Being on saturation watch rather than drought watch is new to me. We’ve had a lot of rain so far this year, with September making a sizeable contribution. The month’s rainfall was well above average, especially on the Heretaunga Plains, where almost triple the month’s average fell. October hasn’t mucked around either. At the time of writing, near the month’s halfway mark, both the Heretaunga and Ruataniwha Plains have already hit 100% of average October rainfall. We have record accumulations at a number of our sites for the year to date.
At the Council’s climate site at Bridge Pa, the soil moisture level is the highest it has been for mid-October since monitoring started there in 2003. Soil moisture is at field capacity or reached saturation across much of the region. River levels were above normal in September and groundwater levels tracked well compared to long term averages. Cloudy conditions muted daytime temperatures in September, but overnight temperatures were a degree above normal and soil temperatures were warmer than usual, finishing the month on approximately 14°C on the Plains.
I’d like to say things will change over the next few months but a notable shift in pattern isn’t predicted. La Niña and negative Indian Ocean Dipole events continue to rumble on. We’re expecting higher than usual sea level pressure over central and southern New Zealand and lower than usual to the north of the country. The pattern favours easterly wind flows, with their potential to bring the region cloud and moisture. Rainfall predictions lean towards normal or above normal totals while temperatures are expected to be warmer than usual, though don’t be surprised if those daytime temperatures are blunted by clouds again. Usually we’d be reasonably happy with the rain forecast but right now I think a breather and some sun would bring more cheer.
Percentage of Normal Rainfall
Dr Kathleen Kozyniak
Principal Scientist Air
Hawke’s Bay Regional Council