Model output discussion - Jan 3rd onwards

[chris55]

22 minutes ago, IDO said:

The gfs goes full on zonal after d10 with a strong westerly flow. This does not tie in with what we have been told to expect so not sure what to make of it:

Absolutely feasible. Though I wouldn’t place much confidence in it. 
 

With the ensuing SSW you’d hope for a more amplified pattern. 
 

We will of course find out as the month progresses:) 

[KTtom]

Some odd comments about zonality, there is nothing zonal about the ukmo 144 chart, yes, a relaxation of the colder uppers, but its not sinking any further, its waiting for a chance to ridge north again, habbit makes it hard not to factor into local preferences, so I speak for those in the west, and we will definately take this after the days on end of rain.

 

[DOdo]

1 minute ago, KTtom said:

Some odd comments about zonality, there is nothing zonal about the ukmo 144 chart, yes, a relaxation of the colder uppers, but its not sinking any further, its waiting for a chance to ridge north again, habbit makes it hard not to factor into local preferences, so I speak for those in the west, and we will definately take this after the days on end of rain.

 

 

yes you would think its the end of the world and of winter by some of the comments

[jacke]

An original lurker here, but felt I must comment on some of the things being said today. Trying to make blunt statements on the basis of current outputs is rediculous. Yes I know it's the purpose of this forum but please accept the level of disarray being shown over the last few days. Having followed weather charts long before most of you were born it is pretty rare that they flip flop to this extent so quickly. I am well old enough to remember the winter of 1963. Please don't make comparisons from anything we have seen so far. Not naming anyone but to say there were milder spells and flooding even during that spell is simply wrong. Look at the records I was there until the thaw finally came the vast percentage of England at least was frigid. Obviously there was not the level of computing available then so difficult chocolate actual forecasting. But one thing was clear. No met forecaster had predicted what was to come more than 48/72 hours beforehand. Trawl each output as,you will, there is plenty of time for this winter to produce. Back to my shell now

[Harsh Climate]

From looking looking at GFS12z esembles at 240h there are still a few very good runs on there. But about 50% poor.

[northwestsnow]

17 minutes ago, Harsh Climate said:

Fair play you went against the grain and called what the ECM and UKMO are now showing. At least you still have your house  

I felt bad this morning saying as much mate.

Hoping as many as possible see some snow this week though ...

UKMO 850s keep the majority cold out to 144 so a solid colder phase nailed on..

Let's see where we are in a few days, I have a feeling IDO s zonal express will be on a short journey but we will see...

[That ECM]

We have people slating the gfs because of what it has shown in the short term but taking fi charts and commenting in detail about how poor they look.  

[BARRY]

4 minutes ago, jacke said:

An original lurker here, but felt I must comment on some of the things being said today. Trying to make blunt statements on the basis of current outputs is rediculous. Yes I know it's the purpose of this forum but please accept the level of disarray being shown over the last few days. Having followed weather charts long before most of you were born it is pretty rare that they flip flop to this extent so quickly. I am well old enough to remember the winter of 1963. Please don't make comparisons from anything we have seen so far. Not naming anyone but to say there were milder spells and flooding even during that spell is simply wrong. Look at the records I was there until the thaw finally came the vast percentage of England at least was frigid. Obviously there was not the level of computing available then so difficult chocolate actual forecasting. But one thing was clear. No met forecaster had predicted what was to come more than 48/72 hours beforehand. Trawl each output as,you will, there is plenty of time for this winter to produce. Back to my shell now

you may be a lurker 

but a talk a lot of sense which the doom mongers on this site should take heed 

 

[phil nw.]

8 minutes ago, jacke said:

An original lurker here, but felt I must comment on some of the things being said today. Trying to make blunt statements on the basis of current outputs is rediculous. Yes I know it's the purpose of this forum but please accept the level of disarray being shown over the last few days. Having followed weather charts long before most of you were born it is pretty rare that they flip flop to this extent so quickly. I am well old enough to remember the winter of 1963. Please don't make comparisons from anything we have seen so far. Not naming anyone but to say there were milder spells and flooding even during that spell is simply wrong. Look at the records I was there until the thaw finally came the vast percentage of England at least was frigid. Obviously there was not the level of computing available then so difficult chocolate actual forecasting. But one thing was clear. No met forecaster had predicted what was to come more than 48/72 hours beforehand. Trawl each output as,you will, there is plenty of time for this winter to produce. Back to my shell now

Yes I was there too but as much as I enjoy those memories they should be discussed elsewhere. 

Just so we don't derail the thread. 

Cheers. 

