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

xii

snusie wrote: »

165kmh winds? Is that a category 5?
Is this stronger than previously expected or on track with the forecast?

Bless

star gazer

The initial motion estimate is a little faster toward the
east-northeast, or 070/7 kt, with Ophelia embedded in the flow ahead
of a large mid-latitude trough pushing east of Atlantic Canada. As
this trough swings eastward over the north Atlantic, Ophelia is
expected to continue accelerating and turn northeastward by day 3
and north-northeastward by day 4. There is high confidence in
the track forecast for the first 48 hours while Ophelia remains a
tropical cyclone. Although there is some model divergence after 48
hours once Ophelia becomes extratropical, the global models remain
relatively tightly clustered through day 4, and they all agree that
Ophelia will track very close to the western shores of the British
Isles on days 3 and 4. As such, very little change was made to the
NHC official forecast compared with the previous advisory. There
is significantly more spread in Ophelia's track by day 5, with the
GFS moving Ophelia over the North Sea while the ECMWF and UKMET
turn the cyclone eastward over Norway. However, NHC's graphical
product suite cannot handle forecast points east of the Prime
Meridian, so the official forecast now cuts off after day 4.

Vertical shear over Ophelia may decrease a bit over the next 24
hours, and the hurricane will remain over marginally warm waters
for the next day or two. Hence, only slight weakening is
anticipated through 48 hours, and Ophelia is forecast to remain a
tropical cyclone during that period. Ophelia is then expected to
merge with an approaching cold front and develop into a warm
seclusion by day 3 to the southwest of Ireland, with baroclinic
forcing likely helping to maintain the cyclone's intensity for
about a day. Some weakening is anticipated after day 3 while
Ophelia moves near the British Isles, but strong winds are becoming
increasingly likely over portions of Ireland and United Kingdom
regardless of the cyclone's exact intensity.

NHC Discussion 17

Hurricane Ophelia is still a Category 2. Saffir-Simpson Hurricane wind scale

Cantona's Collars

Reckless Abandonment wrote: »

We've gone form lamppost watching to . Where is the lamppost

Waiting for it to blow down.

my3cents

star gazer wrote: »

.....



Met Eireann 5 day Atlantic forecast.

Am I to understand from that link that this is likely to be all wind and very little rain?

George Sunsnow

snusie wrote: »

165kmh winds? Is that a category 5?
Is this stronger than previously expected or on track with the forecast?

Gusts could reach that anywhere from the south coast to Donegal
Currently it looks like gale or severe gale only in eastern areas
There will be squal lines with thunderstorms and stronger damaging gusts even in the east
The esb will be busy for a week

That’s assuming the center of the low tracks over Cork Kerry north through limerick/Clare Galway Mayo Sligo Donegal
Strongest winds immediately east of the low and on squal lines heading northeast ,the squal lines bringing a taste of the more severe gusts everywhere

Power outages will be widespread even in the east if current indications become reality

Akrasia

snusie wrote: »

165kmh winds? Is that a category 5?
Is this stronger than previously expected or on track with the forecast?

you got your Kph mixed up with your Mph there Snusie

George Sunsnow

my3cents wrote: »

Am I to understand from that link that this is likely to be all wind and very little rain?

It will be fast traveling so heavy rain associated with it will pass through fast in bands
It’s when lows and fronts get stuck that you get unusually bad flooding rains
This lows current forecast track doesn’t look like causing that
Tidal surges are a probability,so flooding there

snusie

star gazer wrote: »

NHC Discussion 17

Hurricane Ophelia is still a Category 2. Saffir-Simpson Hurricane wind scale

I accidentally read mph as kmh. Rookie mistake.

munsterlegend

Met Eireann did update their weather advisory this morning but not too much change except likely to be a wind event on Monday.

http://m.met.ie/weather-warnings.aspx?t=National

5am EDT (10am Ire) chart. Just a 4 day outlook now. NHC does not do graphics for east of the Greenwich meridian.

savj2

snusie wrote: »

165kmh winds? Is that a category 5?
Is this stronger than previously expected or on track with the forecast?

