nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

Child Item

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.

Find more posts tagged with

Quick Links

Comments

Kermit.de.frog

ICON 12z

Gaoth Laidir

Hurricane Ophelia Discussion Number 26
NWS National Hurricane Center Miami FL AL172017
1100 AM AST Sun Oct 15 2017

After displaying a distinct eye overnight, recent satellite imagery
indicate that the cloud pattern of Ophelia has begun to deteriorate
and the eye is no longer apparent. The deep convection is also
weakening fast and consequently, Dvorak numbers have begun to
decrease while analysts are trying to lower them as much as the
technique allows. The best estimate of the initial intensity is 80
kt. Given the cold waters of about 20 deg C, and the strong shear,
Ophelia is forecast to gradually weaken and become a post-tropical
cyclone later today.

They're trying to lower them? What does that mean? Sound like they're trying to make it not look as bad as it is!

TheMilkyPirate

star gazer wrote: »

That H coming into Ireland isn't something you see every day.

That's a direct hit for the south-east. I work in rosslare harbour with a commute from Wexford town I'm really starting to think about what I'm going to do.

sdanseo

thomasj wrote: »

https://twitter.com/metofficestorms/status/919575455229009920

Wording it that way is irresponsible. Implies to the uninitiated that situation improving.

It's not really. Still a high Cat 1 close to Cat 2 and forecast to hit Ireland with the same winds as all along. (65kt is hurricane force)

24H 16/1200Z 51.5N 9.5W 65 KT 75 MPH...POST-TROP/EXTRATROP

thomasj

https://twitter.com/metofficestorms/status/919575455229009920

JanuarySnowstor

Well its a direct hit now!!

star gazer

That H coming into Ireland isn't something you see every day.

sdanseo

Another jump east in track. More counties surely must now be headed for red warnings.

Discodog

M.T. Cranium wrote: »

Having reviewed a visible satellite loop I would say the storm is still tropical and the eye has reduced in diameter to about 5 miles (current position 40N 16W). It appears to be making the turn north in the last three hours.

The waters ahead are not all that cold either, near 20 C in Biscay. And the strong southerly flow will bring a slight warming further north.

This storm may continue to be a hybrid like Sandy up until landfall.

Storm surge issues should be taken very seriously on this track (from SSW). You know the terrain better than me, but any coastal villages with exposure to the south or southwest may have inundations up to 3 metres above normal high tide and powerful waves could be bringing in debris from beaches.

Luckily the tides are about a metre below their maximums. Having said that, the coastal destruction a few years ago also didn't coincide with the highest tides

star gazer

HAZARDS AFFECTING LAND
WIND: Gale-force winds are expected to begin across southern
Ireland by early Monday morning and gradually spread northward
across the country during the day. Hurricane-force winds are
expected to reach the southern portions of Ireland by Monday
afternoon and spread inland across the country into Monday night.
Preparations to protect lives and property should be rushed to
completion by this afternoon.

Wind speeds atop and on the windward sides of hills and mountains
are often up to 30 percent stronger than the near-surface winds
indicated in this advisory, and in some elevated locations could be
even greater.

RAINFALL: Ophelia is expected to produce rainfall amounts of 2 to
3 inches (50 mm to 75 mm) with isolated totals near 4 inches (100
mm) through Tuesday across western Ireland and Scotland. Across
eastern Ireland, rainfall amounts will average around 1 inch (25 mm)
or less.

STORM SURGE: A dangerous storm surge is expected to produce
significant coastal flooding near and to the east of where the
center of the post-tropical cyclone makes landfall. Near the coast,
the surge will be accompanied by large and destructive waves.

Advisory 26

star gazer

Hurricane Ophelia Discussion Number 26
NWS National Hurricane Center Miami FL AL172017
1100 AM AST Sun Oct 15 2017

After displaying a distinct eye overnight, recent satellite imagery
indicate that the cloud pattern of Ophelia has begun to deteriorate
and the eye is no longer apparent. The deep convection is also
weakening fast and consequently, Dvorak numbers have begun to
decrease while analysts are trying to lower them as much as the
technique allows. The best estimate of the initial intensity is 80
kt. Given the cold waters of about 20 deg C, and the strong shear,
Ophelia is forecast to gradually weaken and become a post-tropical
cyclone later today.

