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13-09-2018, 05:16   #1
Kermit.de.frog
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Post Tropical Storm Helene 17/18 Sep 2018

Expected to transition to a tropical storm soon from a hurricane.


It would be worthwhile keeping an eye.

Ex-Helene looks set to bring strong winds and heavy rain close to Ireland within 120 - 136 hrs after effecting the Azores as a tropical storm.





NHC discussion

https://www.nhc.noaa.gov/text/refres...l/130238.shtml?

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MOD NOTE: Updated title and included a yellow warning at this stage. Can update title if needs be as forecasts become clearer.

Last edited by Meteorite58; 14-09-2018 at 21:09. Reason: Mod Note re title.
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13-09-2018, 06:39   #2
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In fact, I suspect that if that output persisted to the next NHC update, they might consider keeping Helene closer to cat-1 hurricane past the Azores. The GFS depiction is the only one with damaging wind gust potential for Ireland, the track is broadly similar to Ophelia and timing of strongest winds is around 10 p.m. Monday to 0400h Tuesday from Munster into the southeast portions of Connacht. Isobars are packed and gusts could be as strong as 130 km/hr if these maps verified. Once again Cork appears to be in the crosshairs of this as yet hypothetical storm.

At the moment, UKMO brings a significant wind potential from Helene about 24h later (Tuesday night into Wednesday morning), not quite as strong as the GFS. The GEM shows Helene dying gradually embedded in the southwest flow ahead of a distant northern low, and almost an extinct circulation crossing southern Britain by Tuesday. Waiting to see the ECM take in just less than an hour from now.

Also the GFS has gusty winds by Thursday 20th from remnants of Florence which gets slowly captured over the lower Great Lakes around Monday and Tuesday then rockets eastward -- the isobars would suggest southwest gusts to about 110 km/hr.

Apparently what has changed for the GFS is that new TS Joyce southwest of the Azores does little more than wave hello and goodbye to Helene and there's a bit of a slingshot effect near the end of the encounter during which Joyce ceases to exist, while Helene seems to deepen somewhat again.

We must stress that in the absence of broader model consensus, the GFS is so far pretty much a lone wolf on this outcome with weak support from UKMO, not really enough to trigger a robust alert but more like notice of a watch situation.
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13-09-2018, 13:10   #3
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This seems a bit too early for a thread, especially as you were complaining about premature threads recently Kermit! Anyway...

What I find interesting about the GFS is how for Florence, a lot of American sources are ignoring it and relying primarily on the ECM. I can't remember where I read it, but I do recall reading that the GFS doesn't include SSTs in its storm modelling - is that correct?
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13-09-2018, 13:18   #4
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The Midland Weather Channel has issued a severe weather warning as Hurricane Helene continues its track towards Ireland.

Meteorologist Cathal Nolan told the Offaly Express, "having assessed the latest weather models and based on my own numerical calculations it looks increasingly likely that hurricane Helene will make landfall in Ireland at some point between 14:00 on Monday and 02:00 on Tuesday next."

"Currently, Helene is 2000km southwest of the Azores and remains a category 1 hurricane, with sustained winds of 130kph and gusts in excess of 170 kph," he continued.

The latest guidance suggests that the strongest winds will occur along the south and west coasts, where gusts could exceed 130-140 kph.

"Overland gusts of between 110-120 are possible. The storm itself is still some time away and therefore it’s exact track and intensity remain difficult to pin down," Cathal explained.

"Helene has taken a very similar track to that of Ophelia last year, which is extremely unusual for an Atlantic hurricane," Nolan told us.

"My concern at present is that the storm could deepen during its approach to Ireland, transforming from a Post Tropical Cyclone into a very powerful Atlantic Storm, which would potentially increase the winds along the west and south coast given the storms angle and interaction with the jet stream," he concluded
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13-09-2018, 14:00   #5
cherryghost
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Nothing crying out for anything beyond Orange if models come good.
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13-09-2018, 14:57   #6
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Quote:
Originally Posted by cherryghost View Post
Nothing crying out for anything beyond Orange if models come good.
Agree. Early days but Helene doesn't look a patch on Ophelia......yet

This was Ophelia at a similar timeframe to Helene now


Last edited by REBELSAFC; 13-09-2018 at 15:11.
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13-09-2018, 15:06   #7
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Agree. Early days but Helene doesn't look a patch on Ophelia......yet
one to keep an eye on though. Ophelia was forecast to weaken a lot before hitting us, it didn't really (or well not as much as forecast). Infact it wasn't really known the strength until the day before because of the rarity of it happening.
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13-09-2018, 15:07   #8
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Grateful for the updates and warnings. In the line of fire out here on the West Coast offshore island. Although Ophelia missed us very neatly as after Clare it turned east into the Midlands.
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13-09-2018, 15:15   #9
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Is it beginning to feel as if these particular "hurricane" events are going to become regular (yearly?) and some of them may be even worse than Ophelia?
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13-09-2018, 15:27   #10
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The rags have gotten wind of it (pun intended)

https://www.independent.ie/weather/h...-37313242.html
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13-09-2018, 15:45   #11
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Now downgraded to Tropical storm
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13-09-2018, 16:22   #12
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https://twitter.com/NHC_Atlantic/sta...57396587864064
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13-09-2018, 20:25   #13
Meteorite58
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ECM and GFS tracking ex Helene more over the UK ( ECM trending this the last two runs ).

A few wobbles on the track so this will take a few days to know for sure. On latest runs it looks quite windy but a much diminished system by the time it reaches our Islands.

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13-09-2018, 20:51   #14
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It's crazy how knife edge this could be - while Helene is making its passage on Tuesday, there's a tremendous large low pressure system hanging around near Iceland that was heading our way. The interaction between it and Helene seems to actually keep us somewhat protected, but you could imagine a small shift either way being....exciting.
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13-09-2018, 21:04   #15
Meteorite58
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It's crazy how knife edge this could be - while Helene is making its passage on Tuesday, there's a tremendous large low pressure system hanging around near Iceland that was heading our way. The interaction between it and Helene seems to actually keep us somewhat protected, but you could imagine a small shift either way being....exciting.
Yea that Low coupled with the Jet seems to be giving Ex Helena that gentle nudge over towards the UK.





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