Storm Ciarán

[Roger J Smith]

Daniel Defoe to the forecast office please. (reference to event, OS dates Nov 26-27, NS would be Dec 7-8 1703, worst storm known to track across s England on a fairly similar track to Ciaran as modelled on GFS 18z). Difference was Defoe storm was at new moon, so a larger storm surge occurred (Bristol area badly flooded). Severe wind damage across south.

Even so, fairly large tidal range for this event too, given moon's orbital position near N declination max after a full moon, would be very concerned about coastal impacts all along the south coast.

[lottiekent]

10 minutes ago, Roger J Smith said:

Daniel Defoe to the forecast office please. (reference to event, OS dates Nov 26-27, NS would be Dec 7-8 1703, worst storm known to track across s England on a fairly similar track to Ciaran as modelled on GFS 18z). Difference was Defoe storm was at new moon, so a larger storm surge occurred (Bristol area badly flooded). Severe wind damage across south.

Even so, fairly large tidal range for this event too, given moon's orbital position near N declination max after a full moon, would be very concerned about coastal impacts all along the south coast.

As it stands, high tide here is 6.8m around 1pm when the strongest of the winds are forecast. 

[Roger J Smith]

This storm is going to slam the south coast and inland south with very strong wind gusts, the central pressure on 00z GFS run stays as before at a record low 949 mbs, and the gradient over the Channel would support 160-180 km/hr gusts. I realize the south coast is quite rugged and only has a few low lying coastal areas with developed land to receive a storm surge of 3-5 meters but where that is the case, total evacuation should be carried out on Wednesday if this monster is still on course. Expect widespread wind damage from southwest storm force winds 120-160 km/hr (and battering coastal waves, surge) in all areas south of the low's track, damage zone could include inland areas as far as Salisbury, Basingstoke, Croydon and all of Kent. I would expect results to show a gradient across greater London. When the low begins to fill around Berkshire later on Thursday, winds will spread out a bit more inland and drop below extreme gust levels into the 90-130 km/hr range for larger portions of the southeast and east. The more extreme gusts will move on into North Sea and Benelux, northern France when this slight moderation takes place, but once a band of very strong winds is created, it takes time for its momentum to dissipate.

South Wales to Severn valley could see the worst of rain-produced flooding, 40-60 mm could fall on already saturated watersheds. Closer to 20-40 mm likely further east. 

A contributing factor giving this extreme potential is the warm surrounding sea temperatures, 16-17 C in Channel. When a very deep upper low spirals down to capture this approaching storm, it will deepen explosively south of Ireland and be at full force approaching southern England around 0300h Thursday.

A lady called and asked if a hurricane was coming and I said yes, it defoe is. This of course is not a tropical storm but it will produce conditions similar to a cat-1 hurricane all along the south coast and could be close to a cat-2 hurricane over marine areas and I would be concerned about Channel Islands and exposed areas of n.w. to n.e. France also.

The low following along on Saturday is also quite deep, currently looks rather subdued for wind potential but there are ways this second low could intensify rapidly too; it will certainly be a fairly significant rain producer on top of all the recent and near future rainfalls expected. 

I would fully expect some red alert conditions on Thursday, likely to include at least Cornwall, Devon, Somerset, south Wales, Bristol area, Dorset, Wilts, hants, all of southeast, possibly also Oxford and n/w of London into Essex. Orange is probably going to run from central Wales to about Lincs, depends on flood potential as warnings could be for wind and/or rain. (and coastal surge, battering waves could be at red alert levels independent of other factors).

 

 

[sunnijim]

Updated fax clearly shows that Exeter now have the Low 100 miles or so further Nirth than ideas of 24hrs earlier.

Marginaly deeper at the same time too ( filling slowly) or steady pressure as it exits.

LATEST below.

24hrs ago thoughts

Edited October 31, 2023 by sunnijim

[richie3846]

7 minutes ago, sunnijim said:

Updated fax clearly shows that Exeter now have the Low 100 miles or so further Nirth than ideas of 24hrs earlier.

Marginaly deeper at the same time too ( filling slowly) or steady pressure as it exits.

LATEST below.

24hrs ago thoughts

I don't believe this is the case. What's changed in this graphic, to my eyes, is the rate of progress through the UK, and not the position. The second image has the low further west, suggesting a slightly later arrival than the first image. I believe the track is basically the same, and hasn't changed overnight, because it's been the case for a few days now, that the low enters via the Bristol Channel and moves sharply North East. 

[sunnijim]

7 minutes ago, richie3846 said:

I don't believe this is the case. What's changed in this graphic, to my eyes, is the rate of progress through the UK, and not the position. The second image has the low further west, suggesting a slightly later arrival than the first image. I believe the track is basically the same, and hasn't changed overnight, because it's been the case for a few days now, that the low enters via the Bristol Channel and moves sharply North East. 

Yes,you are right.

Note to self,don't post at 5am having watched a thunderstorm since 4am!

[Roger Stockman]

GFS 18z chart observations:

Could we have another named storm for Saturday morning as this looks a bit nasty for potentially Ciaran affected areas 

Edited October 31, 2023 by Roger Stockman

[Lincs Observation]

Morning all the latest view, some pretty horrific numbers here 

 

Edited October 31, 2023 by Lincs Observation

[minus10]

Gfs 0z edging slightly north again for 0z..

18z 

 

18z

[Skullzrulerz]

1 minute ago, minus10 said:

Gfs 0z edging slightly north again for 0z..

18z 

 

18z

Seems a bit of a standoff between GFS/ECM over the low pressure position.

ECM has it a far bit more south no? 

 

[The PIT]

3 minutes ago, minus10 said:

Gfs 0z edging slightly north again for 0z..

