Model Output Discussion - 1st - 7th January

[Cheshire Freeze]

The ECM ensembles will be of interest later, probably best to save this set for comparison reasons to the 00z and 12z set of tomorrow.

[Jason T]

Well what a difference a few hours make. This is my theme for the ecm all will be clear at the end..

Edited January 7, 2012 by silver line

[nick sussex]

Seemingly good model agreement then with the GEM0z, GFS12z, JMA12z and ECWMF12z all forecasting a Scandinavian High by day 8 though the westward extent is up for grabs.

I am actually a little skeptical of the ECWM12z outcome from day 7 onward as it seem to strengthen the Jet Stream (would attempt to sink the high) while the other models keep it weak.

As the Arctic high edges in to the pole its likely to give the jet alot more energy as it displaces colder air further south, theres nothing wrong with that if the PV is further west and the energy is forced under the block.

You can have a monster PV on the western side of Greenland and get a good Scandi block but you must have the block reinforced with energy heading into Iberia and the Med.

This acts to help draw the cold air westwards and supports the block and stops it from sinking.

[Cheshire Freeze]

In my eyes there are 2 major issues here.

Firstly today's developments are some of the most rapid turnaround seen on this forum. In terms of pattern change I don't think you can get more positive developments.

Secondly, We have seen many potentially impressive Easterlys at closer range evaporate in front of our eyes, and there are many ways in which this can go wrong , particularly with no real blocking to the NW.

Saying that we have had good charts tonight.

Yes I remember all too well that easterly saga a few years back.....that was particularly galling, especially as -20 uppers were forecast on one or two runs at 120 hours out!

[January Snowstorm]

GP must be having a wry little smile to himself this evening.

This dramatic change in fortunes couldn't have been called more accurately

Lots of ifs and buts ahead but if GP does get it right it certainly begs the question as to why the Met cant do a more reliable effort than the current rubbish they drole out

As teits said a few days ago, the azores high staying in situ was the last thing likely to happen yet the Met stuck to it relentlessly

Edited January 7, 2012 by January Snowstorm

[Jason M]

All depends what you want?

If its cold but dry weather then yes

If its snow then no its not quite perfect for snow see post 1306

Would not bet on that . I'd wager that the first snow showers would be showing their hand over the SE.

A long way off but given the time frame and a fair bit of inter model agreement there must be a better than evens chance of a change. We just need to find out now imo whether were looking at an easterly or a near miss.

Jason

[ChartViewer]

In my eyes there are 2 major issues here.

Firstly today's developments are some of the most rapid turnaround seen on this forum. In terms of pattern change I don't think you can get more positive developments.

Secondly, We have seen many potentially impressive Easterlys at closer range evaporate in front of our eyes, and there are many ways in which this can go wrong , particularly with no real blocking to the NW.

Saying that we have had good charts tonight.

Hmmmm please could you explain that Jackone?

Regards

[Timmytour]

66 pages.

I'm thinking that the next weeks worth of comments on the models will either go over 100 pages or require more than just the one thread.

While still not showing anything dramatic in the way of the sought-after cold being delivered, in terms of posturing where it might come from the latest model runs are giving us bales rather than single straws to clutch upon

[Cheshire Freeze]

GP must be having a wry little smile to himself this evening.

This dramatic change in fortunes couldn't have been called more accurately

Lots of ifs and buts ahead but if GP does get it right it certainly begs the question as to why the beeb cant do a more reliable effort than the current rubbish they drole out

As teits said a few days ago, the azores high staying in situ was the last thing likely to happen yet the Met stuck to it relentlessly

Well IF this theme continues it will be very intriguing as to how the METO handle the potential in their longer range forecasts. I do get the impression that the METO and GP use very different methods of long range forecasting with the METO seemingly reliant on computer simulations whereas I think GP tends to take a less ethnocentric approach to forecasting- taking into account a plethora of 'out there' variables. It is, in my opinion, where the METO fall down when other factors appear to override what 'should' happen according to computer models.