Satellite fixes indicate that Ophelia is moving toward the
north-northeast or 025 degrees at 33 kt, well embedded within the
fast flow ahead of a large trough. This pattern is expected to
persist, so no significant change in track is anticipated before
dissipation. Guidance continues to be in remarkably good agreement
and most of the models bring a weakened post-tropical Ophelia to the
southern coast of Ireland Monday morning (AST or Miami time).
Thereafter, the cyclone will continue over northern Great Britain
until dissipation.

Strong winds and rains associated with Post-Tropical Ophelia will
arrive well in advance of the cyclone center. Residents in those
locations should consult products from their local meteorological
service for more information on local impacts.

KEY MESSAGES:

1. Ophelia is expected to be a powerful extratropical cyclone with
hurricane force winds while it moves near Ireland and the United
Kingdom. Direct impacts from wind and heavy rain in portions of
these areas are likely, along with dangerous marine conditions. For
more details on the magnitude, timing, and location of impacts from
post-tropical Ophelia, residents in Ireland should refer to products
issued by Met Eireann, and residents in the United Kingdom should
refer to products issued by the Met Office.

FORECAST POSITIONS AND MAX WINDS

INIT 15/1500Z 41.6N 16.0W 80 KT 90 MPH
12H 16/0000Z 46.0N 13.0W 75 KT 85 MPH...POST-TROP/EXTRATROP
24H 16/1200Z 51.5N 9.5W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 17/0000Z 57.0N 5.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
48H 17/1200Z 60.5N 1.5W 35 KT 40 MPH...POST-TROP/EXTRATROP
72H 18/1200Z...DISSIPATED

$$
Forecaster Avila

Discussion 26

hatrickpatrick

Slimity wrote: »

Hopefully they go red tonight then, as the morning will be too late for preparations.

NCHurricane2009 posted a blog update last night in which he said "preparations in Ireland should be completed within the next 36 hours", which would mean that tonight is already pushing it a bit

Meteorite58

https://twitter.com/NASA_SPoRT/status/919568065871994880

Slimity

DOCARCH wrote: »

In time, I think they will end up with red warning.

Hopefully they go red tonight then, as the morning will be too late for preparations.

DOCARCH

Slimity wrote: »

Based on the Arpege projections should more counties not be in the red warning? Wicklow, Dublin, Kildare?

In time, I think they will end up with red warning.

Slimity

Meteorite58 wrote: »

An idea of what gusts could be like tomorrow. Cant get any more of the map on this model.

Based on the Arpege projections should more counties not be in the red warning? Wicklow, Dublin, Kildare?

Mod Note: good to edit out the pics to save space, thanks.

hatrickpatrick

Anyone who doesn't read Jeff Masters' blog at Weather Underground should start doing so now, he gives an incredible in-depth analysis of the science behind these events and unlike most websites, the comments section tends to be full of weather enthusiasts who know what they're talking about like here, as opposed to mindless political crap.

https://www.wunderground.com/cat6/ophelia-hits-category-3-destructive-winds-tap-ireland

I would also highly recommend NCHurricane2009's comments, as he goes into the wider atmospheric context which gives rise to tropical storms each day, and has correctly called many tropical waves over the years as future hurricanes days before they have been picked up by the NHC:

https://disqus.com/by/nchurricane2009/

Meteorite58

An idea of what gusts could be like tomorrow. Cant get any more of the map on this model.

ninebeanrows

Fairly tight gradient!!

M.T. Cranium

Any further questions about local impacts, post on the other thread, this one should be reserved for more general discussion of the storm. I know it's confusing now that there are level 3 tags on both threads, but I will assist by not answering posts of that nature here, while answering them there (if I can).

Rougies

Donegal Storm wrote: »

Nothing on the met website yet but Meteoalarm suggesting that they've issued an orange rainfall warning now as well with 40mm+ possible, Joanna Donnelly said on the farming forecast that they'd be issuing one this afternoon

It's on the MetÉ warnings page.

