Alastair Thompson Profile picture
Oct 13 19 tweets 9 min read
#CentralAmerica #ExtremeWeather update thread.

Sunrise over #Karl is imminent. Its going to be another interesting day I think. Image
Image
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. ImageImage
Visible high resolution image via @TropicalTidbits Image
Satellite animation first light zoomed in on the two storms.
A view of the north western quadrant and the squall line coming in over the sea associated with the arrival of an arctic blast.
.@zoom_earth view of the same approaching interaction
And a close up on #TSKarl at sunrise.
At 458,000km2 of overall sunrise convection & adjacent cloud and 187,000 km2 of intense sunsrise convection the 2 parts of #KARL are certainly starting stronger this morning than yesterday. ImageImage
This animation is 4 hours and started at 7am local time so well before sunrise. At first glance it looks like the northern part of the RH arm of Karl is already being effected by west-east shear.

On the LFS there is clearly aspinning vortex there, albeit with little structure.
Here is what is forecast to happen to this storm over the next 117 hours. This is the 13:06Z GFS model run for Precipitable water, which is mostly what this event is all about - that and the Tehuantepec wind gap #TSKarl #Karl is expected cross around midnight tonight.
However according to the forecast that is far from the end of this as far as Mexico is concerned. Several more Tehuantepec wind gap events are forecast after #Karl gets squelched over the following 200 hours.
Looks like inter-ocean ping pong with storms accross the Tehuantepec gap - with a high probability of more hurricanes.

There is a real forecast possibility of two more before the 18th, which could raise Central America's Hurricane count to 4 in 10 days.
Which is why I am so interested in what happens to #Karl.

When the remnants of #Julia went through the gap the storm became two - #Karl & #Invest99E. This sort of thing could conceivably continue beyond next Tuesday.

Current 29/10 Forecast: Image
It would perhaps be farcical if it weren't also killing people, and destroying property and infrastructure.

The 2nd cause to this event is this >>

Animation: Unusual atmospheric conditions in North America delivering an endless series of arctic wind blasts.
Its almost like north America has been occupied by a weather hydra that hates hurricanes. The endless series of arctic blasts are also preventing water from escaping the Carribean and Gulf via the usual route up the Eastern Seaboard.
In monitoring this I am hoping to see #Karl get away to the East and restore a normal weather system. Pakistan had 20 straight days of aberrant torrential rain and it was the catastrophe of the year. It would be terrible for Central America if something similar happened again.
This explanation is partly for #NHC_Atlantic's forecasters who may by now be wondering why a journalist is constantly second guessing their cyclone warnings.
That's me for this thread - I will be back later to see what has happened.

Ciao.

/ends

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More from @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. Image
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.
Read 32 tweets
Oct 13
[#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.
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.
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 36 tweets
Oct 13
And now, finally, @NHC_Atlantic has put up a new advisory on #TSKarl #HurricaneKarl

...AIR FORCE RESERVE HURRICANE HUNTERS INVESTIGATING KARL...
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
Oct 12
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.
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
Oct 12
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.
Here are its first three hours as a hurricane.
And this is the most recent @NHC_Atlantic discussion bulletin for #TSKarl, issued 2 hours ago.
Read 13 tweets
Oct 12
These storms which are forming over Cuba and Haiti are 1200 to 2000kms away from #KARL but it is clear that the cause is #TSKarl, which still has not been designated as a hurricane even though its convection field now covers 454,000 kms.
Read 8 tweets

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