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In Depth Model Discussion, Analysis and Summaries


Paul

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

One would expect the increased ozone to have moderated the cooling seen at the 30hPa level which has now dipped well below average. What is surprising though is that the polar vortex hasn't increased dramatically in strength as a result at that level and remains slightly below average. This could be as a result of the modifying effect of the easterly QBO combined with the very cold tropical stratosphere which decreases the temperature differential.

C, Has the Tropical Srat.cooled to the same extent as over the poles?

If so the temp.differential would be maintained thus possibly maintaining the status quo regarding the strength of the vortex.

Is it that simple assuming other signals such as Easterly QBO remain similar?

Edited by phil n.warks.
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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

C, Has the Tropical Srat.cooled to the same extent as over the poles?

If so the temp.differential would be maintained thus possibly maintaining the status quo regarding the strength of the vortex.

Is it that simple assuming other signals such as Easterly QBO remain similar?

Hi Phil,

The tropical stratosphere has been cold for some time and has not cooled recently alongside the polar stratosphere cooling. In that regard the temperature differential is increasing but it is not as bad as it could be. It is just another piece in a large complex jigsaw.

c

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

Hi Phil,

The tropical stratosphere has been cold for some time and has not cooled recently alongside the polar stratosphere cooling. In that regard the temperature differential is increasing but it is not as bad as it could be. It is just another piece in a large complex jigsaw.

c

Thanks C.

Edited by phil n.warks.
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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

High chance that model performance will dip over the next few days.

We have a complex trough developing in the Atlantic whilst the progression of the MJO in the Pacific looks very problematic right now. Add to that, tendency in angular momentum plots are showing a sharp increase in westerly winds around 50N (polar jet flow increased) c/o mountain torques, that translates to real issues to resolve so sticking with ensemble mean guidance would appear the best way forward.

The GWO is just in phase 4:

http://www.esrl.noaa.gov/psd/map/images/gcm/gwo_40d.gif

I think a continutation in phase 4 looks a reasonable assumption for the next 5-10 days given the state of angular momentum.

I posted a day ot two ago that the composites for phase 4 were a bit ambiguous. In light of model outputs over the last 24 hours, these now make sense....

a weak trough centred over the UK with ridge in place to the west. Given the pattern of the last few weeks, SSTA which favour a -NAO and upwelling wave in the upper troposphere, we should expect some +VE height anomaly to our north and north-east forcing the jet on a more southward tack.

This looks a reasonable solution for days 8-14. On this basis, any break in the cold pattern looks unlikely. Atlantic airmasses will attempt to work in - that is the nature of any trough, however, the degree of modification of the lower layers looks open to doubt and we must ask the question, what happens if the trough remains in place for any duration ? The most likely solution is for the longwave pattern to put an upper ridge behind the trough which builds over the top to perpetuate the surface cold for an extended period.

Next week continues to look like an increasing snow threat. Becoming less cold from the west is quite possible although any ridge building in from the west will sustain cold and there is the nagging suspicion that the tendency will be for higher pressure to the north and north-east which will maintain an easterly feed.

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Posted
  • Location: Bishopbriggs, near Glasgow
  • Weather Preferences: Cold snowy winters, warm dry summers
  • Location: Bishopbriggs, near Glasgow

High chance that model performance will dip over the next few days.

We have a complex trough developing in the Atlantic whilst the progression of the MJO in the Pacific looks very problematic right now. Add to that, tendency in angular momentum plots are showing a sharp increase in westerly winds around 50N (polar jet flow increased) c/o mountain torques, that translates to real issues to resolve so sticking with ensemble mean guidance would appear the best way forward.

The GWO is just in phase 4:

http://www.esrl.noaa.gov/psd/map/images/gcm/gwo_40d.gif

I think a continutation in phase 4 looks a reasonable assumption for the next 5-10 days given the state of angular momentum.

I posted a day ot two ago that the composites for phase 4 were a bit ambiguous. In light of model outputs over the last 24 hours, these now make sense....

a weak trough centred over the UK with ridge in place to the west. Given the pattern of the last few weeks, SSTA which favour a -NAO and upwelling wave in the upper troposphere, we should expect some +VE height anomaly to our north and north-east forcing the jet on a more southward tack.

