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

DOCARCH

munsterlegend wrote: »

The french will be disappointed.

C'est la vie!

irishfeen

From watching hurricane coverage from the US, its the NE quadrant around the eye of a storm which gets the brunt and surge right??

Looks like Cork and Kerry are going to get an awful doing. We are about 190m ASL in North Cork - I will give updates as much as I can but we will almost certainly lose power being so rural.

Currently - 11.8 degC, 90% Humidity, 986.9 hpa

hatrickpatrick

Any chance of thunderstorms / mesocyclones with this or will the core have cooled too much for that my the time it transitions?

PokeHerKing

Gaoth Laidir wrote:

There will be no hurricane eye over Ireland. There will be the centre of the depression, which we always get. The country is totally overreacting to this.

You're always spot on but either way the kids get a day off and so do I!

Better to be safe than sorry.

Gaoth Laidir

The One Doctor wrote: »

How does an eye make any difference? The tropical storm still has a massive amount of energy and is currently reintensifying due to the warm waters around Spain. We're had destructive storms before with no eye to them.

What people need to understand is the destructive potential of fast moving air.

Wind energy is proportional to the third power of the wind speed; if windspeed doubles, the destructive energy increases eight times.

So 150kph winds are four times as destructive as 100kph winds.

The risk of injury to people comes from 'entrained debris', basically things (deckchairs, wheelie bins, branches, broken glass) being caught by the wind and hurled at you. The danger relates to the energy of the wind. The more wind, the heavier the object it can hurl at you and your house.

And this one will also have no eye.

Wind energy is proportional to the square of speed, not third power. 150 kph is only 2.25 times more energy, not 4 times. When you get to Cat 2 or 3 is where this relationship gets really serious.

Anyway, this is off topic. It is what it is. It's looking like hitting with Force 11 sustained winds and maybe 80 knots in some parts. Let's move on.

Donegal Storm

I suspect the red warning nationwide is simply for operational reasons, so many areas, particularly inland Munster and Leinster are borderline red for gusts and even if they're technically not under a red warning downed trees will be inevitable so its just the safest option to have a blanket warning.

Would agree with GL that there's a massive overreaction today though, forecast winds on most models are nothing we haven't seen multiple times before, I've experienced plenty similar intensity storms in Donegal and 'stay indoors' warnings are a bit over the top for all but immediate coastal areas. Better safe than sorry though I suppose, maybe the harmonie model is showing more severe winds than what we have access to

MuddyDog

Can there be twisters that make landfall because of this?

DOCARCH

Gaoth Laidir wrote: »

Let's move on.

Agreed....

MJohnston

MuddyDog wrote: »

Can there be twisters that make landfall because of this?

Estofex is indicating "isolated tornado risk" and has been for a while:

http://www.estofex.org/

Interestingly, they've also issued a 'Mesoscale Discussion' with this info that we should keep an eye on:

Overall synoptic conditions for a potential sting jet or major cold-conveyor belt (CCB) jet event seem to be in place, also supported by numerous fine-mesh models and even global models.

The most extreme winds should weaken during the end of the MD but intense CCB jet winds approach S-Ireland later-on from the S.

Oscarziggy

Oscarziggy wrote: »

The BBC shipping forecast says this for Fastnet --
I've never heard the term in red used before .
Regards


Fastnet
Gale Warning: Gale warning issued 15 October 09:55 UTC (Open)
Southerly hurricane force 12 expected later
Wind
Cyclonic, mainly south or southwest, 5 to 7, increasing severe gale 9 to violent storm 11 later, occasionally hurricane force 12.
Sea State
Moderate or rough, becoming high or very high later, occasionally phenomenal.
Weather
Fair then rain.
Visibility
Good becoming poor.

The Douglas sea scale. 'Phenomenal' is the severest sea state.

http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/douglas-sea-scale

Cantona's Collars

DOCARCH wrote: »

Moving quickly now alright....I retract my earlier theory of a possible miss!

Egalite,Fraternite,Ophelia.:p:p:p

crustybla

Around how fast is it moving at the moment?

crustybla

crustybla wrote: »

Around how fast is it moving at the moment?

Fast enough to party

star gazer

Hurricane Ophelia Advisory Number 27
NWS National Hurricane Center Miami FL AL172017
500 PM AST Sun Oct 15 2017

...OPHELIA STILL A HURRICANE BUT EXPECTED TO BECOME A POWERFUL
POST-TROPICAL CYCLONE TONIGHT...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION

---

LOCATION...44.6N 13.3W
ABOUT 840 MI...1355 KM NE OF THE AZORES
ABOUT 505 MI...810 KM SSW OF MIZEN HEAD IRELAND
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...NNE OR 25 DEGREES AT 38 MPH...61 KM/H
MINIMUM CENTRAL PRESSURE...971 MB...28.68 INCHES


WATCHES AND WARNINGS

---

There are no coastal tropical cyclone watches or warnings in effect.

Interests in Ireland should monitor products issued by Met Eireann,
and interests in the United Kingdom should monitor products issued
by the UK Met Office.


