Model Output Discussion - mid Autumn

[tight isobar]

I’m not going to get into run 2 Synoptics just yet .. but it’s vivid in graphic, a notable storm is in- riding, and the euro is on a direct hit for large populated England! .. further we see a classic binocular sync.. so it’s possibly hit- after hit via breeding lp’s making inroad’s- keep watching!!!!   

[Mike Poole]

All models seem to agree that this is very much a double whammy.  We are not in a classic zonal setup here, and the GEM evolution out to T240 shows how the second system slams into the UK while the first is pretty much still there:

There’s even a little low in the middle that gets absorbed in it.  Very disruptive spell of weather.

[Rain All Night]

1 hour ago, Mike Poole said:

All models seem to agree that this is very much a double whammy.  We are not in a classic zonal setup here, and the GEM evolution out to T240 shows how the second system slams into the UK while the first is pretty much still there:

There’s even a little low in the middle that gets absorbed in it.  Very disruptive spell of weather.

Interestingly given my location, the ECM ensemble makes the Saturday low look a lot less notable than the Thursday one from a wind perspective (you can still see its footprint on the precipitation total though):

You can also see the suggestion of something brighter and chillier for the following week.

How pleasing to get these outputs an hour sooner today, and every day for the next five months!

Edited October 29, 2023 by RainAllNight

[ANYWEATHER]

I think the stormy winds are for a French Affair , .......

[Man With Beard]

1 minute ago, ANYWEATHER said:

I think the stormy winds are for a French Affair , .......

That's the recent trend, yes. But with the low having shifted at least 400 miles south in the past 36 hours, it would be good to see a few more runs before calling it. 

[alexisj9]

3 minutes ago, ANYWEATHER said:

I think the stormy winds are for a French Affair , .......

Second one shows south coast impacts, it also shows it's still intensifying between the two.

[alexisj9]

7 minutes ago, ANYWEATHER said:

I think the stormy winds are for a French Affair , .......

My mistake I though it was two sea level winds, second is at 850.

[sunnijim]

14 minutes ago, ANYWEATHER said:

I think the stormy winds are for a French Affair , .......

Was sceptical this morning as GFS seemed out on a limb with the Southerly dive,however all models now seem on board with "trend setting GFS"

Another correction South or the status quo being maintained tomorrow might see the met office warning reworded to focus on Channel Island impacts rather than mainland u.k.

Edited October 29, 2023 by sunnijim

[Catacol]

7 hours ago, IDO said:

Looking at the mean wind, we can see the usual trend of the system(s) being modelled further south as we get nearer the event(s). GFS 06z mean:

Except that this is not what the modelling is showing. ECM is currently very consistent - last 4 runs has the storm entering through the tip of Cornwall with very little deviation. Will be interesting to see whether we get a trend developing. GFS meanwhile is edging ever so slightly north in my interpretation, though it is fine lines for sure at this stage. 

00z Sat

12z Sat

00z Sun

12z Sun

The (in my opinion less reliable) 06z and 18z runs tell the same story, 06z Sat the furthest north

 

If there is a noticeable trend so far it is for the system to stall and fill.  At long range the ECM initially had it quickly losing intensity by Saturday

While GFS by Saturday had it pushing through on a very southerly trajectory into Europe

Both those solutions - which would have lessened the impacts considerably - have now been binned. We have a storm that is growing in strength, looking like it will sit in the jet, propped against higher pressure to the east and fill in a way that will not please those in flood areas. Secondary storm set to hit on Saturday developing out of the same trough sat within the jet streak.

All this means that we are looking at a high impact event that I still think will trend slightly northwards in the coming days. France certain to be hit - southern parts of the UK also.

I'm with Tamara on this one (and we haven't always seen eye to eye!) - current climate impacts sitting on top of developing forecasting techniques is creating a nasty mix. I'm not sure it is possible anymore to rely on seeing average weather. Most of the time developments will sit within the average envelope but the number of times that envelope is being broken is getting more and more frequent, and if this storm develops into one of the nasty global events that are impossible to miss these days then it really isn't good news, even for weather enthusiasts. 

