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

M.T. Cranium · 12-10-2017 4:37pm

The NHC official track is placed slightly east of the GFS and the midpoint of the positions is 54.0 N 10.3 W which is basically just off Belmullet, so their track places west coast in the path of strongest winds which can be expected to occur 50-100 miles east of the track.

My suggestion would be that the earliest that we would go to a level 2 here is Saturday 10 a.m. and for a level 3 there would have to be consensus for 140 km/hr gusts at 24h.

Neither of those steps may be required and if the outlook becomes less threatening then the thread title will be edited to something more reflective of the situation. For now I am confortable with the phrase "threatens a high impact windstorm" because that is verbatim what the NHC track implies.

fraxinus1 · 12-10-2017 4:40pm

Iancar29 wrote: »

Seriously???????

Folk on here saying it will stay out west.

nagdefy · 12-10-2017 4:45pm

fraxinus1 wrote: »

That's good to hear. I was going to ask a neighbour to have a look at the shed roof but no need to. I hope Met Eilean feel silly now with their hype about high impact weather. Meet a neighbour earlier and it was all talk about a big storm. I told him the word is it will stay out to sea to the west.

Quite a silly comment. It's Thursday pm. No doubt there'll be upgrades and downgrades until Monday.

A yellow warning with potential to upgrade is sensible at this stage. 'Met Eilean'???

Gaoth Laidir · 12-10-2017 4:52pm

Not often we get a mention by the NHC.

Hurricane Ophelia Discussion Number 14
NWS National Hurricane Center Miami FL AL172017
1100 AM AST Thu Oct 12 2017

Ophelia's satellite presentation consists of a distinct eye in infrared imagery surrounded by a ring of cloud tops of -50C to -70C. The initial intensity of 80 kt is based on a blend of the latest subjective and objective Dvorak estimates, which range from 77 to 95 kt. Little change in intensity is expected during the next 48 hours, as Ophelia will remain over SSTs of 25-26C and in a low to moderate shear environment. After that time, the cyclone should begin extratropical transition as it interacts with a potent mid-latitude trough moving eastward across the north Atlantic. This baroclinic interaction should maintain Ophelia at hurricane intensity through 96 hours, with slow weakening expected after that time as the extratropical cyclone occludes.

Ophelia has moved little since the last advisory, with the cyclone currently situated south of the mid-latitude westerlies. The initial motion estimate is a slow north-northeastward drift at around 2 kt. A steadier northeastward motion should begin by 12 h when the aforementioned upper-level trough begins to exert influence on Ophelia's motion. An east-northeastward acceleration is expected at 24 through 48 h, followed by a turn back to the northeast and north-northeast at days 3 through 5 as Ophelia interacts with the southern portion of the trough. Through the first 48 hours, the new NHC track forecast is similar to the previous one and lies near the middle of the guidance envelope. Later in the forecast period, there remains a fair bit of east/west spread in the track of Ophelia near Ireland and the United Kingdom, which isn't usual at these time ranges. The NHC forecast at these times is similar to the previous one and lies on the right side of the deterministic guidance envelope but is near the middle of the ECMWF, UKMET and GEFS ensemble members. Regardless of the exact track, post-tropical Ophelia is likely to bring some impacts to Ireland and the United Kingdom as a powerful extratropical cyclone in 4 to 5 days.

While the track guidance keeps the center of Ophelia east of the Azores, a tropical storm watch or warning could be needed for the eastern Azores later today or tonight because of the expected increase in the size of the tropical-storm-force winds in the northwestern quadrant of the cyclone.

KEY MESSAGES:

1. Ophelia is expected to transition to a hurricane-force post-tropical cyclone by Monday when it moves near Ireland and the United Kingdom. While post-tropical Ophelia will likely bring some direct impacts from wind and heavy rain to portions of these areas, as well as dangerous marine conditions, given the forecast uncertainty at these time ranges it is too soon to determine the exact magnitude, timing and location of the impacts. Residents in Ireland and the United Kingdom should monitor the progress of Ophelia for the next several days. For more information on local impacts, residents of Ireland should refer to products issued by Met Eireann and residents in the United Kingdom should refer to products issued by the Met Office.

