Deep Low to Impact NZ... AGAIN (24th to 28th Nov)

[melja]

8mm at chch airport today when only morning and evening drizzle is forecast.

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[Richard]

A convergence line running down the coast over Kaiapoi and airport bought that rain, dry in the city

[spwill]

Plenty of rain modelled for the upper North Island, a lot of it will be short duration heavy falls from Cb.

Dewpoint up to 19C tomorrow, our first day of humid weather for the new season

[Cantab03]

In all honesty though, the models have been up and down like a yo-yo for the last week or so. Struggling to keep up with the atmospheric conditions currently. Less than 24hrs ago, they were picking more than 4x what they are currently saying for ChCh. Don't be surprised it it swings back on tonights run.

This is true due to the complex nature of the system. However, to be fair both models are liking the idea now of keeping the bulk to the heavier rain around Amberley northwards through Monday and Tuesday. There has been some consistency from the last 3 model runs around this, with a gradual declining trend on each run. I feel this system will need to revert within the next 12 hours to push further south if it is going to, otherwise with 48 hours we can start locking in a bit more certainty for the current target area. I'd expect to see Metservice revising their outlook to downgrade their confidence for areas south of Banks Peninsula overall.

EDIT: They have kept the high confidence right down to Eastern Otago, perhaps due to the saturated ground there thresholds are different for this upcoming event.

[David]

Metservice 3 day model has gone a little crazy for Auckland over the weekend showing almost 200mm... compare to GFS which only has about 15mm modelled...

[snowchaser01]

In all honesty though, the models have been up and down like a yo-yo for the last week or so. Struggling to keep up with the atmospheric conditions currently. Less than 24hrs ago, they were picking more than 4x what they are currently saying for ChCh. Don't be surprised it it swings back on tonights run.

This is true due to the complex nature of the system. However, to be fair both models are liking the idea now of keeping the bulk to the heavier rain around Amberley northwards through Monday and Tuesday. There has been some consistency from the last 3 model runs around this, with a gradual declining trend on each run. I feel this system will need to revert within the next 12 hours to push further south if it is going to, otherwise with 48 hours we can start locking in a bit more certainty for the current target area. I'd expect to see Metservice revising their outlook to downgrade their confidence for areas south of Banks Peninsula overall.

EDIT: They have kept the high confidence right down to Eastern Otago, perhaps due to the saturated ground there thresholds are different for this upcoming event.

Either that or they are seeing something we aren't...

[NZ Thunderstorm Soc]

Well, I hope it dosen't rain too much down here as we are quite sogged and saturated already and I see that MS has rain for all days on their long range outlook
.....but then I think we will return to a more westerly flow in December which should dry things out

[snowchaser01]

Metservice have further updated their SWO to mention the chance of " unusually large and significant amounts of rain" in parts of the North Island.

[Cyclone Tracy]

Asymmetrical cyclonic gyre is now spinning hard in the SW Tasman. Down in the low 970’s. Significant atmospheric river now developing ahead of the main frontal boundary pushing into multiple troughs and a warm front. The MS High Resolution rainfall model is going rogue with the increased water vapour at mid levels over the tropics and subtropics I'd say. Chances of a mother convergence zone into the NI has increased looking at this developing feed . Back to the popcorn

http://tropic.ssec.wisc.edu/real-time/m ... anim=html5

[snowchaser01]

A severe weather watch has now been issued for North Otago and South Canterbury

[tich]

A convergence line running down the coast over Kaiapoi and airport bought that rain, dry in the city

Had a wet period where I was at work in Ilam. But not all Chch got the rain - nothing at Jeff's Hillmorton station.

[Chris W]

The convergence line produced heavy rain between about Kaiapoi and Leithfield on my morning commute.

[snowchaser01]

Latest GFS run for CHCH. moisture back up to the levels they were a couple of days ago, with nothing showing later in the week now. best part of 80mm could potentially cause some problems.

[Richard]

The convergence line produced heavy rain between about Kaiapoi and Leithfield on my morning commute.

Was fascinating hey, drove through it on the way to CHCH, the inflow on the SE side which looked impressive.

[Thunder081]

Time lapse showing this storm hitting SE Aussie then moving into the Tasman Sea

[snowchaser01]

I really don't know what to think about this system currently... up and down like a yo yo, sitting on a knife edge, could go either way. Time will tell I guess.

EDIT: Where is CT when we need him... eating popcorn I suspect?

[snowchaser01]

The convergence line produced heavy rain between about Kaiapoi and Leithfield on my morning commute.

Was fascinating hey, drove through it on the way to CHCH, the inflow on the SE side which looked impressive.

Certainly 11mm that was not forecast at Christchurch Airport.

[Bradley]

Latest run of EC throwing up some interesting numbers in the latest run with nearly 300mm for Kaikoura and 40mm for Christchurch, quite a contrast...

[NZ Thunderstorm Soc]

Was fascinating hey, drove through it on the way to CHCH, the inflow on the SE side which looked impressive.

Certainly 11mm that was not forecast at Christchurch Airport.

Just like the downpour we had in Geraldine this afternoon as posted on the General November Weather thread.

[jamie]

Yea CT’s posts are certainly informative and appreciated here


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[NZ Thunderstorm Soc]

Latest run of EC throwing up some interesting numbers in the latest run with nearly 300mm for Kaikoura

Oh no
That will wash the railway out again just after promoting the first run of the Coastal Pacific

[snowchaser01]

Latest run of EC throwing up some interesting numbers in the latest run with nearly 300mm for Kaikoura and 40mm for Christchurch, quite a contrast...

Well safe to say that 300mm in Kaiks would pose huge problems for the ever frail coastal road. My pick is somewhere around the 80mm mark for Christchurch.

[snowchaser01]

Yea CT’s posts are certainly informative and appreciated here


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Absolutely... one of the highlights of my day is reading the knowledge he chooses to share with us!

[NZ Thunderstorm Soc]

Yea CT’s posts are certainly informative and appreciated here

Absolutely... one of the highlights of my day is reading the knowledge he chooses to share with us!

I agree. Even though I don't understand some of the terminology he uses, he is an important asset to this forum

[snowchaser01]

Absolutely... one of the highlights of my day is reading the knowledge he chooses to share with us!

I agree. Even though I don't understand some of the terminology he uses, he is an important asset to this forum

HAHA some of it is in one ear and out the other... I have to agree with you there!