We go again?

Let’s hope we don’t slip!

Seems like the ‘beast from the east’ was a long time ago doesn’t it? Now looks like we have another cold spell in the works, which rather satisfyingly, fits in with my post on Feb 18th. And particularly this chart which shows a composite of 18 weak vortex events.

Strong + weak vortex composite

Essentially what this shows is the lag effect from an SSW if you will. So lets take that and put it next too what happened last month shall we?

drawing

So our day 0 was around mid month, so comparing with the graph, it looks likely that another pulse is coming, around 30 days after the initial event. What does this mean for us? That a cold spell is likely and that unfortunately for some, there is little sign of any spring like weather for the foreseeable, I would say getting well into April at the earliest now for anything properly spring like. Not a good outlook for those looking for better weather!

In the nearer term again though, it looks like a very cold easterly flow coming in at the weekend but detail on how long and just how cold and widespread it’ll be is up for debate, as is the snow risk……… I would say a blend of the ECM and GFS today is more likely than the UKMO today but we’ll see.

ECM 120 march 12th 12zGFS 120 12th march 12z

 

Let’s see what happens!

Ryan.

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The beast commeth

Well following on from my last post we can now have a quick look at snow amounts for the coming week, not taking into account the uncertainty of the low moving up from the south on Friday just yet.

Here’s the GFS chart for this evening, certainly one to save.

GFS 6 hours 12z 25th feb

Big area of high pressure over Scandinavia pushing extremely cold air our way. How cold? A cold pool nearly on par with January 1987’s. Uppers over the UK are expected to get down to -16c, maybe we can squeeze a -17c? With such cold air coming across a relatively warm surface; the north sea, convection will initiate and snow will fall right down the entire eastern side of the country, and pushing inland.

img_4909

Here’s the satellite picture over the north sea, we can already see cloud forming and pushing west, this is the beginning of the north sea snow machine firing up. Snow showers will start filtering in to the east this evening and carrying on into the week, lighter at first, but getting heavier. The met office have a yellow warning for a cm or two on Monday morning down Lincolnshire round the Norfolk coasts into the south east. That is just the start.

img_4910

These snow showers will get heavier and more persistent right down from the north east of the country to the south east into the Thames estuary. The met office warning for this is shown below on Monday with up to 4inches in places.

img_4911

Onto Tuesday, and things get a little more meaty, snow showers carrying on right from Scotland all the way down to the south east. On Tuesday morning an area of snow will move in from the north sea tracking south west, some disagreements about just where this will be but the threat of up to 6 inches off this. It looks to come in somewhere around Scarborough sliding south west towards the wash, into the midlands and wales, it’ll weaken a lot before it gets to wales but the threat of some flakes there. All the while, snow showers continuing throughout the day,

UKMO fax

This is the UKMO fax chart for Tues morning, you can see the disturbance off the north east coast there and also a convergence in the south east. This will bring a fair amount of snow through Tuesday into Wednesday. Fax chrt fro jlfax

Fax chart for midnight Tuesday into Wednesday. See the trough coming towards the north east there.

 

Snow showers will start to ease later on in the day on  Wednesday for the east and south east as the flow veers more south easterly while snow will continue to pile into those further  up the east coast right up to NE Scotland.snow map

This area in the SE looks best for the biggest accumulations. Possibly  25cm or even a little more as snow piles up. Snow accumulations up to a foot in some places when all said and done across the UK. Favoured would be north east, into eastern Scotland aswell. Basically snow here, snow there, snow every f*cking where.

snow map

I’m on a highway to snow.

Update on Fridays snow potential coming tomorrow or Tuesday.

Something stirring?

Its been far too long since my last post, so it must be looking good for me to be doing a blog post eh?

We are on the cusp of a spell of weather the UK has not seen for many years, with the threat of severe cold and snow. More on that in a bit. Let’s have a quick look at the failed easterly in January and why it was never going to amount to anything, and why this is different.