[Catacol]

1 hour ago, Man With Beard said:

That's the recent trend, yes. But with the low having shifted at least 400 miles south in the past 36 hours, it would be good to see a few more runs before calling it. 

You're going to need to post some images of this - because I'm looking at modelling for Thurs to Sat and seeing no such thing. 400 mile shift south? This was the GFS 3 days ago

 

18z tonight for the same date

Maybe I'm hallucinating....

Edited October 29, 2023 by Catacol

[Snowboy111]

58 minutes ago, sunnijim said:

Was sceptical this morning as GFS seemed out on a limb with the Southerly dive,however all models now seem on board with "trend setting GFS"

Another correction South or the status quo being maintained tomorrow might see the met office warning reworded to focus on Channel Island impacts rather than mainland u.k.

I’ll let you know how things go. That’s if I’m not blown into France. Proper exposed to this. Gonna be brutal. 

[Fitzwis]

8 minutes ago, Snowboy111 said:

I’ll let you know how things go. That’s if I’m not blown into France. Proper exposed to this. Gonna be brutal. 

Indeed. Will be interesting to see how our local met predict and handle this one, including when warnings will be issued encompassing tide alerts. Stay safe my friend.

[Mapantz]

49 minutes ago, Catacol said:

You're going to need to post some images of this - because I'm looking at modelling for Thurs to Sat and seeing no such thing. 400 mile shift south? This was the GFS 3 days ago

MWB may have been referring to this chart Catacol, which was posted on Friday by minus10?!

[Snowboy111]

53 minutes ago, Fitzwis said:

Indeed. Will be interesting to see how our local met predict and handle this one, including when warnings will be issued encompassing tide alerts. Stay safe my friend.

Well we don’t have a met here, just observers, so our info is from your Met. I suspect they’ll do it Tuesday eve. They’re not one for going early. Tides aren’t too bad. No springs so that’ll help. But we’re exposed so I fear a hell of a battering for a good 24 hours. No doubt you’ll record a 1mph quicker wind speed than us

[Norrance]

Latest fax chart for midday Thursday. Some very high winds along the South coast if this track is maintained and lots of rain for many. 

[alexisj9]

4 minutes ago, Norrance said:

Latest fax chart for midday Thursday. Some very high winds along the South coast if this track is maintained and lots of rain for many. 

Oh it slightly further north than yesterday's, thats not good, puts the south well and truely in the wind field.

Edited October 29, 2023 by alexisj9

[Newberryone]

Admittedly it’s a day 10 chart and of course subject to change but the 12z Ecm does at least seem to be holding out the prospect of something calmer and perhaps more settled after next weekend. Even in the days preceding this day 10 chart pressure does seem to be gradually on the rise from the southwest, finally moving the jet stream that bit further north. Temps would probably be about average or perhaps slightly above considering it would be a rise in pressure from the Azores. 

[Jordan S]

I think the above fax charts where yesterday’s update, this one below seems to be the updated one today for Thursday, storm more elongated, strongest winds for channel and south coast but all of the south at risk of some damaging winds if track is shifted slightly northwest of this in the coming days which seems more likely of course.

Seems to be three possibilities for inland England and to a lesser extent Wales. The most likely being periods of gust in excess of 50mph inland as already been said, with 70-80mph isolated 90mph in exposed coastal parts as has been mentioned particularly also by the met office.

A Less likely outcome being relatively light winds for most of the time inland southern England except for the initial band of rain and southerly winds, with very heavy rain being the main problem due to centre of storm passing over the south excluding the south coast.

Least likely outcome of very damaging wind gusts of 70+mph inland over the south with 100mph worryingly close to the south coast and certainly over the English Channel. Regardless this storm looks likely to cause big problems for the south coast atm. But worth watching closely for the rest of southern England 50-55mph with trees in full leaf and saturated ground really is significant and rather damaging. 

here’s the latest Gfs for the storm.

