Ex-TC Lusi affecting NZ - Mar 14-17

[Manukau heads obs]

it hasnt gone exactly to orginal plan so far....
originally was supposed to head east from vanuatu and intensify quickly over open waters then curve SE and accelerate and the move S and even SSW

but instead its been moving SSE down the island chain of vanuatu which has slowed its intensification
its now moving more SE into open waters....so should not rapidly intensity
sure has lots of moisture around it to feed in...

[Richard]

I see its now been forecasted to move down the west of the NI to cross Nelson/Nth Canterbury

[einzack]

getting off topic slightly, but it's gaining relavence as the week passes....
regarding Cyclone Bola, there was a thread over at localweather.net.nz with some reminiscing last year:
http://www.localweather.net.nz/smf/cycl ... clone-bola

which had a table of rainfall totals for some East Coast locations which was rather interesting.
I'll try to post it here as an attachment.

[CWUweather]

getting off topic slightly, but it's gaining relavence as the week passes....
regarding Cyclone Bola, there was a thread over at localweather.net.nz with some reminiscing last year:
http://www.localweather.net.nz/smf/cycl ... clone-bola

which had a table of rainfall totals for some East Coast locations which was rather interesting.
I'll try to post it here as an attachment.

That is an interesting PDF, I cant see places getting 800mm this time, up around 200-300mm in parts maybe?

[Manukau heads obs]

BOM model flip flopping alot...back to original track, for now,(maybe slighty west of that)
GFS has been alot more consistant

[CWUweather]

BOM model flip flopping alot...back to original track, for now,(maybe slighty west of that)
GFS has been alot more consistant

Yes, BoM have been flipping alot.... backed right off the other day. READY models saying 80mm for Christchurch this morning..... bit steep?

[Bradley]

I would say the median rainfall if you average the 3 major models together is between 40-70mm for Christchurch at this stage, 40mm being a bit on the low side I would say!!

[NZstorm]

I'm picking 180mm for the wettest spots such as the eastern hills of Northland and the Coromandel ranges. The eastern ranges over the upper South Island look like getting a decent downpour as well. These tropical systems don't tend to have much instability in our latitudes due to warm upper air (500mb -5C). But the very strong orographic effects can really crank up the rainfall.

[NZstorm]

BOM model flip flopping alot...back to original track, for now,(maybe slighty west of that)
GFS has been alot more consistant

I never look at the BOM model but its based on the UKmet I believe.

[Nev]

I see MS issued their first Watch this morn…

MetService - Severe Weather Watch

Valid to 11:04am Thursday 13 Mar 2014

SEVERE WEATHER WATCH FOR NORTHLAND, AUCKLAND, COROMANDEL PENINSULA ISSUED BY METSERVICE AT 1104hrs 12-Mar-2014

CYCLONE LUSI EXPECTED TO BRING SEVERE WEATHER TO MANY REGIONS DURING THE WEEKEND.

Cyclone Lusi is expected to move out of the tropics Friday or Saturday. Current forecasts track Lusi just west of the North Island on Saturday then across the upper South Island on Sunday, before moving away to the east on Monday.

Rain and easterly gales are expected to spread onto northern New Zealand from later Friday and southwards across the remainder of the North Island and upper South Island during Saturday. This Watch is for the likelihood of heavy rain exceeding warning criteria in Northland, Auckland and about the Coromandel Peninsula late Friday or Saturday. Easterly gales are also expected in these areas from later Friday and the Watch also covers the likelihood of these becoming severe.

Also, in coastal areas from eastern Northland to western Bay of Plenty, heavy swell combined with very strong onshore winds and low atmospheric pressure could lead to large onshore waves and storm surge.

For the remainder of the North Island and upper South Island, expect a period of heavy rain during the weekend, especially in regions exposed to the east and northeast. Easterly gales are likely in most places, and the risk of these becoming severe is highest in the lee of ranges, such as the Kaimais. Although severe weather is likely, at this stage there is still considerable uncertainty regarding the track of the low and exact areas that will be affected.

People are advised to keep up to date with the latest forecasts, as Warnings will be issued, as well as updates to this Watch, with many other areas likely to be included.

This Watch will be reviewed by 11am Thursday March 13

[Manukau heads obs]

the current M/S marine forecast is the low side...

[David]

the current M/S marine forecast is the low side...

Looking at Colville marine forecast, it does say 50 kts on Saturday... that's reasonably in line with the GFS prediction

[Manukau heads obs]

Hauraki Gulf and Waitemata harbour is only 45kts/35 respectively
at this stage...
and then westerly of only 20 kts on sunday?

may get revised up tomorrow...