Edited January 7, 2012 by CreweCold

[bluearmy]

good agreement but the data could easily change overnight. one step at a time. the parallel gefs not nearly as impressive from a cold perspective as the normal ones.

[TEITS]

Warmer SST's yes are favorable for Snow and do generate convection...But only if they are bringing a cold source of temps from Scandy/Siberia whick deliver for the UK.....At present temps over the Continent are poor.........Not sure id be that confident any Easterly would bring the rainbow to cold lovers.

Current muck over Sweden/Denmark is hugely mild

I really don't understand why your basing this on current temps. If the orientation of the HP is backing the cold W then current temps have no significance. Look at the charts below and note and how quickly the cold airmass moves S.

http://www.wetterzentrale.de/pics/Rtavn1442.png

http://www.wetterzentrale.de/pics/Rtavn2402.png

The main issue isn't the current temps across Europe but whether we can get the cold airmass to hit the UK. If it did then due to how this synoptically develops then upper temps as low as -15C would be possible.

[Tom Montalbano]

Some very sensible posts above re. not getting carried away with the 12z runs but certainly a remarkable turnaround from the last few days.

Would advise too, not to get hung up on how the synoptics look 8/10 days down the line, dont analyze every isobar placement to the nth degree.

The overall trend is looking very hopeful at the moment but as a lot of us realise, the situation can quickly go pear-shaped.

Ian Brown is quite right to point out that model archives must be littered with failed easterly synoptics, many more examples than the classic holy grail charts of Jan 1987, Jan 1985, etc but for obvious reasons we dont see these posted.

Btw, dont know if you remember Ian, I work for a Bookmaker. A cheeky enquiry, anymore of the 100/1 and 25/1 available about an easterly by those dates you mentioned this morning? :winky: Seriously, what would you make those odds now?

Have to say another very informative post from Steve M explaining how many hurdles we have to cross to develop those sort of synoptics which deliver an easterly with cold and snow.

Quick thank you to Nick S.for answering my query on those charts from the 00z ECM showing where forecast pressure deviates from the mean of the runs.

Regards,

Tom.

Edited January 7, 2012 by TomSE20

[SMU]

last one from me tonight-

2 points..

* Over the next few days we may see some spectacular ensembles- especially from the GFS, obviously its exciting eye candy & I will be the first person to post incredible snowy easterlies- however I think we have all been here long enough to know it might not happen, could get thwarted at the last minute go titicus verticus blah blah blah- So for those who dont want the cold- youve had the last 3 months- let the people who are desperate to see some frost & snow enjoy the rollercoaster build up & if it doesnt happen we knew it might not anyway- but we enjoyed the trip down memory lane from years like 85 ,87 & 2010!

* In terms of the ECM ensembles tonight I would expext to see a dip at the surface of the debilt ensembles at day 8-10 on the early run & when we see the 10-15 extended version again i would expect to have seen the mean drop & some SOLID clustering around the freezing mark, remember the Scandi high CAA is expected to peak ( if it happens) at Day 9-12 so the peak of cold at the surface will be around day 12/13 in the suite with clustering either side...

Best regards

Steve

[nick sussex]

Regarding the eastwards progression of troughing out of the USA the GFS 12hrs run has been disregarded and not used by NOAA.

NO SIGNIFICANT CHANGES WERE MADE TO THE PREFERRED FORECAST 500 MB

HEIGHTS/SEA LEVEL PRESSURES BASED ON THE 12Z RUNS. THE 12Z GFS WAS

LIKE THE 06Z GFS IN MOVING THE SOUTHERN STREAM LOW RAPIDLY OUT OF

THE SOUTHWEST AND AN OPEN WAVE ACROSS THE SOUTHERN PLAINS AND

SOUTHEAST. THE 12Z GFS IS CONTRASTED BY THE LESS PROGRESSIVE 12Z

UKMET/12Z GEFS MEAN/12Z ECMWF...WHICH ARE SLOWER WITH THE FORWARD

PROGRESSION OF BOTH THE NORTHERN AND SOUTHERN STREAM TROUGHS.

WITH THE 12Z GEFS/UKMET/12Z ECMWF CLOSE TO EARLIER PREFERRED

GUIDANCE...AND A LONG TERM GFS BIAS TO MOVE CLOSED LOWS TOO

QUICKLY EAST...NO ADJUSTMENTS WERE MADE BASED ON THE 12Z GFS.

[Buzz]

Now lets not all get too giddy, things can and will change over the next few days. The building blocks to cold are coming together, but we all know just how pear shaped things can go from here on.

I was just about to say the exact same thing. Things will very likely flip flop for the worse (and maybe even for the better) over the next few days, but if the worst happens (and to avoid excessive sales of Prozac), let's hope people don't get too carried away with these decent runs.

Remember, we still have over a week to go, and given the way that the model output has changed recently, it very likely WILL change again, high res output or not.

[Frosty.]

good agreement but the data could easily change overnight. one step at a time. the parallel gefs not nearly as impressive from a cold perspective as the normal ones.

How often have we been here before, it's only potential at this stage but we are definately going to see a lot more fi charts with some bizarre looking cold patterns as the strat warming and the upcoming bigger scale strat warming begins to impact, enjoy the ride.

[cyclonic happiness]

OMG! I don't care if this gets deleted (well I do really but hey) The ECM tonight has just made me spit a huge chunk of carrot cake all over my space bar lol!

Can it be that there could be an easterly waiting in the wings a mere week and a half away?? Aww I'm so happy, you cannot imagine how happy I am.....

Just look at all that cold pool of air marching westwards from a frozen Europe!!!

And don't tell me I'm ramping, I couldn't care less, just allow me to bathe in the warm waters of a big freeze. (at least until the downgrades )

[J10]

Hmmmm please could you explain that Jackone?

Regards

Quite simply (while remembering the caveats I also posted), GFS and ECM are great charts tonight, for those wanting a pattern change and cold potential, that is abundantly clear.

[SMU]

Regarding the eastwards progression of troughing out of the USA the GFS 12hrs run has been disregarded and not used by NOAA.

NO SIGNIFICANT CHANGES WERE MADE TO THE PREFERRED FORECAST 500 MB

HEIGHTS/SEA LEVEL PRESSURES BASED ON THE 12Z RUNS. THE 12Z GFS WAS

LIKE THE 06Z GFS IN MOVING THE SOUTHERN STREAM LOW RAPIDLY OUT OF

THE SOUTHWEST AND AN OPEN WAVE ACROSS THE SOUTHERN PLAINS AND

SOUTHEAST. THE 12Z GFS IS CONTRASTED BY THE LESS PROGRESSIVE 12Z

UKMET/12Z GEFS MEAN/12Z ECMWF...WHICH ARE SLOWER WITH THE FORWARD

PROGRESSION OF BOTH THE NORTHERN AND SOUTHERN STREAM TROUGHS.

WITH THE 12Z GEFS/UKMET/12Z ECMWF CLOSE TO EARLIER PREFERRED

GUIDANCE...AND A LONG TERM GFS BIAS TO MOVE CLOSED LOWS TOO

QUICKLY EAST...NO ADJUSTMENTS WERE MADE BASED ON THE 12Z GFS.

Hi Nick-

i do remember posting last night it was all about the Eastern US troughs & how they behaved- also they needed to be slower!

S

[Cheshire Freeze]

Regarding the eastwards progression of troughing out of the USA the GFS 12hrs run has been disregarded and not used by NOAA.

NO SIGNIFICANT CHANGES WERE MADE TO THE PREFERRED FORECAST 500 MB

HEIGHTS/SEA LEVEL PRESSURES BASED ON THE 12Z RUNS. THE 12Z GFS WAS

LIKE THE 06Z GFS IN MOVING THE SOUTHERN STREAM LOW RAPIDLY OUT OF

THE SOUTHWEST AND AN OPEN WAVE ACROSS THE SOUTHERN PLAINS AND

SOUTHEAST. THE 12Z GFS IS CONTRASTED BY THE LESS PROGRESSIVE 12Z

UKMET/12Z GEFS MEAN/12Z ECMWF...WHICH ARE SLOWER WITH THE FORWARD

PROGRESSION OF BOTH THE NORTHERN AND SOUTHERN STREAM TROUGHS.

WITH THE 12Z GEFS/UKMET/12Z ECMWF CLOSE TO EARLIER PREFERRED

GUIDANCE...AND A LONG TERM GFS BIAS TO MOVE CLOSED LOWS TOO

QUICKLY EAST...NO ADJUSTMENTS WERE MADE BASED ON THE 12Z GFS.

Though the ECM is even quicker Nick, the JMA shows a similar but slower progression

[Jason M]

Regarding the eastwards progression of troughing out of the USA the GFS 12hrs run has been disregarded and not used by NOAA.

NO SIGNIFICANT CHANGES WERE MADE TO THE PREFERRED FORECAST 500 MB

HEIGHTS/SEA LEVEL PRESSURES BASED ON THE 12Z RUNS. THE 12Z GFS WAS

LIKE THE 06Z GFS IN MOVING THE SOUTHERN STREAM LOW RAPIDLY OUT OF

THE SOUTHWEST AND AN OPEN WAVE ACROSS THE SOUTHERN PLAINS AND

SOUTHEAST. THE 12Z GFS IS CONTRASTED BY THE LESS PROGRESSIVE 12Z

UKMET/12Z GEFS MEAN/12Z ECMWF...WHICH ARE SLOWER WITH THE FORWARD

PROGRESSION OF BOTH THE NORTHERN AND SOUTHERN STREAM TROUGHS.

WITH THE 12Z GEFS/UKMET/12Z ECMWF CLOSE TO EARLIER PREFERRED

GUIDANCE...AND A LONG TERM GFS BIAS TO MOVE CLOSED LOWS TOO

QUICKLY EAST...NO ADJUSTMENTS WERE MADE BASED ON THE 12Z GFS.

Another positive this evening. A number of comments tonight about the PV over Greenland. Its perfectly possible to get an easterly with the PV sat there, but its unlikely to last more than 2-3 days as the jet will sink the Scandi high. Getting the PV moved is more about longevity of any outbreak than anything else. Wish that Azores high would clear off though.

[Cheshire Freeze]

Another positive this evening. A number of comments tonight about the PV over Greenland. Its perfectly possible to get an easterly with the PV sat there, but its unlikely to last more than 2-3 days as the jet will sink the Scandi high. Getting the PV moved is more about longevity of any outbreak than anything else. Wish that Azores high would clear off though.

There is time for that PV to at least back off westwards slightly in subsequent runs but I doubt there is much room for manouvre. As I said, this attempt may be a false start.

[Isolated Frost]

Another positive this evening. A number of comments tonight about the PV over Greenland. Its perfectly possible to get an easterly with the PV sat there, but its unlikely to last more than 2-3 days as the jet will sink the Scandi high. Getting the PV moved is more about longevity of any outbreak than anything else. Wish that Azores high would clear off though.

Bit of an easterly toppler situation, with that jet energy eventually riding over that high. I would still love the scenario, and with a possible MMW.. then the arctic profile may act more favourable and the PV could easily re-locate.

[nick sussex]

Hi Nick-

i do remember posting last night it was all about the Eastern US troughs & how they behaved- also they needed to be slower!

S

Yes lets hope they take the scenic route and stop off at a diner for a long while!

I wonder if this new trend is in relation to the slowing of the zonal flow in relation to the recent strat warming, the last time we saw the output suddenly switch to an easterly was Feb 2009 but i think that was a SSW which reversed the flow.

[SMU]

Yes lets hope they take the scenic route and stop off at a diner for a long while!

I wonder if this new trend is in relation to the slowing of the zonal flow in relation to the recent strat warming, the last time we saw the output suddenly switch to an easterly was Feb 2009 but i think that was a SSW which reversed the flow.

yes plus we havent seen any modelling of the superwarming yet!

That could be waiting in the wings for Feb-

All I want to see is that phase 2 of the jet 180-228 a bit more amplified-

S