Having just done a post on the unstable weather conditions due to the warm water in the Tasman Sea I had a quick look at Met Vuw.
​There is a tropical storm coming down from the Pacific, which is a bit early in the season but not unusual.

 What is interesting is that the storm is forecast to go down the West coast and over the warm water in the Tasman Sea where it picks up heat and energy, it intensives and the pressure drops tp 992.
​To make it worse the storms southwards path is blocked by a high pressure system and it gets stuck.
​Much like the hurricane that struck Texas.

This is a four day forecast and a lot can change but you can see the effects of the warm water in the forecast.

​The ocean water in the Tasman sea is up to 6 C warmer than normal and it will have an unpredictable effect on the weather. The first and obvious outcome would be that the extra heat will raise the moisture content of the atmosphere by 8% for every extra degree of temperature rise and the extra heat can drive stronger storms. 

Instead of rain we are in a drought so what’s happening?
New Zealand has a ridge of mountains down the West coast that effectively stops rain getting past them and we need easterly winds to bring us rain to our populated areas. The current drought is due to the increased prevalence of Westerly winds due to global warming in the Southern Ocean and the very warm weather is due to the warm water in the Tasman Sea warming the winds. 

We have also had sunny, clear skies due to the high-pressure systems coming from the west. High pressure systems are from dry air descending from 10,000 metres and effectively blot out low pressure systems which rise from the sea and rise to 3000 or 5000 metres shedding moisture and heat as they ascend.
Drought is the biggest killer to our environment and to our farming economy and food production. It can kill millions of trees, dry up streams and destroy grass and other farming produce.

​Powerful rainstorms wash away topsoil and flood our estuaries with silt as well as causing damage to our infrastructure and homes.
 So what can we expect?
The drought is already with us and we still have the warmest part of the summer months to come so we can expect it to intensify.
There must also be a big risk of powerful rainstorms causing flood damage but that is less predictable and are more likely to happen later in the summer or autumn.