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

Meteorite58

Gaoth Laidir

12Z early intensity guidance kind of as you were. Just under Cat 1 (1-minute sustained) from around late afternoon Monday. 10-minute sustained slightly lower.

Jpmarn

Drumpot wrote: »

Has the warm humid weather we have today any relation to this event ?

Simple answer is no as the hurricane is too far away. However the southerly flow is forecasted to persist for quite a few days. There just happens to be a hurricane just at our side of the Atlantic and this southerly flow will bring this storm in our direction. But we can easily have this weather today and no hurricane in the middle of the ocean.

Kermit.de.frog

Gaoth Laidir wrote: »

12Z early intensity guidance kind of as you were. Just under Cat 1 (1-minute sustained) from around late afternoon Monday. 10-minute sustained slightly lower.

Interesting it could still arrive in the southwest with Cat 1 winds on Monday.

Meteorite58

Worth putting the latest guidance from the NHC in full here.

NHC


[000
WTNT42 KNHC 131440
TCDAT2

Hurricane Ophelia Discussion Number 18
NWS National Hurricane Center Miami FL AL172017
1100 AM AST Fri Oct 13 2017

The eye of Ophelia has become a bit more apparent in visible and
infrared imagery during the past couple of hours, but the cloud tops
around the eye have also warmed recently. The initial intensity is
set to 85 kt based on a blend of the latest subjective and objective
Dvorak CI and Final-T numbers. The hurricane will remain in an
environment of marginal SSTs and light to moderate shear for the
next day or so, which suggests little change in intensity during
that time. By 36 hours, the shear will begin to increase as a
powerful upper-level trough approaches from the west, but Ophelia
should remain at hurricane force during extratropical transition as
it undergoes a favorable interaction with the aforementioned trough
and takes on a warm seclusion structure. The transition process
is expected to be complete by 72 hours, and post-tropical Ophelia
should gradually weaken as the cyclone occludes beneath the upper
trough. The low-level circulation of Ophelia is expected to
dissipate over Scandinavia by day 5.

The initial motion estimate is 060/10. The track forecast reasoning
remains unchanged from the previous advisory. Ophelia should move
east-northeastward ahead of the approaching upper-level trough with
a steady increase in forward speed through the next 24 hours. The
hurricane should turn northeastward by 48 hours followed by a
north-northeastward motion at days 3 and 4. The track model guidance
is in good agreement on this overall scenario, but there are some
differences in forward speed beyond 48 hours. The new NHC track
is similar to the previous one and lies between the latest TVCA
multi-model consensus and the HCCA corrected consensus aid through
the forecast period. On this track, the center of Ophelia is
expected to move southeast of the Azores during the next 36 hours
and then move near or over Ireland and the western part of the UK in
3 to 4 days. Given the expected increase in the size of Ophelia's
wind field during extratropical transition, impacts from strong
winds and rain are becoming increasingly likely over portions of the
British Isles regardless of the exact track of the center.

While the NHC track continues to keep the center of Ophelia south
and east of the Azores, 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 the
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.

A 1242 UTC ASCAT-B pass was helpful in analyzing the 34-kt wind
radii around Ophelia.

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 becoming more 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 13/1500Z 31.8N 32.9W 85 KT 100 MPH
12H 14/0000Z 32.6N 30.9W 85 KT 100 MPH
24H 14/1200Z 34.1N 27.3W 85 KT 100 MPH
36H 15/0000Z 36.5N 22.6W 80 KT 90 MPH
48H 15/1200Z 40.7N 17.9W 80 KT 90 MPH
72H 16/1200Z 51.0N 11.5W 70 KT 80 MPH...POST-TROP/EXTRATROP
96H 17/1200Z 60.0N 4.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 18/1200Z...DISSIPATED

$$
Forecaster Brennan/I]

Coax

coillsaille wrote: »

The official Dept of Education guidelines state that schools "should consider closing" if in an area covered by a red warning, not that they must close.
I waa told before the reason for this is that if the school makes the decision then the Dept can compel the school to make up the lost time during Easter holidays but not if the school was instructed to close. Cannot confirm that is definitely true though.

Many thanks for that.

I got a response that the school will close if a red warning is issued.

Makes it easier to plan ahead with an answer.

cherryghost

So its set to have tropical features right up til its forecast to hit the south-west. Sustained winds now 100mph and expected to stay steady for a while yet.

Meteorite58

Forecast winds from the NHC

FORECAST VALID 16/1200Z 51.0N 11.5W...POST-TROP/EXTRATROP
MAX WIND 70 KT...GUSTS 85 KT.
50 KT...100NE 140SE 110SW 60NW.
34 KT...270NE 270SE 270SW 240NW.

https://twitter.com/NHC_Atlantic/status/918850764340105217

Meteorite58

ICON 06Z

Pangea

I take it from that map the worst winds will be away from the eye on the right hand side?

Kermit.de.frog

Guy on the Weather Channel just after saying we "could be dealing with a land falling hurricane in Ireland, believe it or not!" based on latest NHC guidance.

