Dr Kathleen Kozyniak
Principal Scientist Air
Hawke’s Bay Regional Council
May rainfall seemed like a good news story at first – reaching 102% of the long term average. The distribution of rainfall wasn’t ideal though and focused on the northern half of the region. The usual suspects, being the Heretaunga and Ruataniwha Plains and the south coast, were short-changed and reached only 60-70% of average May rainfall. It’s six consecutive months of below normal rainfall for those areas. They keep mounting.
River flows averaged only 40% of normal May flows and groundwater levels ended the month predominantly below normal. Soil moisture levels recovered nicely in locations north of Napier. It’s a different story for those to the south where you’d be hard pressed to find anywhere that had close to median levels for May and some sites, like Bridge Pa, couldn’t find a way out of the lowest 10th percentile of readings. Soil temperatures ranged from 8°C to 11°C as we tipped into winter, which is about normal, and air temperatures were mild for May.
La Niña is no longer a player in our weather and the neutral mode should persist through winter and spring. The main feature for winter seems to be lower than normal sea level pressures across Australia and the Tasman Sea. We are likely to get a mix of northeasterlies and westerlies as a result, warmer than usual temperatures and near normal rainfall. Both NIWA and Metservice are throwing the possibility of above normal rainfall in their forecasts, the former for the winter season and the latter for June. Our southern half would really appreciate it.
Percentage of Normal Rainfall