Alastair Thompson Profile picture
Feb 5 20 tweets 12 min read
NZ's #ExtremeWeather event is not over.

Simulations of the area of tropical moisture that brought torrential rains to the South Island now show a storm system moving south into the Tasman Sea resulting in intense rainfall across Northern NZ through Feb 12th.
Forecasts for this system's exact impact remain highly uncertain but four major global forecasting models are in agreement that some form of extreme weather for NZ will be result.

These are the latest ensemble tropical storm "spaghetti" track graphics for storms north of NZ.
The event is expected to begin within 24 hours these are four different models showing the intense area of atmospheric moisture moving over Northern NZ this morning (Sunday) NZT.
And these four model simulations update the PWAT (precipitable water) picture as of Monday morning. Typically areas of dark red and purple such as you see in these plots will produce heavy rain, especially when moving southwards into colder air.
The storm is not expected to be particularly intense in pressure terms though some of the models show it strengthening and it could do so.

The simple physics of a very large mass of very wet water moving over NZ for several days will produce #extremeweather.
These are the two latest GFS and ECMWF model forecasts wrt to air pressure - as you can see they are broadly similar - but cannot be relied on beyond the next three days - if SP09 develops into a stronger storm, whatever is about to happen will change.
The next four animations show four different "deterministic" (i.e. physics based) computer model simulations of what could happen to the very wet air mass. Firstly Canada's CMC.
Secondly we have the Australian ACG model (which as explained in an earlier thread [2 days ago] quoted below) is in its relatively early stages of development.
The Canadian model is closely associated with the American GFS model which you see here - and which is the most sophisticated - and which settled on this scenario earliest.
And finally we have the European @ECMWF model - the 2nd mature tropical weather model which continues to have a slightly preferable outcome with most of its impacts (at least in this run) expected in the North Island.
@ECMWF In summary we have four "not great" possible scenarios for this #ExtremeWeather event - similar but different.

Add in the fact that the orchestrator in this event, namely SPO9/92P, is still weak and a long way away and all this turns into a major headache for forecasters.
The models have been changing significantly between runs and as this develops the @weathermodels_ GFS IWVT (Integrated Water Vapour Transport) animation will likely be the best means to keep track of what to expect.

This plot combines Water, Wind and Pressure data in one.
These plots are from the preceding run showing the picture at 96, 132, 144 and 168 hours (12th Feb) by which time the model expects this to be over.
Here we have four sequential simulation outcomes, from Feb 3, Feb 4 and Feb 5 model runs for this theoretical end-date for this event from the one model.

But note all four are likely to be wrong and we will only know with some degree of certainty what will happen at 48 hours.
That said, as this event is initiating today, we can also say with some degree of confidence that this new phase in the ongoing atmospheric river event associated with this tropical convection system will effect the North Island - and possibly in a fairly extreme fashion.
We currently have for possible rainfall long range rainfall outcomes to get an idea about what this might look like. The first was used in the OP and comes from the GFS Model.
The second from the @ECMWF and the clear and dramatic difference between the two relates to the path of tropical storm of interest SP09/92P.
Here are the current rainfall solutions from all four models discussed in this thread, two detailed, the other two regional.

IMO all indicate a serious enough threat to justify informing people and enabling them to make whatever preparations they need to make.
While there remains a lot of uncertainty about how much rain will fall where and when, we certainly have reason to be concerned that a lot of rain could fall almost anywhere in NZ as a result of this dangerous weather system.
/ENDS

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More from @althecat

Feb 6
#Batsirai #ExtremeWeather Update Thread 6:

The center of Intense Cyclone Batsirai has nearly completed its crossing of Madagascar but the storm/wind field continues to impact the southern half of the island.
The most intense rainfall was concentrated near the Capital City Antisirabe, the 4th largest city moving slowly. Extreme flooding in this area appears likely. And there were two additional extreme rainfall events in the North and the West of the island, fueled by the storm.
We see in this image that the eye of the storm (with its most damaging winds) remained intact for several hours after landfall finally losing its structure in the early hours Sunday Morning.

The lightning display as seen in satellite imagery during this period is extraordinary.
Read 16 tweets
Feb 6
If @AP @AFP @BBC and @Reuters choose to cover this latest, unsigned, media statement issued by @reda_getachew’s close partner in the TPLF information warfare operation addressed to the AU, it should be called what it is.

I.E. a statement issued by the rebel TPLF leadership.
The “Nutty Professor’s” statement (as he is colloquially known) is an expanded version of @reda_getachew’s recent tweets dressed up to look like it comes from an independent source. ImageImage
This paragraph is particularly absurd. On June 28th the GoE announced a unilateral ceasefire. And on around 15 July the TPLF launched an offensive against Afar, just as they are doing again now. Image
Read 5 tweets
Feb 6
They are nothing of not consistent about this. See no evil, hear no evil, speak only evil.
… by omission.

The TPLF Leadership who are solely responsible for maintaining their attacks on Afar since mid December are enabled and empowered by the silence of UN Agencies @OCHA_Ethiopia @WHO and @WFP_Ethiopia on the truth about why aid is not getting to Tigray.

#NoMore
Why can’t @OCHA_Ethiopia @WFP_Ethiopia just say it. They must know.

“The humanitarian crisis situation in Tigray is due to ongoing offensive military action against Afar civilians by TPLF forces which has been blocking the aid corridor since July 202.”
Read 8 tweets
Feb 5
#Batsirai #ExtremeWeather Update Thread:

Cyclone Batsirai is weakening and accelerating on its final approach to Madagascar's East Coast. But while lower winds will be helpful - it's primary impact - widespread very heavy rain - is likely to be extreme.

The official forecast has not been updated, the eyewall landfall (diminished by the filling of the eye) is likely to take place a little later than forecast but wind and rain is already building over the island as is obvious in the satellite imagery.
As of 20 minutes ago the center of the cyclone had roughly 100kms to travel to the shoreline. It will a bring a significant tidal surge with it, especially on the southern side and likely cause significant coastal flooding over a large area of the coastline.
Read 14 tweets
Feb 4
#ExtremeWeather Split screen.

Two world's apart.

The US Eastern Seaboard and Madagascar.

The US experiencing yet another of what it calls "bomb cyclone". Madagascar about to experience a cyclone which will be much more like a bomb.
Both #Extrremeweather events caused by climate change, and 30+ years of failure to address known extreme damage to the biosphere caused by avoidable harms.

One nation responsible for the peril.

Another defenceless against it's catastrophic harms.
In one nation the harms will be felt mostly in travel delays.

In the other nation many will likely die, and 100s of thousands will have their lives scared and livelihoods threatened, and will likely be dependent on humanitarian aid for months if not years.
Read 4 tweets
Feb 4
#Batsirai #ExtremeWeather Update Thread.

As a poster child for the impact of climate change on developing nations this cyclone, is a truly terrifying phenomena. In the next 24 hours it will make landfall at most likely Cat 4 or Cat 5 Hurricane Strength.

The animation above is live and covers the last three hours. This animation shows the last 24 hours.

Madagascar is an impoverished nation of nearly 30 million people the majority of whom live in the path of this Cyclone's wind and forecast extreme rain.
Whilst at Cat 4 strength a day ago what was already Intense Cyclone #Batsirai underwent a eyewall replacement and slowed down, it is now accelerating and strengthening.
Read 10 tweets

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