Post Tropical Storm Helene 17/18 Sep 2018

Kermit.de.frog

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/refresh/MIATCDAT3+shtml/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.

M.T. Cranium

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.

MJohnston

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?

squarecircles

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

cherryghost

Nothing crying out for anything beyond Orange if models come good.

REBELSAFC

cherryghost wrote: »

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

SleetAndSnow

REBELSAFC wrote: »

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.

Graces7

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.

amandstu

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?

frash

The rags have gotten wind of it (pun intended)

https://www.independent.ie/weather/hurricane-helene-will-not-be-a-repeat-of-ophelia-says-weather-expert-37313242.html

pad199207

Now downgraded to Tropical storm

refusetolose

https://twitter.com/NHC_Atlantic/status/1040257396587864064

Meteorite58

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.

MJohnston

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.

Meteorite58

MJohnston wrote: »

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.

GeneHunt

A storm of any size next week could be very costly, as the National Ploughing Championships starts on Tuesday in Offaly (A Tented Village), with thousands expected to attend - could it be cancelled on safety concerns.

Cork Boy 53

GeneHunt wrote: »

A storm of any size next week could be very costly, as the National Ploughing Championships starts on Tuesday in Offaly (A Tented Village), with thousands expected to attend - could it be cancelled on safety concerns.

I would imagine there would need to be at least an orange, more likely a red warning for that to happen. A case of wait and see I guess.

cian1500ww

NHC 5pm update:

GeneHunt

Sorry I didn't mean the whole show - All three days, but the first day cancelled. However the second day could be in jeopardy too. An Agricultural show in the UK last January (LAMMA) had to cancel it's second day on safety grounds following high winds overnight. This storm is still a long way off, it maybe even miss us (fingers crossed) but we need to keep an eye on it.

MJohnston

cian1500ww wrote: »

NHC 5pm update, the cone of uncertainty has widened:

The cone is pretty much the same compared to the earlier NHC update, but the track is a little bit further east and a good bit later. Be interesting to see what happens if Helene delays long enough to escape the influence of that Iceland low - we could end up getting hit by the low and Helene in a 2 day period.

Reckless Abandonment

GeneHunt wrote: »

A storm of any size next week could be very costly, as the National Ploughing Championships starts on Tuesday in Offaly (A Tented Village), with thousands expected to attend - could it be cancelled on safety concerns.

Farmers are Well used to bad weather. Would need to be very bad to cancel it. Would be a real shame after the summer we've had for a storm to wreck their big day out.

uck51js9zml2yt

Reckless Abandonment wrote: »

Farmers are Well used to bad weather. Would need to be very bad to cancel it. Would be a real shame after the summer we've had for a storm to wreck their big day out.

They'll be grand. Sure haven't they been crying out for a bit of rain

Meteorite58

Nice deep Low, moving along quickly. Track a bit closer to the SE, E coast on this run.

ninebeanrows

Looks fairly nasty there. I think the timing is very uncertain yet as the system will move very erratically over the next 72 hours, I could easily see this being a Wednesday event.

MJohnston

The Netweather GFS charts has the 3 hour frames in between the 6 hours on Meteociel, and it helps here because most of Ireland's impact from Helene will be in one of those missing frames:



That (as forecast) would be right up there in Red-level warning rainfall amounts for parts of the west.

MJohnston

That Icelandic low swinging its tail around on Wednesday would also bring quite cool temperatures for the time of day (3pm here):

Meteorite58

What is going on here. ICON 18Z has Ex Helene arriving Monday. Seems to have it whipped along by the Jet and re intensifies as it gets phased with the large Icelandic Low ? Can see pressure dropping as it gets closer to the SW.

An Outlier or on to something ?

Meteorite58

ICON shifted the storm further E more in line with the ECM keeping the strongest winds off / along the E coast. GFS and WRF keeping strong winds with high gusts over Ireland.

GFS brings it late Mon / early hours of Tues , ECM more towards 07.00 Tues.

To Note very strong winds possible later Tues or Weds more so on Atlantic coastal counties .

giveitholly

Will there be much rain associated with helene

hairyslug

Can anyone tell me what I should be expecting for Wales early next week, am off camping.

Wanderer78

hairyslug wrote:

Can anyone tell me what I should be expecting for Wales early next week, am off camping.

I'd be keeping an extremely close eye on weather reports, particularly for the UK, and have alternative accommodation plans just encase

Planet X

hairyslug wrote: »

Can anyone tell me what I should be expecting for Wales early next week, am off camping.

You should be expect very bad and stormy weather........

ThaitaniumM

GFS 06Z has Helene shifted W

Wanderer78

ThaitaniumM wrote: »

GFS 06Z has Helene shifted W

spotted that alright, will be a while before we nail this one down

squarecircles

west coast takes a battering on the 06z run,it seems to be deepening as it approaches the south coast of ireland,quite vicious







monday night is looking very balmy
as ex helene drags up sub tropical air.

