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Alastair Thompson

Oct 12 • 7 tweets • 4 min read

This has to be the most spectacular cyclone genesis ever! The remnants of #HurricaneJulia become (what is most likely) #HurricaneKarl.

Close up view of the last six hours. It looks as if the #TSKarl (soon to be #HurricaneKarl reversed direction again and is heading back north into the shear, and soon the night. It will be interesting to see whether it continues to strengthen and survives the night.

This is a truly extraordinary storm. One for the history books. The role of the separated southern storm (the other part of #HurricaneJulia's remnants cut in half by the Tehuantepecer now over the Pacific which was feeding Karl in making this possible deserves closer examination.

Here are the two children of #HurricaneJulia, there remains a possibility that #Invest99E may also become a hurricane. At present it may be close enough to #Karl to be being inhibited by it.

In this view we can see another Arctic blast coming south which will in all likelihood prevent Karl from ever making a US landfall if it does survive the night, and the severe shear winds that it will soon move back into as it travels north.

The stunning macro-scale satellite imagery of this storm also deserves an acolade. This was also a characteristic that was very obvious with #HurricaneJulia, well before she became a hurricane.

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More from @althecat

Alastair Thompson

@althecat

Oct 14

[#ExtremeWeather #ClimateChangeNow DATA ANOMALY THREAD – Central & North America]
In this thread I release five sets of data which appear to show atmospheric geo-engineering over North America at unprecedented scale, seemingly for the purpose of keeping hurricanes away.

During observations of #Invest91L #HurricaneJulia & #TSKarl in Central America there was an issue elephant sized mystery in the room – a tangential one, namely what is going on with the Arctic?

The constant impact of a the endless series of arctic blasts on forecasts came particularly obvious when hurricanes in both the Atlantic and Pacific were shown in a forecast moving south in model forecasts.

https://twitter.com/althecat/status/1578842257910034434?s=20&t=qFFD-PpHjkIr_Vhn4-MuiQ

Read 32 tweets

Alastair Thompson

@althecat

Oct 13

https://twitter.com/althecat/status/1580317553855197184

#CentralAmerica #ExtremeWeather update thread.

Sunrise over #Karl is imminent. Its going to be another interesting day I think.

https://twitter.com/althecat/status/1580317553855197184

1. Sunrise on Karl, it may be a trick of the early light but I can see a larger low level circulation that fully surrounds the 2nd larger part of Karl.

2. The second image says where we are supposed to be now in the model timeline and it certainly looks about right.

Read 19 tweets

Alastair Thompson

@althecat

Oct 13

https://twitter.com/althecat/status/1580458294539603968

[#NotYetAHurricaneKarl update Thread, waiting for sunrise ed. #ExtremeWeather #ClimateChangeNow ]

The ridge to the north of #Karl has moved south a fair bit and appears to be pushing #Karl to the south at the eastern edge of the offical NHC Track cone.

https://twitter.com/althecat/status/1580458294539603968

Here's another view where you can see the leading edge of the ridge that is pushing down on the hurricane capturing it near the entrance to the Tucanpecer's northern funnel.

@NHC_Atlantic

Lookingclose at the last four hours @NHC_Atlantic may have a point about #NotYetAHurricane #Karl not quite yet being a hurricane - as predicted by the GFS it has collapsed and broadened out close to midnight as the models said.

Read 29 tweets

Alastair Thompson

@althecat

Oct 13

@NHC_Atlantic

And now, finally, @NHC_Atlantic has put up a new advisory on #TSKarl #HurricaneKarl

...AIR FORCE RESERVE HURRICANE HUNTERS INVESTIGATING KARL...

https://twitter.com/althecat/status/1580346284824612864

Current satellite imagery shows why NHC thinks Karl will also be pushed through the Tehuantepecer wind gap for a 2nd time - its all a matter of timing. Karl is already clearly outside their cone, the railway lines show where a ridge is building as dry air pushes south.

You can see the scenario in the latest GFS model here. But bear in mind that this is based on the assumption that Karl is still a tropical storm. And as you can see it is expected to decay very rapidly over night.

Read 8 tweets

Alastair Thompson

@althecat

Oct 12

https://twitter.com/althecat/status/1580339871608020992

Its now pretty clear what is going on. #HurricaneKarl #TSKarl is caught in an atmospheric river generated by #TD99E (in a similar way to how #HurricaneIan was) and headed towards florida - not Mexico.

https://twitter.com/althecat/status/1580339871608020992

The second overlay is a special "steering" product that allows you to see where a cyclone is headed - it focusses on the 500-850hpa wind range (1.5 to 5.5kms high winds ) which are particularly important for pushing cyclones.

And as you can see #HurricaneKarl is being steered towards northern Florida at present.

Read 6 tweets

Alastair Thompson

@althecat

Oct 12

@TropicalTidbits

This IR satelllite image [src: @TropicalTidbits] shows #TSKarl is unquestionably now #HurricaneKarl. It also shows it is not moving towards the Mexico coast line as per the current @NHC_Atlantic forecast - but moving NE. And the transformation into this was 3 hours ago.