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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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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.

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

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.

Meteorite58

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

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

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

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

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

sdanseo

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

star gazer

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

JanuarySnowstor

Well its a direct hit now!!

thomasj

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

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

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.

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!

Kermit.de.frog

ICON 12z

sdanseo

Track comparison 0900Z vs 1500Z

munsterlegend

sdanseo wrote: »

Track comparison 0900Z vs 1500Z

Looks a good 50 miles east on the south coast anyway.

Gaoth Laidir

Today's 12Z Hirlam is a slight downgrade on the 06Z. Below shows chart for midday tomorrow (12Z left, 06Z right). Force 10-11 max sustained winds along the south coast with that.

hatrickpatrick

For anyone who doesn't usually follow hurricanes / tropical systems, remember that the cones on these charts are not the outer limits of the storm's effects - they're estimations as to where the eye of the storm is going to be. So in other words, the black line with the circular H symbol is the best guess for where the eye will go, but the shaded area on either side is the possible error in that forecast. Wind, rain and other effects will extent far beyond the cone - the cone refers only to the position of the storm's centre.

M.T. Cranium

On the track, I suspect they have overcorrected a bit because the hurricane kept to the right of the predicted track most of the past 36 hours but at this point it may swerve almost due north, the main jet stream is still off to the west enough that it has time to do that before resuming a NNE track, so I would not be surprised if the actual track is closer to the earlier estimate than the new one.

After transition this won't be lacking for a warm sector, temperatures on the north coast of Spain are generally at or above 30 C. (and all that is feeding directly into the developing expanding circulation).

The nowcasting portion of this event is going to be tremendously interesting, I think.

Xenji

Gaoth Laidir wrote: »

Today's 12Z Hirlam is a slight downgrade on the 06Z. Below shows chart for midday tomorrow (12Z left, 06Z right). Force 10-11 max sustained winds along the south coast with that.

Do you know why those isolated purple patches seem to be popping up around Mayo?

crustybla

M.T. Cranium, I wish I was in your house. Fascinating stuff.

Gaoth Laidir

12Z Hirlam animation, showing a less potent - but still potent - scenario.

sdanseo

hatrickpatrick wrote: »

For anyone who doesn't usually follow hurricanes / tropical systems, remember that the cones on these charts are not the outer limits of the storm's effects - they're estimations as to where the eye of the storm is going to be. So in other words, the black line with the circular H symbol is the best guess for where the eye will go, but the shaded area on either side is the possible error in that forecast. Wind, rain and other effects will extent far beyond the cone - the cone refers only to the position of the storm's centre.

Right, a very important point too. See below the 50kt wind probability (10kt increments, purple is >90%) from the 09Z advisory. Latest ones not updated yet and these probabilities will increase significantly.

50kt = about 7kt above red warning threshold.

Gaoth Laidir

Xenji wrote: »

Do you know why those isolated purple patches seem to be popping up around Mayo?

They're relatively calm winds. Look at the left of the scale on the bottom, that's them.

shmaupel

Xenji wrote: »

Do you know why those isolated purple patches seem to be popping up around Mayo?

I asked something similar earlier, apparently the colour legend on the charts can be a little confusing and those 'purples' are slower winds than the actual purples. If that makes any sense.

Xenji

Gaoth Laidir wrote: »

They're relatively calm winds. Look at the left of the scale on the bottom, that's them.

Ah sorry, those purple colors are quite similar when looking on a phone.

Bonzo Delaney

How far behind live is nullschool.net

spookwoman

Bonzo Delaney wrote: »

How far behind live is nullschool.net

looks like its running from reports 15.00 UTC
Click on the word earth