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Model Output Discussion - The Run In To Christmas


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I think the confidence re big cold pattern must be seriously dented now and it always concerned me that even when a Greenland HP formed it was quickly flattened or broken through? a true GHP wouldn't wane so easy.  So was that 'signal' for a GHP correct and the current flattening wrong or was the initial signal to amplify that much wrong?  Unfortunately I think we are seeing what is likely imo to happen with a brief cold shot before Mr Atlantic comes back to dominate. 

I think it was about 3 days ago when we had a set of 'poor for cold' runs and then the eye candy returned, now its melting away again on the 00z.  I didn't see yesterdays 12z but I have read that the ECM was cold poor again....will it all flip again?  My money is on transient.  However, I spoke of the colder attack would probably need more than one bite at the cherry and I think we'll get this cold northerly blast after Xmas towards NY but a short event rather than prolonged. 

Well the way my LRF has gone with December being miles milder and miles flatter than expected....I'm a tad concerned that my average [to touch mild] January may become a blow torch!! :w00t:

On a serious note the lack of real blocking to take any hold is frustrating and it seems that it may continue.  I have to agree too that Cohen's update isn't that inspiring either

 

BFTP

Edited by BLAST FROM THE PAST
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Unfortunately, there needs to be a recognition that if we share at *this tentative juncture* the exact nature of what we have as Ops Centre guidance, certain individuals will inevitably extrapolate/wa

If the UK can't get cold from an upstream pattern with a negatively tilted troughing setting up over the ne USA , indeed the best set up since two winters ago then I will seriously consider throwing m

The good news just keeps on coming!   Upstream pattern is falling into place to deliver what many people in this thread want to see, NCEP give us the best update since winter 2012/2013,  indeed I'm

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For those that aren't into SADOMASOCHISM I recommend reading the latest from Judah Cohen as posted by I'm dreaming on Strat thread

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

Disappointing read to be honest. We were hoping for a SSW in late December/early January and now this is pushed back to late January (if it happens). It is becoming clear that the cold hearted winter forecast is in jeopardy!

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I'm going to approach that GFS(P) run with extreme caution. It's not even supposed to be here.

 

It's just another run.. With all the normal 6z data fed into it. Granted it's back early'r than projected. 

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Disappointing read to be honest. We were hoping for a SSW in late December/early January and now this is pushed back to late January (if it happens). It is becoming clear that the cold hearted winter forecast is in jeopardy!

As we know though we don't need an SSW for cold to these parts. It's just one factor in a minefield of possibilities. I agree it would appear better for one to surface soon but let's keep our feet on the ground.

EDIT: PM beat me too it :-)

Edited by P-M
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I was going to say this last night but was a little confused then as to why there was so much surprise that a model disagreed with others at days 9/10 as if it had suddenly become the reliable timeframe, and I didn't really see what was weird/odd about the t+216 ECM last night as in it won't or hasn't before occurred synoptically.

Can anything be discounted 100% unless there is a clear glitch or the models physics/maths is broken? It does seem it might not have been too far wrong sadly, though we can't really say that yet at such a timeframe. 

 

 

The GEM has an annoying habit of predicting warmer 850mb temperatures than what actually verify,even at short timescales,so as a result is not on my christmas card list. :laugh:

 

attachicon.gifcor_day6_T_P850_G2NHX.png

 

Is the light blue the parallel run (I was under that impression before), in which case it is doing slightly worse on average than the current GFS?

Edited by Evening thunder
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How important is this - NAO and SSW?

It is talked a lot on here but is it the be all and end all?

Was there a -NAO and SSW in the harsh winters of 2009 and 2010 etc?

Just curious as everyone seems to be writing off winter, surely you can get lots of snow without SSW and this NAO lark?

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Nothings clear past the N/year at least K, Let's not get to carried away.. We don't 'need' a SSW for a cold spell.

A SSW could help us to get a proper Greenland high. What becomes apparent once more is that the models have overestimated the pressure rise in Greenland. As the time of a forecasted Greenland high approaches the models weaken the heights there and in the end we end up with a toppler or nothing. Is there something that has changed in the Greenland area that doesn't allow heights there during the Greenland months?

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the gfs 06z is a shocker for coldies.... after yesterdays was such a promising one. it highlights the volatility within the atmosphere atm.

Dont worry Mushy its in the bin :smiliz39:

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Nothings clear past the N/year at least K, Let's not get to carried away.. We don't 'need' a SSW for a cold spell.