DISCUSSION AND 48-HOUR OUTLOOK

---

At 500 PM AST (2100 UTC), the center of Hurricane Ophelia was
located near latitude 44.6 North, longitude 13.3 West. Ophelia is
moving toward the north-northeast near 38 mph (61 km/h), and this
general motion is expected to continue through Monday. On the
forecast track, the center of Ophelia will cross over Ireland on
Monday, however strong winds and rain will extend far from the
center.

Maximum sustained winds are near 85 mph (140 km/h) with higher
gusts. Ophelia is expected to be a hurricane-force post-tropical
cyclone when it nears the coast of Ireland on Monday.

Hurricane-force winds extend outward up to 60 miles (95 km) from the
center and tropical-storm-force winds extend outward up to 255 miles
(405 km).

The estimated minimum central pressure is 971 mb (28.68 inches).


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. Strong winds will then spread inland across the
Ireland and parts of the UK into Monday night. Preparations to
protect lives and property should be nearing completion.

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.


NEXT ADVISORY

---

Next complete advisory at 1100 PM AST.

$$
Forecaster Zelinsky

Advisory 27

Yarghhh

crustybla wrote: »

Around how fast is it moving at the moment?

https://earth.nullschool.net/#current/wind/surface/level/orthographic=-15.81,39.45,1472/loc=3.231,45.302

star gazer

Hurricane Ophelia Discussion Number 27
NWS National Hurricane Center Miami FL AL172017
500 PM AST Sun Oct 15 2017

Ophelia's cloud structure is declining rapidly, and microwave and
shortwave IR imagery indicate that the low-level and mid-level
centers are becoming separated. However, some deep convection is
still present near Ophelia's center, and an SSMIS pass from 1827 UTC
indicated that the hurricane still has an inner core that is
separated from a front to the north and west. The estimated maximum
winds have been decreased slightly to 75 kt given the overall decay
of the cloud structure. However, the cyclone's favorable position
relative to an upper-level jet streak is likely contributing to
deepening of the low as the wind field expands substantially. Only
a slight decrease in the maximum winds is therefore expected before
the post-tropical cyclone reaches Ireland. After that time,
interaction with land while the cyclone occludes should cause it to
weaken more rapidly. Around 48 h, the cyclone's circulation is
likely to become ill-defined and dissipate near the western coast of
Scandinavia.

Ophelia has continued to move toward the north-northeast, and the
initial motion estimate remains 025/33 kt. There has been no change
to the track forecast reasoning since Ophelia is already embedded
within the flow associated with a large mid-latitude trough. This
should keep Ophelia on a north-northeast heading as it passes over
Ireland and the UK on Monday. The dynamical guidance remains in
very good agreement on the track of Ophelia, and very little change
has been made to the track forecast.

Since Ophelia will be post-tropical as it approaches Ireland and the
UK, strong winds and rain will arrive over land areas sooner than
the center. For more information on local impacts, consult products
from local meteorological services in Ireland and the United Kingdom
for more information.

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.

2. Individuals are urged to not focus on the exact track of Ophelia
since strong winds and heavy rainfall will extend well outside of
the NHC forecast cone.


FORECAST POSITIONS AND MAX WINDS

INIT 15/2100Z 44.6N 13.3W 75 KT 85 MPH
12H 16/0600Z 49.2N 11.3W 70 KT 80 MPH...POST-TROP/EXTRATROP
24H 16/1800Z 54.3N 7.5W 55 KT 65 MPH...POST-TROP/EXTRATROP
36H 17/0600Z 58.5N 2.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
48H 17/1800Z...DISSIPATED

$$
Forecaster Zelinsky

Discussion 27

crustybla

star gazer wrote: »

Advisory 27

Just copped speed there, thanks!

5pm (EDT, 10pm Ire) NHC graphics chart.

EDIT: as per MT's guidance below, add 5 hours to the times shown to get the Irish time.

nkay1985

Is it moving faster than expected and, if so, how does that affect the impact times and overall picture? If it moves faster, would that mean it passes faster so less chance of damage?

downwiththatsor

5am wind speed from Met Eireann Short Range forecast page
http://www.met.ie/forecasts/short-range.asp

M.T. Cranium

Not the first time we've had to post this, but times on NHC guidance maps are set to eastern North American time zones (AST is same as EDT) and those are 5 hours behind IST, so add five hours to your time estimates. Just saw some discussions about arrival around 0600 but really that's 1100h IST.

This is my updated forecast ...

UPDATE -- Sunday 15 October 2017 9 p.m.
________________________________________

Overall, my thinking about the storm tomorrow has not changed. Some recent guidance has been perhaps 1-2 hours faster with the arrival time but I was working off that assumption since the one thing I trust the most about the GEM model is its upper level depictions and that was screaming fast phase. In layman's terms, what fast phase means is that this storm will rapidly transform from a truly tropical system (which is barely the case now as the low moves north from about 43N 14W), into a powerful frontal cyclone. This will rotate the entire system faster and bring the strong winds currently running along to the east of the low into the whole country and at a faster pace than the low centre, forcing an occluded front to form in an arc running a little ahead of the low itself. That will become the focus of the strongest winds inland, but south and southwest coastal locations will continue to have very strong winds for several hours after the low and associated fronts pass.

