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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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munsterlegend

mirrorwall14 wrote: »

I know it’s for Monday? I also know that models roll out overnight and I’m wondering what times so I can check them since I’ll likely be awake anyways. I knew all the times way back in the big freeze but I’ve forgotten

I would say around 8am would be a good time in the morning. MT will have his analysis of the overnight models in his forecast. However from tomorrow evening in it will be a nowcast as no one is fully sure on the exact path or strength.

Paully D

star gazer wrote: »

50 Knot:

Forgive my ignorance, but that image appears to show Ophelia heading more to the west, and not as much to the south-east as I have seen in other models, no?

BorneTobyWilde

adox wrote: »

Weather on RTE finished with the line " we have got something to look forward to on Monday" :eek:

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

donal.hunt

mirrorwall14 wrote: »

sword1 wrote: »

It's for Monday, hopefully it will be downgraded tomorrow

I know it’s for Monday? I also know that models roll out overnight and I’m wondering what times so I can check them since I’ll likely be awake anyways. I knew all the times way back in the big freeze but I’ve forgotten

The NOAA ones are every six hours so 4AM, 10AM, 4PM, 10PM for those.
Met Eireann ones are usually 0600, 1200, 1800, 0000 I believe...

spookwoman

Updated NOAA

Cannon_fodder

sdanseo

Latest NHC update. Of specific note comparison between predictions 6 hrs ago and now:

1500UTC

INIT 14/1500Z 34.8N 26.6W 100 KT 115 MPH
12H 15/0000Z 36.5N 23.0W 95 KT 110 MPH
24H 15/1200Z 40.5N 18.0W 90 KT 105 MPH
36H 16/0000Z 46.5N 14.0W 85 KT 100 MPH...POST-TROP/EXTRATROP
48H 16/1200Z 51.5N 11.0W 75 KT 85 MPH...POST-TROP/EXTRATROP
72H 17/1200Z 59.0N 6.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
96H 18/1200Z...DISSIPATED

2100UTC

INIT 14/2100Z 35.9N 23.7W 100 KT 115 MPH
12H 15/0600Z 38.0N 20.0W 95 KT 110 MPH
24H 15/1800Z 42.8N 15.3W 85 KT 100 MPH
36H 16/0600Z 48.8N 12.3W 75 KT 85 MPH...POST-TROP/EXTRATROP
48H 16/1800Z 54.0N 9.3W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 17/1800Z 59.5N 3.5W 40 KT 45 MPH...POST-TROP/EXTRATROP
96H 18/1800Z...DISSIPATED

Essentially, they expect it to become extratropical around the same time, and still hit 53N at around 65kt - Category 1 force - but keep going for longer afterwards before dissipating.

Note the size of the cone is much narrower, so much less uncertain. This doesn't seem to be any further west, even though it might look that way, because the cone only shows the position of the centre and not the size of the storm, as they explain.

nagdefy

spookwoman wrote: »

Updated NOAA

Quite a shift to the east??

Are any other posters going googley eyed with charts?:)

I mean that in a good way. Thanks to everyone for the wonderful contributions.

Re. rte weather forecasts. It's very difficult to hit the right note. You don't want to cause panic, but you are trying to be professional and serious. Joanna was fine. Her comment about looking forward to Monday was typically her! But she got the serious parts in with the comparisons to Darwin and Debbie.

And as we all know by now it's a fluid situation and may end up a bit of a now cast.

sdanseo

nagdefy wrote: »

Quite a shift to the east??

Are any other posters going googley eyed with charts?:)

I mean that in a good way. Thanks to everyone for the wonderful contributions.

Re. rte weather forecasts. It's very difficult to hit the right note. You don't want to cause panic, but you are trying to be professional and serious. Joanna was fine. Her comment about looking forward to Monday was typically her! But she got the serious parts in with the comparisons to Darwin and Debbie.

And as we all know by now it's a fluid situation and may end up a bit of a now cast.

