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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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Gaoth Laidir

Latest NWS 48-hr forecast for 00Z Monday.

squarecircles

Dead calm today,it will make the wind all the more noticeable come Monday

Donegal Storm

Its likely to be a fairly typical Irish storm for most people I'd think, if your house has survived the likes of Darwin and countless other winter storms then I wouldn't worry about structural damage. Coastal Cork up to Galway on current guidance is the only area that will experience true storm force winds, maybe Waterford and Wexford as well if the track shifts slightly.

The main danger this time is that trees are still in leaf and the wind is from an unusual direction so a lot of potential for falling trees which could happen just about anywhere

patneve2

Off topic but GFS now showing a storm just as nasty as Ophelia for next weekend :eek:

firemansam4

Gaoth Laidir wrote: »

Yes, so Cat 1 winds looking unlikely at the moment based on that.

I think sustained Cat1 winds looking unlikely but looking like 100 MPH+ gusts at the tip of Cork, Kerry could be possible with sustained 60 MPH winds, this would be more than your usual winter gales, I think for the rest of the country its not going to be much more though, of course just as a guess at this stage.

Wanderer78

patneve2 wrote: »

Off topic but GFS now showing a storm just as nasty as Ophelia for next weekend :eek:

spotted that alright

frozenfrozen

neat

Villain

Trying to call the finer details of this event wil he difficult right up to Monday morning.

I don't know what drugs ARPEGE is on but I hope it has a come down soon!

Harry Palmr

How many think climate change would mean the potential for a succession of autumn storms?

lucernarian

This is the problem with more extreme events like this for Ireland... Still very hard to get the specifics right 3 days out. I hope people understand that the worst case scenario has to be prepared for, and a "hurricane forecast for Ireland" doesn't mean Johnny Smith in Tullamore will see much more than a normal wet and windy day out of it. Even right now it's clear that the very southern coast will get the worst of it, much like how Darwin was a terrible storm but had little impact on much of the country.

I read about Hurricane Faith, reaching past the Faeroe Islands in 1966... Don't know how that's even possible. It's a good reminder to not write off Orphelia until we're pretty sure with the forecasts. I don't know how good observation reports and buoys are in that part of the Atlantic, but I suspect they're not as widespread as what's in the Carribbean/Gulf.

fraxinus1

pad199207 wrote: »

Dont feed it man

What do to mean ' Don't feed it man'? I along with 99.9% of the population rely on Met Eireann for my weather forecasts. Now as it stands they have not issued anything other than an advisory. We are apparently only 48 hours from what some on here have described as severe and historic. I am not saying they are wrong but to suggest that one is trolling simply by pointing this fact out is unfair. I have not disputed there will be strong winds. But until Met Eireann make a call, I'm remaining on the fence. If they do up there warnings then I will 100% take heed.

flaneur

Harry Palmr wrote: »

How many think climate change would mean the potential for a succession of autumn storms?

Very slightly higher water temperatures equates to an enormous amount of extra energy in the system. Just think of how much energy it takes to raise that volume of water and air 1°

That energy will express itself in wind and storm activity.

firemansam4

Somewhere between 2AM on Monday and 2AM Tue it goes from Hurricane force winds to Tropical Storm force winds acording to this model now

Villain

Met Eireann won't activate weather warnings until closer to the event when forecasting is much more accurate. For now an advisory is all they can do with confidence.

I would expect them to issue warnings tomorrow and based on Darwin in 2014 I'd imagine they will side on the higher side of caution as their change from Orange to Red was very late in the day then.

JanuarySnowstor

They said on thus mornings broadcast they would issue warnings this evening

jasper100

fraxinus1 wrote: »

What do to mean ' Don't feed it man'? I along with 99.9% of the population rely on Met Eireann for my weather forecasts. Now as it stands they have not issued anything other than an advisory. We are apparently only 48 hours from what some on here have described as severe and historic. I am not saying they are wrong but to suggest that one is trolling simply by pointing this fact out is unfair. I have not disputed there will be strong winds. But until Met Eireann make a call, I'm remaining on the fence. If they do up there warnings then I will 100% take heed.

Exactly, until Met Eireann issue warning this stuff is merely speculative and hypothetical.

In the event that specific counties get a level 3 warning tomorrow there is plenty of time tomorrow to tidy away trampolines and wheelie bins, move cars away from trees etc.

luimneachboy

jasper100 wrote: »

Exactly, until Met Eireann issue warning this stuff is merely speculative and hypothetical.

In the event that specific counties get a level 3 warning tomorrow there is plenty of time tomorrow to tidy away trampolines and wheelie bins, move cars away from trees etc.

Theres a few posters here that got darwin spot on and met eireann didnt!! Personally id go with their advice before met eireann

dm09

Question - My cat likes Whiskas but if there's a gale blowing above 30kts she'll only eat tuna .
If I have 3 cats and one pony and it's upgraded to level orange , how many cans of tuna will I need to buy if I'm living above 50'N ?

*Just kidding , Great thread guys :-D

firemansam4

Interesting:

Quote NHC Discussion page:

Hurricane Ophelia Discussion Number 21
NWS National Hurricane Center Miami FL AL172017
500 AM AST Sat Oct 14 2017

Ophelia's 20-nmi-diameter eye has continued to become more distinct
and cloud-free, with the eye temperature now reaching 15 deg C.
Satellite intensity estimates range from T4.5/77 kt from TAFB to
T5.0/90 kt from SAB and T5.5/102 kt from UW-CIMSS ADT. For now, the
initial intensity will remain at 85 kt, which is an average of the
available intensity estimates.