This looks a reasonable solution for days 8-14. On this basis, any break in the cold pattern looks unlikely. Atlantic airmasses will attempt to work in - that is the nature of any trough, however, the degree of modification of the lower layers looks open to doubt and we must ask the question, what happens if the trough remains in place for any duration ? The most likely solution is for the longwave pattern to put an upper ridge behind the trough which builds over the top to perpetuate the surface cold for an extended period.

Next week continues to look like an increasing snow threat. Becoming less cold from the west is quite possible although any ridge building in from the west will sustain cold and there is the nagging suspicion that the tendency will be for higher pressure to the north and north-east which will maintain an easterly feed.

Another excellent summary giving the state of the atmosphere, thamks for taking the time to post.

SS2

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Posted
  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire

Yes there is definately a disturbed pattern developing in the stratosphere which at the moment would suggest a re-inforcing of a negative NAO.

I am not sure how this will play out with the MJO signal for a high to our north retrograding eastwards. For this reason I would agree with GP that models are likely to be somewhat unreliable beyond the short timeframe.

What I have noticed is an unusual about turn in the global wind oscialltion which suggests to me that angular momentum is not really going to pick up that much.

GWO 40 Day composite

It looks to me like we may go through pahse 5, 6 and 7 very qucikly with anugular momentum looking much more la nina like.

Short term coming up this week we have a change in wind direction possible as a battle occurs between the atlantic and the continental cold over the UK. The difference between an easterly cold wind and this scenario is that there is probably a lot more moisture in this scenario. I currently have my eyes on the early hours of wednesday.

In this situation of course precipitation is much more likely to turn into sleet or rain, which is why the timing in the early hours of the morning interests me.

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Thanks for the updates, guys. Although, I cannot grasp all the details, I do get the gist...You've outperformed the models so-far with this spell... :yahoo::)

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Posted
  • Location: Wigan 259 ft ASL where it always rains
  • Weather Preferences: Hot Sun ,Snow and Cold
  • Location: Wigan 259 ft ASL where it always rains

High chance that model performance will dip over the next few days.

We have a complex trough developing in the Atlantic whilst the progression of the MJO in the Pacific looks very problematic right now. Add to that, tendency in angular momentum plots are showing a sharp increase in westerly winds around 50N (polar jet flow increased) c/o mountain torques, that translates to real issues to resolve so sticking with ensemble mean guidance would appear the best way forward.

The GWO is just in phase 4:

http://www.esrl.noaa...gcm/gwo_40d.gif

I think a continutation in phase 4 looks a reasonable assumption for the next 5-10 days given the state of angular momentum.

I posted a day ot two ago that the composites for phase 4 were a bit ambiguous. In light of model outputs over the last 24 hours, these now make sense....

a weak trough centred over the UK with ridge in place to the west. Given the pattern of the last few weeks, SSTA which favour a -NAO and upwelling wave in the upper troposphere, we should expect some +VE height anomaly to our north and north-east forcing the jet on a more southward tack.

This looks a reasonable solution for days 8-14. On this basis, any break in the cold pattern looks unlikely. Atlantic airmasses will attempt to work in - that is the nature of any trough, however, the degree of modification of the lower layers looks open to doubt and we must ask the question, what happens if the trough remains in place for any duration ? The most likely solution is for the longwave pattern to put an upper ridge behind the trough which builds over the top to perpetuate the surface cold for an extended period.

Next week continues to look like an increasing snow threat. Becoming less cold from the west is quite possible although any ridge building in from the west will sustain cold and there is the nagging suspicion that the tendency will be for higher pressure to the north and north-east which will maintain an easterly feed.

I do not pretend to understand the majority of what you have written ,i can just about but the bones together but not the meat on them (if you understand my strange analogy), but i would like to say thanks for a wonderfully written explanation of what could /will happen once again, i look forward to your posts as they are unbiased ...thats enough of the praise (you'll think you have a stalker next :unsure:)..Excuse my ignorance but are you a professional meterologist/forecaster ?