 

18z 

 

 

18z

Are those knots, mph, kmh or the expected number of carrots floating in the english channel. My maths teacher would have big red circle round that as would my degree lectures. Always lable graphs otherwsie it's meaningless.

Going to be interesting to what the models show tonight. Only impact for us will be a bit more rain.

[Lincs Observation]

I think the next four runs possibly 6 runs will still not nail this down, I’m pretty adamant that it not until the early hours of Wednesdays runs that we will have more of a grasp on what is to come. It will be a very last minute dot com situation. 

[sunnijim]

1 minute ago, Skullzrulerz said:

Seems a bit of a standoff between GFS/ECM over the low pressure position.

ECM has it a far bit more south no? 

 

Looks like Met Office have disregarded the ECM output,the updated fax is almost a carbon copy of the GFS.

Would imagine a blend of other models and the in house Deecider show that solution of a more Northern run  compared to ECM.

[James Maidstone]

1 minute ago, sunnijim said:

Looks like Met Office have disregarded the ECM output,the updated fax is almost a carbon copy of the GFS.

Would imagine a blend of other models and the in house Deecider show that solution of a more Northern run  compared to ECM.

Arpege and Icon in line with GFS on track of storm now.  ECM kind of on its own both with the initial position further South an the track across the country

[Lincs Observation]

For me my interest will be in its exit, currently progressing to exit via east anglia, this would put us in here in Lincs in a easterly flow of winds in what is a very flat county. The point being it could be quite tasty here for a short time as this storm promptly rattles through.

 

[minus10]

5 minutes ago, The PIT said:

Are those knots, mph, kmh or the expected number of carrots floating in the english channel. My maths teacher would have big red circle round that as would my degree lectures. Always lable graphs otherwsie it's meaningless.

Going to be interesting to what the models show tonight. Only impact for us will be a bit more rain.

The 'arrows' indicate knots and direction while the colouring indicates kmh re @Mapantz above..

Ecm 0z / 18z for comparison..

[ANYWEATHER]

49 minutes ago, sunnijim said:

Looks like Met Office have disregarded the ECM output,the updated fax is almost a carbon copy of the GFS.

Would imagine a blend of other models and the in house Deecider show that solution of a more Northern run  compared to ECM.

I wouldn't rule the Ecm out, but if you look at the storm it's at its most aggressive before it hits the UK ,the Bay of Biscay will take a pounding along with coastal communities there....

[SizzlingHeat]

GEM and UKMO have the storm further south as opposed to GFS and icon. Could go down to the wire regarding its track. Wont be resolved until much closer to the time I would imagine 

[Cassivellaunus]

Anyone else surprised Met office haven't gone to amber for the wind yet?

Seems fairly certain that the south is likely to get at least 80mph winds potentially higher if the track stays a little north.

People are saying it's a record low pressure but is that just for November? I see the lowest ever low over UK land was in Scotland. 

[ANYWEATHER]

Slight wobbles from the models ,but the lions share of the strongest winds will still at least be over the English channel ,thank goodness. I think the Channel Islands are going to be right in the firing line, interesting that this storm peaks around early Thursday morning, so less people on the move. The UKV has a sting in its tail for Cornwall in picticular first thing on Thursday ,with potentially 100 mph gusts especially on the Atlantic Coast. ...

[philglossop]

Well last evening I had the pleasure of driving to a meeting in Okehampton and back. And whilst the rain was heavy as expected across the Moor from Tavistock northwards, driving home the main issue was flooding. Not serious but enough to show the ground is saturated with run off.

High tide on Thursday is a worrying 0748 at Bovisand so the tide is incoming right at the wrong time here. Barbican in Plymouth will flood on that,  as will other southern coast towns and villages.

I have a feeling we're going to hit Amber later then possibly a red later? They've avoided red for us even with Arwen which was brutal a few years back.

Schemes starting to wind down workwise. 

 

 

[Shaunado]

I watched a MetO forecast in the evening who said the Nov record low pressure is set to be broken.

[Snow Queen one]

All models show me that my area is going to suffer high winds so i am not looking forward to this storm.  

[Jo Farrow]

14 minutes ago, Cassivellaunus said:

Anyone else surprised Met office haven't gone to amber for the wind yet?

Seems fairly certain that the south is likely to get at least 80mph winds potentially higher if the track stays a little north.

People are saying it's a record low pressure but is that just for November? I see the lowest ever low over UK land was in Scotland. 

No.

The heads up early warning is there, the storm name is aiding comms on this event. They usually wait until 10/11am to update their warnings.

There is a steady rhythm to this kind of thing and repercussions when amber or red warnings appear, it kicks of lots of logistical processes.

Decision making - Severe weather warnings and The Matrix

WWW.NETWEATHER.TV

---

Yellow, Amber and Red warnings - all warn of severe weather but not all yellow warnings are equal. The UK uses an impact-based system. Extra understanding is needed for good decision making.

 

[philglossop]

3 minutes ago, Jo Farrow said:

No.

The heads up early warning is there, the storm name is aiding comms on this event. They usually wait until 10/11am to update their warnings.

There is a steady rhythm to this kind of thing and repercussions when amber or red warnings appear, it kicks of lots of logistical processes.

Decision making - Severe weather warnings and The Matrix

WWW.NETWEATHER.TV

---

Yellow, Amber and Red warnings - all warn of severe weather but not all yellow warnings are equal. The UK uses an impact-based system. Extra understanding is needed for good decision making.

 

Indeed- Amber weather warnings for storms trigger a different way of working in local authorities Highways and if you need to sort stuff out you claim against a 'storm" payment code rather than the day to day budget. Something I had no idea of until last Winter but it's clever stuff and saves money long term