Centreline on NHC @ 21Z vs 15Z looks about 10km further east. Very marginal.
Add that to the fact that the storm is still a Cat 3, and expected to last longer, to my mind says upgrade. But as I've mentioned before in the thread MT, Gaoth etc would be hundreds of times more knowledgeable about the mechanics of it where I'm only really comparing charts as opposed to analysing them.

spookwoman

Looking at the forecast on https://www.ventusky.com/?p=51.0;-5.9;5&l=wind using the ICON and GFS models they both seem to show the south east and east getting hit

emeldc

The charts in #1385 and #1388 seem to be the same only compleatly different as regards the position of the worst winds. Maybe I'm just reading it wrong

MJohnston

nagdefy wrote: »

Quite a shift to the east??

Not quite - you need to understand what those wind probability charts represent. Close to the current position of the hurricane, they literally represent how likely those areas are to receive particular strengths of winds.

However, the further you get along the predicted track of the storm (ie. further into the future), the probabilities change not just because areas are less likely to get hit by particular strength winds, but also because the likelihood of the forecast being correct is less certain.

nagdefy

sdanseo wrote: »

Centreline on NHC @ 21Z vs 15Z looks about 10km further east. Very marginal.
Add that to the fact that the storm is still a Cat 3, and expected to last longer, to my mind says upgrade. But as I've mentioned before in the thread MT, Gaoth etc would be hundreds of times more knowledgeable about the mechanics of it where I'm only really comparing charts as opposed to analysing them.

Cheers sdanseo. Your playing a blinder yourself. Excellent posts. I'm ok for the historical events but not too great on the forecasting front;)

CloughCasey1

nagdefy wrote: »

Quite a shift to the east??

Are any other posters going googley eyed with charts?:)

I mean that in a good way. Thanks to everyone for the wonderful contributions.

Re. rte weather forecasts. It's very difficult to hit the right note. You don't want to cause panic, but you are trying to be professional and serious. Joanna was fine. Her comment about looking forward to Monday was typically her! But she got the serious parts in with the comparisons to Darwin and Debbie.

And as we all know by now it's a fluid situation and may end up a bit of a now cast.

Agree with that. She usually knows her stuff. She usually comes across no more than the usual suspects on here as a total weather nerd. She looked like she was bursting to tell everyone what may/might/probably will happen and would only love to be showing the general public of the ifs and buts of what is LIKELY to happen. She looked nervous.....and rightly so....as she knows the severity of the upcoming situation and she also knows that she has to act 100% professional on the national airways.

NASlad

Odds on this being a complete flop and not half as bad as we're expecting?
Can't say I'm too worried yet. Will make up my mind Sunday night.

TomOnBoard

Castlebar in the eye at 2 P.M. on Monday looks about right, yeah?

nagdefy

MJohnston wrote: »

Not quite - you need to understand what those wind probability charts represent. Close to the current position of the hurricane, they literally represent how likely those areas are to receive particular strengths of winds.

However, the further you get along the predicted track of the storm (ie. further into the future), the probabilities change not just because areas are less likely to get hit by particular strength winds, but also because the likelihood of the forecast being correct is less certain.

Cheers MJ just after realising that now. It's probability of hitting not a forecasted track.

Rougies

Gaoth Laidir wrote: »

Looking forward to readings from Sherkin Island and Roches Point. Also, could have anomalously high Föhn readings from Valentia. Later on, Mace Head and Belmullet will be interesting.

Do you mean in terms of temperature readings?

MJohnston

emeldc wrote: »

The charts in #1385 and #1388 seem to be the same only compleatly different as regards the position of the worst winds. Maybe I'm just reading it wrong

You are (sorry!) - pay attention to the force of the winds that is listed in the title of the charts, one is showing the probabilities for 34+ knots winds, and the other for 50+ knot winds. You can check out all 3 wind speed probabilities charts (the third is for 64+ knot winds) here:

http://www.nhc.noaa.gov/refresh/graphics_at2+shtml/205031.shtml?tswind120#contents

nagdefy

CloughCasey1 wrote: »

Agree with that. She usually knows her stuff. She usually comes across no more than the usual suspects on here as a total weather nerd. She looked like she was bursting to tell everyone what may/might/probably will happen and would only love to be showing the general public of the ifs and buts of what is LIKELY to happen. She looked nervous.....and rightly so....as she knows the severity of the upcoming situation and she also knows that she has to act 100% professional on the national airways.