Oscar Bravo

Siobhan Ryan on rte 1 forecast there. severe warnings will be issued tomorrow.stay tuned to forecasts and the website for updates.

munsterlegend

Kermit.de.frog wrote: »

Guy on the Weather Channel just after saying we "could be dealing with a land falling hurricane in Ireland, believe it or not!" based on latest NHC guidance.

the trampoline will be coming in Sunday afternoon.

JCX BXC

In regards to flights, everything before Monday will be fine, (at least in terms of weather), Monday morning may be okay, for example the morning rush will probably clear without any disruption, although it's too early to tell.

Really, there's no way anyone could tell you until Sunday evening when the TAF's come out, and even then they're only valid for 24 hours after that.

Remember, flying is never guarenteed due to the strict safety regulations around it. Personally I think there could be disruption at all airports (based on current forecasts) with possibly the exception of Belfast if the winds aren't awful. The forecast wind direction won't do DUB or NOC any favours.

Basically Monday Afternoon/Evening is the only period in which I'd assume as high risk of disruption to flights, all other times should be fine (Sunday/Tuesday should be fine).

If you wish, I will update with the TAF's (Terminal Area Forecast, basically the forecast for the airport) on Sunday evening at around 6:15 when they come out.

MJohnston

Pangea wrote: »

I take it from that map the worst winds will be away from the eye on the right hand side?

That's basically how all Atlantic, northern-hemisphere storms of this nature work, yep.

stevenup7002

Am I reading that right? 180 km/h gusts over Waterford?

Villain

Latest NHC updates go not make for good reading, we need downgrades here or we are in trouble.

Storm 10

If this hits as bad as forecast on Monday the only saving grace will be that it will be at its worst during daylight hours.

Gaoth Laidir

Latest 1-km visible sat image. Sexy beach...

Ms Doubtfire1

it's going to rain and be windy.What else is new..?8-)

cdsb46

Not sure if it is related to the Storm or not but the Public Appointments Service have just cancelled all exams that were due to take place on Monday, could be just a coincidence though

Villain

Ms Doubtfire1 wrote: »

it's going to rain and be windy.What else is new..?8-)

These kind of posts belong in After Hours, I like a bit of fun as much as the next person but at present this storm has the potential to a severe event and making light of it helps no-one.

Let's hope it does pass as just a windy day but based on the data available at present that does not look likely, so I'd prepare for worst case scenario and keep the jokes where they belong for now

squarecircles

Noticed the ESB out in Force today in Westport,lots of trees being clipped aswell by council staff

Gaoth Laidir

Current 500 hPa chart, showing the trough extending from the north Atlantic south towards Ophelia.



Sunday, 18Z. Ophelia interacts with the upper trough just west of Iberia (just off the bottom of the chart). From this point on is where the uncertainty lies. How exactly will that upper trough extend south and in what state will Ophelia be as it interacts with it?



Monday, 18Z. Looks like the upper trough is already right over the centre, so deepening has stopped. The upper low starts to fill.

Dutchy

Doing me best to warn work colleagues & family members alike.
They're laughing it off & saying they'll get the tin hats prepared.
Still time for its trajectory to change but I do believe, in light of recent charts, a sterner warning should be issued by Met Eireann. I'm flying to the UK on Sat evening & due to return back to Dublin Monday evening. I'm preparing for an uncomfortable night in Gatwick Airport.

MJohnston

Dutchy wrote: »

Doing me best to warn work colleagues & family members alike.
They're laughing it off & saying they'll get the tin hats prepared.
Still time for its trajectory to change but I do believe, in light of recent charts, a sterner warning should be issued by Met Eireann. I'm flying to the UK on Sat evening & due to return back to Dublin Monday evening. I'm preparing for an uncomfortable night in Gatwick Airport.

You should probably consider getting that flight change now instead of waiting!

Dutchy

MJohnston wrote: »

You should probably consider getting that flight change now instead of waiting!

That's the thing - who really knows, at this stage, as to when is the best time to fly back. It may expedite and land earlier?

MJohnston

Dutchy wrote: »

That's the thing - who really knows, at this stage, as to when is the best time to fly back. It may expedite and land earlier?

What time Monday evening?

Keep an eye on the TAF forecasts (The F stands for forecast but whatever :pac:) that JCX BXC mentioned, they should at least give you 24 hours notice of any likely cancellations.

Personally, I'd be looking for a Gatwick hotel with a free last-minute cancellation policy and booking it now, before everyone else figures it out!

Dutchy

MJohnston wrote: »

What time Monday evening?

Keep an eye on the TAF forecasts (The F stands for forecast but whatever :pac:) that JCX BXC mentioned, they should at least give you 24 hours notice of any likely cancellations.

Personally, I'd be looking for a Gatwick hotel with a free last-minute cancellation policy and booking it now, before everyone else figures it out!

Cheers for that & apologies to all as I know this is trivial is light of what's ahead of us all. Due to fly back @ 5.30 pm. I'm in agreement - to book a hotel close to Gatwick & cancel if we do see blue sky. Great advice & thank you

Kermit.de.frog

Path more or less similar on GFS 12z run - center stays just off west coast but the low is slightly deeper and the gradient tighter, slightly stronger winds overall.