Bob Blog 22 Jan 2017

WEATHERGRAM
YOTREPS
Compiled Sun 22 January 2017

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.

The Tropics are still having a quiet period between active cyclones.
Rather unusual for the to be so quiet for so long.NASA has noticed this anomaly
and is Facebooking about it at www.facebook.com/NASAHurricane/

My theory, as far as South Pacific is concerned is that the recent temperature
anomaly between (hotter than normal) Australia and (colder than normal ) NZ has
been producing more westerly winds, knocking the subtropical ridge north of
normal, and thus weakening the SPCZ. We had those two deep low across NZ as
mentioned in last week's weather gram, and I think this means the subtropical
ridge is now about to be able to shift south onto central/southern NZ during
next few weeks.

Rain maps show that an active low affected the area south of Southern cooks and
French Polynesia last week, and changes elsewhere were minimal.
Rain for the past fortnight may be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ remains about the same this week as last week, expect for noticable
activity in the Fij/Tonga/Niue area culminating in development of a tropcial low
south of Niue at 25S by end of the week. That low is expected to travel slowly
south next week.
Check out the expected tropical accumulated rainfall for next week from
windyty.com

Subtropical ridge (STR)
High in central Tasman sea on Monday is expected to fade over northern NZ by
Wednesday.
A new High is expected to spread into the south Tasman Sea on Thursday, and
cross central/northern NZ area on Sunday 29 Jan.

Tasman Sea/NZ Area troughs.
A deep low is expected to move off to southeast of NZ on Monday (23rd Jan)
A front is expected to cross South Island on Tuesday and North Island on
Wednesday.
Another front is expected to cross South Island on Sunday and North Island on
Monday 30 Jan. This is Auckland Anniversary day, so anticipate a change around
then to SW 20 gust 30 knots.

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