I understand that the whole country is now under a level 3 or red warning. I think this was probably done more for public safety and planning reasons than strictly based on model guidance, and it makes sense to me for a number of reasons which I posted elsewhere on the storm thread.

But here's what to expect in some detail, subject to revision at the morning forecast.

Overnight, winds will steadily increase from the southeast (more like east to northeast in northern counties and along the west coast). By daybreak, the wind speeds near the south coast will be 60 to 100 km/hr, about 50 to 80 km/hr on the west coast and across some exposed parts of the midlands and about 40 to 60 km/hr further north. Heavy and at times thundery rain is likely especially near the west coast and some distance inland towards the midlands.

Between 0800h and 1100h, winds will increase in the south and veer to southerly 100 to 150 km/hr. Depending on where the centre tracks into Kerry (most likely somewhere near the mid-point of the various peninsulas) winds along the west coast will increase to 90 to 130 km/hr from the north-northeast with heavy rain. The strong southerlies will quickly push inland with the frontal system forming and possibly setting off squally showers and thunderstorms. Winds of 90 to 130 km/hr are likely to get into the midlands by noon with the risk of tornadic wind streaks developing near thunderstorm cells.

On the east coast, winds will steadily increase all morning to reach about 70 to 110 km/hr by mid-day and then will increase more gradually in the afternoon to peak around 90 to 130 km/hr by late afternoon, the direction likely is SSE but SSW to the west of the Wicklow and Dublin hills.

Around 2 p.m. with the low somewhere near or over Clare, heavy rain and strong northeast winds will be widespread in Connacht with the southerlies intruding into east Galway and Roscommon. By about 5 p.m. the centre will be tracking closer to Knock and west Sligo and winds over western Connacht will swing around to northwest at 70 to 120 km/hr. About this phase of the storm, inland southerlies will begin to show a gradual decrease also in the 70 to 120 km/hr range, and the southwest will be seeing southwest winds at 70 to 110 km/hr. Rain will wrap around the centre. Anyone in the track of this low centre (and it could include Galway city and Sligo town) will notice an interval of 30 minutes to one hour of relative calm but it would be a shorter interval if you don't get into the exact centre.

IMPACTS -- I am expecting widespread moderate damage and isolated severe damage reports. The widespread moderate damage will be mostly tree limbs down, entire trees down but not onto buildings, and roof tiles or other building material blown into streets or pavements. Severe damage would be coastal flooding from storm surges of 2-3 metres, stream flooding in parts of Connacht mostly, and trees falling onto cars or buildings. The south coast will see the worst of the wind gusts and storm surge, locally there could be gusts to 170 km/hr. I don't think too many reading this will experience higher than 130 km/hr but most will be in the 110-130 range at some point. Stay safe and avoid unnecessary travel or walking during the height of this storm.

Akrasia

[Deleted User] wrote: »

5pm (EDT, 10pm Ire) NHC graphics chart.

This looks like Ophelia might still be a hurricane at landfall (or very close)

thomasj

Akrasia wrote:

This looks like Ophelia might still be a hurricane at landfall (or very close)

No. It's a tropical storm with hurricane force winds.

Gaoth Laidir

18Z early intensity forecast, showing a 5-knot increase on earlier earlier runs. 12 hours is when it will approach Cork.

batman2000

M.T. Cranium wrote: »

Not the first time we've had to post this, but times on NHC guidance maps are set to eastern North American time zones (AST is same as EDT) and those are 5 hours behind IST, so add five hours to your time estimates. Just saw some discussions about arrival around 0600 but really that's 1100h IST.

I'd say because Met Eireann said tonight it's expected at 6am.

drunkmonkey

MJohnston wrote: »

Estofex is indicating "isolated tornado risk" and has been for a while:

http://www.estofex.org/

A little Irish tornado or a proper one? It's the first mention of it i've seen.

gozunda

The storms latest depiction on nullschool shows a very distinct eye / centre despite other reports of the eye having begun breaking down ...


https://earth.nullschool.net/#current/wind/surface/level/orthographic=-14.05,52.24,1362

batman2000

Yes, a clear eye and also keeping intensity

Middle Man

gozunda wrote: »

The storms latest depiction on nullschool shows a very distinct eye / centre despite other reports if the eye having begun breaking down ...


https://earth.nullschool.net/#current/wind/surface/level/orthographic=-14.05,52.24,1362

Wind speed has picked up (from 100 to 120kph since 7pm) on the Western side - Still 100kph on the Eastern side were it was around 130kph @ 4pm.

Lenny5

Could there be any unusual cloud formations, lightning, hail, or other weird events with this storm tmrow? Just wondering as its such an unusual event.