ECM day 10 old

Here’s the ECM prediction from the 3rd of January for the 13th. As you can see it was going for a cold easterly. At the time I thought any easterly was unlikely, why? PV too strong for the high to establish, there was no real stratospheric support for an easterly.

GFS old

Sure enough, this was as close as we got, the high collapsed like a jenga tower in an earthquake. This time however, things are just a tad different.

We have seen one of the biggest Sudden stratospheric warmings on record.

zonal winds

Here’s the zonal wind plot at 60N 10hpa showing a huge reversal of the polar westerly’s, this has torn the polar vortex in two. With one lobe over Europe and the other over Hudson bay.

10hpa gfs

If that wasn’t enough to pump the vortex, 2 days ago a warming peaked right where the main Hudson bay vortex was located.

gfs strat warm

Net result? Total demolition of the stratospheric polar vortex. Thus a higher chance of colder weather based off that, but to add further credence to this, the split was in a near perfect place to allow a Scandinavian high to form, in the troposphere where we see our weather.

The stratospheric high located over Svalbard is pretty much perfect if you want an easterly.So we have support from the strat. There was also the small matter of a massive MJO wave through phase 6 and importantly phase 7. Which also favours higher pressure over Scandinavia. So now we can begin to see why we are seeing historic charts such as this.

GFS at day 5 12 19th feb

We have not seen such synoptics shown for many years, and the sheer depth of cold coming out of Russia heading west into Europe is very rare indeed.

GFS uppers

This means that we have the very rare chance of historic cold reaching the UK.

This week then, we will see the high building over Scandinavia and a slack easterly setting up mid week onwards. It will get colder as we get into the weekend with that windchill really starting to make its presence felt. Snow flurrys likely mostly sunday onwards into the following week when we should be getting the deep cold over the UK, making the snow risk more widespread while feeling bitterly cold everywhere. I wont go in to too much detail yet, as the exact orientation of the high is still up for grabs, so associated depth of cold and snow can still change. (GFS and especiallyECM) would have snow depths in the feet)

Little further on there is good confidence in a retrogression of the high to Greenland, like the ECM 12z OP from today.

WOW ECM

Here at day 8 we see the high being sucked up towards Greenland, I feel this is more likely than the GFS which brings low pressure too far north and somewhat spoils the retrogression. The result of this would be the UK locked in cold well into March, with northerly or north easterly winds continuing,  something which the met office have alluded too in there longer term outlook.

Just a quick muse on even further ahead, I see March and perhaps into April too having a high potential for blocking around the northern hemisphere, in response to the massive SSW. The effects of an SSW are felt for many weeks.

Strong + weak vortex composite

These are the lag times, we are seeing the first pulse here around 10 days, note the pulses 25-30 days and 35-50 days out. So a much higher chance of a cold March here for sure.

 

Off topic but remember that the NAO (North atlantic Oscillation) does NOT drive the weather pattern. It is simply a reflection of the pattern. It is not an atmospheric driver like the MJO for example, or an SSW, merely a reflection of the pattern in the north Atlantic, I have seen people getting confused about this.

That’s it for me on this one. See you soon.

Get set, it’s coming.

Winter 2017/18 thoughts. A better chance of cold?

GFS snow charts are already being posted where ever you look. A sure sign that winter is just around the corner!

It’s the start of November, where does the time go? Its the time of year when I start to get a ‘feel’ for what winter may hold so I’ll have a brief run down of what I’m thinking currently, bearing in mind it’s still early for a proper forecast.

Here’s October’s 500mb pattern that brought us a very mild and dry month.

compday.bQ5Rmacitj

The northern pacific ridge is prevalent on this image, and I feel that will continue to be a feature in the coming months. I think at times we will see an amplifying of this ridge pole ward which would teleconnect to heights over Greenland, giving a chance of colder weather to the UK.

