BOBGRAM7 issued 21 Feb 2010

WEATHERGRAM
YOTREPS
Issued 21 Feb 2010
Bob McDavitt's ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas come from
the patterned world of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

TROPICS
RENE has had its day, and now there is a concentration of South pacific
convergence zone convection in a line from Tuvalu to Tokelau to Northern
Cooks which seems to be most active near EQ 160W. A low has now formed
near 8S 160W., The EC model output suggests that this low move south
near the 160W line bothering the Cook Islands, reaching the Rarotonga
area around wed /Thu 24/25 Feb, and other model output suggest that
a/another development may form next week. .So if you are in the Cooks
keep tuned, if you have Internet then you can get the EC model at
http://bit.ly/ecoz but you'll have to select Southern Hemisphere to see
the Low/cyclone.. (the next name on the cyclone list is SARAH, but this
Low , at this stage, hasn't earned a name yet )

Elsewhere around the South Pacific there is just scattered unorganised
convection, but there may be a Tropical low over NW Australia this week
and there is a cyclone GELANE in the South Indian Ocean.

SUBTROPICS

The subtropical ridge is strong and hugging 35S to 40S in the South
Pacific.

The High centre east of the North island today , sun 21 Feb, should
steadily wander east and then fade when it reaches 35S 150W on Sat 27
Feb

The next HIGH should cross Bass Strait on Thu 25 Feb and then the
central Tasman Sea on Fri 26 Feb and central NZ on Sat 27 Feb=== third
anticyclonic weekend in a row for NZ.

North of these Highs there are well defined between 15S and 30S, and
occasionally there is a squash zone near 30S.

NEW ZEALAND

Between the two Highs is a transitional trough. It is bringing some
warm air from Australia, so temperature in the SE of the Si may soar to
30 C in the prefrontal gusty NW winds on Mon 22 Feb.

The low associated with this trough is likely to peak on Tuesday in the
South Tasman sea and its associated frontal band should bring heavy rain
to W of the South Island on Wed 24 Feb, then weaker rain to west of
North Island on Thu 24 Feb, followed by a southerly/southwest wind
change with showers for eastern areas on Friday 26 Feb

So it's a mediocre mid-week transition from one weekend BBQ High to
another J

The terms used are more fully explained in the METSERVICE Yacht Pack.
More info at http://weathergram.blogspot.com
Feedback to bob.mcdavitt@metservice.com