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Dr. Judah Cohen’s latest weekly blog (20th Nov) has just been published and he discusses the forecast increased WAFz/poleward heat transport impact on the stratospheric PV:

  • Troposphere-stratosphere coupling has been relatively quiet, allowing for the stratospheric polar vortex to strengthen. However predicted uptick in energy transfer from the troposphere to the stratosphere is predicted to dislodge the PV centre from the Pole towards Eurasia.

  • The displacement of the PV centre towards Eurasia opens up the stratospheric PV to subsequent disruptions and could eventually result in a more significant disruption of the stratospheric PV in the coming weeks or later.

http://www.aer.com/science-research/climate-weather/arctic-oscillation

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gfsnh-10-384.png?0

Bit of a warming been showing up towards the end of the last few GFS ops- something to keep an eye on perhaps?

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1 hour ago, northwestsnow said:

gfsnh-10-384.png?0

Bit of a warming been showing up towards the end of the last few GFS ops- something to keep an eye on perhaps?

I remember the last 2 years GFS for almost the entire winter had one of those in fi but they kept being pushed back and back for weeks, I'll believe it when it's at around t+192h

Edited by ArHu3
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8 minutes ago, ArHu3 said:

I remember the last 2 years GFS for almost the entire winter had one of those in fi but they kept being pushed back and back for weeks, I'll believe it when it's at around t+192h

Yeah im sure you are right :)

Like you say i too will believe it when it gets into reliable but its something to watch...not sure if Doctor Cohen said something about the Pv being prone to warmings as it gets displaced so interesting to watch.

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Berlin zonal day 10 worth a post .....

Edited by bluearmy

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9 minutes ago, bluearmy said:

Berlin zonal day 10 worth a post .....

Holy ----!!

ecmwfzm_u_f240.gif

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14 minutes ago, Radiating Dendrite said:

What is this showing?

 

Warming, zonal wind reversal, wave breaking?

Reversal of zonal mean winds between from 70N to the pole quite a long way up into the stratosphere.

- From about 7mb almost right the way down to the tropopause.

 

EDIT : I did think it was an SSW when I first looked (I was looking at the 70N) and realised it couldn't have been when viewing the10mb height chart. Still mighty impressive D10 forecast considering time of year and temps are running well below average right now over the pole now.

Edited by feb1991blizzard
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Best not to over react to a day 10 op strat chart which has been led from the trop which we know is unreliable. The 00z run would not be quite so reversed looking at the 10hpa strat output so we may already have seen the most extreme output on this phase this morning from Berlin. 

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25 minutes ago, feb1991blizzard said:

Reversal of zonal mean winds between from 70N to the pole quite a long way up into the stratosphere.

- From about 7mb almost right the way down to the tropopause.

 

EDIT : I did think it was an SSW when I first looked (I was looking at the 70N) and realised it couldn't have been when viewing the10mb height chart. Still mighty impressive D10 forecast considering time of year and temps are running well below average right now over the pole now.

FYI: we are talking about the graph below? You may have uploaded the wrong image because the one in your post is very unexciting ;)

 

ecmwfzm_u_f240.gif

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2 minutes ago, Ruben Amsterdam said:

FYI: we are talking about the graph below? You may have uploaded the wrong image because the one in your post is very unexciting ;)

 

ecmwfzm_u_f240.gif

We are talking about the one you've just put up, that's the same as the one ive put up though??

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12 minutes ago, Ruben Amsterdam said:

Nope, not here :p

Untitled.thumb.png.56a5ffcfa9ce844ba7561d600eebbca2.png

 

Must be the different time zones between Yorkshire and Holland !! 

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Certainly some interesting strat forecasts being produced by both ECM and GFS at the moment. Hopefully they will edge nearer the reliable over the coming days. I believe the tweet below from Dr. Cohen is based on this morning's GFS 06z run:

 

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Another great tweet and superb visual representation of what is in play..

 

How do I embed these again?

 

Edited by Paul
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Good postings above. Late November traditionally sees the Polar Vortex establish itself towards its winter base state, a weak ineffectual PV going into December is therefore noteworthy, lets see how things pan out.

Recent winters of 2008, 2009, 2010 and 2012 saw quite a diffuse PV, in the case of 2010 exceptionally so - though quickly rebounded in early Jan.. the other winters brought plenty of cold outbreaks. Last year, saw a rather weak PV as well but other factors overrode any potential split or long-lasting displacement-however, I'm rather encouraged with developments at the moment and the effect of other factors that we could be about to see a winter where the PV comes under continuous attack..

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38 minutes ago, damianslaw said:

Good postings above. Late November traditionally sees the Polar Vortex establish itself towards its winter base state, a weak ineffectual PV going into December is therefore noteworthy, lets see how things pan out.

Recent winters of 2008, 2009, 2010 and 2012 saw quite a diffuse PV, in the case of 2010 exceptionally so - though quickly rebounded in early Jan.. the other winters brought plenty of cold outbreaks. Last year, saw a rather weak PV as well but other factors overrode any potential split or long-lasting displacement-however, I'm rather encouraged with developments at the moment and the effect of other factors that we could be about to see a winter where the PV comes under continuous attack..

All feels a bit like the winter of 09 to me. The trop completely dominated the pattern and we got a cold winter out of an otherwise questionable set of conditions. Of course i could be getting giddy here, there are plenty of day 10 Berlin charts which have not come to fruition. 

As a data man though i am very encouraged that we will likely see a sub -1 AO value though. There is a significant bias towards cold winter months (cold being 1C below the 1981-2010 average) albeit there were two spoiler winters which were mild. 

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IMG_2894.thumb.PNG.8231b7433f44cf3da4ca14140c8d4fdf.PNG

The NASA GMAO forecast shows that the zonal winds around the vortex at 10hPa will weaken in the next week or so.

IMG_2895.thumb.PNG.03df70ab1b166cc4037f45d4a80c7b1c.PNG

The CFS ensembles, especially the Control, show a weakened vortex throughout the winter. However two ensemble members hold a stronger vortex until New Years. 

IMG_2892.thumb.PNG.2076dcc99f449aae9d1b2e33781e8a23.PNG

Another way at looking at the vortex through CFS is the AO forecast, which is mostly neutral until mid January, when CFS predicts a more -AO based outlook.

Below you have the CFS 10hPa temperature forecasts for December, January and February. You can see a warmer/weaker vortex, as the winter progresses.

IMG_2896.thumb.PNG.8bcdfe217e615c86e8cd77e524fb1b82.PNG

IMG_2897.thumb.PNG.4dff31e9b963a0d04f90a8f5e6b085e8.PNG

IMG_2898.thumb.PNG.bccebc82b3c455661e03303d75f9bd77.PNG

Edited by Snowy Hibbo
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