New Years Day 2015 Storm Discussion

[Zenarcher]

Yes downgrade after downgrade with this one. Pretty much all of the models are not showing a storm anymore but perhaps still windy on New Years Day just not stormy. The CMA and CFS both still go for a storm hitting Scotland though.

[Liam J]

Little bit surprised as this wave is riding along on a very powerful jet streak with a steep thermal gradient over the Atlantic, obviously not in the sweet spot for rapid cyclogenesis. I wonder could the wave deepen more rapidly than the models are showing into something noteworthy with a short lead time? The potential is there. 

Edited December 29, 2014 by Liam J

[Liam J]

looks like just another wet and windy day in winter ,won't even open the curtains !!!...

Shame! This could have been a significant weather event but more often than not they get downgraded. 

[Mokidugway]

Shame! This could have been a significant weather event but more often than not they get downgraded.

it is but I'll likly be very hungover anyway .... Edited December 29, 2014 by Mokidugway

[Zenarcher]

Little bit surprised as this wave is riding along on a very powerful jet streak with a steep thermal gradient over the Atlantic, obviously not in the sweet spot for rapid cyclogenesis. I wonder could the wave deepen more rapidly than the models are showing into something noteworthy with a short lead time? The potential is there. 

 

Same here the models seemed so confident on the storm it was just the track that needed to be decided but as we saw with each run downgrades happened. I do remember the 3rd of January 2012 storm was downgraded by some of the models when it was only 48 hours away only to get a big upgrade a few hours before it hit although a sting jet happened that day something only the high res models picked up hours before it hit.

[johnholmes]

Little bit surprised as this wave is riding along on a very powerful jet streak with a steep thermal gradient over the Atlantic, obviously not in the sweet spot for rapid cyclogenesis. I wonder could the wave deepen more rapidly than the models are showing into something noteworthy with a short lead time? The potential is there. 

 

It will depend where the minor trough in the upper atmosphere is placed in relation to entry and exit parts of the jet and indeed if the jet has the right pattern for a deepening surface feature. It needs to enter at the right entrance and exit at the left exit for this to happen; the jet itself has to be diffluent, that is the air flows slower at the exit than at the entrance. Hard to say if this will happen. The odds I suppose are against it judging from the model outputs latterly but it is a fair way off.

[Liam J]

It will depend where the minor trough in the upper atmosphere is placed in relation to entry and exit parts of the jet and indeed if the jet has the right pattern for a deepening surface feature. It needs to enter at the right entrance and exit at the left exit for this to happen; the jet itself has to be diffluent, that is the air flows slower at the exit than at the entrance. Hard to say if this will happen. The odds I suppose are against it judging from the model outputs latterly but it is a fair way off.

Guess we'll just have to keep an eye on the model outputs in the coming days, it's still 3 days away which means plenty of time for further changes before we reach Thursday. Should be within range of the hi-res models by tomorrow afternoon. 

 

NMM 12 showing gusts of 50-60mph so still a very windy day potentially.

 

 

 

 

 

Edited December 29, 2014 by Liam J

[knocker]

The GFS (P) this morning has the depression forming mid Atlantic and zipping along on the jet and affecting N. Scotland but not looking too bad as it's still developing at this stage. A different story in Scandinavia where they could have some very nasty weather. No snow threat in the UK and it actually produces some above average temps. The GFS is along the same lines.

Charts courtesy weatherbell

 

 

Edited December 30, 2014 by knocker

[Zenarcher]

A slight upgrade this morning from some of the models along with the GFS at the moment its looking very stormy for some parts.

 

1st of January 6am to 12pm - Gusts across the West and North could reach 60mph with some places in the West of Scotland seeing over 70mph.

 

 

3pm - All of the UK and Ireland by this point will see strong gusty winds the worst will be in Northern parts with 60 to 70mph.

 

 

6pm - Gusts will range from 40 to 60mph across England at this point and while the North see's the wind drop down in speed there's a chance of 80mph gusts for the far Northern Scottish Isles.

 

 

9pm - While the rest of the UK and Ireland continue to see the wind speeds drop theres still a chance of 40 to 60mph gusts though. The Northern Scottish Isles see gusts over 85mph.

 

 

That's how it looks at the moment of course this needs to be watched closely for any further upgrades or downgrades but I have a feeling the exact detail won't be known until tomorrow.

[Zenarcher]

A few of the models have updated to their 12z runs and overall today there seems to be a upgrade from yesterday.

