bob blog 12 Dec

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 December2021
The first tropical cyclone for this South Pacific cyclone season has just
been named by the Bureau of Meteorology, Australia as RUBY. It is in the
Coral Sea and may reach New Caledonia during Monday night/Tuesday and pass
to the northeast of NZ on Thursday
An active pulse of extra convection, called an MJO (Madden Julian
oscillation) is moving along the equator and should disturb our weather for
the next two to three weeks. The MJO was named in 1971, fifty years ago,
when Roland Madden and Paul Julian studied equatorial wind data. It is a
pulse of extra energy that forms in the Indian Ocean then travels eastwards
along the equator until it fades near the dateline. It can be tracked
watching cloud and rain patterns and is known to increase the risk of
cyclone formation.
At present the zone of extra convection is expected to linger over the
South pacific for the next three weeks.

A site to check is the sophisticated modelling done by Meteo France as shown
on the New Caledonian weather web site at
www.meteo.nc/nouvelle-caledonie/cyclone/coin-des-experts. This shows the
results of a regression model using 2 predictors for the state of the MJO, 3
to measure ENSO and IOD, and one to measure the climatological seasonal
cycle. Their latest map shows that there is a high probability of a cyclone
forming between 19 and 25 dec around Fiji.

EQUATORIAL WESTERLIES
This MJO has triggered a zone of strong west-northwest winds along the
equator. When this happens in December it normally is a precursor to
tropical cyclones. This one has almost produced a twin of tropical
depressions, but these two are perhaps too far apart to feed off each other.


TROPICS
Cyclone RUBY is now the Coral Sea and there is a tropical depression east of
Philippines,
The 'wind accumulation' setting in Windy.com set to next ten days gives an
indication to each model's current forecast for each cyclone path, showing a
storm over Philippines and a gale over New Caledonia is likely this week

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ remains active from Solomons to Fiji. TC RUBY is in the Cora Sea
and expected to pass by northern part of New Caledonia and near Loyalty
Island during Monday night/Tuesday.

HIGHS and LOWS
LOW L1 is just a trough over southern Cooks tonight and is expected to form
on local Monday and go southeast and peak on Wednesday.
HIGH H1as been a blocking high east of NZ last week but is this week
expected to travel off to the northeast.
LOW L2 is in the mid Tasman Sea and expected to cross central NZ on
Wednesday, preceded by an active front on Tuesday night, and followed by a
south to southwest flow on Thu/Fri/Sat.
HIGH H2 is expected to cross Tasmania on Thursday and then go northeast
across the Tasman Sea. into south Tasman Sea this weekend and then follows
H1.
L3 is expected to travel from 50s to 55s, south of Tasmania on Wednesday and
south of NZ by Friday.
The outlook for next week is that ANOTHER TROPICAL LOW may from and travel
south near Vanuatu, and another trough may cross the Tasman Sea. Time your
travel to avoid these.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for 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 txt 64277762212
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>