when is the next la nina going to hit?

Answer 1

La Niñas do not "hit". They are an accentuation of normal conditions when the Southern Oscillation Index is strongly positive. The term is a convenience used to describe strongly positive periods but la niñas do not have the strong pattern and signature of an el niño. The southern oscillation is more of an oscillation between normal and el niño than it is between la niña and el niño.

Added:
Summary: Pacific Basin remains primed for La Niña

Although computer models show a La Niña event is likely in 2007, there hasn't been any consistent development in that direction across the range of ENSO indicators during May. Current conditions in the equatorial Pacific remain neutral.

The precursors for the development of a La Niña event are still evident. The most important is the presence of substantially cooler than normal conditions in the Pacific Ocean subsurface - a situation that has persisted since mid-January - which have led to cooler than average surface waters in the eastern Pacific. These surface waters are a little cooler than they were three weeks ago, although during the past fortnight there has been some slight warming along the equator in response to a basin-wide weakening of the Trade Winds. La Niña events are characterised by stronger than average Trade Winds.

There is no apparent trend as yet in the amount of convection (high cloud) near the date-line, and the SOI remains slightly negative. A switch to consistently reduced convection and positive SOI values would be favourable indications for La Niña development.

The fact that all major international coupled models show further cooling of the equatorial Pacific Ocean over the coming months, suggests that there is an elevated chance of a La Niña event occurring in 2007. Conversely, this suggests that the El Niño risk is very low. Historically, La Niña events bring wetter than normal conditions across much of the eastern half of Australia from autumn onwards.

Answer 2

La Nina is already in progress and will stick around until the end of this year. However, there is a slim chance that La Nina might continue into next year. A normal La Nina lasts 9 to 12 months.

Answer 3

i dont know but one thing i can tell you to do is watch the news