NZ Weather Forum

NZstorm wrote: ↑Mon 30/09/2019 08:40 Tomorrow looks like the first spring hail set up and some of the horticultural regions could be affected. Looking like Nelson and Hawkes Bay/Gisborne the most exposed to a localised hail downpour.

Hail and storm activity tomorrow will be proportional to the amount of surface heating that can occur.

500mb chart midday tomorrow.

500mb chart.gif

Awhituobs wrote: ↑Tue 01/10/2019 08:28 my sep report or my location
http://weather-display.com/windy/gb/cli ... 92019.html
much wetter than normal here . Temperature overall average (average is for last 15 years)
windspeed up on normal

MetService September 2019 Summary - 'Unusually cold':

During the first few days of September, a Tasman Low produced warmer, wetter weather for northern New Zealand (Tauranga northwards), as well as Nelson and Marlborough. It was subsequently a wetter than usual September for parts of Northland, Auckland, Coromandel and northern Waikato, also Nelson and Marlborough. Elsewhere, cold, showery weather resulted in monthly rainfall totals that generally ranged between 60 and 100 percent of September normal.

By the 5th of the month, however, persistent cold southerlies kicked in across the country. These unseasonable cold outbreaks continued through the month, producing an extremely cold September for southern, eastern and northern parts of the South Island. Temperatures were also below average for the western South Island, as well as around Wellington and the Wairarapa. For the remainder of the North Island, monthly temperatures were closer to normal.

Sudden Stratospheric Warming (SSW) occurred in early September over the southern pole, but impacts have failed to penetrate down to the troposphere (where the weather occurs). Recent cooler temperatures over New Zealand have not been influenced by the SSW, but instead have been driven by frequent Southern Ocean southerlies washing up and over New Zealand, as per MetService forecast.

Sep 2019 Average Temps, Rainfall, Sunshine and departures from 1981-2010 normals ℅ NIWA

Site                     T-max °C       T-min °C      T-mean °C     Rain mm      Sun hrs

Auckland, Mangere       16.7  +0.4     9.9  +0.3    13.3  +0.3    123  120%    180  119%
Auckland Aero           16.7  +0.3    10.0  +0.3    13.3  +0.3    126  140%
Tauranga Aero           16.8  +0.2     8.9  +0.6    12.8  +0.4     97  115%    n/a   n/a
Hamilton Aero           16.5  +0.2     6.5  +0.3    11.5  +0.2    124  123%
Hamilton, Ruakura       16.5  +0.1     7.2  +0.5    11.8  +0.3    151  164%    146  100%
Wellington, Kelburn     13.7   0.0     8.0  +0.1    10.8   0.0     78   79%    167  102%
Christchurch Aero       15.2  +0.4     3.7  -0.2     9.4   0.0     55  135%    185  109%
Dunedin, Musselburgh    13.4  +0.2     4.7  -1.2     9.1  -0.4     39   80%    202  150%
Greymouth Aero          13.7  -0.4     6.2  -0.4     9.9  -0.5    194   93%    153  115%