TC Hale

2022-23 Season TC Tracking Monday, 09 January 2023 0 Comment

4 minutes reading time (857 words)

9th Jan 2023 2100hrs

The 2022/23 TC season kicked off, seeminigly with a bit of a whimper at 1pm on 7th Jan 2023, when TC Hale was officially named as a Cat 1 cyclone, forming to the west of Mackay, Australia. However by 7pm on 8th Jan, it had been downgraded to a tropical depression.

So - what's the big deal about Hale? Why would we want to blog this TC, that now no longer exists? The key part of Hale's story is what it does next! Ex TC Hale has continued to move south east. The latest expected track for the depression is as follows:

There is still a bit of variability in the track - for example the previously published track map had the depression going slightly further south. However the bulk of the bad weather is likely to be on the East Coast of the North Island down to Wellington and Marlborough. So what is going on? Why the weird path?

Taking a look at the ECMWF model output from Windy.com, you can see below that a high pressure remains in place just enough enough to the east of Canterbury, to push the low pressure downwards before it can then move east following the predominant wind pattern.

You can see how the high pressure sits below the depression as it moves down. This forces the pressure gradient to increase, and therefore the winds to increse. In the video, winds of around 70km/h are represented by the red areas..

You'll also notice the High pressure being squeezed out to the right, meaning the only path for the ex TC is down. Once the high pressure moves further to the east, the depression then gets a push from the west, from the high pressure sitting over Tasmania.

So that sorts out the path of the storm. Who is ging to cop the bad weather?

Taking a look at the same model, this time with a rainfall overlay, we see the following:

As you can see (Red and pink in the video represent 20 to 30mm of rain) Auckland is expected to see some rain, then the east coast of the north island. There have recently been significant amounts of rainfall in these areas so the Metservice have published weveral watches for these areas.

The storm that was forecast by MetService to last several days was expected to cause coastal damage, slips, surface flooding, road closures and power cuts.

Heavy rain was expected in Coromandel Peninsula for 24 hours from 10pm on Monday, Gisborne for 28 hours from 10pm on Monday, and in Hawke’s Bay for 17 hours from 3pm on Tuesday, MetService said.

The heaviest rain was forecast in Gisborne, where 200mm to 250mm was expected. Large waves were expected to hit eastern coastlines from Northland to Wairarapa on Tuesday and Wednesday.

Waka Kotahi NZ Transport Agency also warned that slips and flooding may force it to close state highways across the North Island, while strong wind might affect the Auckland Harbour Bridge on Tuesday and Wednesday.

(Stuff.co.nz and Metservice)

We'll be keeping a further track on Ex TC Hale over the next few days.

10th Jan 2023 9:30pm

Cyclone Hale progressed onto the north of the North Island, impacting Northland, Auckland and Coromandel. There's plenty of updates on the impacts in the News Items section below.

By 7pm tomorrow night the centre of the depression is expected to be over Hawke Bay, after transitioning through just north of Taupo. Central pressure is around 990 hPa. This drives the associated rain into the East Coast of the North Island, south of Hastings, down to Wellington. Rainfall accumulations are expected to be about 12mm of rain per 6 hours.

There's still a bit of heavy rain for parts of the East Coast of the North Island tonight and tomorrow as well as Coromandel, and Metservice have a number of watches and warnings in place for these areas:

NOTE you should always refer to the Metservice website for the latest information on current watches and warnings as information on this page / site may not be up to date.