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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

Samaris wrote: »

Been a bit focussed on there too - my home town. The bay opens right out into the direction of the storm, so I hope the prom is closed off - you know yourself what eejits are like for going and standing on it during storms. And I'd be a bit dubious of the amusement park as well, given its exposed position (and poor upkeep, at least when I lived there). I'd expect if there's damage it'll be places like The Atlantic, Majestic, Splashworld & whatever Celtworld/Storm is now and the apartments around there, plus Newtown and the part that dips down to the little pier near the Magic Well.

Most of the town is well raised up anyway, so flooding is unlikely to be an issue. Not much protection from the wind though.

I'd say the prom will be closed. Have to laugh at people driving down it during the bad storms. The amount of pebbles debris flying through the air is unreal and dangerous. Tides not too bad only a 3.8m at 3.45pm and depending on the direction of the wind it might not be the worst.
I wonder if it could be another Christine with lumps of the road torn up around the end of the prom

sdanseo

Interesting - no, fascinating - to watch the progression of the storm on the satellite images from yesterday to today.
http://eumetview.eumetsat.int/mapviewer/

Yesterday 1500Z

Today 1500Z

Also a quote on the netweather forums that's worth a giggle:

I always wanted to visit Ireland. Looks like I've missed my chance as it'll be gone by Tuesday morning.

Kermit.de.frog

M.T. Cranium wrote: »

I think there's some confusion on the colour coding of gust speeds, the map shows output in knots but colour coding scale at the base of the map seems to be km/hr.

The GFS compared to ICON shifts the maximum wind impact closer to the west coast although certainly there's a good rush of south to southwest gales into the midlands, and the portion of the west coast spared from storm force gusts is pushed back to a small part of Mayo (the ICON would say all of Mayo).

The GEM looks about the same as previous runs, I don't think it has picked up on the more intense t=0 situation.

Blending all this together I think it means about what the current warnings suggest with potential for pockets of severe damage in parts of west Munster. Timing the strongest winds for something like 10:00 to 13:00 on the south coast and in Kerry, to about 14:00 to 17:00 in Galway and midlands.

Outcome for east coast still somewhat uncertain, could be anywhere from strong level one to marginal level three so level two the best bet.

+1

Arpege out - I would class this timestamp as "dangerous" for the south west too.

arpegeeur-0-48.png?12

So still varying ideas on intensity to narrow down here.

munsterlegend

TheMilkyPirate wrote: »

Interesting to note that Debbie in '61 had downgraded to a Cat-1 approaching the Azores, Ophelia upgraded to a Cat-3 approaching the same position.

I think Debbie was travelling faster though. As other have said it will deintensify to a borderline Cat1 force but still interesting alright to see it's development.

Doltanian

Discodog wrote: »

Looking at the track there is potential for a lot of downed trees. The winds could change by 180. So the trees get pushed all the way in one direction & then in the opposite. Perfect for snapping roots.

I would advise people not to park near trees

Also park well away from buildings where falling slates and tiles will wreck your car.

Jobs OXO

nagdefy wrote: »

Holy Christ.. that's scary..really scary..

Are there evacuation plans if required? The East seems likely to escape most of it

munsterlegend

Gaoth Laidir wrote: »

It will be travelling slightly slower than Debbie so I would not imagine we will see any worse winds than then.

you are not one to hyperbole situations but if you are saying it may even come close to a once in generation event like Debbie then this is potentially a very noteeworthy event.

Discodog

Looking at the track there is potential for a lot of downed trees. The winds could change by 180. So the trees get pushed all the way in one direction & then in the opposite. Perfect for snapping roots.

I would advise people not to park near trees

JanuarySnowstor

I'd be pretty sure Met Eireann will expand the red alert shortly to cover most of South and West

M.T. Cranium

I think there's some confusion on the colour coding of gust speeds, the map shows output in knots but colour coding scale at the base of the map seems to be km/hr.

The GFS compared to ICON shifts the maximum wind impact closer to the west coast although certainly there's a good rush of south to southwest gales into the midlands, and the portion of the west coast spared from storm force gusts is pushed back to a small part of Mayo (the ICON would say all of Mayo).

The GEM looks about the same as previous runs, I don't think it has picked up on the more intense t=0 situation.

Blending all this together I think it means about what the current warnings suggest with potential for pockets of severe damage in parts of west Munster. Timing the strongest winds for something like 10:00 to 13:00 on the south coast and in Kerry, to about 14:00 to 17:00 in Galway and midlands.

Outcome for east coast still somewhat uncertain, could be anywhere from strong level one to marginal level three so level two the best bet.

TheMilkyPirate

Interesting to note that Debbie in '61 had downgraded to a Cat-1 approaching the Azores, Ophelia upgraded to a Cat-3 approaching the same position.

philstar

taytobreath wrote: »

Bus Eireann have cancelled their school buses Monday because of it.

much to the disappointment of the drivers & pupils i bet

BorneTobyWilde

SO looks like Monday is cancelled.

jacksie66

This post has been deleted.

taytobreath

Bus Eireann have cancelled their school buses Monday because of it.

Kermit.de.frog

I know MT has mention ICON but the GFS is not far behind in severity, track and depth.

By any standard this is testing.

gfs-0-48.png?12

sdanseo

Gaoth Laidir wrote: »

As MT said, not much has changed in the forecast for Monday. People talking about evacuating the southwest need to calm down. A Cat 3 will not hit us.

