Bob Blog 22 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 22 Oct 2023

LOLA's origins

Last week we looked at the Australian and South Pacific Cyclone outlooks for
the coming season. In my "what to avoid" summary I concluded that "Low L3
is expected to deepen over northern Vanuatu next week and maybe travel SW
into Coral Sea. Avoid this next week."

Well "Low 3" has now been named LOLA


and is the first cyclone of the new season that nominally starts on
1November.
LOLA was named ten days before season start. Why so early?
Looking at the satellite imagery, It seems that LOLA follows the normal
recipe for cyclone cooking.

1. Heat the sea to over 26C

2. Add lots of moisture a gang of tropical squally thunderstorms

3. And spin. As the gang of thunderstorms tumble together, they create
an area where air is vented up and outwards faster than it can be drawn in
from the fringes.
4. The central pressure drops, making more isobars on the weather map,
making a faster spin. This continues as long as the system has warm sea
and moist air to feed on.


Looking at the streamlines ...


.. It seems that the centre of action that has allowed LOLA to form is
related to the warm water over the central Pacific. Prior to its formation
there was a zone of equatorial westerlies all by itself near the dateline.
not an extension of the Asian monsoon. LOLA formed with an equatorial twin
thanks to those equatorial westerlies. So, it formed around 5S, very close
to the equator, an unusual spot for a South Pacific Cyclone -- these
usually form on the South Pacific Convergence zone. This may be related to
El Nino. It is associated with a shift of the Walker cell into the central
Pacific, especially when combined with a positive Indian Dipole.



See https://tinyurl.com/hadleywalker

So, 2023 is an El Nino year with an active zone near the equator. The same
pattern happened in 1972 and helped form TC BEBE 19th-29th October. It also
formed near 5S.


TROPICS
NORMA is near Baja California and TAMMY is near the Caribbean .TEJ is making
landfall over Yemen And LOLA is deepening as it approaches Vanuatu..

WEATHER ZONES
A lot to avoid this week.
The South Pacific Convergence zone is expected to stay from Solomons to
LOLA. Another branch is expected to linger north of Fiji to Samoa. A trough
should linger from Southern Cooks to south of Tahiti. LOLA is expected to
deepen as it moves slowly south near Vanuatu and peak at category 3 by
Wednesday then travel south or southeast maybe towards NZ next weekend.
Avoid.
HIGHS and LOWS
Low L1 east of NZ is expected to travel east.
HIGH H1 over NZ is expected to follow L1.
Trough is expected to roll northeastwards across the Tasman Sea followed by
strong SE winds and southerly swells up to 5m. Should reach from Bundaberg
to Northland by Friday. Avoid.
This is followed by a HIGH that stretches from central Tasman Sea to South
Island by next weekend.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>