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Extratropical Storm Ophelia - Technical Analysis Only - MOD NOTE post #1

M.T. Cranium

Mod note

This is a busy thread and as a result the Mod Team will be taking a zero Tolerance approach to trolling and flaming

Don’t say you weren’t warned!!

And please don’t feed
Thanks

Just briefly for now, recent model runs (12z Wed 11th) have shown a track near Ireland for strong extratropical low (Ophelia) with timing converging on Monday 16th during the daytime hours.

The GFS model was of some concern but the ECM now has a very high impact low depicted at 965 mbs just about 70 miles southwest of Valentia by mid-day Monday.

This would evidently track through Ireland and Scotland on a generally NNE to NE path, which would bring damaging wind gusts into most of Ireland.

Too early to get very specific about impacts or peak wind speeds but these maps got my interest and look as intense as storm "Darwin" in 2014.

I wanted to get a dedicated thread into existence so that we can focus on this storm rather than using the tropical seasonal thread. Also, please note, obviously if this verifies a level 3 warning would be justified and at some point we will consider upgrading the current level 1 which is appropriate mainly because of the uncertain outcome, but an event of at least level 1 status seems almost locked in given the model consensus.

The GEM model is currently an outlier, like the rest of the pack it shifted east but that took its earlier eastern Ireland windstorm into Britain instead. It would be unusual for the GEM to beat out all these other models at five days so I don't give that much weight. However, it needs to be mentioned that this storm is currently a long way away (southwest of Azores) and relatively small for a hurricane, which it is about to become later today (last advisory had it as a high end tropical storm).

We shall see how the models respond to developments. The track towards Ireland makes sense when you consider how warm it is likely to be on the weekend and the position of the long-wave trough slowly moving east from the central Atlantic.

This could be a high impact windstorm for Ireland and the forum will be buzzing from now until the event comes into clear focus, after which it may be hyperactive, so post wisely with useful info as it comes along.

Mods, I will get in touch if I feel that a higher level or title change is needed. Get ready for a very busy few days.

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Gaoth Laidir

Latest SST anomaly map, showing warmer than normal waters on its projected track.

Here are the actual water temperatures.

squarecircles

“There is a lot of uncertainty as to the exact evolution and movement of this weather system during the coming four days, but storm-force winds, outbreaks of heavy rain, and very high seas are threatened” the forecasting service said.

“Met Éireann will maintain a close watch on the evolution and issue further advisories and warnings as these are warranted” the statement said.

Speaking to The Irish Times, Met Éireann meteorologist Jean Byrne said it was “very difficult” to track or predict what path the storm would take over the weekend.

“It does look like it will come very close, or pass over Ireland, so that will have a definite impact in terms of very strong winds, and high seas” she said.

“The latest tracks have it coming very close … but the there is still a lot of uncertainty” she said. Ms Byrne said the forecasting models find it difficult to track the particular type of extra-tropical storm. She said different models have the storm impacting different parts of the country currently.

Ms Byrne said Met Éireann was liaising with the United Kingdom Met Office, and the United States National Hurricane Centre in Miami, Florida.

Kermit.de.frog

Weather channel starting to cover this now. Say they are watching Ireland closely.

https://weather.com/storms/hurricane/video/ophelia-10th-named-hurricane-in-the-atlantic

Gaoth Laidir

Doltanian wrote: »

This will be the most devastating storm to strike Ireland since The night of the big wind in 1839

Hurricane Charley in 1986 was an event known for catastrophic flooding and unprecedented amounts of rain but wasn't a huge wind event. Hurricane Ophelia will cause carnage on Monday along the Western Seaboard with Kerry and West Cork to be severely effected if it does strike here.

I don't think it will be worse than Debbie in 1961. I can't see gusts of 98 knots or anything near it being recorded this time. Remember, the NHC work off 1-minute sustained winds, whereas our observations are 10-minute averages. A 1-minute average will always be higher than a 10-minute, so their predicted "65-knot sustained winds" would be reported as much lower in reality in the standard observation network. That's why a 150-knot typhoon is stronger than a 150-knot hurricane, as typhoons are based on 10-minute means, not 1-minute.

dacogawa

lucernarian wrote: »

I never understood what many of those abbreviations meant, like CLP5 for example

As they said in the model "if anything in this graphic causes confusion, ignore the entire product"

Personally I think the GFS has been off on major weather events over the last 18/24 months and the ECM has got it mostly right, these have been things like, storms, snow, winds at high tides, etc.

