BOBGRAM issued 26 Feb 2011

WEATHERGRAM
YOTREPS
Issued 26 Feb 2012
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 of weather maps, so please fine-tune to your place. Dates are in UTC unless otherwise stated.

La NINA continues to relax in the atmosphere. Average atmospheric SOI (30day running mean) was 0.58 on 20 Feb and -0.3 on 26 Feb, its first negative week since April 2010.

There is a zone of enhanced tropical convection stretching from Indian Ocean across Indonesia to North Australia and this is expected to reach Coral Sea between 10 and 15 March
. The South Pacific Convergence zone SPCZ has been weak for the past week and mainly concentrated between Tuvalu and Northern Tonga. During the coming week a small trough is expected to bud off the SPCZ over southern Tonga by Tuesday 28 Feb and then move off to the south, as the SPCZ slowly rebuilds over Coral Sea,

SUBTROPICAL RIDGE STR
High1 near 140W and south of French Polynesia is blocked and should stay put this week, causing features upstream to bunch up and stall.

High2 in North Tasman Sea is expected to go further north on Monday and the swing eastwards along 30S on Tuesday and Wednesday then merge with high 1 east of 180 on Thursday.


High3 currently in Aussie Bight is expected to cross south of Tasmania on Friday and into the South Tasman on Saturday its them and should cross Tasmania on Friday and then into South Tasman Sea on Saturday/Sunday/Monday 3/4/5 March,

TASMAN SEA/NZ AREA
FRONT is expected to move from Tasman Sea onto South Island on Tuesday 28 Feb, A LOW should deepen on this front to east of the South Island on Wed/Thu 29 Feb/1 Mar producing 2 days of S or SW flow over NZ. This Low should move away on Friday 2 Mar and thus produce light winds over NZ but an EASTERLY flow over southern South Island.

A new LOW should form near Lord Howe Island on Thu 1 Mar and deepen as it moves onto the Auckland area on Sat 3 March with a strong S or SE flow over NZ. Avoid,

The terms used are more fully explained in the METSERVICE Yacht Pack.
More info at http://weathergram.blogspot.com
Feedback: bobmcd@xtra.co.nz, work: bobmcdavitt@hotmail.com