FORECAST POSITIONS AND MAX WINDS

INIT 12/1500Z 30.5N 35.6W 80 KT 90 MPH
12H 13/0000Z 30.9N 34.9W 80 KT 90 MPH
24H 13/1200Z 31.6N 33.4W 80 KT 90 MPH
36H 14/0000Z 32.7N 30.8W 75 KT 85 MPH
48H 14/1200Z 34.4N 27.3W 75 KT 85 MPH
72H 15/1200Z 40.9N 18.8W 75 KT 85 MPH
96H 16/1200Z 51.0N 12.5W 65 KT 75 MPH...POST-TROP/EXTRATROP
120H 17/1200Z 60.5N 5.5W 55 KT 65 MPH...POST-TROP/EXTRATROP

squarecircles · 12-10-2017 4:53pm

Head of forecasting, Gerald Fleming, says at this stage it's difficult to gauge how the storm will play out.

"We're looking at the possibility of stormy weather coming our way early next week - Sunday night, Monday, maybe even into Tuesday morning - with the remnants of a hurricane or tropical storm Ophelia wrapped up in it.

"At the moment, because it's four days away, there are a lot of possibilities as to how this might evolve, we are anxious to keep an eye on it.

"But be aware, this could be a complete non-event, or it could be a severe event."

Breakingnews.ie

FutureGuy · 12-10-2017 4:57pm

As someone who only ever uses the forum to see if his parents house is going to be ok, can someone break it down please.

If the worst possible scenario plays out and the storm hits us, would it be worse than Desmond in 2014?

Gaoth Laidir · 12-10-2017 4:57pm

Latest wind analysis, showing max winds 69-knots 33 nautical miles southeast of the centre.

De Bild · 12-10-2017 5:03pm

fraxinus1 wrote: »

You know perfectly well that's a typo you pompous git

No i didn't. I thought you were laughing at Met Eireann. Look i'm not going to engage in childish name calling. You probably need to step back from the forum for a few hours.

coillsaille · 12-10-2017 5:10pm

FutureGuy wrote: »

As someone who only ever uses the forum to see if his parents house is going to be ok, can someone break it down please.

If the worst possible scenario plays out and the storm hits us, would it be worse than Desmond in 2014?

What part of the country is the house in?

nagdefy · 12-10-2017 5:10pm

fraxinus1 wrote: »

You know perfectly well that's a typo you pompous git

Like De Bild i felt you were belittling Met Eireann.

I agree with him. Take a break for a few hours.

You're the guy had a 2wk meltdown when FI 'snow' never transpired last January.

FutureGuy · 12-10-2017 5:11pm

coillsaille wrote: »

What part of the country is the house in?

Near Charleville on the Cork/Limerick border. Sorry, that would have been useful information.

JCX BXC · 12-10-2017 5:12pm

FutureGuy wrote: »

Near Charleville on the Cork/Limerick border. Sorry, that would have been useful information.

That's quite far inland, is there any reason in particular that the house would be more at risk that other dwellings in the area?

JanuarySnowstor · 12-10-2017 5:13pm

Bullseye for Ireland on ukmo

dacogawa · 12-10-2017 5:13pm

I'm sure we'll know how it's going to pan out by this time tomorrow, I think it'll pull west, the ECM should be a good guide which is out in a short time...

pad199207 · 12-10-2017 5:14pm

GFS looks further West this evening, however the UKMO shows all yee coastal dwellers may move inland!

FutureGuy · 12-10-2017 5:15pm

JCX BXC wrote: »

That's quite far inland, is there any reason in particular that the house would be more at risk that other dwellings in the area?

Our land survived everything for 30 years, but Desmond broke 5 large trees. Hence my need to gauge it. My dad is elderly so will need help to make sure things are well in place before the weekend.

Gaoth Laidir · 12-10-2017 5:17pm

12Z SHIPS output showing the storm moving at around 31-32 knots around 120 km or so from land at 12Z Monday. Max sustained winds 49 knots.

JCX BXC · 12-10-2017 5:24pm

FutureGuy wrote: »

Our land survived everything for 30 years, but Desmond broke 5 large trees. Hence my need to gauge it. My dad is elderly so will need help to make sure things are well in place before the weekend.

Alot of that type of damage seems to come from years worth of wind events and can often depend on the direction.

From a West Clare perspective, storm desmond caused near no damage in comparison to the great storm of Wednesday 2014.

coillsaille · 12-10-2017 5:24pm

FutureGuy wrote: »

Our land survived everything for 30 years, but Desmond broke 5 large trees. Hence my need to gauge it. My dad is elderly so will need help to make sure things are well in place before the weekend.

