Extratropical Storm Ophelia - Technical Analysis Only - MOD NOTE post #1

M.T. Cranium · 11-10-2017 7:52pm #1

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.

JCX BXC · 11-10-2017 7:55pm

Have only realised the potential severity of this now! As I've said in the other thread, I hope nothing too severe or damaging comes about but the weather enthusiast inside me is jumping for joy at the thought of some actual weather!

At a minimum, it will be somewhat interesting on here! Thanks in advance for anyone who will supply information, Meteorite, Syran, Oscar Bravo and M.T, don't let us down!

Meteorite58 · 11-10-2017 8:08pm

This is the ECM 12Z MT is mentioning. 5 Days out so adjustments to track and intensity to follow no doubt but certainly looks like a possibility of a significant event.

Meteorite58 · 11-10-2017 8:11pm

Just for tasters...

JCX BXC · 11-10-2017 8:14pm

Am I seeing things or does that suggest 179km/h gusts over the dingle peninsula?

M.T. Cranium · 11-10-2017 8:24pm

You are not seeing things, but be aware that the average forecast error at 120h is on the order of 200-300 miles so those winds could hit anywhere this actually goes.

For example, when Irma was five days out from Florida, the track was predicted to be near the east coast, by event time that had shifted 150 miles west to the Keys and west coast, then it actually came in about 30-50 miles east of the late guidance.

Something like that same range of uncertainty exists here, with the added wrinkle of Ophelia's current small size which makes five day forecasts somewhat more uncertain than if we were dealing with a large cat-4 west of Bermuda heading towards Europe.

On the other hand, when you look at the large scale set-up, where else is this likely to go, it's going to ride up the thermal gradient between a cold central Atlantic and a warm south-central Europe.

Meteorite58 · 11-10-2017 8:24pm

Looks a bit extreme, here is the mean wind speed chart for 16.00, the center of the ex tropical storm just off the Dingle Peninsula on this run so one would expect the strongest winds around its SE / NE quadrant. Long long way off yet to be certain how this will pan out.

ninebeanrows · 11-10-2017 8:29pm

A very interesting synoptic evolution - certainly not a set up we are used to - will be fascinating to see how it evolves.

Meteorite58 · 11-10-2017 8:30pm

The 12Z GFS on a very similar track and intensity as the ECM

Gusts

Oscar Bravo · 11-10-2017 8:33pm

JCX BXC looking forward to your TAF updates that day!

Meteorite58 · 11-10-2017 8:36pm

The ARPEGE showing a bit track more W and arriving earlier, not often you see the models so close to each other 4 / 5 days out.

squarecircles · 11-10-2017 8:59pm

What's the protocol with regards naming extra tropical storms that had originally been named hurricanes.If it impacts Ireland will it be become Storm Brian or remain Ex- Ophelia ?

Reckless Abandonment · 11-10-2017 8:59pm

Excellent. Finally some interesting weather. But from following the hurricane season the other side of the Atlantic, one thing I've seen time and time again is these storms never end up where the models are saying they will this far out. But really looking forward to the rollercoaster

squarecircles · 11-10-2017 9:05pm

After moving past Spain, forecasters expect Ophelia to come quite close to the Irish coast as a strong storm on Monday.

Businessinsider.com

11-10-2017 9:08pm

squarecircles wrote: »

What's the protocol with regards naming extra tropical storms that had originally been named hurricanes.If it impacts Ireland will it be become Storm Brian or remain Ex- Ophelia ?

Because this storm had tropical origins, they'll keep the name.

Poker Face · 11-10-2017 9:08pm

Flying from Dublin at 2pm on Monday to USA, should I be getting worried??

HighLine · 11-10-2017 9:13pm

Is it worth considering how many similar Atlantic systems approached Ireland last year only to peel off north at 1-2 days out?

Donegal Storm · 11-10-2017 9:34pm

Poker Face wrote: »

Flying from Dublin at 2pm on Monday to USA, should I be getting worried??

Just keep an eye on things here and on met.ie for now, its still nearly 5 days away and likely won't be as bad as models are currently showing. Still no guarantee it'll even be a direct hit for us

11-10-2017 9:40pm

Officially a hurricane now:

5:00 PM AST Wed Oct 11
Location: 30.0°N 36.1°W
Moving: E at 3 mph
Min pressure: 990 mb
Max sustained: 75 mph

squarecircles · 11-10-2017 9:46pm

HighLine wrote: »

Is it worth considering how many similar Atlantic systems approached Ireland last year only to peel off north at 1-2 days out?

I doubt many were extra tropical lows or had such an irregular synoptic evolution as this one with such strong model consensus.

