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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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spookwoman

Nice electrical storm on the north tip of the center.

https://en.sat24.com/en

Rougies

To those thinking it's going to miss us to the west, the path is forecast to veer more NE soon.

It may go more more west than forecast too of course.

Meteorite58

The Arome is a good Hi Res model ( seems to be showing lower wind speeds than previous runs and shifting the strongest winds away from Kerry on this one, could be an outlier, have to compare a few models and get an average, Similar mean speeds to the HIRLAM )

Mean

Gust

Autochange

Rougies wrote: »

To those thinking it's going to miss us to the west, the path is forecast to veer more NE soon.

What does the red bar running through the centre of the country mean?

Gremlin

Rougies wrote: »

To those thinking it's going to miss us to the west, the path is forecast to veer more NE soon.

That's quite interesting. I'd be amazed if at this late stage the models were that far off. If it takes that little kink that is indicated by the models then it would be a remarkable prediction.

Monkeynut

Autochange wrote: »

What does the red bar running through the centre of the country mean?

at the top it has different models. its the nhc model which is red.

lucernarian

spookwoman wrote: »

Nice electrical storm on the north tip of the center.

https://en.sat24.com/en

I also noticed a dry slot in the immediate western vicinity of what's left of the "core", wonder what that entails.

I'd call it now and say that Cork Airport will see a gust of 150 kph, Dublin Airport about 120kph, Shannon might see 140kph and Knock about 110-120kph. I'm hoping the all-Ireland red alert was overkill, based on the latest forecasts, but it's too dangerous to start equivocating at this late stage

Rougies

Autochange wrote: »

What does the red bar running through the centre of the country mean?

That's the NHC forecast, this chart:

http://www.nhc.noaa.gov/storm_graphics/AT17/refresh/AL172017_5day_cone_with_line_and_wind+png/204644_5day_cone_with_line_and_wind.png

Kermit.de.frog

In case anyone is in any doubt of the potential we are facing.

IMG_0992.PNG.c6c4a6c0e54f5fa80945d61238391b41.PNG

Rougies

Gremlin wrote: »

That's quite interesting. I'd be amazed if at this late stage the models were that far off. If it takes that little kink that is indicated by the models then it would be a remarkable prediction.

Yeah it's amazing how accurately the models can predict these things of such a massive scale. Earlier it looked like she was going to miss us to the east but changed course exactly as modeled.

Meteorite58

Is that a center opening up on the last frame

Super-Rush

Interesting projected track here.

https://www.windy.com/?46.514,-9.009,5,a:CCqGU

Cantona's Collars

Meteorite58 wrote: »

Is that a center opening up on the last frame

Maybe the Jetstream influencing it?

Hastentoadd

Cantona's Collars wrote: »

Maybe the Jetstream influencing it?

I asked the same question. No answer

BoatMad

lucernarian wrote: »

I also noticed a dry slot in the immediate western vicinity of what's left of the "core", wonder what that entails.

I'd call it now and say that Cork Airport will see a gust of 150 kph, Dublin Airport about 120kph, Shannon might see 140kph and Knock about 110-120kph. I'm hoping the all-Ireland red alert was overkill, based on the latest forecasts, but it's too dangerous to start equivocating at this late stage

150 is a hell of a gust

I don't see from the models any justification in downgrading the storm

JCX BXC

Not much new in the TAF's at midnight.

Dublin

No real change to note, max gust 50kts

Shannon

Max gust has been revised up to 65kts and heavy rain added to the forecast.
TEMPO 1611/1614 13040G65KT 3000 +RA

Cork

Max gust still at 70kts, heavy rain added to forecast.
TEMPO 1611/1614 18050G70KT 3000 +RA

Knock

Max gust still 50kts, heavy rain added to forecast
TEMPO 1612/1618 3000 +RA BKN007

Meteorite58

ARPEGE 18Z ( most recent )

In case anyone is in any doubt of the potential we are facing.

Yes the ARPEGE has been very consistent, one of the most reliable I think, often outperforms the GFS )

Mean speeds

Gusts

spookwoman

Cantona's Collars wrote: »

Maybe the Jetstream influencing it?

something happening

[Deleted User]

So the red / purple is bad yes?

Oscar Bravo

M!Ck^ wrote: »

So the red / purple is bad yes?

spot on

Rougies

Hastentoadd wrote: »

I asked the same question. No answer

There's no simple answer to the question in context of a possible eye forming. Yes, the jetstream is influencing it. The jetstream is what's bringing it to Ireland right now

MJohnston

M!Ck^ wrote: »

So the red / purple is bad yes?

Please look at the scale shown at the bottom - it is in km/h which is stated in the (French) title in blue at the top left.

Middle Man

spookwoman wrote: »

something happening

Looks like progress is much faster than predicted...

lucernarian

Meteorite58 wrote: »

Is that a center opening up on the last frame

On an equally dramatic note, the last frame shows a somewhat westerly component to its movement?!

Edit: a bit of a nowcast but I'd up the max forecast gust for Shannon airport to 140 kph now compared to what I posted not long ago. And possibly lower it for Dublin to 100-110 kph. Also knock/Belfast to reach 130 kph gusts.

Gaoth Laidir

Sea area forecast, mentions Force 11, possibly Force 12 on southern coasts before noon.

Issued at 22:00 on 15-Oct-2017

Sea Area Forecast until 0000 Tuesday 17 October 2017

Issued at 0000 Monday 16 October 2017

Gale Warning: In Operation

Small Craft Warning: See Gale Warning

Meteorological Situation at 2100:A deep depression (ex hurricane Ophelia) of 973 hPa centred 300 miles northwest of Iberia tracks rapidly northeastwards and will cross Ireland during Monday. Its associated frontal systems and extremely strong wind flows will affect the country.

Forecast for Irish coastal waters from Malin Head to Howth Head to Valentia and the Irish Sea
Wind: Increasing southeast gale force 8 imminent; further increasing violent storm force 11 during the forenoon (possibly Force 12 on south coasts), veering southwest in the evening.
Weather: Heavy and persistent rain.
Visibility: Moderate overnight, decreasing poor tomorrow.

Forecast for Irish coastal waters from Valentia to Erris Head to Malin Head
Wind: Northeast force 6, becoming cyclonic variable Gale 8 to storm force 10 during the forenoon.
Weather: Occasional heavy rain
Visibility: Good tonight, becoming moderate to poor in rain.

Outlook for a further 24 hours until 0000, Wednesday, 18 October 2017: Gale to storm force westerly winds gradually easing strong. Rain clearing to squally showers.

Next update before 0700 Mon 16-Oct-2017

server down

The ARPEGE models seems to hammer the east. And yet the taf has low enough gusts for Dublin.

sdanseo

That hole in the middle is an eye. How long lived it'll be is anyone's guess, but there's no mistaking it.

Paully D

Middle Man wrote: »

Looks like progress is much faster than predicted...

A good thing IMO in terms of people realising the seriousness of what is ahead and not making people go to work etc.

It would be ideal if this started hitting no later than commute times for that reason IMO.

bloopy

sdanseo wrote: »

That hole in the middle is an eye. How long lived it'll be is anyone's guess, but there's no mistaking it.

What does that mean if it is an eye?
Sorry for the questions. Been following this thread for the last day or two and it seems this storm keeps surprising people.

JCX BXC

Worth noting that Belfast international airport is forecasting a gust of 60kts, so either they're over estimating or Irish airports are grossly underestimating.