MJohnston

I think it should probably be noted (for the onlookers) that there is probably a high chance of some form of at least orange-level impact from ex-Helene at this stage. The eastern side of the system has quite strong winds and gusts, nothing out of the ordinary for Ireland, but still strong. The western side has heavy amounts of precipitation (in the 20-30mm/hr range). So, some models are showing it going west, some are showing it going east, but either way, some of us will be in line for either strong winds or heavy rains.

highdef

MJohnston wrote: »

I think it should probably be noted (for the onlookers) that there is probably a high chance of some form of at least orange-level impact from ex-Helene at this stage. The eastern side of the system has quite strong winds and gusts, nothing out of the ordinary for Ireland, but still strong. The western side has heavy amounts of precipitation (in the 20-30mm/hr range). So, some models are showing it going west, some are showing it going east, but either way, some of us will be in line for either strong winds or heavy rains.

Trees in full leaf is certainly going to be a contributing factor with regard to any warnings that may be issued.

squarecircles

MET ÉIREANN BRIEFING REGARDING TROPICAL STORM HELENE AS OF NOON, FRIDAY 14TH SEPTEMBER

Tropical Storm Helene

Tropical Storm Helene is the system which is pertinent to us here in Ireland because current guidance indicates that Helene will take a northeastward track towards our shores early next week. Tropical Storm Helene is already transitioning to an extra-tropical cyclone southwest of the Azores Islands. This means that Helene will lose it’s tropical characteristics including it’s warm core, organised deep convection and closed surface wind circulation and become more akin to the low pressure systems we are used to seeing in our part of the world. It will develop fronts, the strongest winds will shift around to the east and south of the low pressure system with the heaviest rain on the western side of the low pressure centre.

The current forecast is that “Storm Helene” or “ex-Tropical Storm Helene” will be to the south of Ireland on Monday night. Current guidance has the low pressure system moving northeastwards up through the Irish Sea overnight Monday and early on Tuesday, although the exact path is still uncertain. A humid spell of wet and windy weather is expected to sweep up over Ireland on Monday night and early Tuesday as a result. Current guidance suggests the potential for warning level winds and perhaps rain with the system.There remains some uncertainty in the track of the system. There remains some uncertainty in the track of the system. Met Éireann forecasters will continue to monitor the situation and issue warnings, as required, closer to the time.

spookwoman

No mention of it during the 1 o'clock forecast and they show the monday and tuesday as pretty normal days. You would think they would put up a note or something to say possible watch this space or something to say there may be a warning issued. Plowing championships next week and they were talking about having a stand etc as if there was no noon briefing.

Sycamore Tree

spookwoman wrote: »

No mention of it during the 1 o'clock forecast and they show the monday and tuesday as pretty normal days. You would think they would put up a note or something to say possible watch this space or something to say there may be a warning issued. Plowing championships next week and they were talking about having a stand etc as if there was no noon briefing.

I don't think they can realistically start talking about Helene so far out when Florence is hammering the US and a typhoon is hammering the Phillipines. They do have coverage of both of those on the main bulletin.

I imagine they will start warning about Helene soon.

btw, your avatar concerns me spookwoman

screamer

In true self interest mode here Helene would have an impact on us if it tracks over us..... Florence will be minimal, and the typhoon won't affect us, so yes I think Met EIREANN should be talking about Helene if nothing else to flag it

squarecircles

flip/flop 12z slams the south and east coast.

irishrover99

screamer wrote: »

In true self interest mode here Helene would have an impact on us if it tracks over us..... Florence will be minimal, and the typhoon won't affect us, so yes I think Met EIREANN should be talking about Helene if nothing else to flag it

TBH I’m not sure 5 days notice is needed even if it’s a red warning.

We don’t live in houses made of wood so a simple, stay indoors announcement a day or two before will suffice.

MJohnston

WXCharts doesn't have the 3 hour frames for the GFS, but they do have a much easier to read color scale:




This would be Orange level warnings, possibly verging on Red level, for parts of the south (and maybe East too, those in-between frames will be vital once the higher-res models come in range).

Frostybrew

I wonder is this the start of a longer term trend? This is the second time in a year that a former hurricane has moved from the eastern Atlantic in the direction of Ireland. Could there be more destructive storms in the years ahead, possibly the equivalent of Cat two hurricanes? Or are they outliers?

squarecircles

oh,how i do look foward to the irish ex hurricane season.

screamer

irishrover99 wrote: »

screamer wrote: »

In true self interest mode here Helene would have an impact on us if it tracks over us..... Florence will be minimal, and the typhoon won't affect us, so yes I think Met EIREANN should be talking about Helene if nothing else to flag it

TBH I’m not sure 5 days notice is needed even if it’s a red warning.

We don’t live in houses made of wood so a simple, stay indoors announcement a day or two before will suffice.

Disagree...what about farmers with stick to sort out....there's plenty of outdoor workers, building sites to be made safe etc and a 2 day warning is frankly too little......

MJohnston

ICON 12z definitely leaning towards Red level warnings for southern counties:

spookwoman

irishrover99 wrote: »

TBH I’m not sure 5 days notice is needed even if it’s a red warning.

We don’t live in houses made of wood so a simple, stay indoors announcement a day or two before will suffice.

If people have to make appointments, travel plowing championships at least they know it may happen. Some says it could hit monday night so that not that far away

squarecircles

someone may need to open an official thread for helene tomorrow if this trend continues.

Kermit.de.frog

This is the official thread

Impacts look minimal at the moment and below an orange warning. System looks to get absorbed and move through quickly on Monday.