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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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Meteorite58

marno21 wrote: »

What can we expect about 30km inland from Tralee? Will it be weaker away from the coast?

Looks very rough, not 100% but something like these for a time.

Gusts

Will have a better idea tomorrow when the short range forecasts come into effect

dfx-

Meteorite58 wrote: »

https://twitter.com/pppapin/status/919240140811390978

That's great clip of its formation, it being stationary spinning by itself and then being carried towards Ireland.

Spanish Eyes

Kensley Deep Children wrote: »

I really think you need Gerry or Evelyn for a situation like this. Joanna just doesn't bring the same gravitas.

I think they might be saving them for tomorrow night, to keep us all calm and collected like.;)

Wombatman

South Coast looking to take the biggest waves.

Gaoth Laidir

Ophelia is around 140 NM south of Santa Maria, Azores now. The TAF for the airport calls for northerly/northwesterly winds of 40 knots gusting to 50 knots from 9 pm tonight to around 9 am tomorrow as the hurricane passes to its east.

TAF LPAZ 141100Z 1412/1518 16020KT 9999 SCT008 BKN015
BECMG 1414/1417 13025KT 5000 RA SCT006 BKN012
TEMPO 1417/1424 VRB25G35KT 1500 +TSRA BKN004 SCT020CB
BECMG 1421/1424 35030G43KT 9999 NSW SCT015 BKN035
TEMPO 1500/1509 34040G50KT BECMG 1509/1512 34020G33KT

Colser

Will the winds be stronger than Darwin and if so will they be much worse?Will it start getting windy by tomorrow night?

Thanks a mill to all the experienced posters here..everytime MT posts it's like a message from God ðŸ˜

[Deleted User]

Kensley Deep Children wrote: »

I really think you need Gerry or Evelyn for a situation like this. Joanna just doesn't bring the same gravitas.

Well, they have to earn their stripes some time....

Irish Steve

definitely not the most confident of forecasts on RTE1, probably because it's the first time she's had to forecast anything even remotely like this, both in terms of where its coming from, and the potential intensity of it.

In nearly 30 years here, I don't think I've seen weather with such a strong wind for so much of the country, what's very clear is that this could cause significant damage to infrastructure, especially ESB, which in passing could also cause some significant broadband issues, as they have a significant high speed fibre network carried on their high voltage network cables, so if overhead cables or pylons are damaged, that could also take out massive chunks of high speed broadband backbone services.

As had been mentioned several times, the devil will be in the detail, a relatively small change in track or the intensity of the storm could mean a massive difference for some parts of the country, and even now, calling it with any more accuracy is just not possible.

space2ground1

Is the current forecast trend for Ophelia to drift slightly westwards? Wexford/Waterford haven’t been included in the red warning.

Just wondering if there’s time for the forecast to change to include those counties or would that be against the trend on track predictions?

Pangea

Kensley Deep Children wrote: »

I really think you need Gerry or Evelyn for a situation like this. Joanna just doesn't bring the same gravitas.

I'm in favour of an Eagleton comeback special

marno21

What can we expect about 30km inland from Tralee? Will it be weaker away from the coast?

Gaoth Laidir

sdanseo wrote: »

Why is it that these analyses seem to be consistently less intense than the NHC's definition of maximum winds? Is it measured a different way or are they using different models?

The NHC always seem to round their estimates upwards from observations to allow for the possibility of undersampling. The chart I post is from 4 different satellite platforms and is based on the 700 hPa windfield extrapolated to the surface using various coefficients that depend on the distance from the storm's centre.

gugsy

Working class heroes wrote:

What time for the next advisory?

smodgley wrote:

when is the next NHC advisory due ? 8pm our time ?

10pm

r93kaey5p2izun

I really think you need Gerry or Evelyn for a situation like this. Joanna just doesn't bring the same gravitas.

smodgley

when is the next NHC advisory due ? 8pm our time ?

Copper_pipe

I live about a mile from the Limerick/Cork birder on the Limerick side.

For the hurricane I’ll consider myself to be on the cork side until Limerick gets added to red alert ....

flaneur

Theresa is on standby !!

cyclops999

TheMilkyPirate wrote: »

Who is your one doing the weather she's awful

She's just excited after conference call from NHS, NWS they don't often get to forecast incoming hurricane

shmaupel

Nettle Soup wrote: »

I think the RTE news and Met Eireann were very open, informative and clear about Ophelia just now. They've handled it well.
I was at a hurling match earlier and everyone is talking about it.

Ditto.

I think they've been quite sensible and measured about the whole thing so far.

RoisinClare6

Weather lady seemed a bit under pressure.