Floki · 11-10-2017 10:00pm

squarecircles wrote: »

I doubt many were extra tropical lows or had such an irregular synoptic evolution as this one with such strong model consensus.

Add in they were coming in from our west and any nudge north was always going to miss us.
This is coming from the south and the natural nudge north won't stop it from hitting us.

JCX BXC · 11-10-2017 10:04pm

Poker Face wrote: »

Flying from Dublin at 2pm on Monday to USA, should I be getting worried??

As we don't know the exact timeframe or positioning it's impossible to tell (too far out), I wouldn't worry yet. If it comes to it, you could be delayed a day (or possibly 2) but that's just the nature of flying!

11-10-2017 10:08pm

Heres the latest NHC 5 day graphic chart (not often one uses an NHC chart with regards to Irish weather!). The track has shifted eastward compared to the previous one.

I've done a screen shot instead of linking directly to the chart itself as these will update. A different chart will look odd if people want to read back over the thread in the future.

adam240610 · 11-10-2017 10:15pm

Gonna follow this, interesting

M.T. Cranium · 11-10-2017 10:17pm

Keep in mind that the times shown on NHC charts are for eastern North America. Their position at 2 p.m. Monday is for 18z (it's 2 p.m. Atlantic Standard Time which is the same as Eastern Daylight Time). So that's actually 7 p.m. Irish summer time.

squarecircles · 11-10-2017 10:27pm

https://mobile.twitter.com/metoffice/status/918131522607239168/video/1

sdanseo · 11-10-2017 10:31pm

Two firsts in that image. First time I've ever seen a "H" on an NHC chart that far east, or an "S" anywhere over land in Europe. There's one thing getting remnants - having something organised enough to still be officially known as a tropical storm is much rarer.

Oscar Bravo · 11-10-2017 10:32pm

Presenter Aidan McGivern goes through how the computer models are dealing with it https://www.facebook.com/metoffice/videos/10155244957849209/

Oscar Bravo · 11-10-2017 10:35pm

Also coming up on 30 years since this

Meteorite58 · 11-10-2017 10:43pm

The UKMO 12Z take on it .

ronnie3585 · 11-10-2017 10:48pm

Latest NHC charts;

Meteorite58 · 11-10-2017 10:52pm

From the NHC

DISCUSSION AND 48-HOUR OUTLOOK

At 500 PM AST (2100 UTC), the center of Hurricane Ophelia was
located near latitude 30.0 North, longitude 36.1 West. Ophelia is
moving toward the east near 3 mph (6 km/h). A slow northeast drift
is expected tonight and tomorrow, followed by an acceleration
toward the east-northeast or northeast.

Maximum sustained winds are near 75 mph (120 km/h) with higher
gusts. Some strengthening is possible over the next 48 hours.

Hurricane-force winds extend outward up to 25 miles (35 km) from the
center and tropical-storm-force winds extend outward up to 70 miles
(110 km).

The estimated minimum central pressure is 990 mb (29.24 inches).

https://twitter.com/convectivewx/status/918226602198265861

https://twitter.com/MattHugo81/status/918198033480912898

Floki · 11-10-2017 10:56pm

Oscar Bravo wrote: »

Also coming up on 30 years since this

That storm was the 16th October 1987.
Our storm forecast for the 16th October 2017.

30 year anniversary.
Happy anniversary everyone!

star gazer · 11-10-2017 10:59pm

Hurricane Ophelia:

Minimum central pressure 990mb, max sustained winds 120km/h and moving East at 6km/h. 1,200km South West of the Azores.

NHC Discussion

Since it isn't clear exactly how strong Ophelia is, the intensity
forecast is low confidence. All of the intensity guidance indicates
that strengthening is likely for the next 24 to 36 hours, however
the near stationary motion of the hurricane could induce some
upwelling and limit the extent to which the hurricane may
strengthen. Around 72 hours, the shear should begin to increase
substantially as Ophelia begins to interact with the approaching
trough, and extratropical transition will likely begin, accompanied
by a broadening of the wind field and a gradual decrease of the
maximum winds. The global models indicate that this process will
complete by 96 h. The new NHC intensity forecast is slightly higher
than the previous forecast, but lies on the lower end of the
intensity guidance for the first 72 h. It is near the consensus
aids thereafter.

Meteorite58 · 11-10-2017 11:01pm

I think we are all a bit skeptical of getting extreme weather in Ireland but this seems to be shaping up to be the real thing. Track will be everything. When you have the NHC / NOAA putting out guidance like above it is definitely time to sit up and take notice.

mNPEOE9.png?1

11-10-2017 11:06pm

18Z GFS.