[ItNeverSnowsInWindsor]

How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

Anyone?

[Thinon]

1 minute ago, northwestsnow said:

I felt bad this morning saying as much mate.

Hoping as many as possible see some snow this week though ...

UKMO 850s keep the majority cold out to 144 so a solid colder phase nailed on..

Let's see where we are in a few days, I have a feeling IDO s zonal express will be on a short journey but we will see...

We must take into account the warming of the surface easterly flow over the North sea. None of the medium term charts quantify this so I would take seemingly low 850s with a pinch of salt.

[Uncertainty]

The diving low ship long ago but the trend for heights building through or just to the west of the U.K. towards day 10 continues to build on the GEFS

12z

6z

0z was flatter still. 
 

GFSP demonstrates this neatly with a big rise in heights NE through NW of the UK

 

This is not a ramp, I have for for many days been resigned to the brief flattening of the pattern in the mid term and, discounting GFS nonsense, the models have been too.

I believe we are looking at a well forecast delay, not a cancellation of the cold.

Remember the Feb 2018 SSW was around the 8th and the snow didn’t really  kick in on the East coast until the 25th so that’s 17 days in what was accepted to be a QTR.

We have to be patient here guys. Wh have what looks to be a double dip reversal that has only just began...

We also have the MJO heading towards the +NAO phases

So we really shouldn’t bemoan the models if we get a short mild spell, it’s been very well advertised and like it or lump it we now need to turn our attention towards the lo res range. If that tropical signal can propagate through the maritimes as some commentators on Twitter have suggested then combined with the above reversal some serious charts must be awaiting us in the near future...

Studying the models after day 10 is relevant and  is very much within the remit of this thread... As we peer through the looking glass towards a mid-late January period that holds so much promise...

 

 

 

Edited January 3, 2021 by Uncertainy

[northwestsnow]

1 minute ago, prolongedSnowLover said:

How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

Anyone?

Above my Pay grade but I suspect there is no specific timeframe ...

 

[Weather-history]

 

11 minutes ago, northwestsnow said:

 

 I have a feeling IDO s zonal express will be on a short journey but we will see...

The GFS 12z op run looks an unsettled outlier amongst its ensembles, anyway at that stage

[Alexis]

I actually like the UKMO. It dispenses with the messy scenario of the low coming down in the wrong location. It shunts it so far east that it will probably push a lot of cold down into Europe and leaves space for our high to build behind, handily supported by low heights to our south.

Edited January 3, 2021 by Alexis

[Ventnor Viking]

The GFS is actually following all other models now with regards to showing a flatter more westerly flow in the latter stages. I know there is excitement re the SSW, but it was never guaranteed to go in our favour. Its easy to lose focus on the output and to get excited about events that haven't happened. Its really important to stay impartial and level headed in these types of setup. For the newer members, please look for consistency between models.  

[bluearmy]

1 minute ago, Updated_Weather said:

So if GFS18z flips again?

are people just gonna outright say it’s wrong?

No - there are enough gefs members with Atlantic amplification in week 2 to make the mean upper ridge part of a still cold regime ....we would expect the pattern to be a little less progressive over the next few weeks so as long as maintain some amplification in the ensembles then we remain in the cold game .....

we may have lost a clean path to a v cold ongoing outlook but winter hasn’t gone away .....

what I will say is that the week 2 strat pattern from gfs op and gefs is very consistent to deliver the board pattern we saw on last nights 18z gfs of Asian trough towards sceuro and ridge in the Canada/greeny sector 

[Weather-history]

5 minutes ago, Weather-history said:

 

The GFS 12z op run looks an unsettled outlier amongst its ensembles, anyway at that stage

Actually it looks as though GFS FI is trending towards anticyclonicity

Friday 15th Jan on 18z ensemble mean chart

0z ens mean chart

06z ens mean chart

12z en mean chart

 

Maybe something to keep an eye on to see if this trend continues

[That ECM]

8 minutes ago, prolongedSnowLover said:

How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

Anyone?

Happened in mid feb. Have a look in the archive charts for exact detail but from memory about two weeks. But this doesn’t mean this will be the same as all are unique.

[Skullzrulerz]

1 minute ago, Weather-history said:

Actually it looks as though GFS FI is trending towards anticyclonicity

Friday 15th Jan on 18z ensemble mean chart

0z ens mean chart

06z ens mean chart

12z en mean chart

 

Maybe something to keep an eye on to see if this trend continues

What would this mean? Especially with the SSW going on?

[Mike Poole]

4 minutes ago, prolongedSnowLover said:

How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

Anyone?