We haven't had a proper cold spell since early 2013, that's nearly two years! In other words, these days we need all the help we can get and a SSW is a big help!

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The good news next week is colder air will be digging south behind a band of rain across central and southern UK with wintry showers and night frosts following from the north, so a frosty few nights and then a vigorous depression crashes into the UK with rain, sleet and snow together with gales to severe gales with colder,showery weather following. It's not mild and mushy anyway. :-)

Edited by Frosty.
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A SSW could help us to get a proper Greenland high. What becomes apparent once more is that the models have overestimated the pressure rise in Greenland. As the time of a forecasted Greenland high approaches the models weaken the heights there and in the end we end up with a toppler or nothing. Is there something that has changed in the Greenland area that doesn't allow heights there during the Greenland months?

 

All depends where the warming takes place and sinks.. But surly K, As we have seen many times in years gone by, It can go either way in these set-ups reg Greenland High's. It just so happens 'this' time it looks to be not as strong as first Model'd (as is usually the case). But still at this range it's very unclear how the Low will sink South over the UK. If it's a toppler so be it, That's just the very nature of how the Models handle things. But it's not a concern to write the heart of winter off.

Edited by Polar Maritime
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All depends where the warming takes place.. But surly K, As we have seen many times in years gone by, It can go either way in these set-ups reg Greenland High's. It just so happens 'this' time it looks to be not as strong as first Model'd (as is usually the case). But still at this range it's very unclear how the Low will sink South over the UK.

My point is not just this projected Greenland high but the fact that it seems to happen almost every time one is forecasted. It seems to me that things have changed in the atmosphere that inhibit Greenland highs in winter. Why is that? Another factor is working here (could it be ice loss?) and therefore a SSW would enhance ours chances but without it the highs fail.

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What i dont understand is where have all the heights gone!! I mean we had some serious greenland heights at 1060 mb and they've just vanished to nothing in literally 24 hours! ! How om earth is that possible!!! Okay a slight downgrade is possible always but nothing to this extent! ! Something is seriously wrong with the models or theyve picked up on a change that wasnt expected.

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My point is not just this projected Greenland high but the fact that it seems to happen almost every time one is forecasted. It seems to me that things have changed in the atmosphere that inhibit Greenland highs in winter. Why is that? Another factor is working here (could it be ice loss?) and therefore a SSW would enhance ours chances but without it the highs fail.

 

Possibly K, Although i have not seen anything over the past few years that's any different to others to inhibit such questioning. 

Edited by Polar Maritime
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I remember the late 80's and 1990's where we hardly saw any wintery synoptics whether it was a GH or a SH. 


 


Still got time this winter and was anything really cold and snowy expected before the New Year .... I've seen more cold weather over the last 4 years than I saw in the 1990's.


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How many times do people need to be told NOT to take one run as gospel? Always look at the trend. Has the trend over the last few days signified milder weather? Not really. Should we be worried? Not really. There are some longterm members here that are already throwing in the towel, seemingly having developed short term memory loss since past Winters. The situation is incredibly fickle as ever!

Disagree. There has been a clear trend in the operationals and GFS ensembles to a 'milder' outcome, not mild by any means but certainly things have gone backwards significantly in the last 48 hours from a decently established euro trough and GH to what appears to be a brief northerly before the AH sticks it's unwanted ore in.

For my mind, I'm not as experienced as many on here but we keep chasing charts 10+ days away, it's something I've seen quite a few times on this forum and normally things never come into a reliable timeframe, despite all that there is still a lot of scatter so every option is still on the table.

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The good news next week is colder air will be digging south behind a band of rain across central and southern UK with wintry showers and night frosts following from the north, so a frosty few nights and then a vigorous depression crashes into the UK with rain, sleet and snow together with gales to severe gales with colder,showery weather following. It's not mild and mushy anyway. :-)

sorry frosty but to me it looks mild upto Wednesday then perhaps a fleeting cold snap over xmas. Before we're back in the milder air. The models have taken a huge jump away from cold over last 36hrs.
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A familiar tale I have been hearing all December with no real cold actually coming to fruition south of Scotland!

At least cold air is trying to push south, last winter was a cold free zone!

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What i dont understand is where have all the heights gone!! I mean we had some serious greenland heights at 1060 mb and they've just vanished to nothing in literally 24 hours! ! How om earth is that possible!!! Okay a slight downgrade is possible always but nothing to this extent! ! Something is seriously wrong with the models or theyve picked up on a change that wasnt expected.

Well we never actually had them though did we... They were falsely modelled.

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