STATUS ORANGE

Rainfall Warning for Connacht, Wexford, Donegal, Clare, Cork, Kerry, Limerick and Waterford

Heavy rain at times on Monday with some local flooding, especially in coastal areas. 40+ mm possible.
Issued:
Sunday 15 October 2017 14:00
Valid:
Monday 16 October 2017 09:00 to Monday 16 October 2017 21:00

STATUS YELLOW

Rainfall Warning for Dublin, Carlow, Kildare, Kilkenny, Laois, Longford, Louth, Wicklow, Offaly, Westmeath, Meath, Cavan, Monaghan and Tipperary

Heavy rain at times on Monday with some local flooding, especially in coastal areas. 25 to 40 mm possible.
Issued:
Sunday 15 October 2017 14:00
Valid:
Monday 16 October 2017 09:00 to Monday 16 October 2017 21:00

https://www.met.ie/nationalwarnings/default.asp

crustybla

I've been reading the wrong thread for ages, this one if far more interesting.

Donegal Storm

Nothing on the met website yet but Meteoalarm suggesting that they've issued an orange rainfall warning now as well with 40mm+ possible, Joanna Donnelly said on the farming forecast that they'd be issuing one this afternoon

http://www.meteoalarm.eu/en_UK/1/0/EU-Europe.html

Doesn't look like it'll be anything too severe but combined with the winds it'll give very hazardous driving conditions

M.T. Cranium

Drumpot wrote: »

Does the storm surge apply to middle/northern east coast ? I am in bettystown and my estate has flooded before in conditions that weren't as bad as this . High tide (due at 10pm tomorrow) followed by prolongued rain caused the problem. I am wondering if my estate needs to be on alert and if we should contact the council!

See what they're planning for sure, but my estimate for your location would be closer to 1.5 metres and perhaps enough before high tide that it won't be quite as bad as it might be (assuming the time you quote is accurate). Your peak in surge will be around 6 or 7 p.m. while tide is still building so you might just get an early peak and a prolonged high tide that reaches 0.5 to 1.0 metres above expected levels at that point.

Oneiric 3

M.T. Cranium wrote: »

I always think Iberia looks like a human face looking west, and today there's quite a sight.
this.

Interesting. Weirdly, I always see Iberia as a face looking south as opposed to west. It's all about personal interpretation I guess.

Meteorite58

Mod Note

This thread is for technical analysis only please - there’s a general discussion thread available for everything else

Thanks

my3cents

M.T. Cranium wrote: »

goat2 ... your question needs a more precise location but I think the strongest winds at most locations between Bantry Bay and Roches Point will be SSW to SW, from Bantry Bay around to Valentia more of a mix of directions depending on exact track of the centre.

question about highest storm surge, technically that is the time when water level is displaced highest vs expected from tide tables, but public will perceive it to be at high tide, and in any case it appears that these are similar, IIRC somebody posted them in the 3-4 p.m. range along the south coast.

Storm surge is likely to peak whenever the centre of the low is to your west and that appears to be 2-3 p.m. for most locations along the south coast.

It's only about two days to new moon by late Monday, astronomical tides must be fairly close to peak I would imagine within a foot?

South coast at Dungarvan they are just over a foot below the highest for the month.

http://www.ukho.gov.uk/easytide/EasyTide/ShowPrediction.aspx?PortID=0756&PredictionLength=7 (start date is the date you click it so updates).

M.T. Cranium

goat2 ... your question needs a more precise location but I think the strongest winds at most locations between Bantry Bay and Roches Point will be SSW to SW, from Bantry Bay around to Valentia more of a mix of directions depending on exact track of the centre.

question about highest storm surge, technically that is the time when water level is displaced highest vs expected from tide tables, but public will perceive it to be at high tide, and in any case it appears that these are similar, IIRC somebody posted them in the 3-4 p.m. range along the south coast.

Storm surge is likely to peak whenever the centre of the low is to your west and that appears to be 2-3 p.m. for most locations along the south coast.

It's only about two days to new moon by late Monday, astronomical tides must be fairly close to peak I would imagine within a foot?

Hooter23

Gaoth Laidir wrote: »

Side-by-side comparison of Arpege and Hirlam mean winds tomorrow at 13Z. The bottom right of each image shows the max winds on that chart, so the Arpege shows 66 knots out to sea south of Cork while the Hirlam has 61 knots. A few knots less along the coast in each case.

I notice how the first chart has violent winds alot closer to the center of the storm which would put parts of the west in danger as it moves north....

_Kaiser_

TheMilkyPirate wrote: »

Sure,

https://weather.us/forecast/2960964-wexford/ensemble/euro/wind-gusts

Ouch! According to that I can expect 44 mph winds (80mph gusts) from about 12 noon and continuing to be pretty bad until midnight