This time around the ECM is giving the worst scenario (and others) and I'm inclined to believe it more than the GFS. I'm sure we'll see on the next runs but I'm going for a hit on the south/west coast with strong winds (and waves) circling around to southern Cork and the south coast. I think by the track Dublin will have the edge taken off it by the Wicklow mountains for the most part but it will still be an event, not like the event for the south and west (especially coasts) which looks like being battered, I'm sure you are use to very bad weather on those sides of the country, maybe not as bad as the charts are showing now but I know a lot of people will show a lot of common sense if these charts do pan out.

If worst comes to worst, try to make sure you have safely tied down or put away anything that's going to become hazardous, if you have elderly or infirm neighbors check in on them before and after, and make sure you and your loved ones are all in the loop if Ophelia is going to hit.

And a huge thanks to M.T., Iancarr, Kermit, Gaoth and too many others to name on this forum for all their in depth information and opinions, it is priceless coming towards something like this (or it's a non event :rolleyes: ).

Stay safe!

nagdefy

Gaoth Laidir wrote: »

I don't think it will be worse than Debbie in 1961. I can't see gusts of 98 knots or anything near it being recorded this time. Remember, the NHC work off 1-minute sustained winds, whereas our observations are 10-minute averages. A 1-minute average will always be higher than a 10-minute, so their predicted "65-knot sustained winds" would be reported as much lower in reality in the standard observation network. That's why a 150-knot typhoon is stronger than a 150-knot hurricane, as typhoons are based on 10-minute means, not 1-minute.

I feel it's far too early to estimate gust speeds. Even if we're pretty sure of a direct hit 36 hrs out. We always tend to both underestimate and overestimate from my experience. Really hard to forecast until very close to the event.

Whatsdastory

Doltanian wrote: »

This will be the most devastating storm to strike Ireland since The night of the big wind in 1839

Hurricane Charley in 1986 was an event known for catastrophic flooding and unprecedented amounts of rain but wasn't a huge wind event. Hurricane Ophelia will cause carnage on Monday along the Western Seaboard with Kerry and West Cork to be severely effected if it does strike here.

Ok i do have a few drinks in me, so forgive me.

Are you winding me up saying it will rival big wing of 1839?
Which i remember hearing about in school years ago, water actually blew off lakes and general devasation.

Gaoth Laidir

nagdefy wrote: »

I feel it's far too early to estimate gust speeds. Even if we're pretty sure of a direct hit 36 hrs out. We always tend to both underestimate and overestimate from my experience. Really hard to forecast until very close to the event.

850 hPa and 700 hPa winds for Monday were showing not more than 90 knots on the 12Z ECM so anything higher than that is unlikely at the surface unless there's an upgrade .

Gaoth Laidir

ECMWF multilevel wind forecast for 12Z and 18Z Monday. The 925 and 850 hPa should give an idea of possible gusts at the surface.

12Z

18Z

dacogawa

Doltanian wrote: »

Hurricane Charley in 1986 was an event known for catastrophic flooding and unprecedented amounts of rain but wasn't a huge wind event. Hurricane Ophelia will cause carnage on Monday along the Western Seaboard with Kerry and West Cork to be severely effected if it does strike here.

Hopefully it wont be as strong as Charley but it does have the wind strength and maybe some more, it doesn't have the rain though so the winds might be stronger but the rainfall won't be near what Charley dropped. The wind, the swell and waves could be a nightmare but we're still nearly 4 days out so things could dim down but I really don't see that amount of water in Ophelia.

nagdefy

Gaoth Laidir wrote: »

850 hPa and 700 hPa winds for Monday were showing not more than 90 knots on the 12Z ECM so anything higher than that is unlikely at the surface unless there's an upgrade .

Right. I suppose i feel it could upgrade. Though more than likely downgrade. Just, pardon the pun, so much up in the air yet

cherryghost

https://www.youtube.com/watch?v=CAa7r0-r28w

[Deleted User]

Fairly compact hurricane at the moment. Quite a distinct eye.

