Alastair Thompson Profile picture
Oct 2 8 tweets 5 min read
#HurricaneIan Update.

Additional extraordinary satellite observations.

As Hurricane Ian was making landfall in the Carolinas its atmospheric river exhaust was arriving in the Netherlands & Germany.
Even the most generous forecasts of the sheer extent of #Hurricane's impacts did not come close. As you can see here in the 12 hours after SC landfall, the Hurricane's remnants brought rain to all of West Virginia and Pennsylvania as well as NYC.
But that was not the end of it, in the evening and overnight yesterday the storm separated from its supporting atmospheric river and continued to revolve over Ohio, NC and Pennsylvania. The center of rotation appears to have been over WV and Eastern NC
By this time the outer limit of the outflow from the remnants of the Hurricane was covering most of the Great Lakes.

Here (getting us up till now) we see the rotation as it making its way slowly eastwards, bringing a rain band heading west over New Jersey, Pennsylvania & WV.
In this image we can see the atmospheric river is getting stronger again fed by both #HurricaneIan and a large area of convection over the Atlantic originating in Nicaragua.

Bottom center you can see the next hurricane candidate #Invest91L on a similar path to Ian.
Neither the ECMWF nor GFS models currently expect #Invest91L to develop into a cyclone fortunately. But it will need watching as it is in Hurricane Lane.
Finally the #HurricaneIAN remnant circulation may still have a sting in its tail, and as it leaves the U.S. for the final time it is forecast to have a final spin over Maryland.
This will bring more rain to some areas which have already received a lot of rain. Here are rain forecasts for Maryland, New Jersey and New York-Long Island.

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More from @althecat

Oct 3
We've reached the "rats in a sack" phase of this new #LizTruss UK Financial meltdown row. The 45% tax rate decision has been canned - and now it looks as if @KwasiKwarteng's deputy @CPhilpOfficial is the designated scapegoat.
Clearly someone had briefed against @CPhilpOfficial for this ^^ interview - suggesting that the idea of the cut to the tax rate had been presented to new PM @trussliz during her leadership campaign.

For her part @trussliz herself is saying that "it wasn't her idea".
This seems a little vague. When it comes to ideas which are likely to assist one get seelected as a PM replacement among a group of 160,000 of well healed @Conservatives members, cutting their tax rate is definitely a "good idea".
Read 8 tweets
Sep 30
I've been trying to figure out how best to visually explain how weird #HurricaneIAN is. This is the perfect illustration.

#HurricaneIAN will split in two, the Western part will head to the Virginias, for a while and then return to the Atlantic coast probably in Maryland.
#HurricaneIAN is a remarkable, and hopefully very unsuual phenomena, two distinct weather systems working together - that have appeared to be a single system for several days.

This, the final act, may be the most extraordinary part of this event. But not the most destructive. ImageImageImageImage
This CMISS animation shows what is happening vert clearly. And this explains a lot about #HurricaneIAN:
- its strength
- its super rapid intensification
- the persistent short range model forecast error
- its ability to remain intact over land
Read 5 tweets
Sep 30
This is what I was worried about the interaction between the atmospheric river and #HurricaneIAN.

The Wastern leading edge of the Atmospheric River is now pumping directly into #IAN and it appears to be strengthening over land. The Eyewall is not yet complete.
A closeup satelite view of what is likelu the center of #Hurricane IAN coming ashore at Charleston half an hour ago.
Read 7 tweets
Sep 30
What is happening in the Carolinas is not just a hurricane. The catastrophic event ahead is probably more due to the Atmospheric River which #HurricaneIAN has directed onshore. The second image here roughly delinates the two.

On the ground however this is one weather event. ImageImage
More on the #HurricaneIAN - Atmospheric River combination, to understand this event in context, this is a very important part of the story.

#ExtremeWeather #ClimateChangeNow.
This thread also looks at this issue. #HurricaneIAN has been embedded in this atmospheric river since it started intensifying explosively.

This combination is I think pretty unusual, and it may lead to unexpected consequences in the Carolinas.
Read 4 tweets
Sep 30
#HurricaneIAN update.

Four radar images over an hour 1-2pm UST.
#HurricaneIAN's motion is not as expected/forecast.

With sunrise approaching energy from the sun increases visibility of the circulation with the development of rain bands in the South Eastern quadrant.
Spaghetti guidance is tightly clustered on Charleston landfall. After moving inland a very sharp turn W/SW is expected with some models even predicting a return back to the Carolina coast.

Tropical rain all the way to the Great Lakes is possible/likely given the size of Ian.
Intensity guidance is very clear that the storm is expected to weaken - based on landfall today. This will change rapidly if Ian does not weaken or landfall quickly.
Read 15 tweets
Sep 30
The NHC's forecasting for #HurricaneIAN remains tricky. Inching closer to the North/South Carolina border. And from satellite data, it looks possible that the center of #HurricaneIan is east of the current line.
The specialist HRRR model, which proved more accurate than the main models in predicting the path across Florida is now in agreement with ECMWF, GFS and NAM-CONUS on the location of landfall, but there is a broad range of intensity from 973-984 mb.
There is also a 6 hour range in arrival time among the four models from 1pm to 7pm. Due to the size of the storm, the impacts of #HurricaneIAN on the Carolinas & beyond are already well and truly underway over night local time.
Read 12 tweets

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