No Cat 5 is greater than 150 mph sustained winds.

This won't be a hurricane. It can't be due to colder waters and interaction with upper level troughs. The storm will tilt with height unlike a hurricane which is symmetrical. The strength will be less than a cat 1 hurricane.

There will be high gusts but sustained winds less than that of a hurricane.

This will be a violent/strong mid latitude storm.

star gazer

my3cents wrote: »

Am I to understand from that link that this is likely to be all wind and very little rain?

The more intense rainfall does appear to dissipate before reaching Ireland and MTC says: "perhaps 10 to 20 mm rain for many".
The wind speeds and potential storm surge look to be the big potential threats depending on where the system ends up.

Tabnabs

That gap between hurricane strength winds and Ireland just got a lot closer with the latest update!

ronnie3585

Great article here; https://www.netweather.tv/weather-forecasts/news/8491-whats-all-this--its-not-a-hurricane--stuff-ophelia-heads-our-way

Should be mandatory reading for anyone in the media before the hysterics start.

my3cents

George Sunsnow wrote: »

It will be fast traveling so heavy rain associated with it will pass through fast in bands
It’s when lows and fronts get stuck that you get unusually bad flooding rains
This lows current forecast track doesn’t look like causing that
Tidal surges are a probability,so flooding there

From the tide tables I've looked at (we do flood on a regular basis) I'm not that worried. We don't have that perfect storm of one of the highest tides of the year coinciding with a storm.

If this event was likely on Thursday then I'd be a lot more worried because thats when we have one of the highest tides of the year.

George Sunsnow

munsterlegend wrote: »

Met Eireann did update their weather advisory this morning but not too much change except likely to be a wind event on Monday.

http://m.met.ie/weather-warnings.aspx?t=National

Can’t complain about their approach to this
Advisory’s are out
Severe Warnings have been mentioned as being possibly posted but not until the exact track is more certain

Larbre34

How rare is a track like this for an Atlantic tropical storm / hurricane, direct NE from the tropics rather than west to the Americas then eventually to Europe like Hurricane Charley?? I cant recall anything like this Ophelia scenario...

RobertKK

INIT 13/0900Z 31.1N 33.9W 90 KT 105 MPH
12H 13/1800Z 31.8N 32.5W 85 KT 100 MPH
24H 14/0600Z 33.1N 29.7W 85 KT 100 MPH
36H 14/1800Z 35.0N 25.5W 80 KT 90 MPH
48H 15/0600Z 37.9N 20.8W 80 KT 90 MPH
72H 16/0600Z 47.9N 13.7W 75 KT 85 MPH...POST-TROP/EXTRATROP
96H 17/0600Z 57.5N 6.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 18/0600Z...EAST OF THE PRIME MERIDIAN

So is that a predicted 85mph sustained wind for Monday?

server down

savj2 wrote: »

No Cat 5 is greater than 150 mph sustained winds.

This won't be a hurricane. It can't be due to colder waters and interaction with upper level troughs. The storm will tilt with height unlike a hurricane which is symmetrical. The strength will be less than a cat 1 hurricane.

There will be high gusts but sustained winds less than that of a hurricane.

This will be a violent/strong mid latitude storm.

It doesn’t actually seem that far off a cat 1. From what am reading.

savj2

Larbre34 wrote: »

How rare is a track like this for an Atlantic tropical storm / hurricane, direct NE from the tropics rather than west to the Americas then eventually to Europe like Hurricane Charley?? I cant recall anything like this Ophelia scenario...

Well the typical track of tropical storms in the Autumn are tropical waves off the coast of Africa just south of the Cape Verde Islands, where the trade winds which blow east to west send the storm towards the Carribean.