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Posted
  • Location: South Shields Tyne & Wear half mile from the coast.
  • Location: South Shields Tyne & Wear half mile from the coast.

Thanks for the updates, guys. Although, I cannot grasp all the details, I do get the gist...You've outperformed the models so-far with this spell... :unsure: :D

And out performed the Met Office in their winter predictions too..!! Well done to those who foresaw this cold period coming way back in Sept/Oct I think i first heard we are in for a cold one...

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Posted
  • Location: North Worcestershire, Midlands. 158m A.S.L.
  • Location: North Worcestershire, Midlands. 158m A.S.L.

And out performed the Met Office in their winter predictions too..!! Well done to those who foresaw this cold period coming way back in Sept/Oct I think i first heard we are in for a cold one...

Top thread, top site, and its great to have people on here who really do know what they are talking about, who are able to explain such complex stuff to the in-experienced weather enthusiasts such as myself. :lol: (Sorry for being off topic.) :lol:

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Posted
  • Location: hertfordshire
  • Location: hertfordshire

I see that ozone levels have increased again or are increasing again over the Canadian side of the

Arctic + convection looks much better today to the east of Indonesia.

All good signs in my opinion together with a lower atmospheric angular momentum.

Latest OLR charts.

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

Interesting link here showing how the -AO has affected the NH winter temperatures.

http://earthobservatory.nasa.gov/IOTD/view.php?id=42260

c

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

A couple of thinks going on at the moment suggesting to me that we might be looking at a third and final cold pattern evolving around the 25-27th January for a week to 10 days.

The MJO is centred in low amplitude phase 5:

despite the majority of GFS ensembles projecting a slowing and reversal of the tropical wave, deep convection is breaking out ahead of the MJO in the western Pacific, extending across 120-140W. Note the position of the current wave to the last time in phase 5 and now.

This suggests that the MJO forecasts (which are rarely accurate beyond day 5) are under estimating eastward progression which should allow convection to become (re)established across the Dateline which teleconnects to a -NAO. Based on empirical wave progression for 200 hPa vorticity anomalies, there are similarities to the mid November - early December wave which took about two weeks to move from from where it is now to the Dateline. This suggests convection to become enhanced around the Dateline 25th January onwards, probably impacting a -NAO signal several days after.

The GWO is in phase 4:

Whilst it may look like a similar evolution to mid December, there is much more of a negative (Nina like) pattern present across the tropics, so we may not see a large expansive evolution of the GWO, probably tilted more towards a phase 0-4 type orbit. Phase 0 teleconnects to ridging across the north Atlantic. Phase 4 composites teleconnect to ridge over Scandinavia.

We are also seeing some indication of a substantive increase in stratospheric temperatures tied into a high amplitude wave 1:

http://strat-www.met...t=temps&alert=1

Last year we witnessed a large warming at about this time of year which was followed by an almost instant response in the atmosphere (remember the early Feb snowfall). Although our friendly upwelling wave has peaked and is now starting to decline, I think there's enough juice in the tank to support a similar response in the atmosphere favouring blocking.

Interestingly, the AO (GFS) ensembles suggest the AO starting to fall again after reaching neutral within the 14 day time frame:

http://www.cpc.ncep....ex/ao.sprd2.gif

This is timed for around 20th January onwards.

Current long term model guidance projects a substantive +ve mean height anomaly over Scandinavia.

http://www.cpc.ncep....y/814day.03.gif

The trough in the Atlantic projected also fits the lower stratosphere where an elongated trough is steadily pushing eastwards. Once this moves further east, there is some chance that the trough will force height rises on its back centred towards Greenland - Iceland.

So the expectation would be for a large blocking ridge over Scandinavia over the next 2 weeks to discontinuously shift back across the north Atlantic towards Greenland allowing winds to shift from the east to the north-east towards month's end bringing a finale to the winter.

February is still looking mild to me, the problem being a lack of blocking and falling angular momentum (look how easily the atmosphere removed westerly winds in the last few weeks) resulting in a Nina-like pattern, off-setting any potential blocking impact tied into the stratosphere warming.