Agree. It's very easy be critical. She has to adjust from conversation with meteorologist colleagues to addressing a nation just versed in the basics. What to say, what to withhold and then when you're live stuff can come out unintentionally as any of us who ever spoke in public know!

Spanish Eyes

MT's update tomorrow will either terrify us, or keep us calm.

sdanseo

NASlad wrote: »

Odds on this being a complete flop and not half as bad as we're expecting?
Can't say I'm too worried yet. Will make up my mind Sunday night.

We're great in Ireland for "ah, it'll be grand" so I don't blame you for seeing it like that.

But when you're looking at a chart produced by the US National Hurricane Center, probably the Gold Standard for this type of thing (although there's a huge side-conversation there about after it goes extra-tropical, UKMO having a lot more experience than NHC as usually they are concentrating on tropical), which gives a 90-100% probability of tropical-storm force sustained winds covering half the island in less than 48hrs....no, I don't think it'll be a "flop". Could well be less severe than we think. Could well be more severe. But it won't be a non-event.

spookwoman

More info 5pm

http://www.nhc.noaa.gov/text/refresh/MIATCDAT2+shtml/141438.shtml

Gallee

Compared with Feb 12th 2014 we had gusts around Limerick around 120kmh initially from South to South West and verring West....am I right in saying that this one on Monday has wind South to South West and not veering West or does it really make any difference. Just looking at what's around our house (tree wise).

crashadder

having lived most of my life in the rather warm part of the world i dont know what to expect or do in terms of preparation. How bad is this going to hit Dublin ?

FutureGuy

Thanks a million to everyone who is contributing their time and effort into breaking it down for the many of us who may not frequent the board. I really want it to be Tuesday.

Gaoth Laidir

sdanseo wrote: »

Latest NHC update. Of specific note comparison between predictions 6 hrs ago and now:

1500UTC

2100UTC

Essentially, they expect it to become extratropical around the same time, and still hit 53N at around 65kt - Category 1 force - but keep going for longer afterwards before dissipating.

Note the size of the cone is much narrower, so much less uncertain. This doesn't seem to be any further west, even though it might look that way, because the cone only shows the position of the centre and not the size of the storm, as they explain.

Also those charts are Mercator projection, so areas further north appear stretched out and larger than they are on the globe. So that cone of error Ireland is not quite as wide.

Jobs OXO

spookwoman wrote: »

Looking at the forecast on https://www.ventusky.com/?p=51.0;-5.9;5&l=wind using the ICON and GFS models they both seem to show the south east and east getting hit

Are we talking oiche na ghaoithe proportions now ?

Donegal Storm

Gaoth Laidir wrote: »

But the anemometer there is I think over 100 metres above the sea so really not of any use.

Will still be interesting what sort of readings we get from it, plenty of areas in Cork and Kerry above 100m so while not an official reading it'll still give an idea of what people might experience.

A shame we don't have a station somewhere in the Kerry mountains like they have in the Cairngorms in Scotland, would be quite an experience on top of Carrauntoohil on Monday!

emeldc

MJohnston wrote: »

You are (sorry!) - pay attention to the force of the winds that is listed in the title of the charts, one is showing the probabilities for 34+ knots winds, and the other for 50+ knot winds. You can check out all 3 wind speed probabilities charts (the third is for 64+ knot winds) here:

http://www.nhc.noaa.gov/refresh/graphics_at2+shtml/205031.shtml?tswind120#contents

Ah right, get ya now. Complete noob at this sh1t. Thanks