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Maybe Scrolly?

Alastair Thompson

Follow @althecat

29 May, 13 tweets, 6 min read

https://twitter.com/althecat/status/1398598640508223489

It appears this pretty looking storm is doing some serious damage. Stay safe Ōtautahi.

https://twitter.com/althecat/status/1398598640508223489

https://twitter.com/grenow/status/1398789885788524546?s=20

And we have a live report from north Canterbury.

https://twitter.com/grenow/status/1398789885788524546?s=20

@NOAA

NOTE: This is not an official forecast. But it is alarming. It seems that that peculiar cloud formation is special in a number of rather alarming ways. [Image: @NOAA's GFS model forecast, latest run.]

@ECMWF

The Euro @ECMWF model is saying pretty much the same thing. The scale is different so it doesn't look as bad. Both of these are till midday on Thursday.

Longer range forecasts show there's not a lot of relief in sight. A second big rain is due to arrive on Saturday. But Northland gets the worst of that.

@NZStuff

Live coverage from the @NZStuff crew here >> stuff.co.nz/national/weath…

Official Met Service warnings here >> metservice.com/warnings/home

And live animations of the storm causing all this here >> zoom.earth/#view=-36.3,17…

Amazing effort to rescue the guy swept away in his car in this. Stuff's live coverage of this flooding event is superb >> stuff.co.nz/national/weath…

The cause of these #CanterburyFloods is remarkable.

This animation (Oz's Access-G Model) starts on Thursday at midday and runs to the end of the southern drama around midday on Tuesday. The water is coming from the tropics.

@ECMWF

Here (Euro @ECMWF model) starts Saturday Morning and provides a closeup view through to the end. The moisture that comes in from the East circles up into Northland and then runs up the East Coast of the North Island.

Its definitely a freakish weather event. #CanterburyFloods

I have let this version (Canada's CMC Model) run to the end.Turns out something similar of tropical origins may be coming through next week. Albeit not nearly as impactful. A big wet westerly front running from Cape Reinga to Bluff. #CanterburyFloods.

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More from @althecat

Alastair Thompson

@althecat

1 Jun

Well its hard to know where to begin with today's #MiddleEast and #HornOfAfrica rainfall forecasts.

The action is now further north, and west. Here we see the consequences of the first phase of what appears to be becoming a continuous #WesternSaharaPlume.

An bit of a battle us underway between a high pressure system over Northern Erope and the plume which is entering at the bottom left in this image of Jetstream level 250Hpa 11km high winds.

While the model forecasts remain optimistic that an orderly jetstream may eventually appear, so far this has not happened. And in the meantime these winds are picking up moisture in the tropics and taking it in large quantities to places where its not expected.

Read 26 tweets

Alastair Thompson

@althecat

30 May

A big day for #WestAfricaMonsoon observation.

A full plume event is becoming obvious in central & eastern Europe + Russia. We also have thunderstorms over the Red Sea, and a low circulation heading towards a collision with water vapour over Israel.

Today's forecasts follow.

@Arab_Storms

Visually speaking this is the most extraordinary looking satellite observation of the day.

Now into its sixth day the #EastAfricaWaterPlume has been generating lots of rain over the Red Sea, both last night and today, & right now just off the coast of Jeddah. @Arab_Storms

Here we see a wider view while it is not that obvious in this view, the stream of water vapour heading up the Western Sahara coast is running fast and hot. Later I will post an initial post tracking its impact in Europe. But for now its worth looking closer at North Africa.

Read 27 tweets

Alastair Thompson

@althecat

30 May

Upstream flow gauges in Temuka, Rangitata, Rakaia & Waimakariri appear to be peaking or in the case of the Waimakariri close to peaking.

Meanwhile the official ECAN alerts page seems to not be freaking out, so that's all good >> ecan.govt.nz/home/flood-war….

Steady as she flows.

"Breakouts" in the Ashburton vicinity & inland, are the major concern at present. But whatever "breakouts" are they sound a lot less alarming than floods and evacuations.

Also no alarm around the major rivers, yet. Also good.

Alerts here >> ecan.govt.nz/home/flood-war…

The remaining concern will be river mouth flood/tide collisions. High tide timing today is around 6.30am near Timaru, 7.50am at the Rakaia and around 8.30am in Christchuch and at the Waimakariri river mouth.

Read 6 tweets

Alastair Thompson

@althecat

30 May

https://twitter.com/althecat/status/1398869729306202118

These Canterbury Floods are moving in to Otago.

https://twitter.com/althecat/status/1398869729306202118

Here is a wider view. This will definitely continue through a fair bit of the night. Question is now how long will it continue tomorrow? The forecast models showed the plume you see coming in from the right sort of petering out and disengaging and tracking north.

A wider view.

Read 10 tweets

Alastair Thompson

@althecat

25 May

With Cyclone #Yaas soaking up all the moisture east of the #MiddleEast and #HornOfAfrica it was a relatively calm day. Albeit not without another intense set of storms along the Red Sea Coast in the Jinzan mountains.

Today's rainfall forecasts follow.

The days began relatively quiet on the #WestAfricanMonsoon front thanks to Cyclone #Yaas. This image shows a strip from the Libyan Coast across the Sahara down to the Congo.

And it remained fairly quiet over the great forests of equatorial Africa today. But further West over the Ivory Coast and the West Sahara the #WestAfricaWaterPlume continued to pump water vapour across the Sahara into Europe.

Read 16 tweets

Alastair Thompson

@althecat

25 May

https://twitter.com/althecat/status/1396938035481169921

Here is the continuation of the #WestAfricaWaterPlume transformation of European weather this morning into something which is both unpredictable and not particularly nice, i.e. windy wet and cold.

https://twitter.com/althecat/status/1396938035481169921

The following three animations are offered to help Europeans who are curious to understand what is going on. Our weather reports tend to be geographically confined in a manner that obscures the bigger picture.

The first shows the water vapour picture over 84 hours till Friday arpund midday. The #WestAfricaWaterPlume can be seen coming in bottom left over Algeria. simultaneously another storm is coming in at speed into the British isles. Hence all the rain.