The first two months of spring have been drier than normal and November is shaping up to be no different. Hawke’s Bay had 56% of average rainfall in both September and October and now sits on 33% of November’s average with two thirds of the month gone. Some areas in the region are having a particularly dry run, the worst hit being the Heretaunga Plains. It’s had four months of below normal rainfall and November will likely be its fifth. The area has received only 13% of its November average to date.
Spring has not only been dry but also warm. Daytime temperatures were more than 1°C above average in both September and October. Overnight temperatures were more subdued, but still near normal in September and above average in October. The warmth and lack of rain sent soil moisture tracking well below median levels for the time of year and likewise groundwater levels and river flows aren’t meeting monthly averages.
The rest of November may not offer much more rain but ingredients exist that should help beyond that. Sea temperatures are warmer than average around New Zealand and in areas where some of our storms originate, such as the Coral Sea and Pacific Islands. A La Niña occurring over summer is a 50:50 call but the Indian Ocean Dipole looks set for a brief negative phase which is more promising than not for our region. The Madden Julian Oscillation, which can promote tropical storm activity, might be active in the region north of New Zealand in early to mid-December.
Seasonal forecast models suggest summer winds will mainly be from the east to northeast (La Niña-like) due to higher than normal pressure over eastern and southern New Zealand and lower than normal over Australia and the Coral Sea. Stubborn anticyclones are currently keeping rainmakers at bay but the forecasts indicate that the dominance of high pressure will shift southward as we progress through summer and that the area of lower pressure will extend closer to northern New Zealand, enhancing prospects of rain. Near normal summer rainfall could be on the cards therefore… hopefully not arriving in one devastating dump. Temperatures should be toasty for the season, spurred on by the warm seas.
All the best,
Kathleen
