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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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TheMilkyPirate

Euro4 looking nasty enough. Id expect widespread coverage of this tomorrow.

Meteorite58

Mod Note : Off topic posts deleted .

Soccarboy11

Copper_pipe wrote: »

So Mallow could get flooded again?

Depends on the storm surge I guess. Usually these things flood from heavy rain but rain isnt expected, but if the surge is big enough it could shoot right up the river, theres no flood defences stopping it. But if the councils aren't already planning with putting out sandbags etc, who knows. Hopefully not. I would doubt mallow would get hit though, thats quite far up.

High tide looks to be around 3PMish Monday in Cobh, which isn't good.

High Tide in Wexford at 5pm on Monday. If it was more SE than S it could be worse (but mid you, the flooding tidal stream is from the south before it enters the harbour)

Cantona's Collars

Maybe someone more qualified could clarify if Ophelia sitting pretty much stationary for the last while has allowed it to suck in the warmth from around it and gain strength, it's unseasonably warm here in Ireland so I'd imagine the source of this warmth coming from the South is feeding this storm even as it moves North.

pad199207

Wow what a tweet

ZX7R

As this hurricane has strengthened into a cat 3 is it possible that it loose less strength and make landfall as a cat 1 hurricane rather than a extratropical storm just wondering

spookwoman

Copper_pipe wrote: »

So Mallow could get flooded again?

Tide times for Kinsale on Monday High Tide 15:44 (3.66m) Garrettstown waves on magic seaweed up to 26ft
Inchdowney up to 30ft

Danno

I have been following this with great interest. It certainly looks set to give Debbie 1961 and Charlie 1987 a run for it's money. Personally I think an evacuation of coastal areas along the south coast should be seriously considered at government level and if they chose to do so, get clearing from midday tomorrow.

star gazer

Wunderground

... As Ophelia reaches Ireland, we can expect winds of 50 – 70 mph are predicted to be slamming into Ireland’s southwest coast, and sustained winds of 40 – 50 mph will likely extend well inland. One concern for Ophelia’s impact on Ireland may be the potential for the ex-hurricane to develop a “sting jet.” This is a current of extra-strong jet stream winds that start out about 3 – 4 km above the surface, then descend over a 3 – 4 hour period. Rain falling into the jet evaporates and cools, causing the winds in the sting jet to accelerate as they reach the ground.
Ophelia is expected to complete the transition to an extratropical storm just off southwest Ireland on Monday morning. As this process unfolds, the wind field of Ophelia will expand, and Ophelia promises to be a damaging wind event for Ireland. Expect widespread tree damage and uprooted trees, damaged roofs, power blackouts, mobile phone coverage interruptions, and flying debris. ...

Lissavane

I'll be interested to see what yr.no predicts when it updates next. Up to now it's forecast for Ireland is reasonably benign.

kub

Copper_pipe wrote:

So Mallow could get flooded again?

It would be a miracle if Mallow gets flooded from a storm surge at sea, considering how far up stream it is on The River Blackwater from where it enters the sea at Youghal.

Cork Harbour has Cobh etc and the City up stream.

RuthieRose

I know we are all talking about lots of wind but how much rain is she bringing? The lakes are fairly full up this end of the country (Cavan). Will flooding become an issue inland too?

Meteorite58

Extended Forecast
Valid: Mon 16 Oct 2017 06:00 to Tue 17 Oct 2017 06:00 UTC
Issued: Sat 14 Oct 2017 18:59
Forecaster: TUSCHY

A level 1 was issued for parts of Ireland, UK and Scotland mainly for severe wind gusts.

... Ireland, W-UK and Scotland...

During the start, a powerful warm seclusion is placed west of the Bay of Biscay with an high-end near BL flow next to the center (850 hPa winds in excess of 50 m/s). Phase diagrams support the idea of an ongoing transformation from tropical to post-tropical during the forecast period although a deep warm-core could persist until this cyclone approaches Ireland during the day from the SW. Intense vertical shear likely results in an enhanced vertical tilt of the warm core betimes but baroclinic dynamics (including a coupled jet configuration) delay any rapid weakening. Numerical guidance still indicates the idea of extratropical transformation (e.g. development of a pronounced vorticiy advection couplet and rapidly increasing baroclinic gradients (fronts) in the surrounding area of the cyclone) but confidence in how fast this transformation occurs remains low.

