Alastair Thompson Profile picture
Oct 8 24 tweets 10 min read
#ClimateChangeNOW #ExtremeWeather #HurricaneJulia update thread 8-10-22

A lot has changed in the last 12 hours - not so much in the short term but in the longer term model track predictions - and therefore in the outcomes which can be expected for the wider region.
Specifically fromthe latest GFS run (and its predecessors) the degree of uncertainty with respect to impacts is increasing. At present Julia is not officially a hurricane and the extent of structure in the 300km wide central area of convection is not known.

Latest GFS Run.
The GFS data has changed the official forecast in line with what we see inthe last model and instead of taking a more northerly path through central America the storm is now expected to cross the Isthmus into the Pacific relatively swiftly.
And this changes everything. The storm appears to still be expected to lose its hurricane status quickly over Nicaragua, but because it will likely be almost half over water - its ability to produce rain is increased not diminished. This is the corresponding model rain forecast.
Here are the two 16-day total rain forecasts for comparison.

Right: Yesterday
Left: This morning

The new version is a lot worse - but neither is necessarily right, as a great deal depends on how strong Julia gets over the nex 48 hours before it reaches Nicaragua.
The next part of this thread will look at the last four model predictions for atmospheric water levels - as that is the underlying cause of this #ExtremeWeather event - high levels of water makes atmosphere unstable, leading to convective storms, increasing the amount of water.
Notably in all four of the latest GFS runs there is an indication that a storm of some kind may form in the Gulf of Mexico. The good news is that storm will probably not be Julia itself - but rather a storm which forms in parts of its output.

RUN 1: 07/06 GFS RUN - IWVT
[IVWT = Integrated Water Vapour Transport measured in kg/m/s = which is really a measure of energy - the kinetic energy of a movement of mass]

In this first 07-06 run #HurricaneJulia remains on a northerly pass (which is no longer indicated) a 2nd storm spins up to the south.
RUN 2: 07/12 GFS RUN - IWVT

6 hours later this run is similar but shows the storms in the west becoming tropical storms - albeit in their infancy. Importantly including one which is in the Gulf.

The media consensus that this event will not affect mainland US no longer holds.
RUN 3: 07/18 GFS RUN - IWVT

Here we see the Hurricane Julia take a more southerly path - to the Pacific coast - disapate, form another storm and eventually arrive in the Gulf. [NOTE: all of these forecasts so far are for 144 hours - which you can see in the time stamps].
This is a comparatively benign forecast. However it is not the end. The trend in change is pointing towards #HurricaneJulia making it out over the Pacific - which is not the case in this model run.
RUN 4: 07/12 GFS RUN - IWVT

This is similar to the previous run - and it is the run which produced the substantially increased rainfall forecast - particularly for Guatemala - and which will also bring significant rains significantly further into Mexico.
The overall trend here remains similar and is moving in a direction which suggests worse impacts in CA than we were expecting yesterday - which were already dire (See thread below). This progression may be due to an increase in total water vapour mass.
Ok. If anyone is following this they may now realise where it is going. And the latest fresh run confirms this hypothesis - the further the path of #HurricaneJulia trends to the south, the more water it will carry across the isthmus into the Pacific.
In this forecast a hurricane then forms over the East Pacific cyclone genesis hot spot, hoovers up a lot of that water and takes it west.

But the remnants of #HurricaneJulia make it back into the Gulf of Mexico on Oct 15th - which could well begin the next phase of this story.
An alternative (hypothetical) and even better scenario is now apparent however. And that is that #HurricaneJulia makes it far enough into the Pacific that she can take all of this moisture with her out into the Pacific.

This is possible if she strengthens more than expected.
A lot is resting on what happens in the next few hours during which #HurricaneJulia is expected to go through her strengthening phase. Interestingly, this latest HRWF model hurricane simulation suggests she may not reach hurricane status at all.
Unfortunately, if correct this (I think) makes the possibility of a successful complete transit of the Central America isthmus less likely
[Readers note] I will revisit the long-range model forecasts once we know the outcome of the central question here - namely how much will #TropicalStormJulia intensify?
Satellite imagery definitely shows a strengthening storm - the central eye has expanded significantly. It also indicates that the trajectory of the storm is towards the southern bounds of the forecast track.
(continuing story)

/ENDS

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P.S. looking a bit closer at this trajectory issue. [Trajectory and Intensity are closely related]
This image is an attempt at extrapolating the current variation from the official @NHC_Atlantic track.

