the monsoonal trough.


WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is intense from Coral Sea to Vanuatu to Fiji. As part of a monsoonal
trough.

Subtropical ridge (STR)
HIGH 1024hPa over central NZ is slowly moving ff to the southeast. A
replacement High 1020hpa is expected to cross Tasmania by Tuesday and reach
southern NZ as 1032 on Wednesday and then peel off to the east from
Thursday.
NZ/Tasman troughs
Highs are expected to dominate the weather pattern over NZ this week. OK for
coastal sailing.
But pattern is not OK for trans-Tasman sailing this week.
One trough in the Tasman Sea is expected to pass by the south of NZ on
Monday,
Another trough should form off New South Wales/Tasmanian coast on
Tuesday/Wednesday then peel off to south.
Low from Coral sea expected to travel around New Caledonia on Wednesday and
then go southwest toward Queensland and fade away before making landfall.
No racing in the Prada cup until finals start on Sat 13 Feb.
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