Extratropical Storm Ophelia - Technical Analysis Only - MOD NOTE post #1

SeaBreezes

Just wanted to say a word of thanks to MT and all the others posting charts and predictions. Living on the south coast near the old head of Kinsale I'm following avidly and tying down anything that could become airborne. Appreciate all the warning and discussion relating to the models. Fingers crossed it swings west and away from us. Or a downgrade. But thank you for the warnings and the technical discussions. Fascinating!

jacksie66

This post has been deleted.

Kermit.de.frog

Don't take risks on treacherous roads.

fryup

hatrickpatrick wrote: »

Lads, no one is asking the key question here - is Teresa Mannion on her way to Salthill Promenade yet?

no she's out in the middle of the atlantic as we speak

Kermit.de.frog

Don't swim in the sea.

P_1

Hopefully this storm isn't the number of the beast

M.T. Cranium

If the GEM evolution is correct, the strongest winds would rapidly develop in two areas, one would be a fast-moving occluded cold front racing north faster than the low centre and by 12z this would be aligned something like Galway to Dublin to southwest Wales, so very strong gusts would develop quickly during the period 09z to 12z throughout the midlands ... and the second zone of very strong winds would be the north-south trough along the west coast which would contain the bent-back portion of the occlusion. Between these features there would likely be squall lines with local wind maxima, so if you were in that zone (for instance around Limerick) it would be quite variable with strong gusts alternating with moderate southwest winds, and also passing squalls with brighter intervals.

If any thunderstorms developed along that occlusion then you could get tornadic wind streaks moving north-northeast and that would be most likely from east Galway to Kildare but very localized. This is what happened with the 1987 storm and unfortunately one of those streaks developed over the New Forest region.

Not saying this is the exact forecast because other models seem to have slight variations on how fast the system occludes. GEM is very fast because it phases the low within 12 hours (00-12z Monday) under a 533 dm upper low (not extreme by October standards but nothing like the 582 dm contour in the warm air mass). You can see the speed of the occlusion just by following the 558 dm thickness contour on those two panels. At 00z ithis runs southeast from the centre into the Biscay coast region, and by 12z it is beyond Paris and almost reaching London.

Deank

fryup wrote: »

no she's out in the middle of the atlantic as we speak

There she blows. :eek:

https://twitter.com/RyanMaue/status/918923414550827008

fryup

what speed is it travelling at ? in mph

Steopo

Just wondering in practical terms for Ireland does it make a difference if a Red warning is issued 72 hours before a storm versus 24/36 hours. Given we're not talking mass evacuation orders (at least I've no recollection of Met E/local authorities ever going down that route even for a Red) then preparedness would be securing loose items, avoiding all travel, sand bags, trimming obvious loose branches, moving if your in mobile home/worried about falling tree and in an Irish context 24/36 hours would seem sufficient for that. Local authorities/fishermen have other considerations but they seem to react early to these situations and are very tuned in to upcoming weather. People might be more aware of the upcoming danger with an early warning but in today's media saturation a high % have already heard about this storm and Red warning on late Sat/Sun would spread very quickly. Just seems to me that practically it wouldn't impact by declaring a Red too early and therefore seems completely sensible to wait closer to the time for more certainty. For US Hurricanes it generally means some type of large scale evacuation so more time is needed for planning.

redsteveireland

Our school has only said in the email that there was a yellow warning in place and if the forecast is correct then you should allow extra time for your journey.??

MJohnston

Steopo wrote: »

Just wondering in practical terms for Ireland does it make a difference if a Red warning is issued 72 hours before a storm versus 24/36 hours. Given we're not talking mass evacuation orders (at least I've no recollection of Met E/local authorities ever going down that route even for a Red) then preparedness would be securing loose items, avoiding all travel, sand bags, trimming obvious loose branches, moving if your in mobile home/worried about falling tree and in an Irish context 24/36 hours would seem sufficient for that. Local authorities/fishermen have other considerations but they seem to react early to these situations and are very tuned in to upcoming weather. People might be more aware of the upcoming danger with an early warning but in today's media saturation a high % have already heard about this storm and Red warning on late Sat/Sun would spread very quickly. Just seems to me that practically it wouldn't impact by declaring a Red too early and therefore seems completely sensible to wait closer to the time for more certainty. For US Hurricanes it generally means some type of large scale evacuation so more time is needed for planning.

We’ve already gone over why it might have been helpful for ME not to announce a red warning early, but to give early guidance that a red warning might be on its way. There are a few examples, one of the biggest is ensuring that schools are prepared to notify parents about what will happen, which they won’t have time to do over the weekend. Other things like Local Authorities being able to do prepartory works that they won’t have time to do on Monday. Or just elderly or infirm people in rural areas being able to have enough time to get stocked up with a few things just in case.

Someone else said it already, but its the context of the weekend that changes the way these warnings will affect things, if it was going to happen on a Wednesday or whatever, it wouldn’t matter as much.

emo72

What about the cork match at turner's cross on Monday? They could win the league! Like... This is important for the cork lads.

star gazer

Hurricane Ophelia Discussion Number 19
NWS National Hurricane Center Miami FL AL172017
500 PM AST Fri Oct 13 2017

Ophelia's eye has become better defined over the past 6 hours.
Although cloud tops near the inner core of the hurricane are warmer
than 24 hours ago, a ring of -50 deg C or colder cloud tops still
surrounds the eye. Dvorak current intensity estimates have not
changed substantially, and a blend of objective and subjective
classifications still supports an initial intensity of 85 kt.