If this is the outcome we are back to the drawing board.
This would likely lead to strengthening of the storm over the Pacific. What happens after that I do not know. But it could result in the storm heading further into the Pacific and taking its atmospheric water with it.

Which would be good.

(P.S ends)
/ends

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More from @althecat

Oct 9
Cat 1 #HurricaneJulia is now making landfall over Nicaragua, its core covers 3/4 of the Eastern Seaboard and will extreme rainfall is underway over more than 50% of the country already. The scale of the storm is comparable to #HurricaneIAN was at Cat 5 on approach to Florida. ImageImageImageImage
#HurricaneJulia's IR presentation on landfall. The colour gradation represents cloud top temperature with yellow representing the coldest and highest parts of the cyclones structure.
Here is the current HRWF hurricane model foreast for Monday evening. A "Wind Gap Event" associated with the narrow isthmus between the Gulf of Mexico and the Pacific Ocean in southern Mexico is currently forecast to dissipate the storm shortly after this moment. Image
Read 11 tweets
Oct 9
The latest article from @declanwalsh is a curious affair. His sources are un-named "Western and Tigrayan" officials and Cameron Hudson (whose affiliation had to be correctd after publication).
The result is a garbled TPLF interpretation of recent events. nytimes.com/2022/10/08/wor…
It looks like a rushed job at the request of a @nytimes foreign desk editor who is even less familiar with the facts of the conflict than Declan Walsh appears to be. Declan's last story on the war was about the questionable kindergarten attack on 26th Aug. nytimes.com/2022/08/26/wor…
For a publication of the statureof the @nytimes - perhaps undeserved now - to publish just two stories in nearly two months about the largest, and 2nd most politically sensitive and controversial war on the planet is journalistic malpractice.
Read 6 tweets
Oct 8
#TSJulia's wind and convection area now covers 2.4 million km, draging moisture off the Pacific Ocean over Panama & Costa Rica. Her outer rain bands extend from Colombia to Honduras - and she is not yet a hurricane.
While #TSJulia or #HurricaneJulia is not expected to last much longer, the #ExtremeWeather event associated with the storm is forecast to bring extreme/catastrophic weather across the entire region over the coming fortnight.

Accumulating rainfall forecast - 16 days. GFS Model
Exactly what will happen is far from clear as the forecasts keep changing but the combination of very high atmospheric water, and a massive arctic blast coming south (even pushing a small hurricane backwards down Mexico's Pacific Coast as you see here is not good.
Read 8 tweets
Oct 8
#HurricaneJulia #TSJulia #CentralAmerica #ExtremeWeather.

A quick update on the wider #HurricaneJulia long term rainfall prognosis for Central America. Which unfortunately is deteriorating significantly in the latest runs.

Left: 180 Hours
Right:384 Hours ImageImage
The first week (Hurricane Julia) is bad, but the rains continue for another full week till the end of the forecast period. The next few tweets show how the model picture has evolved.
The full runs are not yet available but we have the first 120 hours - till 13th Oct.

Here's the IWVT (Atmospheric Water Transport/Energy) view - which shows #TSJulia crossing into the Pacific and taking a portion of the saturated atmosphere with her north west up the coast.
Read 5 tweets
Oct 8
#ClimateChangeNOW #ExtremeWeather #HurricaneJulia update thread 8-10-22 (late evening CEST)
The possibility Julia may never become a hurricane is clearly on the cards. Her continued divergence (southwards) from the offical track also has signifcant implications r.e. impact.
This is illustrated in the latest GFS model run. The full 16 day run is a little implausible but this 165 hours is at least credible.

As you can see here the remnants of Julia cross the isthmus (as discussed in the last update) and then moves deeper into the Pacific.
The first image here is the rain solution for that first 165 hours.

The second is a rainfall solution through to 300 hours. Whilst still alarming to say the least, it is different from earlier runs wrt more rain over the southern coasts than the northern coasts. ImageImage
Read 18 tweets
Oct 7
I get that the TPLF do not want to attend peace AU talks, ever, anywhere.

But I am amazed at the lengths they seem to be prepared to go to in order make sure they do not discuss peace so they can continue a completely pointless war that is killing 1000s of their children.
Enlisting the @WHO, @JosepBorrellF, a majority of the European Parliament and the UNHRC and the former President of Kenya in this project is a master work, especially whilst keeping them all in the dark about the master plan.
But to what end?

Do the TPLF love war so much that they seek to never stop? Even if it means living in caves and hiding from drones and seeing their families and friends die?

It really is a tragedy. The peace talks ought to be on tomorrow in South Africa.
Read 6 tweets

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