Bob Blog 12 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 12-Feb 2023

CYCLONE GABRIELLE
The MJO cycle is spreading a positive boost of energy across northern
Australia and into the Wester Pacific this week and this has activated a
necklace of cyclones.


Cyclones DINGANI, FREDDY, and GABRIELLE. D on the Indian ocean name list and
F and G on the Australian name list. More cyclones are likely next week.

Cyclone GABRIELLE is no angel and is behaving more like a GABBY or even a
CRABBY and is expected to do a crab-like sidestep to the right towards
Auckland tomorrow.

Yesterday 11 Feb GABRIELLE moved over Norfolk Island, on 11th and peak gust
of NE 102kph at 2:30pm and lowest measured pressure 958.0 at 10pm.

Today GABRIELLE has left the tropics but is still a cyclonic storm so
changes its name for Tropical Cyclone GABRIELLE to Cyclone GABRIELLE. There
is a squash zone of strong winds south of GABRIELLE travelling southwards
across Aotearoa North Island. These winds are strong enough to bring cross
winds gusting over 100km/hr to exposed parts of Hauraki Gulf and close the
Auckland harbour bridge (now) and Auckland airport (on Monday). The cyclone
is staring to de-intensify and estimated central pressure is 967 and rising.

However, on Monday the system is start finding resistance to a smooth SE
path due to a new HIGH east of NZ. The eye is on a wobbling path (like an
out of balance washing machine) and this resistance may coincide with one of
its wobbles strong enough to make GABRIELLE do a sidestep southwards towards
Auckland. As this happens the system may ingest cooler air from the south
and this may cause thermogenesis and allow the system to re-intensify.

Lots of "may" in this outlook and in my illustrated blog at metbob.com is a
meteogram from this afternoon's GFS data for Auckland area.
The time axis is in UTC and estimates the baro (thick black) may drop to 968
on Monday local night. If so, that will be a new record for Auckland. There
is an easterly gale (thin black/ dots for gusts) starting today and easing
from late Monday, and a well-defined peak in the rainfall (blue shading) to
over 20mm/hr on Monday afternoon 6mm/hr=heavy rain).

WEATHER ZONES
South Pacific Convergence Zone SPCZ
The SPCZ is expected to remain active across the Coral Sea /New
Caledonia/Fiji and Tonga to French Polynesia.
Tropical lows may form on the Monsoonal trough north of Australia and non
the SPCZ near Tonga later this week.
Avoid most of the tropics this week as they are looking squally.
However to north of GABRIELLE there is expected to be a zone without trade
winds and that may be useful for getting east.
Travel from Australia is looking ok this week.
It will take until Thursday or Friday before the wind and rain of GABRIELLE
departs from NZ and allows some sailing to or from there again.

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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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at bottom).
Weathergram archive (with translator) is at weathergram.blogspot.co.nz.
Contact is bob@metbob.com or txt 64 277762212
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