From this  .  .  .  .  To this

 

 

 

 

 

 

 

 

 

Yesterday’s relatively small low compared to the predictions of tomorrow’s giant pool of low pressure.

A low pressure system developing in the southern Tasman Sea and across New Zealand continues to keep forecasters on their toes today.  The low, which is expected to grow to the size of Australia, is set to bring rough weather to both islands from Thursday night and last several days, through until Wednesday next week.   The storm is going to bring heavy rain, gales and thunder to some regions and end with a blast of cold air right off the polar caps.

Head weather analyst Philip Duncan says the storm has 4 main characteristics – rain, wind, snow and wind-chill.

“Strong winds are expected to build over the North Island later tomorrow and will rise to gale force in exposed places south of Auckland.  Then, western areas especially, are in for several showery, windy days”.

Saturday morning sport may well be cancelled again this weekend as the wintry storms sets in.

Mr Duncan says the low is certainly a complicated one.  “It’s so big and so unstable our weather models are changing regularly.  Our 3:30pm update today shows a mixture of snow flurries and rain across coastal Canterbury on Monday night and Tuesday next week however the wind direction appears to contradict this – coming from the south west which is usually a drier direction”.

“Due to the size of the low pressure and its unstable characteristics we feel it’s best to share this information early and update regularly if the system changes direction, weakens, or strengthens.  This is not an ‘out of the box’ low”.

Mr Duncan says while the low is extreme in size but shouldn’t be a repeat of previous storms.  “Yes it’s large but that helps spread the energy over a much wider area – in other words, it can dull the impact of wind and rain”.

The Weather Watch Centre is expecting snow flurries to low levels across Southland during Friday night but easing on Saturday as winds shift from southerly to warmer westerly.  The coldest air looks likely to move over the South Island later on Monday and during Tuesday.  “If it’s not snowing it’ll certainly be close to it.  The wind chill will be bitterly cold by Tuesday and this will be the biggest concern for farmers with new born animals”.

 

This image sent in by a weatherwatch.co.nz reader shows an impressive rain cloud over Auckland’s Northern Motorway this morning creating a large rainbow over the city.