Kermit.de.frog

Latest advisory from NHC is the same forecast but slightly more east track overall.

These probabilities will increase further.

The system is likely to arrive as extratropical with hurricane force gusts.

M.T. Cranium

Model update is ominous ...

GFS has moved its track back east towards the Atlantic coastal counties and is now almost as intense as other model guidance. About 6 hours slower than most other guidance (strongest winds Monday afternoon/evening).

GEM holds firm from last run and brings intense centre up the west coast. UKMO is similar.

Arpege and ICON are maxed out very high impact depictions also near the west coast with some tendency to move the centre slightly inland over Mayo.

Even the JMA has the same general theme.

Awaiting the ECM update now...but have already requested an upgrade to level 2 at this stage, so that may change at any moment on your screens.

The guidance goes into level 3 territory but would be holding off to Saturday to go that high.

goat2

not looking forward to this

fred funk }{

goat2 wrote: »

not looking forward to this

I am.

Gerard93

Hi All
Thanks for the great posts on this following it from the start, I may have missed but what time is this due approx on Monday???

blackwave

Genuinely starting to get nervous about this considering that most trees still have a good leaf cover and with the projected winds there will be a lot of downed trees.

511

fred funk }{ wrote: »

I am.

I'm really, really excited about this.

Stephen Hawkins football boots

Would this storm be strong enough to close Dublin Airport?

Reckless Abandonment

Stephen Hawkins football boots wrote: »

Would this storm be strong enough to close Dublin Airport?

Possibly remove parts of it to.

M.T. Cranium

The 96h ECM places the centre in Donegal Bay -- it may look somewhat subdued but I would imagine intermediate panels unavailable on most internet sources would give a similar picture to the Arpege model. I'm sure some here will have access and post some more detailed ECM guidance.

I have no desire to see any of this guidance verify, there would be severe damage in parts of the southwest and west if the Arpege was correct, GFS looks most impactful for Galway and Mayo. That's a rather narrow range within which everything else would fall at this point.

I am sure there will be twists and turns along the way but Ophelia has started to move a bit faster this morning and is now close to 31N 34W.

Chances for this (compare to my earlier estimates) now appear to be:

Level 3 in some part of Ireland _ 50%

Level 2 strongest alert level _ 30%

Level 1 strongest alert level _ 20%

No real chance of avoiding any level of wind impacts.

Rainfall situation is probably not a big concern but some parts of north Connacht could see a heavy downpour Sunday into Monday if the fronts stall until mid-day Monday. While most of the country would likely see 20-30 mm totals, some places around west Mayo could see 30-60 mm.

Some tracks would give a few parts of Mayo and Donegal a break from strongest winds and some expose all locations, so that's too close to call.

Some unprecedented wind damage could occur in west Munster on any outcome resembling current Arpege model. Hurricane strength south winds interacting with the terrain could create local lee wave situations and I think it would be prudent for the Kerry, Cork, Limerick and Clare local authorities to do some emergency planning around potential for severe wind damage locally (gust potential on some maps being over 150 km/hr).

Let's hope there is a shift in this guidance closer to the time but the convergence is rather ominous.

goat2

I think Desmond will look like a drop in the ocean compared to what we are in for, more like a storm we had about 3 to 4 yrs ago that came fast went fast, but caused a lot of damage on its path, and once again I am expecting the worst, and hoping for the best

Meteorite58

Gust Chart

[Deleted User]

Depending on the timing I might head southwest for this, hopefully I'm not in work at the time.

goat2

Thinking the peninsula's in the south west are going to get the worst of it, but praying for better, the eye moving v close to the Dingle area

Meteorite58

Must be very close for the Irish authorities to start issuing warnings/ guidance on an increasingly higher chance of a significant windstorm and the potential damage.

LkWMRLc.gif?1

JCX BXC

Situated in West Clare, up a hill, with a line of sight looking towards Kerry for over 50km here.

Over the weekend I may want to look at some battening down.

Meteorite58

GFS surface pressure, mean wind speeds in Kts ( note winds showing up for Weds and Thurs in from the W )

IpScbAe.gif?1