Edited by Glacier Point
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Posted
  • Location: st albans
  • Location: st albans

GP, NOAA cpc keep referring to a more Nino type pattern evolving week 2 with a strong southern stream taking charge. are you saying that this third cold spell would evolve a few days after this but we would see a more nina type pattern to follow through feb? this is obviously at odds with current general thoughts of many that a straightforward nino feb would generate blocking to the northeast.

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

GP, NOAA cpc keep referring to a more Nino type pattern evolving week 2 with a strong southern stream taking charge. are you saying that this third cold spell would evolve a few days after this but we would see a more nina type pattern to follow through feb? this is obviously at odds with current general thoughts of many that a straightforward nino feb would generate blocking to the northeast.

Hi Nick.

Straightforward is not an accuate descrption of this Nino, afterall, we could not have gone through the last 6 weeks if it were a standard 'getting colder in February' Nino.

Take a look at the fall in GLAAM over the last few weeks..

http://www.esrl.noaa.gov/psd/map/images/aam/glaam.gif

that's a 2.5 SD drop in angular momentum which is not consistent with Nino-coupled atmospheres. Bearing mind also we tend to see the global atmosphere start to resist westerly winds during the late winter - spring periods, I could easily see the next burst of convection in the Indian Ocean (MJO phase 1) during February drop momentum further to Nina-like territory. Those positive wind anomalies acros 30-40N will I think tend to shrink and the easterlies either side increase leading to a progressive Nina-like pattern setting up inspite of the SSTAs in the Pacific.

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Posted
  • Location: Sale (Cheshire)
  • Weather Preferences: Dry and cold...
  • Location: Sale (Cheshire)

GP, quick question, when you look at february, do you see a mildish, cyclonic pattern or something more similar to 2008 (when up here we had 2 weeks of t-shirt weather by day and below freezing nights) baring in mind that month tend to a quiet one normally?

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

GP, are there any other comparable El Nino February's that have had predominantly low GLAAM and a La Nina'ish' atmosphere?

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

This might answer a few of the posts above... composites for February where the MEI > +0.5 and low angular momentum:

Suggest a Euro High solution and this seems to be where the long range modelling is going. Whether the MJO and stratospheric warming can modify this towards month's end and force height rises to our NW and lowering heights over Iberia is a watching brief.

This also gives us some clues as to how the medium term pattern (mid January onwards) might evolve. This would tend to support the idea that the block forming over Scandnavia is going to become a dominant feature and repel the Atlantic weather fronts extending across the UK which would allow colder continental air to creep back across the UK, south-eastern parts most particularly.

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

This might answer a few of the posts above... composites for February where the MEI > +0.5 and low angular momentum:

Suggest a Euro High solution and this seems to be where the long range modelling is going. Whether the MJO and stratospheric warming can modify this towards month's end and force height rises to our NW and lowering heights over Iberia is a watching brief.

This also gives us some clues as to how the medium term pattern (mid January onwards) might evolve. This would tend to support the idea that the block forming over Scandnavia is going to become a dominant feature and repel the Atlantic weather fronts extending across the UK which would allow colder continental air to creep back across the UK, south-eastern parts most particularly.

Thanks, GP.

That composite does look very feasible with the main polar vortex centered over Eastern Siberia - it seems that we are heading that way in 10-15 days time with the way the possible displacement is shaping up. Perhaps it wouldn't take too much to get those NW height rises from that position during the month at least once so not all doom and gloom. And as I mentioned in the strat thread there could be some seriously cold air to tap into.

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

Long range model guidance is starting to catch onto the idea of heights building to the north although this looks quite transient and lacking any deep cold pooling necessary to make it really significant.

Crucially, the rise in relative angular momentum has ceased leaving us closer to a La Nina (low angular momentum) base state than El Nino.

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/glaam.sig.90day.gif

Positive (westerly) wind anomalies over 25-45N are more than offset by negative (easterly) wind anomalies across the extratropics and across the tropics. There is also some evidence I think of eddies starting to transport momentum into the mid latitudes starting to crank up the Pacific and latterly the Atlantic Polar Jet, a signature of overall negative tendency (La Nina) returning to the atmospheric state.

