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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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JanuarySnowstor

My thoughts before the 12zs come out is that there's a clear nudge West by the gfs since this time yesterday. I'm very surprised the Met didn't wait until this evening to do a warning. If the ecm moves more towards gfs then let's be clear there is no storm!

We'll know a good bit more by tonight but the trend this morning is West and away from our shores

goat2

JanuarySnowstor wrote: »

My thoughts before the 12zs come out is that there's a clear nudge West by the gfs since this time yesterday. I'm very surprised the Met didn't wait until this evening to do a warning. If the ecm moves more towards gfs then let's be clear there is no storm!

We'll know a good bit more by tonight but the trend this morning is West and away from our shores

hoping not to lose some of my roof again this Monday as happened a few yrs ago, when MT warned us, trees came down also, missing the home, but have kept things at safe height since

Gaoth Laidir

12Z Early guidance out. 96-108 hours is what we're looking at.

Seems like a westward shift in track compared to the official track (red).

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fraxinus1

JanuarySnowstor wrote: »

My thoughts before the 12zs come out is that there's a clear nudge West by the gfs since this time yesterday. I'm very surprised the Met didn't wait until this evening to do a warning. If the ecm moves more towards gfs then let's be clear there is no storm!

We'll know a good bit more by tonight but the trend this morning is West and away from our shores

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.

George Sunsnow

Oh for fcuks sake
Met Éireann have only issued a yellow and only said theyre watching it
That it has the potential to be high impact etc

Often criticized here for no mention of uncertainty’s
You guys,a lot of you guys are never happy

Iancar29

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.

Seriously???????

Bsal

Met office latest forecast

https://www.youtube.com/watch?v=TGThwsLopXY

star gazer

Wind speed up a bit, pressure down and track similar, not much change forecast for the next two days or so.

...OPHELIA MEANDERING SOUTHWEST OF THE AZORES...
...EXPECTED TO BEGIN MOVING NORTHEASTWARD LATER TODAY...

SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
LOCATION...30.5N 35.6W
ABOUT 715 MI...1145 KM SW OF THE AZORES
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H
PRESENT MOVEMENT...NNE OR 20 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES

NHC advisory 14
It's still too early to predict the exact impact Ophelia will have on Ireland, but it's important to at least be aware of the potential danger.
For those interested in the way the US National Hurricane Centre deals with uncertainty in their track forecast cone

Ophelia Water vapour image. Yellow is drier air.

cherryghost

FORECAST POSITIONS AND MAX WINDS

INIT 12/0900Z 30.3N 35.6W 75 KT 85 MPH
12H 12/1800Z 30.7N 35.2W 80 KT 90 MPH
24H 13/0600Z 31.3N 34.0W 80 KT 90 MPH
36H 13/1800Z 32.2N 32.0W 75 KT 85 MPH
48H 14/0600Z 33.7N 28.6W 75 KT 85 MPH
72H 15/0600Z 38.5N 20.5W 75 KT 85 MPH
96H 16/0600Z 49.0N 13.5W 70 KT 80 MPH...POST-TROP/EXTRATROP
120H 17/0600Z 59.0N 7.0W 55 KT 65 MPH...POST-TROP/EXTRATROP

Gaoth Laidir

M.T. Cranium

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

Iancar29 wrote: »

Seriously???????

Folk on here saying it will stay out west.

nagdefy

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

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

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

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

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

De Bild

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

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

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

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

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

Bullseye for Ireland on ukmo

dacogawa

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

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

FutureGuy

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

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

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

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

Pinch of salt