Little change in strength is expected while Ophelia remains a
hurricane, since the relatively cool SSTs along the hurricane's path
will likely be offset by low shear and cold upper-level temperatures
for the next 36 h. Extratropical transition will likely begin
shortly after that time, as Ophelia begins to interact with a large
upper-level trough approaching from the west. The dynamical
guidance suggests that Ophelia will deepen in response to the
trough, and although the forecast does not explicitly show it, I can
not rule out that Ophelia will briefly intensify as it undergoes
extratropical transition. By 72 hours, the cyclone is expected to
occlude and begin weakening, though the expansion of the wind field
will result in impacts over portions of the British Isles,
regardless of its exact location or strength. By 96 hours,
continued weakening and interaction with land will likely cause the
surface circulation to become ill-defined, and dissipation is
expected shortly thereafter.

Ophelia is beginning to accelerate toward the east-northeast and the
initial motion estimate is 060/11 kt. Very little change has been
made to the official track forecast. Ophelia is still expected to
continue picking up speed on an east-northeast heading while passing
south of the Azores during the next 24 to 36 hours. By 48 hours,
interaction with the aforementioned upper-level trough will cause
Ophelia to turn toward the northeast and approach Ireland and the
western UK in about 72 h. The track guidance is tightly clustered,
especially through 72 h, and the new NHC track forecast is close to
the various multi-model consensus aids. Although the center of
Ophelia is not expected to reach Ireland or the UK until about day
3, 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 late Saturday or Saturday night due to an approaching cold
front. Any deviation to the left of Ophelia's forecast track could
bring stronger winds to the 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 13/2100Z 32.3N 31.8W 85 KT 100 MPH
12H 14/0600Z 33.4N 29.5W 80 KT 90 MPH
24H 14/1800Z 35.2N 25.4W 80 KT 90 MPH
36H 15/0600Z 38.2N 20.3W 80 KT 90 MPH
48H 15/1800Z 43.1N 16.0W 80 KT 90 MPH
72H 16/1800Z 53.2N 10.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
96H 17/1800Z 60.5N 2.5W 45 KT 50 MPH...POST-TROP/EXTRATROP
120H 18/1800Z...DISSIPATED

$$
Forecaster Zelinsky

NHC Discussion 19

JCX BXC

redsteveireland wrote: »

Our school has only said in the email that there was a yellow warning in place and if the forecast is correct then you should allow extra time for your journey.??

Generally its poor information on their behalf, I find many lay people can be shockingly poorly informed of the weather. However to be fair to them confidence isn't to an acceptable level to be calling shots yet.

If upgraded I'm sure theyll change their stance.

I'd urge people to wait until at least tomorrow evening to change plans.

Kermit.de.frog

Latest from National Hurricane Center (Discussion posted above)

Donegal Storm

emo72 wrote: »

What about the cork match at turner's cross on Monday? They could win the league! Like... This is important for the cork lads.

I was just thinking the same watching the match, their long wait might last another week yet!


No real change on the rte forecast just there, mentioned storm force winds, gale force well inland and storm surges. Also an interview with Gerard Fleming who said that it's potentially damaging and that he hoped it won't be as bad as Debbie. The storm is definitely in the public consciousness at this stage so plenty of opportunity for everyone to prepare, the constant talk of warning levels is tiresome.

fryup

is this an ex-hurricane ? are the real deal?

pad199207

I wonder if MT could give an overview or summary on this evenings output and where we stand at the moment. Track wise and strength wise?

sdanseo

fryup wrote: »

is this an ex-hurricane ? are the real deal?

It'll be a hurricane-force post-tropical cyclone. Not that anyone on Valentia Island on Monday will give a flying fart about the official title.

emo72

fryup wrote: »

is this an ex-hurricane ? are the real deal?

Have you been drinking?

Deank

fryup wrote: »

is this an ex-hurricane ? are the real deal?

See here, and yes they are.

kingshankly

Hopefully this isn’t as bad as it’s looking I’m driving the first train out Tuesday morning horrible feeling not knowing what is around the corner

Pangea

On met eireann they are called it exophellia sounds like a medical condition

luimneachboy

Kermit.de.frog wrote: »

Latest from National Hurricane Center (Discussion posted above)

Has this latest model you have shifted more West? In that case is it not good news that it's moving more westerly with days left to arrival

Gaoth Laidir

ECMWF 925 and 850 hPa winds throughout Monday. Max winds around 75 knots at 925 hPa at 18Z, with the worst winds east of the Shannon.

12Z


18Z


00Z

Oneiric 3

Great near time satellite imagery of the storm on this site. Takes a while to load but well worth it.

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=full_disk&x=18754&y=4749&z=4&im=60&ts=1&st=0&et=0&speed=140&motion=loop&map=1&lat=0&p%5B0%5D=16&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=20171010150038&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider

Kermit.de.frog

luimneachboy wrote: »

Has this latest model you have shifted more West? In that case is it not good news that it's moving more westerly with days left to arrival

It's better for the east but it could swing back east just as easy. It's horrible for the western half of the country. It's forecast to be strong Category 1 strength storm.

Still time to go yet.

TheMilkyPirate

Some of them ecm ensembles are very tasty for me down here in Wexford

Rougies

kingshankly wrote: »

Hopefully this isn’t as bad as it’s looking I’m driving the first train out Tuesday morning horrible feeling not knowing what is around the corner

What's the protocol the morning after a storm? Would they send out a recon train first to make sure the track is clear?