 

The next deep low moving into far southern parts by Friday/Saturday time will only exacerbate problems but this primarily a rain maker with the strongest winds over southwestern coasts and over France.

Edited October 30, 2023 by Jordan S

[WYorksWeather]

Going to get back to my usual post today, but will be a quick one. Storm Ciaran has been well covered by others, so I'll look at T+114/120, T+162/168, and T+234/240 comparing GFS 18z to ECM 12z.

At T+114/120, GFS backs the remnants of Ciaran up the east coast and back to northern England. ECM has it on a more conventional west to east track.

 

At T+162/168, the remnants of another storm (too early to be calling this potential Storm Debi?) are passing to our east. GFS is faster to move it through, ECM still has it fairly close to the east. Nevertheless, low pressure still well in charge.

 

At T+234/240, GFS has yet another low moving in, admittedly less deep than the last one. Also an absurd Greenland high setting up at 1060mb! ECM is less interested in the Greenland high, and is hinting more at a rise in pressure from the SW, though only beginning to influence the UK at this stage.

 

Rainfall accumulations to T+240 show the highest accumulations for the SW corner. GFS shows an additional risk area of 100mm or more for NW England.

  

Moving into the GFS extended, we see a couple of attempts to raise heights over the UK, but it's all pretty feeble quite frankly, and after that it's just more unsettled weather for the foreseeable. Temperatures near normal to perhaps a little below average. Position at T+384 is shown.

 

 

[IDO]

GFS is maintaining a more southerly track for the coming storm, and the 0Z op has the eye of the storm over the south, with the most damaging winds missing most of us, though the SW and E Anglia may catch some stormier conditions. 

UKMO and GEM are variations of this track.

The GFS D7 accumulated rainfall shows the worst in the channel, but S England is getting higher than average amounts:

[alexisj9]

1 hour ago, IDO said:

GFS is maintaining a more southerly track for the coming storm, and the 0Z op has the eye of the storm over the south, with the most damaging winds missing most of us, though the SW and E Anglia may catch some stormier conditions. 

UKMO and GEM are variations of this track.

The GFS D7 accumulated rainfall shows the worst in the channel, but S England is getting higher than average amounts:

Looks to me the whole south coast gets hit with winds too, not just rain, it might not go far in land, but coastal towns do exist thanks.

[Rain All Night]

4 minutes ago, alexisj9 said:

coastal towns do exist thanks.

We might not by this time next week 

[ANYWEATHER]

After what seems like a tempestuous start to the ten day period ,both gfs and ecm show things settling down somewhat with colder,calmer conditions as we move towards the end of this ten day timescale. ......

[Rain All Night]

1 hour ago, ANYWEATHER said:

After what seems like a tempestuous start to the ten day period ,both gfs and ecm show things settling down somewhat with colder,calmer conditions as we move towards the end of this ten day timescale. ......

Charts to illustrate your post:

Are the machine learning models on board? Not really...

Is the ECM ensemble on board? Potentially, it's there on the table:

Edited October 30, 2023 by RainAllNight

[Man With Beard]

Update on Thursday's storm: The most severe winds are more frequently being modelled to the North France coast (including the Channel Islands), where risks of 100mph winds are still very much alive. Whilst that may sound like better news for the South coast of England, the brunt of the storm remains modelled uncomfortably closeby, and so it is simply too early to rule out the more severe 90mph+ impacts of the storm brushing the southern counties, or indeed a further southerly correction removing storm force winds altogether.

50 miles north of the coast, or away from a line from Bournemouth to Norfolk, not much to worry about at this stage.

The UKV brings 90mph+ winds to Cornwall first thing on Thursday, and then 88mph to the SE coast later on:

 

The UKMO brings 90mph winds to Kent, and the ARPEGE isn't far off, with Cornwall also seeing high winds:

 

The GFS has similar zones for highest impact but probably 75-80mph at the most extreme: