Model output discussion pm 13/01/2016

[chris55]

20 minutes ago, Redwood said:

why is that n easterly incoming (too my untrained eye)

It was a bit of leading/misleading post to be honest.

There was a poster on the threads a while ago who was very good at posting historical charts and analysing them to show us how the cold made it to our shores and what the relevant set-ups were at the time.

One of his famous threads was "where did that easterly come from" and it talked about historic synoptic set ups that initially look mild but then very quickly turn into a cold easterly for the UK. 

The above ECM chart does look mild and wet for the UK (as a whole) but with the vertical warm air advection northwards on the meridian line (which would help to inflate high pressure to the east) and the general blocked pattern to the east with a big cold pool in situ, it looks like the kind of chart that could very quickly turn into an easterly for the UK.

I know the ECM 12z simply pushes the Atlantic in past the UK as the run progresses but if you look at what unfolds to the east you can see how a very cold easterly for the UK would not be out of the question.

 

Edited January 20, 2016 by chris55

[mountain shadow]

I personally see decent potential in the ECM. 

At day 10 the vortex is split asunder at 500hpa and its a matter of waiting for the chips to fall in our favour. Whilst there is a segment of the PV over Greenland it is not one all consuming mass. 

 

[ANYWEATHER]

Hi Folks! As one cold spell ends perhaps another one begins....  So whats been on the table today if you want cold? A good 00z gfs, followed by a stonking 06z and a terrible 12z. The Ecm produced a terrible 00z run ,but a very interesting run from the 12z. We are now entering deep mid winter, and entering the coldest part of the year for the Northern Hemisphere. So enjoy the rollercoaster....Lots to play for...

[phil nw.]

Nothing to excite the Winter fans in the models for the next week or so with the south westerlies setting in.

The earlier 06z GFS run was clearly a cold one against the majority of the suite.The next week looks rather mild/mild but looking at the ens graph on the 12z run a case could be made for more average conditions after that. 

the Op run trends milder after the 27th against the set.

At this stage i wouldn't say more than that but we are still seeing the warming of the Strat.and forecasts of mean zonal winds decreasing over the next 10 days.This should translate into raising Polar HT anomalies in time and we can see a trend for this developing in the CPC graph as the AO index starts to slide into -ve territory. 

At this stage no strong signal for cold but maybe enough signs in the ens. that we are not entering a protracted mild setup ala December and with a chance of another pattern change early February as the vortex continues to warm. 

[Chris1986]

37 minutes ago, phil nw. said:

Nothing to excite the Winter fans in the models for the next week or so with the south westerlies setting in.

The earlier 06z GFS run was clearly a cold one against the majority of the suite.The next week looks rather mild/mild but looking at the ens graph on the 12z run a case could be made for more average conditions after that. 

the Op run trends milder after the 27th against the set.

At this stage i wouldn't say more than that but we are still seeing the warming of the Strat.and forecasts of mean zonal winds decreasing over the next 10 days.This should translate into raising Polar HT anomalies in time and we can see a trend for this developing in the CPC graph as the AO index starts to slide into -ve territory. 

At this stage no strong signal for cold but maybe enough signs in the ens. that we are not entering a protracted mild setup ala December and with a chance of another pattern change early February as the vortex continues to warm. 

Models I believe are confused at the moment, evolution to a genral consensus will have to be a waiting game. We are currently seeing various permutations based on best guess. I hope over the coming days thr models will get a more defined grasp of strat trop strat coupling and the SSW. I do believe however we will not see the corrallation in the models until the last minute. Fingers crossed and all that jazz  

[Derbyshire_snow]

Anything can happen we all know how the models have been up and down  like a big dipper this past week at one point it was all doom and gloom that we wouldn't see any snow at all yet many had a decent snowfall on saturday.

Patience is the key don't get hooked up on a few model runs we all know that things can change in a blink of an eye i wouldn't be surprised if we find ourselves talking about the next incoming cold spell by the weekend.

[mulzy]

No real change in the extended (days 11-15) ECM ensemble mean - negative height anomalies around Iceland and positive height anomalies over the Iberian peninsula.

This is well reflected in the De Bilt ensembles - rock solid against any cold.

http://projects.knmi.nl/exp/pluim/vijftiendaagse/index.php?run=12

Patience may well become the key word going forward.

To lift the mood in here, try ensemble 5 of the 12z GEFS (just for fun of course!).

Edited January 20, 2016 by mulzy

[nick sussex]

The ECM tried to raise the interest levels but just too much energy heading east aided by the PV. The overall pattern it showed however was better than the 00hrs run. At least with the Russian block staying far enough north you'll get some trough disruption near the UK which stops the Euro high from getting too far east in towards the Med.

It does look a bit of a stalemate , whether that changes we'll have to see over the next few runs but overall tonights ECM is far better than last nights borefest.

[winterof79]

Such fine parameters holding the cold from our shores at this very moment.

 

The cold recedes for a while over the next week but Europe is cooled now and ripe for retrogression once our PV is punch drunk

[tight isobar]

Agree nick sussex.

Ecm was heading in good territory' but scuppered with the low shutting down the Russian link up with Scandinavian height. But' that maybe de-ja-vue..as I seem to recall having a similar post discussion with yourself before the current cold spell where things were being scuppered by an uncanny similar scenario. ..but with the Canadian lobe' and height to Greenland where the door kept getting closed 'via' an lp stretching from the lobe...very similar ecm tonight. given other factors involved. .but we got there in the end...even if it wasn't a fruitful as it could have been. ...However its again an open book of options/opportunity! !!!..and with obvious other tweaks and factors to play ball...but the overall point is flagged^^...

[Singularity]

I think, or at least hope, that we'll know a lot more about how we'll end the month once we get within 24 hours or so of the mountain torque event penciled in for 4-5 days time. Past experience suggests to me that the models can make a right hash of how the impacts propagate across to our part of the world, even when you haven't got an unusual tropical profile messing with things such as we have this season.

I have seen enough conclude that the easterly outcome for the second half of next week is still the less likely outcome, but stopped well short of discounting it yet due to the previously voiced issues with how the models handle the gradually dropping global AAM in the short-term, something that will be impacting the ensembles heavily as well.

 

As a final note, it is quite extraordinary just how strongly the GFS 12z det. managed to maintain a very mild zonal theme right out to day 16. It's as if the MT event never happened... or maybe the fact GEFS still manage to send the AAM negative has something to do with it? A hole in my knowledge there! 

 

[JeffC]

2 minutes ago, Singularity said:

I think, or at least hope, that we'll know a lot more about how we'll end the month once we get within 24 hours or so of the mountain torque event penciled in for 4-5 days time. Past experience suggests to me that the models can make a right hash of how the impacts propagate across to our part of the world, even when you haven't got an unusual tropical profile messing with things such as we have this season.

I have seen enough conclude that the easterly outcome for the second half of next week is still the less likely outcome, but stopped well short of discounting it yet due to the previously voiced issues with how the models handle the gradually dropping global AAM in the short-term, something that will be impacting the ensembles heavily as well.

 

As a final note, it is quite extraordinary just how strongly the GFS 12z det. managed to maintain a very mild zonal theme right out to day 16. It's as if the MT event never happened... or maybe the fact GEFS still manage to send the AAM negative has something to do with it? A hole in my knowledge there! 

 

Can I ask what may be a daft question? Is it a particular range of mountains where a weather system coincides and causes a MT event or is it all the mountains everywhere? Sorry if off topic!

[nick sussex]

6 minutes ago, tight isobar said:

Agree nick sussex.

Ecm was heading in good territory' but scuppered with the low shutting down the Russian link up with Scandinavian height. But' that maybe de-ja-vue..as I seem to recall having a similar post discussion with yourself before the current cold spell where things were being scuppered by an uncanny similar scenario. ..but with the Canadian lobe' and height to Greenland where the door kept getting closed 'via' an lp stretching from the lobe...very similar ecm tonight. given other factors involved. .but we got there in the end...even if it wasn't a fruitful as it could have been. ...However its again an open book of options/opportunity! !!!..and with obvious other tweaks and factors to play ball...but the overall point is flagged^^...

The ECM has several chances to disrupt more energy se'wards rather than ne which would improve its output, whether it does so we'll see tomorrow. The GFS since its earlier easterly tease is now more progressive than the ECM. Although signs towards day 7 that its trying to pull the deepest part of the PV further west.

[Jason T]

6 minutes ago, JeffC said:

Can I ask what may be a daft question? Is it a particular range of mountains where a weather system coincides and causes a MT event or is it all the mountains everywhere? Sorry if off topic!

Here you go JeffC.

Hopefully this will explain the answer you need.

 

 

[Derbyshire Snow]

My evening update of GFS run. Very similar to previous op runs   so far. No chance of heights developing again over Greenland and to the north, increasingly strong flow of depressions steaming in from the atlantic bringing severe gales, mild temperatures and some heavy rain at times. Areas to watch are for the previously flooded areas again.

Jet stream out of US even stronger than last night which does not augur well for any strengthening of a Scandi, Siberian High pushing towards UK.

I can see no light unfortunately for cold weather on this model run as at t183. Hopefully ensembles are better but i doubt it. Unfortunately ECM are agreeing with this as well

 

A long road back as the Azores high looks strong. Very hard to get optimistic for cold, but stormy weather may prove interesting.. a recipe for rapid cyclogenesis

[Trom]

Himalayas I believe (at the current time)  

Edited January 20, 2016 by Trom

[marksp]

3 hours ago, Lynxus said:

Thats @10Hpa so quite high up. Pretty much the polar vortex if im not mistaken.

I dont think it has a HUGE direct impact on our weather

This is a bit more interesting at the 850hpa mark.

http://earth.nullschool.net/#current/wind/isobaric/850hPa/orthographic=-1.22,51.20,512

thanks for that, cheers I have bookmarked it 

[Singularity]

I've just realised that if you run the 12z and probably from the looks of it so far 18z GFS det. runs through +192 to +384 you can see how it basically decides to move the entire polar vortex from Canada across Greenland toward Europe as one consolidated feature - essentially following the stratospheric movement but lagged by a number of days. The process is slow enough that it's still not reached Europe as of the end of the 12z run, will the 18z be any faster I wonder?

How often does the vortex actually manage to move about like that in the troposphere without being at least stretched or even broken down? Not sure I can recall seeing it manage that any time since I started paying attention to the N. Hem charts in 2009.

I get the intense cyclogenesis element though, as deeply unstable air moves over the ocean during the transit process. The trouble is GFS has a simplistic approach with large, deep storms when it can be a whole lot messier. That's where the amplification of the pattern comes into it and why the MT event could make things interesting while the vortex makes its move.

The ECM 12z det. has the more disorganised look to the vortex that I'd expect to see.

I feel I have read too much into today's individual runs to be honest, despite Tamara's advice in this thread yesterday. I just can't help myself, I enjoy this kind of analysis too much! It's the making the forecast part that becomes less amusing 

Edited January 20, 2016 by Singularity

[markw2680]

6 minutes ago, Derbyshire Snow said:

My evening update of GFS run. Very similar to previous op runs   so far. No chance of heights developing again over Greenland and to the north, increasingly strong flow of depressions steaming in from the atlantic bringing severe gales, mild temperatures and some heavy rain at times. Areas to watch are for the previously flooded areas again.

Jet stream out of US even stronger than last night which does not augur well for any strengthening of a Scandi, Siberian High pushing towards UK.

I can see no light unfortunately for cold weather on this model run as at t183. Hopefully ensembles are better but i doubt it. Unfortunately ECM are agreeing with this as well

 

A long road back as the Azores high looks strong. Very hard to get optimistic for cold, but stormy weather may prove interesting.. a recipe for rapid cyclogenesis

I'm sure things will all change again come the , we all no not to get hung up on one run, the models are all over the place and tbh haven't got a clue atm

[Methuselah]

14 minutes ago, nick sussex said:

The ECM has several chances to disrupt more energy se'wards rather than ne which would improve its output, whether it does so we'll see tomorrow. The GFS since its earlier easterly tease is now more progressive than the ECM. Although signs towards day 7 that its trying to pull the deepest part of the PV further west.

But - more importantly - what will the weather do?

[Derbyshire Snow]

later in this run there are  some heights leaving Unites States which is visible on this map, ridge pushing north. It may buckle the jet stream, may pruduce a more north westerly flow and allow some interesting weather to develop over here

 

Edited January 20, 2016 by Derbyshire Snow

[Ali1977]

6 minutes ago, Derbyshire Snow said:

later in this run there are  some heights leaving Unites States which is visible on this map, ridge pushing north. It may buckle the jet stream, may pruduce a more north westerly flow and allow some interesting weather to develop over here

 

This is how the METO see it getting colder I think, not from an Easterly. I wonder how their meeting today went ref Febs weather...Hopefully still looking progressively colder, sooner rather than later before the Sun start strengthening and days lengthen !!

FI PV looking a bit sorry for itself by start of Feb....this is good news.

Edited January 20, 2016 by Ali1977

[Derbyshire Snow]

6 minutes ago, Ali1977 said:

This is how the METO see it getting colder I think, not from an Easterly. I wonder how their meeting today went ref Febs weather...Hopefully still looking progressively colder, sooner rather than later before the Sun start strengthening and days lengthen !!

Hi Ali,

Exactly. I think the change in our weather has to come from the west to begin with. We need a cut off of this jet stream either with heights to the west or north Atlantic, and then we can take it from there.  The jet stream has to buckle. Thats a big Azores high though, that needs to weaken as well.I do like the latter part of the run better, lots more promise for the future. Greenland high trying to build, PV on the move ,not sure if it will make it on this run

Edited January 20, 2016 by Derbyshire Snow

[TEITS]

1 minute ago, markw2680 said:

I'm sure things will all change again come the , we all no not to get hung up on one run, the models are all over the place and tbh haven't got a clue atm

I beg to differ.

The models have been consistent with a positive NAO i.e low heights to our NW with high pressure to our S for many days now. The models have also been consistent with high pressure to our NE. The problem is even if we do see low pressure going underneath the high to our NE, the low heights towards Greenland are likely to prevent the block to our NE to extend W.

I seem to recall some forecasts based on teleconnections saying the end of Jan/early Feb is when winter will bite. Well at the moment I see no evidence of this in the output. Infact the current output is like something from a horror film. Maybe the forecasted cold spell will be put back to mid Feb.

 

[MP-R]

4 minutes ago, TEITS said:

 

I seem to recall some forecasts based on teleconnections saying the end of Jan/early Feb is when winter will bite. Well at the moment I see no evidence of this in the output. Infact the current output is like something from a horror film. Maybe the forecasted cold spell will be put back to mid Feb.

 

I wonder if that was partly taking into consideration just normal seasonal expectation. What the models show is highly unusual for this point in the winter with the PV ramping up within a week of the quietest month of the year. 

I'll be watching the models like a hawk over the next few days and only when at least 3/4 of models and runs show southwesterlies will I retire for a while. Biting easterlies one minute, tropical southwesterlies the next... all to play for in my opinion.