The GWO is being held in a flat orbit which favours alternating phase 0 and 4. The overall state of the atmosphere closely resembles phase 4 although currently in phase 0 (anticpiated to switch back to phase 4 in the next few days as torques increase).

http://www.esrl.noaa.gov/psd/map/images/gcm/gwo_40d.gif

Phase 4 composite:

Another important consideration is the state of the polar vortex which is being shifted rapidly by the warming of the upper and middle stratosphere. Notice how the vortex is forecast to shift in shape and position from t24 to t192:

This suggests an Atlantic trough migtrating towards western Europe, something picked up by long range tools. It is this signal which is probably helping to raise heights to the north (and south) as the trough disrupts.

For the end of the month and into February, a difficult forecast discussion to capture, being very complex. The MJO is still making some progress eastward and this throws an interesting variable into the mix should it reach phase 7/8 and the GWO hit phase 0. The sub-tropical jet is still strong with a well-developed surface pool just to our east so a cold and probably unsettled (the combination of the two being stressed there) regime to finish the month.

For the first third of February, I can see the GWO starting in phase 4 (Scandinavian trough signal) before global momentum tumbles again setting up a Euro ridge picked out by those composites for the remainder of the month.

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Long range model guidance is starting to catch onto the idea of heights building to the north although this looks quite transient and lacking any deep cold pooling necessary to make it really significant.

Crucially, the rise in relative angular momentum has ceased leaving us closer to a La Nina (low angular momentum) base state than El Nino.

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/glaam.sig.90day.gif

Positive (westerly) wind anomalies over 25-45N are more than offset by negative (easterly) wind anomalies across the extratropics and across the tropics. There is also some evidence I think of eddies starting to transport momentum into the mid latitudes starting to crank up the Pacific and latterly the Atlantic Polar Jet, a signature of overall negative tendency (La Nina) returning to the atmospheric state.

The GWO is being held in a flat orbit which favours alternating phase 0 and 4. The overall state of the atmosphere closely resembles phase 4 although currently in phase 0 (anticpiated to switch back to phase 4 in the next few days as torques increase).

http://www.esrl.noaa.gov/psd/map/images/gcm/gwo_40d.gif

Phase 4 composite:

Another important consideration is the state of the polar vortex which is being shifted rapidly by the warming of the upper and middle stratosphere. Notice how the vortex is forecast to shift in shape and position from t24 to t192:

This suggests an Atlantic trough migtrating towards western Europe, something picked up by long range tools. It is this signal which is probably helping to raise heights to the north (and south) as the trough disrupts.

For the end of the month and into February, a difficult forecast discussion to capture, being very complex. The MJO is still making some progress eastward and this throws an interesting variable into the mix should it reach phase 7/8 and the GWO hit phase 0. The sub-tropical jet is still strong with a well-developed surface pool just to our east so a cold and probably unsettled (the combination of the two being stressed there) regime to finish the month.

For the first third of February, I can see the GWO starting in phase 4 (Scandinavian trough signal) before global momentum tumbles again setting up a Euro ridge picked out by those composites for the remainder of the month.

I like the idea of a cold and unsettled end to January, suggesting that we may see an arctic blast as opposed to drier continental blast. Suggests that those heights will be more over Greenland especially if there is development of a scandi trough.

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Posted
  • Location: North Norfolk/Southampton
  • Location: North Norfolk/Southampton

This suggests an Atlantic trough migtrating towards western Europe, something picked up by long range tools. It is this signal which is probably helping to raise heights to the north (and south) as the trough disrupts.

For the end of the month and into February, a difficult forecast discussion to capture, being very complex. The MJO is still making some progress eastward and this throws an interesting variable into the mix should it reach phase 7/8 and the GWO hit phase 0. The sub-tropical jet is still strong with a well-developed surface pool just to our east so a cold and probably unsettled (the combination of the two being stressed there) regime to finish the month.