The SSW doesn’t have any direct impact on the 850s.  It has an impact on wind flows and positions of blocking patterns etc, which will in turn allow the normal weather in the troposphere to impact on the 850s.  That’s why it is uncertain whether we will go cold after a SSW, it depends where the dice fall.  But usually 2/3 of the time we do - and that is for any SSW.  With what we know about the state of the atmosphere at all levels coming into this, we can probably use Bayesian updating to modify this to 7/8.  I’m not going any further.  

This chart explains why I think that, the NAM plot that shows the equivalent of the AO at all levels of the atmosphere.  It is negative everywhere from the SSW onwards.  This is why there won’t be ‘flushing down of the westerlies’ because there aren’t any.  

So it should be quick, really, but just that maybe 1/8 call where yes we get the -AO but the -NAO doesn’t play ball for our small island.  Hope that helps.

[mother nature rocks]

24 minutes ago, jacke said:

An original lurker here, but felt I must comment on some of the things being said today. Trying to make blunt statements on the basis of current outputs is rediculous. Yes I know it's the purpose of this forum but please accept the level of disarray being shown over the last few days. Having followed weather charts long before most of you were born it is pretty rare that they flip flop to this extent so quickly. I am well old enough to remember the winter of 1963. Please don't make comparisons from anything we have seen so far. Not naming anyone but to say there were milder spells and flooding even during that spell is simply wrong. Look at the records I was there until the thaw finally came the vast percentage of England at least was frigid. Obviously there was not the level of computing available then so difficult chocolate actual forecasting. But one thing was clear. No met forecaster had predicted what was to come more than 48/72 hours beforehand. Trawl each output as,you will, there is plenty of time for this winter to produce. Back to my shell now

As this is aimed at me I feel I need to reply!! I have changed my text to thaw( don’t know why I put flood)

it was a 3 day ‘warm up’ which induced a thaw with burst pipes etc!! Circa Jan 25th 1963.

Goes to show even in the coldest part of winters ‘warm ups’ can happen!! 
 

Then the beast returned.

So anything is possible in current output.

Check Winter Watch!

MNR

[chionomaniac]

For me, I am not too concerned about the change in model direction over the last 24 hours.  I suspect it is SSW related. Also I think it is highly likely to be temporary.  

If you remember yesterday, I demonstrated that there was a minimal push of westerly winds propagating down prior to the negative u winds associated with the SSW. Well, I think the models may have underestimated this, as can be seen from the ECM u wind forecast.  It appears that there is a greater push of westerlies into the trop. 

However, this appears temporary, before negative u winds are back in control.

 

So, it won’t be long before the roller coaster changes direction again.

 

[Man With Beard]

21 minutes ago, prolongedSnowLover said:

How long does it take for SSW to take effect on the 850s ? How long did it take in 2018 beast from the east from when the winds reversed to negative ?

Anyone?

As someone mentioned above, it was about 2 weeks between SSW and the start of the beast from the east. But as Mike Poole mentioned, there isn't a specific relationship between the SSW and 850s

[Trom]

1 hour ago, John88B said:

Serious question from a complete novice when it comes to reading the models but is it worth even looking at the models for a period of time if a SSW can shuffle the deck so much so to speak? Thanks in advance.

Yes and no.  My experience has been that initially after the SSW (which still is 2 days out), the models struggle to process how the downwelling will impact the trop.  So you get a lot of volatility between both models and runs.  Then the SSW will take between 2 week and 2 months for the impact to be felt.  In 2018 we had a QTR (quick trop response) and we actually felt that impact within 2 weeks.  The models started to show some consistency again fairly quickly (post event).  I'm not a strat expert but it's been suggested that the response from strat to trop will be quick this time too.  So I'd expect a lot of volatility (people on here like to refer to it as Shannon entropy but don't get me going on that one), between runs and between models.  If the response is quick expect to see the volatility dropping over the next week.  Posters on here correctly state that the models know there is going to be a warming but the main issue is the interaction of the strat and trop and the outcome.  We know reversal of wind is likely as is blocking but exactly where the blocking sets up seems to take longer to resolve.  I think the key to remember is no poster or model has this dialled in.  SSW have only been studied in earnest fairly recently.

So don't despair if runs flop from ultra cold to mild.  If we are lucky with the SSW (and we seem to be around 2/3rds of the time), then expect to see colder solutions impacting the models some time post 5th of Jan (speed of the propagation being key).

There are some great posters on here so try to follow them.  It takes a little bit of time to understand how to read a model but once you can you get a better idea of who to pay credence to.  

Edited January 3, 2021 by Trom