Global SST’s

anomnight.11.2.2017

At the minute we currently have weak La Nina conditions in the pacific. The interesting thing about this event is it is a more eastern pacific based one, which is thought to favour a negative wintertime NAO. Research courtesy of Wenjun Zhang

imageproxy

Polar vortex

This year we are seeing a much more normal development of the polar vortex than was seen last year.

winds current

As you can see last years line(blue) showed we had significantly below average zonal winds at this time and through November, indicating a very weak polar vortex. This promised so much but delivered little to us in November and December. This years(pink) and the forecasted in orange, show that we are much nearer to average. So nothing out of the ordinary for this years PV so far.

I feel that there is  a decent chance of an SSW this winter in January, which would give the chance of a negative AO and possibly NAO developing later in January into Feb, But this is very speculative and can be very hit and miss for the UK.

Summary

I think the watch word for this winter at the moment is transient. I don’t think we will see a lock in of mild zonal conditions, but I don’t see a big freeze with a lock in of severe cold. I think we will see transient episodes of negative AO and NAO giving colder conditions to the UK at times. But not long-lasting cold. This would however be an improvement on recent winters! Something nearer to the seasonal average for this winter I feel at this point with something for those who like mild and those who like cold.

Early days still and plenty of water to pass under the bridge yet. Remember, when you’re looking at a cold spell for the UK; If it can go wrong , it probably will!

Thanks for reading.

Ryan.

Guess who’s back. Back again

Its been a while hasn’t it? I’m back as winter begins to show its hand around the northern hemisphere, where it is already starting to tighten its icy grip over the Siberian plains.

A taster for what to expect here in the UK in the coming winter? Now that is a question.

I will have a post coming soon looking at winter.

And I am thinking about adding a ‘mental health’ page on here too discuss what I’m thinking and feeling and to discuss the world and to hear what other people think? Let me know what you make of that idea.

I may also post my adventures around the country on here to, and post some photographs. I have some lovely ones from my stay in the lake district last week.

Any other thoughts or ideas give me a shout.

Ryan.

December thoughts

It has been two weeks since my last post in which i said i would be able to give you a better idea of where i think we are heading as we go into winter.

Here are the key points from that last blog post:

Key points!

  • I think the next 2 weeks will shape what happens not only in the last third of November but also the start of winter
  • Key thing to look out for is the polar vortex staying weak and zonal winds staying weak
  • Thing can change very quickly and the vortex can get its act together quickly, so its important we continue to see pressure put on the vortex and stop its usual rapid strengthening at this time of year
  • Look out for the Aleutian low anomaly continuing which will help keep the PV weak, also look out for a Pacific storm spinning up which could change the pattern or further reinforce the Aleutian low
  • Should we see the pattern change and less pressure put on the vortex things wont look as exciting for the rest of November into the start of winter
  • However, should the current and embedded trend for the AO and the NAO to be largely negative(AO has 0.7 correlation to the NAO) then their most certainly be the threat of wintryness
  • BIG POINT HERE: The atmosphere is currently in a phase which is supporting blocking and a slow moving pattern, unlike other years there seems to be little evidence of an overriding force, such as ENSO, to change this pattern and flip to relentless westerlies
  • This could suggest we will see this certain pattern repeating, ie, blocking over the arctic and perhaps into greenland
  • As such i feel the first two weeks of November will be fairly chilly and blocked, but only a relatively small chance of proper cold and snow, as its so early
  • After this there are hints of a chance of proper cold as we near the end of the month and into december, again subject to what we see in the next week or 2

 

So have things continued to look positive or not?

I should say so.

Lets have a look at November so far

nov-16

surface-temps-nov

 

So a pretty chilly and blocked start to the month there.  Note the continued persistence of the Aleutian low. So lets start ticking things off the list.

  • Aleutian low 
  • Weak PV
  • Little sign of any rapid strengthening of the PV

A key point here is the Aleutian low again, now this is because the atmosphere is resembling EL nino rather than La nina, meaning this low has stuck around and effectively helped to weaken the polar vortex. Because the atmosphere is in this state, it should also allow continued bouts of amplification: ie better chance of heights to our north, which is what we want for cold weather.