For the first third of February, I can see the GWO starting in phase 4 (Scandinavian trough signal) before global momentum tumbles again setting up a Euro ridge picked out by those composites for the remainder of the month.

Hi GP - thanks for another excellent analysis. As always, I thoroughly enjoy reading them, though I wish my technical understanding was better - your winter forecast is certainly proving to be pretty accurate. I can certainly see evidence within the models of a cranking up of the polar jet and deep in FI, GFS seems to be toying with the idea of a Scandinavian trough. Also, none of the models are keen to keep the block to our east in situ. It seems like a very complex set up, one which the models are likely to struggle with over the next week and it looks like FI could be a short timescale?

Edited by Steve Edgefield
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Posted
  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire

Yes I have a suspicion we could be in for a cold spell towards the end of the month. Stratospheric vorticity charts indicate a strong signal for high pressure towards the med and a weekening signal for high pressure towards russia.

I notice how 8 days out the signal for that russian high has disappeared or gone south which is not well depicted in the forecasts at the moment. I think this is a historical bias coming out in the models. Unfortunately the icelandic low is still present. So for the next eight days at least we can expect some rather unsettled conditions.

After that the stratospheric vortex displacement begins to move a bit more eastwards at lower levels.

This leaves me with the idea that we could see a blocked atlantic pattern at around 13 days out especially if we are into MJO Phase 7 or 8. For once I think the old adage that what weather new york has we will see a week later might be true.

Edited by BrickFielder
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Posted
  • Location: Brighton (currently)
  • Location: Brighton (currently)

After that the stratospheric vortex displacement begins to move a bit more eastwards at lower levels.

This leaves me with the idea that we could see a blocked atlantic pattern at around 13 days out especially if we are into MJO Phase 7 or 8. For once I think the old adage that what weather new york has we will see a week later might be true.

Thanks for your thoughts. In other words we should forget the Siberian/Russian High and start looking to the west for the next cold spell.

Fingers crossed!

Karyo

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Posted
  • Location: Shirley, Croydon, Greater London
  • Location: Shirley, Croydon, Greater London

Long range model guidance is starting to catch onto the idea of heights building to the north although this looks quite transient and lacking any deep cold pooling necessary to make it really significant.

Crucially, the rise in relative angular momentum has ceased leaving us closer to a La Nina (low angular momentum) base state than El Nino.

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/glaam.sig.90day.gif

Positive (westerly) wind anomalies over 25-45N are more than offset by negative (easterly) wind anomalies across the extratropics and across the tropics. There is also some evidence I think of eddies starting to transport momentum into the mid latitudes starting to crank up the Pacific and latterly the Atlantic Polar Jet, a signature of overall negative tendency (La Nina) returning to the atmospheric state.

The GWO is being held in a flat orbit which favours alternating phase 0 and 4. The overall state of the atmosphere closely resembles phase 4 although currently in phase 0 (anticpiated to switch back to phase 4 in the next few days as torques increase).

http://www.esrl.noaa.gov/psd/map/images/gcm/gwo_40d.gif

Phase 4 composite:

Another important consideration is the state of the polar vortex which is being shifted rapidly by the warming of the upper and middle stratosphere. Notice how the vortex is forecast to shift in shape and position from t24 to t192:

This suggests an Atlantic trough migtrating towards western Europe, something picked up by long range tools. It is this signal which is probably helping to raise heights to the north (and south) as the trough disrupts.

For the end of the month and into February, a difficult forecast discussion to capture, being very complex. The MJO is still making some progress eastward and this throws an interesting variable into the mix should it reach phase 7/8 and the GWO hit phase 0. The sub-tropical jet is still strong with a well-developed surface pool just to our east so a cold and probably unsettled (the combination of the two being stressed there) regime to finish the month.

For the first third of February, I can see the GWO starting in phase 4 (Scandinavian trough signal) before global momentum tumbles again setting up a Euro ridge picked out by those composites for the remainder of the month.

Joe B from AccuWeather says that ECMWF NINO forecast is picking up on the collapse of the Nino. He's ramping this up quite a bit. Interesting times ahead.

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