[Bradley]

Amazing agreeance at present between the four major forecast models, they are all forecasting between 60-75mm for Christchurch for this event, first time I have ever seen all the models showing the same rainfall totals for a system like this! Whether this figure of around 70mm of rain actually eventuates is another thing but great to see the models starting to firm in their forecasts! Hopefully there won't be too much change in them in tonight’s run either…I think residents of Christchurch who were affected by storm last week should start preparing now, I have a woman at work who lives on the heathcote who is beside herself with worry now for this weekend, she was flooded last Tuesday and now looks like the same dose again! I do feel very sorry for her but at the same time I excited by this system!

[Nev]

Today's MS weekend outlook includes more of the South Island…

MetService - Severe Weather Outlook

Issued: 2:11pm Wednesday 12 Mar 2014
Valid from Friday 14 March 2014 to Monday 17 March 2014

Cyclone Lusi is expected to move out of the tropics Friday or Saturday. Current forecasts track Lusi just west of the North Island on Saturday, then across the upper South Island on Sunday, before moving away to the east on Monday.

Rain and easterly gales are expected to spread onto northern New Zealand from late Friday, then move southwards over the North Island on Saturday. The rain then spreads over the South Island on Sunday, with northwesterly gales developing about the lower North Island and Cook Strait.

A Watch is currently in force for Northland, Auckland and Coromandel Peninsula, and is likely to be extended to further areas closer to the time - please refer to Watch for further details.

As indicated, there is a high risk of heavy rain and severe easterly gales about Northland, Auckland and the Coromandel Peninsula from late Friday into Saturday, with a moderate risk for remaining North Island areas from Taranaki to the Hawkes Bay northwards. On Sunday, there is a moderate risk of heavy rain about Nelson, Marlborough, Canterbury and north Otago, but a low risk about Manawatu, Wairarapa, Wellington and Buller. In addition, there is a low risk of severe southeast gales about Wellington, Kapiti Coast and the Marlborough Sounds, but a moderate risk of severe northwest gales later in the day about the Marlborough Sounds, Wellington and Wairarapa.

On Monday, conditions improve about many parts of the country as the remains of cyclone Lusi move away, however, a front is expected to move on to the South Island, bringing rain to the West Coast, possibly heavy about Westland.

MetService Severe WX Outlook - Is. Mar 12, 2.11pm.png

[spwill]

Yes, unfortunately it is bad news for those living in the Christchurch flood zone.
Very much need the rain around here especially given the weather pattern is looking dry again after this system goes through.

[Michael]

The westerlies at the top probably weaker as it be humid air and no tasman high at that day to blow its nuts,as for the rain had enjoyed not having to weed or use the lawnmower though

[melja]

Cant say I have ever seen a model run like this over Canterbury before the bloody thing is smack bang on top of us.
I only hope the CCC has learnt something from past events bad sadly im not sure on that one.

[Razor]

Cant say I have ever seen a model run like this over Canterbury before the bloody thing is smack bang on top of us.
I only hope the CCC has learnt something from past events bad sadly im not sure on that one.

I'm not quite sure what you want the council to do....stop the rain falling on the city and into the earthquake damaged pipes that gerry brownlee and the insureres aren't helping get fixed?

It just backs up that the red Zones needed to happen, and perhaps there are wider areas that should have/ could also be red zoned.
fAnyway, back on topic- it this is SE or E hopefully we will see that traditional 'rain shadow' effect from the peninsula and only have light rain in town

[tich]

The models show the storm moving quickly away to the southeast, followed by a west to northwest flow on Monday. This should limit the heaviness of the rain. The storm last week persisted for about 2 days over us.

[Richard]

it this is SE or E hopefully we will see that traditional 'rain shadow' effect from the peninsula and only have light rain in town

Yep that would be fine and then the dry parts of Canterbury can get the heavier variety

[treetop]

thats a huge "red Zone" melja !

[Avalanche]

mmm i dont know how heavy would the rain be torrential? 75mm doesnt seem like much if it rained over a few days but i guess if it came down like in a few hours that would be different. what does the RED mean on the chart for Metvuw? The heaviest falls for sure but how much and how long will it rain like that for?

[Nev]

...what does the RED mean on the chart for Metvuw? The heaviest falls for sure but how much and how long will it rain like that for?

MetVUW's forecast charts are based on GFS. They're updated about every 6 hrs and the original accompanying scale goes from 1mm to 20mm. Red in this case means more than 20mm over 6 hours. Also note that their charts may not update as quickly as some other sites.

[Storm Struck]

This will be much different to that of last weeks rainfall event over the city, the rain last week was heavy to persistant in a southerly flow but the rain coming this weekend is from the E-SE so there will be pockets of the city perhaps over southern Christchurch and closer to the cashmere hills that will get less rainfall due to the sheltering affect.
My concern is the potential amount of rain that could fall over such a short space of time with this one, given the easterly rain can often be one of the most torrential.
We could be looking at about 6-7 hours of very heavy falls across many parts of the region.
Although the E-SE flow will be strong I am thinking the tail inbehind as the low departs and the oncoming front hitting the west coast as part of another system will bring some brief gale force westerlies for the Canterbury region on Monday.