I'm no expert but I reckon all you can do at the moment is keep monitoring this thread and Met E. It will be late Saturday I'd say before things are closer to being certain. But you may have to make the call on your parents' place before then based on the info available at the time.

cherryghost · 12-10-2017 5:25pm

Pinch of salt

Longboard · 12-10-2017 5:32pm

cherryghost wrote: »

Pinch of salt

pad199207 · 12-10-2017 5:36pm

GFS could be going on it’s own with this one!

12-10-2017 5:54pm

11am (4pm Ireland) NHC 5 day graphic outlook.

Kermit.de.frog · 12-10-2017 6:01pm

Gas

PukkaStukka · 12-10-2017 6:06pm

Met Eireann 6pm forecast has issued a preliminary warning re this event, but advise that that this is a developing situation and people need to follow the forecasts till then.

+1 to Met, this is the right call even if this turns out to be a non event.

TitianGerm · 12-10-2017 6:11pm

First time poster here but looking at the above graphs would I be right thinking Waterford/Wexford could be hit quite hard by this one?

jasper100 · 12-10-2017 6:11pm

That chart says 3 day error is 105Nm. There is a very good chance this could miss us completely.

M.T. Cranium · 12-10-2017 6:13pm

12z GEM has moved west to direct hit on Ireland, cyclone moves from 48N 11W at 00z Monday to intense stacked low near Belmullet 12z. This would be a high impact track for most of Ireland.

This removes the one eastern outlier from the model guidance suite.

12z GFS is comparatively slower and further west. This would be a level one alert for parts of Connacht and sub-alert for rest of Ireland.

More clarity after 12z ECM registers its vote perhaps.

jasper100 · 12-10-2017 6:13pm

emmetkenny wrote: »

First time poster here but looking at the above graphs would I be right thinking Waterford/Wexford could be hit quite hard by this one?

Cork, Kerry, Waterford and Wexford would potentially be where it reaches landfall on Irish shores from what I can see. That's if it lands a direct hit here at all.

Kermit.de.frog · 12-10-2017 6:16pm

http://edition.cnn.com/2017/10/12/world/hurricane-ophelia-ireland/index.html

CNN have got this. Expect Anderson Cooper and Wolf Blitzer to arrive over the weekend.

59b5944fe4b0f22e0e9f0145_1455589917779-yrd15k_t_1505072275660_640_360_400.gif

JCX BXC · 12-10-2017 6:17pm

jasper100 wrote: »

Cork, Kerry, Waterford and Wexford would potentially be where it reaches landfall on Irish shores from what I can see. That's if it lands a direct hit here at all.

Looks alot worse in Clare than Waterford and Wexford!

JCX BXC · 12-10-2017 6:19pm

Kermit.de.frog wrote: »

http://edition.cnn.com/2017/10/12/world/hurricane-ophelia-ireland/index.html

CNN have got this. Expect Anderson Cooper and Wolf Blitzer to arrive over the weekend.

We have Tereasa Mannion, we're fine!

server down · 12-10-2017 6:26pm

jasper100 wrote: »

That chart says 3 day error is 105Nm. There is a very good chance this could miss us completely.

IS the error not in the cone, though? If not whats the point of the cone.

EDIT:

Of course if it tracks to the west of that cone of probability it wont affect Ireland much at all. The centre -- presumably the most probable - will.

M.T. Cranium · 12-10-2017 6:46pm

Right, the actual track usually falls within the cone, in rare cases it has shifted further than the edges of the cone which is what the NHC have found operationally to be something like the 95% certain to verify zone. Don't forget that the cone uncertainty is also operating in elapsed time, in other words, there is uncertainty at each of the cone-bisecting elapsed times such as 72h, 96h, and that is not visually apparent, the error there is probably a little larger in spatial terms than the spread of tracks.

The timing uncertainty can be seen comparing GEM and GFS, already at least 8 hours in the vicinity of Ireland, and 4 deg of longitude.

sdanseo · 12-10-2017 6:56pm

M.T. Cranium wrote: »

Right, the actual track usually falls within the cone, in rare cases it has shifted further than the edges of the cone which is what the NHC have found operationally to be something like the 95% certain to verify zone. Don't forget that the cone uncertainty is also operating in elapsed time, in other words, there is uncertainty at each of the cone-bisecting elapsed times such as 72h, 96h, and that is not visually apparent, the error there is probably a little larger in spatial terms than the spread of tracks.