 

UKMO shows a 990mb low pressure system sweep over the NW of Scotland. The GME has it slightly lower down to 985mb and later the isobars get very tight over the far North of Scotland giving very stormy winds,

 

 

The olds GFS model shows a 985mb low similar to the GME buts its the new GFS model that has things looking interesting. Here's the 3pm gust chart showing widespread 50 to 60mph gusts with the NW of Scotland seeing 85mph.

 

 

By 6pm the low deepens further more and the gusts get higher over Northern Scotland where winds over 95mph could be possible,

 

 

Some other models haven't updated yet they will soon over the next few hours but today so far we have seen some upgrades to this storm and it needs to be watched closely now.

[Skullzrulerz]

Indeed I think this is going to have be watched carefully despise it being downgraded in the last few days all of the sudden it's been upgrade after upgrade. Tonight's models runs should help us of how strong the storm may be.

[knocker]

The GFS (P) has possible hurricane force winds for the far north of Scotland. The ops has it a tad further north.

Chart weatherbell

 

Edited December 30, 2014 by knocker

[Liam J]

Despite the downgrades of yesterday the latest model runs have now gone back to show a pretty potent storm crossing N'rn Britain on Thursday. Gusts of up to 70mph for N England northwards with 80-90mph gusts potentially for parts of Scotland. Looking pretty serious now surprised no warnings have been issued yet, still some uncertainty regarding precise track and depth I suppose looking at the ensembles as some don't make much of it. 

 

Euro4 looks to have the approaching low a bit further south.

 

Edited December 30, 2014 by Liam J

[Daniel*]

I thought the downgrades would gather in pace, I was wrong... let's say if the worst of the winds were in London and the Home Counties (heavily populated) I think the METO would give a red warning, since up there its sparsely populated and the locals are hard wearing, nothing really new to them, I see an amber. Regardless quite a fierce storm in the making, any further upgrades and it could get dangerous.

[Mokidugway]

I thought the downgrades would gather in pace, I was wrong... let's say if the worst of the winds were in London and the Home Counties (heavily populated) I think the METO would give a red warning, since up there its sparsely populated and the locals are hard wearing, nothing really new to them, I see an amber. Regardless quite a fierce storm in the making, any further upgrades and it could get dangerous.

yes our crofts are very tough ,and sometimes the Lord of the manor lets us stay in the big house if things get to bad ....

[Liam J]

The 12z GME would give some extreme winds to N Scotland! Some models are really going for it while others are much less keen on developing the wave, I expect the Meto will be waiting for more clear guidance before thinking about issuing warnings, could go either way this one! ECM rolling out now and not making much of it at all. 

 

 

Euro4 has the low tracking a bit further south and it brings gales/severe gales into many northern and western areas. 

 

 

Edited December 30, 2014 by Liam J

[Liam J]

The CMA has the low deepen rapidly from 1000mb to 975mb in 12 hours! Very windy for much of the UK.

 

[Zenarcher]

12z ECM this evening doesn't make much of it. The ECM sends it South across Ireland, Wales and England bringing windy weather but nothing severe so it still might not come to much at all.

Edited December 30, 2014 by weathermaster

[Liam J]

Surely by tomorrow we'll see more in the way of agreement across the models?! Hard to make a forecast for Thursday going on latest guidance (available to the public) with large variations in track & intensity. I suspect the Meto don't see much of a threat or else there would likely have been some sort of warning in place at less than 48hrs away.

[Skullzrulerz]

There seem to a quite of bit of uncertainty at the moment with the models at just over 2 days out.

[Liam J]

Can anyone post the ECM postage stamps for Thursdays low or post a link to them? Thanks. 

[IDO]

Can anyone post the ECM postage stamps for Thursdays low or post a link to them? Thanks. 

 

Should update soon: http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!72!pop!od!enfo!enplot!2014123000!!/

[Liam J]

Should update soon: http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!72!pop!od!enfo!enplot!2014123000!!/

Thank you

[Liam J]

Not much to get excited about on the ECM ensemble forecasts, just a normal windy day in store. The models which are showing rapid cyclogenesis I expect will back down over the next few runs. The ECM never really wanted to deepen the low and has remained the case up to now including the 50 EPS members. 

 

http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!48!pop!od!enfo!enplot!2014123012!!/

[Liam J]

 

Yes but we can't yet be too clever/deterministic. A developmental situation, certainly, but with oscillating potential from last 2-3 runs. Currently, Exeter offer 30% PROB of the version bringing disruptive winds/sting jet potential.

Taken from the MOD, thanks to Ian Fergusson (Fergieweather) for this bit of info. Low/moderate potential for something more severe. 

Edited December 30, 2014 by Liam J