Meteorite58 · 11-10-2017 11:08pm

sdanseo · 11-10-2017 11:09pm

It's almost as if all the models have gone and asked the NHC what they think.

server down · 11-10-2017 11:33pm

Is this storm considered to be ex hurricane on Sunday merely because it has left the tropics, or because it will weaken, or do other factors come into play?

Could it have hurricane speed winds?

Meteorite58 · 11-10-2017 11:35pm

This is interesting as ex Tropical Ophelia phases with the trough on Sun evening

https://twitter.com/RyanMaue/status/918234156743712768

https://twitter.com/RyanMaue/status/918235494533746689

fYGKoJI.gif?1

fraxinus1 · 11-10-2017 11:41pm

This is worrying. If this materialises then we need to prepare for major damage and fatalities. I'm cancelling a drive to Galway planned for early next week and getting in supplies as power will be lost. I'm warning folk.

tomcosgrave · 11-10-2017 11:41pm

Have to say I'm sceptical. Have been looking at this system since it formed and especially since it started to head east - firstly it was aimed at North Africa. Then Spain. Then France yesterday. Now Ireland. My guess is the models will update and it will head towards Iceland and will miss Ireland.

Donegal Storm · 11-10-2017 11:50pm

fraxinus1 wrote: »

This is worrying. If this materialises then we need to prepare for major damage and fatalities. I'm cancelling a drive to Galway planned for early next week and getting in supplies as power will be lost. I'm warning folk.

It's still nearly 5 days away, no point cancelling anything yet, theres every chance it'll just end up a typical windy day

George Sunsnow · 11-10-2017 11:53pm

server down wrote: »

Is this storm considered to be ex hurricane on Sunday merely because it has left the tropics, or because it will weaken, or do other factors come into play?

Could it have hurricane speed winds?

Yes it could have hurricane aka force 12 speeds
Whether they’re in Ireland or not is debatable but looking likely

Oscar Bravo · 11-10-2017 11:58pm

Joanna donnelly on Radio 1 just now saying that more or less its been hyped in the media and that it will more than likely just a wet and windy episode however they will be keeping an eye on it. she perhaps should of said nout until a day or two more passes.

Meteorite58 · 12-10-2017 12:00am

Met Eireann remaining calm : Current indications suggest a stormy day for Monday is possible, but uncertainty on the detail remains, due to the nature of the track of the Atlantic storm system. The situation will be monitored throughout the weekend but at the moment it looks like it will be a windy day with further spells of rain.

The GFS showing weaker winds than the ECMWF, usually the other way round.

squarecircles · 12-10-2017 12:14am

Oscar Bravo wrote: »

Joanna donnelly on Radio 1 just now saying that more or less its been hyped in the media and that it will more than likely just a wet and windy episode however they will be keeping an eye on it. she perhaps should of said nout until a day or two more passes.

Isn't that her style generally, blaze,about this kind of stuff.

Meteorite58 · 12-10-2017 12:14am

For the record, can see how the ECM is showing much stronger winds.

Yr0MXYG.png?1

Note 850hPa winds

VKUz9rF.jpg?1

M.T. Cranium · 12-10-2017 1:15am

Ophelia looks better organized and it may be as strong as 80-90 knots (next update due around 0400h). I don't mean to imply this would lead to a stronger low near Ireland, the ECM has pretty much maxed out that potential.

Latest position about 30.0 N and 35.6 W.

George Sunsnow · 12-10-2017 1:25am

M.T. Cranium wrote: »

Ophelia looks better organized and it may be as strong as 80-90 knots (next update due around 0400h). I don't mean to imply this would lead to a stronger low near Ireland, the ECM has pretty much maxed out that potential.

Latest position about 30.0 N and 35.6 W.

I presume MT that the NHC doesn’t overfly hurricanes this Far East or on this kind of track,so we’ll be without their handy eye data?

M.T. Cranium · 12-10-2017 1:55am

They mentioned not flying into this storm earlier today, but their satellite techniques should be fairly reliable, maybe the UK or France could get their hands on a dropsonde and get a reading on Saturday. If the ECM is right there's an ocean buoy in its path for Sunday night's readings.

The 1987 under-prediction (for England) was mostly due to the failure of forecasting models to pick up on the rapid deepening, you can see from Michael Fish's 24-48h maps that the wave was expected to deepen gradually as it crossed England but instead it bombed out in the first six hours and reached the eventual forecast central pressure somewhere near Coventry instead of Bergen. That made all the difference.

With this one, we're in the opposite situation, how long will this low retain a deep central pressure that we should know within 5 mbs by Saturday.

Extratropical Storm Ophelia - Technical Analysis Only - MOD NOTE post #1

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