In short then, currently we are looking at an overall picture that is, unlike previous years, conducive to high latitude blocking, which we have seen so far this autumn, and i feel this will repeat. This is also better than previous years in which we have been relying on an SSW in January.

Lets look ahead now to the rest of November into winter.

I think from around mid month  onward until somewhere around the last few days of the month, we will see a mainly NW-SE jet tilt, with low pressure to the north of the country, with winds generally from a northerly quadrant, sometimes west of north, nothing too dramatic but a largely chilly feed from the north looks likely.

The end of the month into December has been flagged for a while now and this is still very much of interest. I believe blocking will return strongly however the exact timing on this is still up for grabs, i think that the period stretching from end of this month to the end of December will have a similar height anomaly to this

20122 (2).jpg

High pressure will pop up to the north west, north and north east of the UK at times. An average negative NAO and AO is likely for the month as a whole. So there is definitely the potential for cold or very cold spells of weather here, but we have to remember that this is still quite a long way off and could change.

I don’t see a full on zonal onslaught until the new year. And a repeat of the last few winters is unlikely through the second half of winter. I see the polar vortex remaining weak until January. So a completely different picture this year to last year where a +NAO dominated mild December was well forecast.

We are at the table this year and the dice are loaded, but we must also remember that nothing is ever certain in weather and things can change very quickly. I will do another post in a week or two once more to see where we stand.

Ryan

Autumn thoughts so far

Well its been a month since my last post and we are now approaching a critical time for thoughts on possible November cold and what the start of winter will be like. Lets have a look at how the atmosphere has behaved so far this autumn.

oct-tay

We are certainly in an unusual atmospheric state so far the autumn, not just the in the pressure patterns we are seeing but also speaking about the stratosphere. We have seen a massive reduction of zonal winds(which are a reflection of the strength of the polar vortex and the subsequent strength of the jet stream), this is of course the opposite of what you’d expect at this time of year.Here is the latest plot from the GFS.

u_65n_10hpa

 

You can see the rapid decent we have started and are forecast to fall to a very low level. More on this in key points.


I posted this a few weeks ago, and i feel it still stands.

Which links us onto what this post is all about, and that is key points to look at!

Key points!

  • I think the next 2 weeks will shape what happens not only in the last third of November but also the start of winter
  • Key thing to look out for is the polar vortex staying weak and zonal winds staying weak
  • Thing can change very quickly and the vortex can get its act together quickly, so its important we continue to see pressure put on the vortex and stop its usual rapid strengthening at this time of year
  • Look out for the Aleutian low anomaly continuing which will help keep the PV weak, also look out for a Pacific storm spinning up which could change the pattern or further reinforce the Aleutian low
  • Should we see the pattern change and less pressure put on the vortex things wont look as exciting for the rest of November into the start of winter
  • However, should the current and embedded trend for the AO and the NAO to be largely negative(AO has 0.7 correlation to the NAO) then their most certainly be the threat of wintryness
  • BIG POINT HERE: The atmosphere is currently in a phase which is supporting blocking and a slow moving pattern, unlike other years there seems to be little evidence of an overriding force, such as ENSO, to change this pattern and flip to relentless westerlies
  • This could suggest we will see this certain pattern repeating, ie, blocking over the arctic and perhaps into greenland
  • As such i feel the first two weeks of November will be fairly chilly and blocked, but only a relatively small chance of proper cold and snow, as its so early
  • After this there are hints of a chance of proper cold as we near the end of the month and into december, again subject to what we see in the next week or 2

To sum up, a very unusual outlook for the time of year. Key period coming up. Run of dry weather continues. Chilly and largely dry first half of Nov? Low confidence for our weather conditions as usual as we move further into Nov.

I will probably add more tomorrow

Ryan