Between 06UTC and 12 UTC, a surge of dry low-stratospheric air wraps cyclonically around the cyclone's center, probably ending the stage of a potential offshore sting jet event but with an ongoing cold conveyor belt jet event. This jet finally approaches Ireland beyond noon from the SW. This extreme wind field remains confined to the immediate region south of the center and probably avoid of deep moist convection. Hence no level assessment for this event. This scenario is dependant on how fast the extratropical transformation occurs but latest guidance continues to support the painted idea.

This surge continues during the day and the dry air at upper-levels circles the depression's center. Numerical guidance (especially limited area models) show the development of numerous vorticity filaments spreading N/NE. A rapid change of lift and subsidence accompanies this activity (similar to moats in tropical cyclones). In combination with the natural broadening of the depression's wind field during extratropical transformation, the overlap of dry air atop the warm/moist marine layer results in a broad area over E-Ireland, Scotland and W-UK with slim chances for enhanced convection (especially along the interface of the dry slot and the northward fanning warm conveyor belt) . A few convective-allowing models indicate an increase in convection during the noon/afternoon hours in the highlighted area.

Forecast soundings show low LCLs and intense LL shear (30 m/s 0-1 km shear and SRH-1 in excess of 400 m^2/s^2) . This is enough for rotating updrafts with an isolated tornado risk. The limited depth of the CAPE layer (up to 750 hPa) with the temperature in excess of 0°C probably keep the chance for lightning activity on the very low-end side due to lack of substantial graupel. Still a low probability lightning area was added for parts of the level 1, where best chances for sporadic lightning activity exist. Beside the tornado risk, downdrafts may bring severe wind gusts to the BL, which can occur well inland.

Right now the gradient wind risk will dominate the general severe risk and hence we will stay with a broad level 1 area for now. With respect to the further development of the hurricane and a potential delayed extratropical transformation (given current intensity boost to a major Cat.3 hurricane), a decrease or increase of convective probabilities is well possible. Please stay informed with your national weather agencies.

km79

Lissavane wrote: »

I'll be interested to see what yr.no predicts when it updates next. Up to now it's forecast for Ireland is reasonably benign.

Yeah was wondering the same
What model do they work off?

munsterlegend

Danno wrote: »

I have been following this with great interest. It certainly looks set to give Debbie 1961 and Charlie 1987 a run for it's money. Personally I think an evacuation of coastal areas along the south coast should be seriously considered at government level and if they chose to do so, get clearing from midday tomorrow.

Yeah it's certainly looks a big one. Usually these appear in FI and miss us or don't materialise.

downwiththatsor

km79 wrote: »

Yeah was wondering the same
What model do they work off?

Ecmwf as far as i know

Itssoeasy

The 9 o clock News will be interesting.

[Deleted User]

7pm image.

thecretinhop

It ia starting to get very worrying.

h7nlrp2v0g5u48

Meteorite58 wrote: »

Mod Note : Off topic posts deleted .

Apologies will try to keep on topic.

mirrorwall14

I’m concerned about the model runs showing the east in the firing line. Could someone more knowledgeable maybe discuss probabilities of those materializing? For midland and eastern areas not used to this type of weather some of those charts are very worrying

Hastentoadd

It seems to cover a bigger area than the size of Ireland. Its absolutely enormous

munsterlegend

mirrorwall14 wrote: »

I’m concerned about the model runs showing the east in the firing line. Could someone more knowledgeable maybe discuss probabilities of those materializing? For midland and eastern areas not used to this type of weather some of those charts are very worrying

There has been a relatively small shift east which can have big implications for our island. Will be interesting to see what the morning models show.

Nibs05

i swear its got more humid in the last hour (east meath)

Kermit.de.frog

That may be the last light we see of the perfect structure which will begin to disintegrate and become more messy.

Harry Palmr

RTE not even mentioning it in the news at 9 headlines.

edit covering it now.

TheMilkyPirate

Harry Palmr wrote: »

RTE not even mentioning it in the news at 9 headlines.

Yes they did it was the second story after the Are Fheis

Itssoeasy

Harry Palmr wrote: »

RTE not even mentioning it in the news at 9 headlines.

Why not ?

mikeecho

Harry Palmr wrote: »

RTE not even mentioning it in the news at 9 headlines.

This could be the biggest natural disaster to hit this island in a long time.
People need to be preparing now, not waiting till it's too late.

Anyway, what will the temps be like?, over the coming days.
Will lack of heating be an issue?

Edit.. they're talking about it now.. 21.07hrs