The initial motion estimate is 060/21 kt. Ophelia is embedded within
deep-layer southwesterly flow on the east side of a broad
mid-latitude trough. The global and regional models remain in
excellent agreement on the trough amplifying over the next 3-4 days,
which will cause the hurricane to accelerate toward the northeast at
forward speeds near 30 kt by 48 hours. The tight clustering of the
NHC model guidance, which shows very little cross-track or
along-track spread, increases the confidence in the official track.
As a result, no significant changes were made to the previous
advisory, and the new forecast track remains near the middle of the
guidance envelope, close to the HCCA and TVCX consensus models.

Ophelia is expected to remain in relatively low vertical wind shear
environment for the next 12 hours or so, which should help the
hurricane retain much of its current intensity during that time,
even though SSTs are only going to be 24-25C. However, upper-level
temperatures that are still about 2 deg C cooler than normal, which
will help to create sufficient instability to continue to drive the
development of inner-core convection. By 36 hours or so, the shear
is forecast to increase to 30-40 kt and the troposphere is expected
to become stable as sea-surface temperatures decrease to less than
20 deg C. However, even those SST values are about 2 deg C warmer
than normal for this time of the year. Those above-average ocean
temperatures are forecast to combine with strong baroclinic energy
associated with a potent, negatively tilted, upper-level trough,
causing Ophelia to transition into a powerful extratropical low
pressure system. By 48 hours, the post-tropical cyclone is forecast
to maintain sustained hurricane-force winds as it approaches
Ireland, with stronger winds expected over higher terrain.

Given that Ophelia is forecast to become extratropical, the wind
field should expand, resulting in impacts over portions of the
British Isles regardless of its exact location or strength. By 96
hours, Ophelia should have weakened due to the interaction with
land, causing the surface circulation to become ill-defined, and
dissipation is expected shortly thereafter.

Although the center of Ophelia is not forecast to reach Ireland or
the UK for another 48-60 hours, wind and rain effects will arrive
well in advance of the cyclone center. Individuals in those
locations should consult products from their local meteorological
service for more information on local impacts.

Tropical-storm-force winds are possible throughout the Azores
beginning tonight, primarily due to an approaching cold front.
However, any track deviation to the west could bring stronger winds
associated with Ophelia's circulation to those islands. Interests
in the Azores should refer to products issued by the Azores Weather
Forecast and Watch Center.

KEY MESSAGES:

1. Ophelia is expected to become a hurricane-force post-tropical
cyclone by Monday before 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 14/0900Z 33.9N 28.6W 85 KT 100 MPH
12H 14/1800Z 35.3N 25.4W 80 KT 90 MPH
24H 15/0600Z 38.3N 20.4W 80 KT 90 MPH
36H 15/1800Z 43.0N 16.0W 75 KT 85 MPH...POST-TROP/EXTRATROP
48H 16/0600Z 48.4N 12.5W 75 KT 85 MPH...POST-TROP/EXTRATROP
72H 17/0600Z 57.4N 6.3W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 18/0600Z 63.1N .5W 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 19/0600Z...DISSIPATED

$$
Forecaster Stewart

pad199207

Waiting with such suspense to see what Met Eireann do with the warnings....

[Deleted User]

At 10 am.

pad199207

Deleted User wrote: »

At 10 am.

Jaysus now that is one for the books! :eek:

Donegal Storm

Just to give an idea of what a difference a slight change in track makes, here's two hi res models, one showing a SW/NE track giving severe gusts right across the centre of the country but just a blustery day in Connemara and Mayo with gusts of 70-90kph. The second one shows a more direct southerly track which gives Connemara and Mayo severe gusts above 140kph so almost twice as strong

firemansam4

Donegal Storm wrote: »

Just to give an idea of what a difference a slight change in track makes, here's two hi res models, one showing a SW/NE track giving severe gusts right across the centre of the country but just a blustery day in Connemara and Mayo with gusts of 70-90kph. The second one shows a more direct southerly track which gives Connemara and Mayo severe gusts above 140kph so almost twice as strong

Looks like Kerry are getting it bad either way....

fryup

Deleted User wrote: »

At 10 am.

thats nearly the same position as yesterday, its moving very slowly

..at this rate it'll be this day next week before it hits us

Kermit.de.frog

It's tricky with this one. We are on that margin between some severe weather and typical winter storm.

Some models show more benign conditions than others. We are not there yet in terms of knowing exact intensity.

I don't think red warnings are warranted but certainly amber in the southwest at least would be right for now.

It's then a case of monitoring developments in the next day or so.

MT and everyone here has done a great job too in my opinion.

[Deleted User]

pad199207 wrote: »

Jaysus now that is one for the books! :eek:

Yep. Not often you get a hurricane and Ireland in the same frame.

Den Creed

firemansam4 wrote: »

Looks like Kerry are getting it bad either way....

A Jesus, and its bin day on Monday in Kerry as well

RoisinClare6

It's like a summers day here at the minute.

Its cool seeing all the different charts and graphics. Its quite interesting

iguana

__..__ wrote: »

Trampoline is too big to dismantle.
Im going to leave it out for the craic. Test to see how good i set it up.
If its gone at least it will give me some more space in the garden.

Move it into as sheltered a spot as you can, take the safety nets down and drive crowbars over the legs like giant tent pegs. That's secured it for me through the storms of the last few winters.