The timing uncertainty can be seen comparing GEM and GFS, already at least 8 hours in the vicinity of Ireland, and 4 deg of longitude.

I remembered reading this earlier this year on NHC's website:

Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time. To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

That 67% is over five years so I guess the certainty in a given year would be relatively higher? (I'm no mathematician, nor will I ever be).

Gotta hand it to the Americans. They can be very officious - but their official websites and information sources are very well explained.

Edit: NHC's interactive map. If this was to come off, all of Sligo, Mayo, Donegal and Kerry as well as most of the western side of the country would experience a true Category 1 Hurricane. The green is 1min. sustained 64kt (75mph) wind.

jasper100 · 12-10-2017 7:14pm

sdanseo wrote: »

I remembered reading this earlier this year on NHC's website:

That 67% is over five years so I guess the certainty in a given year would be relatively higher? (I'm no mathematician, nor will I ever be).

Gotta hand it to the Americans. They can be very officious - but their official websites and information sources are very well explained.

Edit: NHC's interactive map. If this was to come off, all of Sligo, Mayo, Donegal and Kerry as well as most of the western side of the country would experience a true Category 1 Hurricane. The green is 1min. sustained 64kt (75mph) wind.

The people of Rosslare must be wondering why they are being left out!

pad199207 · 12-10-2017 7:15pm

Looks like ECM has the perfect storm for Ireland this evening. Worst case scenario for the South Coast.

dacogawa · 12-10-2017 7:16pm

The 96 on the ECM is out, it didn't go west... :eek:

ECM1-96.GIF?12-0

Kermit.de.frog · 12-10-2017 7:17pm

ECM 12z

B2DC6C39-D5D0-48E2-A187-B68D7BFC8D59.gif.db22ea1c72fe0fd10a4960692142f501.gif

Meteorite58 · 12-10-2017 7:18pm

A few interesting observations

https://twitter.com/pppapin/status/918534724712325121

https://twitter.com/MattHugo81/status/918533282077315072

https://twitter.com/RyanMaue/status/918493506800406528

https://twitter.com/RyanMaue/status/918493732336435202

https://twitter.com/metoffice/status/918504887775842309

Qw5800h.png?1

M.T. Cranium · 12-10-2017 7:18pm

Did anyone earlier mention the 12z Arpege? It rocks the house and moves a touch to the east of the NHC track (by perhaps 50 miles). Well here comes the 12z ECM ...

... and it's heading for west Munster with very strong winds depicted at 96h -- a touch slower than previous pace, worst of the storm would be 15-18z presumably.

Iancar29 · 12-10-2017 7:18pm

ECM

UKMO

GFS

GEM

I think we can see what the current outlier is...

JanuarySnowstor · 12-10-2017 7:19pm

Looks like a direct hit for here. WOW!

Cee-Jay-Cee · 12-10-2017 7:22pm

JanuarySnowstor wrote: »

Looks like a direct hit for here. WOW!

Best disassemble the kids trampoline on Saturday :eek:

Meteorite58 · 12-10-2017 7:22pm

The 96 on the ECM is out, it didn't go west...

Note 850 hPa Winds

M.T. Cranium · 12-10-2017 7:22pm

It should be noted, the Met Office commentary of course only applies to the UK and their maximum wind gusts would be for Derry and western Scotland, parts of (Republic of) Ireland could expect 80-100 mph gusts consistent with their scenario.

Frankly, some of this guidance looks worse than Debbie 1961, don't you agree?

dacogawa · 12-10-2017 7:23pm

Looks like a swing east on the 120?!?

ECM1-120.GIF?12-0

km79 · 12-10-2017 7:25pm

Only seen this thread now
12 pages in a day
I'm scared

JCX BXC · 12-10-2017 7:26pm

Expecting downgrades, got the opposite. Plenty of time yet for it to change completely however some of that guidance looks quite frankly scary!

I'd love to give wind updates from West Clare but if that comes off I'm not confident of my current weather station set up so it would be coming inside for safe keeping!

Meteorite58 · 12-10-2017 7:28pm

My money is on the ECM and the other European models

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

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