Meteorite58

https://twitter.com/pppapin/status/919231886744080385

https://twitter.com/pppapin/status/919235137681920001

https://twitter.com/pppapin/status/919240140811390978

leahyl

Have to say, just can’t take to that Joanna Donnelly at all.

Nettle Soup

I think the RTE news and Met Eireann were very open, informative and clear about Ophelia just now. They've handled it well.
I was at a hurling match earlier and everyone is talking about it.

sunbabe08

TheMilkyPirate wrote: »

Who is your one doing the weather she's awful

I was thinking that as well. Need a more steady hand for this situation

Jobs OXO

M.T. Cranium wrote: »

Looking at that ICON map, you know something is up when the map has winds stronger than anything in the legend (that dark patch in the white zone). hope everyone grasps that the white zone is gusts of 200 km/hr being predicted so the dark patch is either seaweed from the Sargasso Sea, or 220 km/hr wind gusts.

Joanna Donnelly looking very spooked on RTÉ. Stumbling and stuttering over words. Not like her at all. Something isn't being shared. Possibly to avoid panic.

TheMilkyPirate

Who is your one doing the weather she's awful

leahyl

M.T. Cranium wrote: »

Looking at that ICON map, you know something is up when the map has winds stronger than anything in the legend (that dark patch in the white zone). hope everyone grasps that the white zone is gusts of 200 km/hr being predicted so the dark patch is either seaweed from the Sargasso Sea, or 220 km/hr wind gusts.

:-O

greysides

Meteorite58

Met Eireann

Weather News

Update on Storm Ophelia

14 October 2017

As of midday Saturday, Hurricane Ophelia situated at approx. 2,500km southwest of Ireland and 500km south-southwest of the Azores in the Atlantic Ocean is currently tracking east-northeast. The latest information from our colleagues in the National Hurricane Centre in Miami indicates that Ophelia will become a powerful post-tropical cyclone (from thereon in ex-Hurricane Ophelia) by Monday, and there is now generally high confidence that the centre of this system will track close to and possibly even over some parts of the west coast of Ireland.

Ex-Hurricane Ophelia is expected to be near the southwest tip of Ireland by Monday morning. From there it looks set to track northwards close to the Atlantic Seaboard at a fast pace to be roughly situated 100-200km northwest of County Donegal by midnight on Monday.

This will be a significant weather event for Ireland with potentially high impacts – structural damage and flooding (particularly coastal) - and people are advised to take extreme care Keep up to date with the warnings.

Met Éireann forecasters have been monitoring this situation closely all week. We have been liaising with our international colleagues, especially at the UK Met Office, and as we are now in the 48 hour window, with access to our high resolution models, we have decided to issue specific warnings. The warnings will be updated as required.

For further information on the evolution of this system, please continue reading.

What will happen with Hurricane Ophelia?

Hurricane Ophelia is expected to undergo an extra-tropical transition over the next 24 to 36 hours. That means its structure and appearance is going to undergo drastic changes as it approaches Ireland. It will lose its hurricane status but will become a powerful extra-tropical storm. Current indications are suggesting that Ex-Hurricane Ophelia will likely engage with an upper trough of low pressure in the mid-Atlantic at some point tomorrow afternoon. This engagement will cause the storm system to accelerate somewhat north-northeast towards Ireland and the UK.

Why will this happen?

As Hurricane Ophelia tracks north from its current position, it will encounter cooler seas and it will eventually come under the influence of the westerlies. The westerlies of the mid-latitudes increase in strength with height, a phenomenon known as vertical wind shear. This shear almost literally chops off the upper part of the hurricane and sweeps it away. Along with the lower sea temperatures of the mid-latitudes this destroys the positive feedback processes within the hurricane. What remains is the former hurricane’s low-level circulation which, if conditions are right, becomes the focus of further development.

What weather is expected?

Rain can be expected over the country on Sunday night and into Monday, though the heaviest and most significant rain will remain out to sea in the Atlantic on the western side of the surface low pressure. But there will also be some heavy and possibly thundery bursts rotating around the low centre itself, so it can be reasonably assumed that counties closest to the centre of the low will see the heaviest rainfall.

At the same time, damaging winds will accompany the low centre with wind gusts of 130km/h or more. The most severe winds will be in coastal counties, with lower impacts likely for central areas. In addition, we can expect very high waves. Sea conditions will be dangerous and large waves may lead to coastal flooding.

M.T. Cranium

Looking at that ICON map, you know something is up when the map has winds stronger than anything in the legend (that dark patch in the white zone). hope everyone grasps that the white zone is gusts of 200 km/hr being predicted so the dark patch is either seaweed from the Sargasso Sea, or 220 km/hr wind gusts.