This storm formed in a usually High pressure zone and was basically stationary. What's going to happen is an upper level low from the mid latitudes will steer the storm north eastwards.

It doesn't happen that much but has happened before.

force eleven

Larbre34 wrote: »

How rare is a track like this for an Atlantic tropical storm / hurricane, direct NE from the tropics rather than west to the Americas then eventually to Europe like Hurricane Charley?? I cant recall anything like this Ophelia scenario...

https://en.wikipedia.org/wiki/Hurricane_Debbie_(1961)

trixiebust

Lurking in this thread for the last few days. Just wanted to say thanks to all the very knowledgeable posters here. I'll continue to follow with interest.

Gaoth Laidir

Latest wind analysis at 09Z, showing 81 knots 21 n. miles from the centre.





00Z ECMWF multi-layer wind forecast for Monday. 925 and 850 hPa winds most useful for estimating gusts. Somewhere in the 70-80-knot range I reckon.

12Z Monday


18Z Monday


00Z Tuesday

RobertKK

If the storm keeps its warm core when it hits then it can still be classified as a hurricane, otherwise it will be classified as an extra tropical cyclone?

Gaoth Laidir

RobertKK wrote: »

If the storm keeps its warm core when it hits then it can still be classified as a hurricane, otherwise it will be classified as an extra tropical cyclone?

No, it may be a post-tropical storm but for a hurricane it needs to have an warm eye, central dense overcast, no fronts, and strongest winds near the centre. This will not have any of those points.

highdef

Hurricane Faith in 1966 remained as a Category 1 hurricane until it reached the Faroe Islands at an unbelievable 62 degrees North and only became extra tropical after it travelled further east into the North Sea.

"After remaining a Category 2 hurricane since August 29, Faith weakened slightly to a Category 1 hurricane early on September 6, as it neared the Faroe Islands.[2] Crossing the North Sea, Faith finally transitioned into an extratropical storm at 1200 UTC later that day, while centered about 125 miles (200 km) east-northeast of Tórshavn"

Full article: https://en.wikipedia.org/wiki/Hurricane_Faith

We're being told that the hurricane cannot remain as a hurricane as it nears Ireland due to cold waters but surely the waters at over 60 degrees north would be much colder, even in early September?

BTW, I do think that it won't be a hurricane when it gets to us, I just found Hurricane Faith to be rather interesting.

Elmer Blooker

Larbre34 wrote: »

How rare is a track like this for an Atlantic tropical storm / hurricane, direct NE from the tropics rather than west to the Americas then eventually to Europe like Hurricane Charley?? I cant recall anything like this Ophelia scenario...

Hurricane Gordon in September 2006 took a similar unusual track as it approached Ireland from the Azores and north west Spain,
https://www.wunderground.com/tropical/tracking/at200608.html
All I remember from Gordon, an extra-tropical storm by the time it reached us, was a lot of branches everywhere the morning after.

Stormy conditions threatened to affect the 2006 Ryder Cup in Straffan, County Kildare, Ireland at the K Club, and September 25 was set aside as an additional "reserve day". The club's media center was briefly evacuated, and one woman at the event was injured after being struck by a tree branch broken by the storm.

Gaoth Laidir

Ophelia's intensity history up to 09Z today.

savj2

RobertKK wrote: »

If the storm keeps its warm core when it hits then it can still be classified as a hurricane, otherwise it will be classified as an extra tropical cyclone?

It can only be classified as a tropical storm (Hurricane etc) if it maintains its tropical characteristics:

eyewall
no fronts
symmetrical
still gaining its energy by convection from warm seas and using its energy by the release of latent heat.

In post tropical transition, it will gain fronts as it interacts with colder drier air. It will derive its energy from a combination of cold/warm interation as well as the release of some latent heat. The core should remain warm as it wouldn't have been long since transition from tropical to post-tropical so this is known as "warm seclusion"

JJJJNR

Could this bring about a cold snap once it heads north ?