We were staring down the barrel of an extended dry period after April became the third successive month of below normal rainfall. The region had less than half of average April rainfall and it had been a similar story in March and February. Soil moisture levels were well below median levels for the month, particularly for areas south of Tangoio. The Bridge Pa site was particularly low and had fallen into the lowest 10th percentile of readings in the site’s record for the time of year. April’s daytime temperatures had been above average and overnight temperatures near normal. The lack of rain for three months meant that both river flows and groundwater levels were feeling the pinch.
Two-thirds through May and the picture was looking much the same. The Heretaunga Plains had received less than 10% of May’s average rainfall. How the tables turned in just a couple of days. The Plains jumped to 171% of the long-term average and the region to 154%, with a few days of May to go.
We are exiting an El Niño phase and entering neutral conditions but there’s the possibility of us later transitioning into a La Niña phase. Despite this, the seasonal forecast models still persist with a predominant westerly flow for winter, based on a prediction of higher than normal pressure across New Zealand and lower than normal south of the country. Sea temperatures along our coast are currently near normal for the time of year. All of this results in a rainfall forecast of near or below average rainfall for the winter season and temperatures that are near or above normal. The recent wet few days might be a harbinger of what we’ll get from a La Niña to come – hopefully not.
All the best,
Kathleen
