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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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Larbre34

10.00am station reports are in. 65 at Roche's P and 63 and Sherkin. S/SE Pressure btwn 980 and 990 hPa

DOCARCH

65kn (gust) at Roches Point at 1000.

MJohnston

Gaoth Laidir wrote: »

The top of that mast is 158 m, so I reckon the helipad is at least 100 metres.

If Cork County Hall is supposed to be a scale comparison, then there’s no chance the helipad is at 100m, as the buidling is 67m yet indicated as still being below the sea level. The math doesn’t work out!

Gaoth Laidir

Donegal Storm wrote: »

Doesn't that suggest that its significantly less than 100m? The base is on the sea bed surely with the blue shading indicating water level?

Sorry, you're right.

TomOnBoard

Met Eireann Wind Map for today seems to be showing lower wind speeds than they were showing yesterday, when there were two arrows in the South and South West showing 100.

Am I wrong to think that things will be a bit easier (albeit dangerous) than thought yesterday?

Gaoth Laidir

The Nutty M wrote: »

What you are looking at in that picture of 158metres height is the height of both the jacket and topside. It sits in 100 metres of water. That's a small platform by comparison to modern platforms.
For reference, the main components of the WMS on Clair Ridge (West of Shetland) sits on the cellar deck at 43metres ASL There are anemometers on each of the 3 cranes up to 79metres but these are not fed into the WMS.

Ah, I see it now. That light blue surface is the water surface. So the anemometer is probably 30 metres above the surface.

Hammer Archer

Fastnet lighthouse now reporting winds of 72kts with gusts of 91kts.

Gaoth Laidir

Donegal Storm wrote: »

Doesn't that suggest that its significantly less than 100m? The base is on the sea bed surely with the blue shading indicating water level?

The top of that mast is 158 m, so I reckon the helipad is at least 100 metres.

The Nutty M

Gaoth Laidir wrote: »

I think the anemometer is at about 100 metres as this is where helicopters land but they do have wave sensors too.

From Kinsale-energy.ie...

What you are looking at in that picture of 158metres height is the height of both the jacket and topside. It sits in 100 metres of water. That's a small platform by comparison to modern platforms.
For reference, the main components of the WMS on Clair Ridge (West of Shetland) sits on the cellar deck at 43metres ASL There are anemometers on each of the 3 cranes up to 79metres but these are not fed into the WMS.

Oscar Bravo

Oneiric 3

Ta muchly boys.

Donegal Storm

Gaoth Laidir wrote: »

I think the anemometer is at about 100 metres as this is where helicopters land but they do have wave sensors too.

From Kinsale-energy.ie...

Doesn't that suggest that its significantly less than 100m? The base is on the sea bed surely with the blue shading indicating water level?

Gaoth Laidir

Oneiric 3 wrote: »

Does anybody have a link to the Met Eireann marine analysis page (which shows hi res map) as can't seem to find it here on search. Cheers.

https://www.met.ie/latest/marine-analysis.asp

Meteorite58

Oneiric 3 wrote: »

Does anybody have a link to the Met Eireann marine analysis page (which shows hi res map) as can't seem to find it here on search. Cheers.

http://www.met.ie/marine/marine_map.asp

Oneiric 3

Does anybody have a link to the Met Eireann marine analysis page (which shows hi res map) as can't seem to find it here on search. Cheers.

Supercell

Does anyone know if wind return periods are available online, would like to get some context in Ophelia's wind reports? I can see that rainfall returns are publically available on http://www.met.ie/climate/products03.asp but no mention of wind returns.

Gaoth Laidir

MJohnston wrote: »

Yeah, weird that they list it on the buoys page, but surely if it is recording wave heights, it must have some sea level observation capabilities?

I think the anemometer is at about 100 metres as this is where helicopters land but they do have wave sensors too.

From Kinsale-energy.ie...

MJohnston

M3 latest hourly observations down to 976.4mb (from 980), wind speed largely the same at 40G53 (up from 39G49), significant wave heights up quite a bit to 5.47m (from 4.06m)

[Deleted User]

Thought I would add this positional graphics chart for historical reference purposes. The last advisory on Ophelia was issued at 11pm EDT (4am here) by the NHC. Not sure the next time the NHC will be issuing advisories for our part of the world. Add 5 hours to the chart times.

star gazer

https://twitter.com/MetEireann/status/919844165164392448
Gusts of 80 knots at Fastnet rock
58 knots Roches point

Donegal Storm

This is what the Arpege model shows for 9am, max gusts around 100-110kph on the south coast which is exactly what we have so far. Expecting a peak around 140-150kh around midday to 1pm if it keeps up its accuracy before the storm quickly weakens as it moves north

MJohnston

DOCARCH wrote: »

Not a buoy. As far as I am aware station is at approx. 100m over sea level.

Yeah, weird that they list it on the buoys page, but surely if it is recording wave heights, it must have some sea level observation capabilities?

Gaoth Laidir

mirrorwall14 wrote: »

Could I ask a question of the technical "team" who are doing such a wonderful job?

Joanna talks about the potential for a stingjet and I know the structure of it (forms high, descends, high winds, lots of damage), however what I don't know is-how would we know it happened? Will satellite or short range models show it or is it a case of going by local reports?

Water vapour imagery will show it up as a very dark small area of dry air near the tip of the occlusion.

DOCARCH

MJohnston wrote: »

Anyone know if the Kinsale Energy buoy listed here:
https://www.met.ie/latest/buoy.asp
Is an actual buoy, or are they using the same elevated data as the weather station there?

Not a buoy. As far as I am aware station is at approx. 100m over sea level.

MJohnston

Anyone know if the Kinsale Energy buoy listed here:
https://www.met.ie/latest/buoy.asp
Is an actual buoy, or are they using the same elevated data as the weather station there?

Discodog

What's the barometric at the centre ? Too many isobars for my eyesight

Meteorite58

flaneur

It doesn't appear to be all that far west on Sat24

patneve2

https://en.sat24.com/en

Quite impressive-looking on sat24. Looks like it will seriously pack a punch in some areas. Expecting a 120/130 gust around these parts...160/170 in the SW

MJohnston

M3 Buoy data of interest:

M5 will also be worth watching as an indicator of eastward extension