At the risk of repeating myself again, the current 100-knot intensity given by the NHC would equate to around 90 knots if this were a typical winter storm because of the difference between the windspeed classifications (1-minute Vs 10-minute). Knock around 11% off the NHC speeds to get the Beaufort speed. Now take that forward to Monday. 30-40 knots of weakening is very possible in the next 48 hours which would take it from its current 90 knots down to a more "survivable" 50-60 knots sustained winds, with of course higher gusts.

Certainly a very notable and interesting event but please let's not lose the run of ourselves here. There is no need for evacuations.

sdanseo wrote: »

Those are 150+ KNOT gusts in purple.
277 km/h.
That is as JanuarySnowstorm said, evacuation level event if it comes off.

nagdefy wrote: »

Holy Christ.. that's scary..really scary..

Just a caveat on my own post here..GL and MT are infinitely more knowledgeable than I. Apologies for being any way sensational, as it is just one model and the winds are offshore. Doesn't mean I'm not still worried.

Gaoth Laidir

nagdefy wrote: »

Hurricane Debbie potential do you think Gaoth Laidir?

It will be travelling slightly slower than Debbie so I would not imagine we will see any worse winds than then.

nagdefy

Gaoth Laidir wrote: »

As MT said, not much has changed in the forecast for Monday. People talking about evacuating the southwest need to calm down. A Cat 3 will hit us.

At the risk of repeating myself again, the current 100-knot intensity given by the NHC would equate to around 90 knots if this were a typical winter storm because of the difference between the windspeed classifications (1-minute Vs 10-minute). Knock around 11% off the NHC speeds to get the Beaufort speed. Now take that forward to Monday. 30-40 knots of weakening is very possible in the next 48 hours which would take it from its current 90 knots down to a more "survivable" 50-60 knots sustained winds, with of course higher gusts.

Certainly a very notable and interesting event but please let's not lose the run of ourselves here. There is no need for evacuations.

Hurricane Debbie potential do you think Gaoth Laidir?

nagdefy

sdanseo wrote: »

Those are 150+ KNOT gusts in purple.
277 km/h.
That is as JanuarySnowstorm said, evacuation level event if it comes off.

Holy Christ.. that's scary..really scary..

Gaoth Laidir

As MT said, not much has changed in the forecast for Monday. People talking about evacuating the southwest need to calm down. A Cat 3 will not hit us.

At the risk of repeating myself again, the current 100-knot intensity given by the NHC would equate to around 90 knots if this were a typical winter storm because of the difference between the windspeed classifications (1-minute Vs 10-minute). Knock around 11% off the NHC speeds to get the Beaufort speed. Now take that forward to Monday. 30-40 knots of weakening is very possible in the next 48 hours which would take it from its current 90 knots down to a more "survivable" 50-60 knots sustained winds, with of course higher gusts.

Certainly a very notable and interesting event but please let's not lose the run of ourselves here. There is no need for evacuations.

SweetCaliber

Samaris wrote: »

Been a bit focussed on there too - my home town. The bay opens right out into the direction of the storm, so I hope the prom is closed off - you know yourself what eejits are like for going and standing on it during storms. And I'd be a bit dubious of the amusement park as well, given its exposed position (and poor upkeep, at least when I lived there). I'd expect if there's damage it'll be places like The Atlantic, Majestic, Splashworld & whatever Celtworld/Storm is now and the apartments around there, plus Newtown and the part that dips down to the little pier near the Magic Well.

Most of the town is well raised up anyway, so flooding is unlikely to be an issue. Not much protection from the wind though.

Yeah, celtworld is long gone and the amusement park is essentially loads of railings now as all have packed up and gone for the winter.

I ask mainly because of where I live, the end of somerville, I can see the sea from my house and the back strand is directly across from my house and the tides get quite high at times.

sdanseo

Kermit.de.frog wrote: »

Latest GFS predicted gusts

Those are 150+ KNOT gusts in purple.
277 km/h.
That is as JanuarySnowstorm said, evacuation level event if it comes off.

Edit: See later in the thread where it has been clarified that speeds are km/h not knots on the colour scale. Please heed the advice of more knowledgeable posters also. It's unlikely to be quite as bad as the above comment would indicate.

nagdefy

stevenup7002 wrote: »

But it says "noeuds" (knots)?

Jaysus it does.. Apologies :eek:

stevenup7002

nagdefy wrote: »

No km per hr. Thankfully

But it says "noeuds" (knots)?

nagdefy

peasant wrote: »

Hang on a sec ...

Is that 100 kt (185 km/h) gusts over Tipp/Limerick/Galway ? :eek:

No km per hr. Thankfully

philstar

but it doesn't seem to be moving? its in the same position as this morning

https://www.ventusky.com/?p=42.0;-20.3;3&l=wind

gozunda

dashoonage wrote: »

ill never understand that...any time there is a warning for that side of the island limerick is always left out :P

County Limerick was left out of the Top level Storm Darwin warning as well. It was only later included as the storm was active ...

sdanseo

Kermit.de.frog wrote: »

These probabilities will increase over next few advisories.

Exactly.

peasant

Kermit.de.frog wrote: »

Latest GFS predicted gusts

Hang on a sec ...

Is that 100 kt (185 km/h) gusts over Tipp/Limerick/Galway ? :eek: