Model output discussion - 5th December 2016 - Into Winter we go

[Dennis]

1 minute ago, Seasonality said:

Apologies for going off piste... No agreement run to run, 06z showing a much flatter pattern for Xmas day. Russian high has all but disappeared.

Right thats what we see for days nows its a or and or 

[bluearmy]

21 minutes ago, Dennis said:

any who knows some about waves pls look at this

 

 

Hi Dennis - these are wave 2 forecasts from the operational ecm run of 5th December for 11th december

Things have moved on now. 

[Dennis]

Just now, bluearmy said:

Hi Dennis - these are wave 2 forecasts from the operational ecm run of 5th December for 11th december

Things have moved on now. 

yes i know but i thought after 2 or 3 weeks you see how it can work trough our troposhere..... on what we see in the weathermodels now ; its a total chaos now every run 

[Seasonality]

I hope for the sake of people in the UK prone to flooding that this run doesn't verify, wet, wet, wet over the Xmas and New Year period. I hope the old chestnut about the 06z being one for the bin is true in this case.

[jvenge]

2 minutes ago, Seasonality said:

I hope for the sake of people in the UK prone to flooding that this run doesn't verify, wet, wet, wet over the Xmas and New Year period. I hope the old chestnut about the 06z being one for the bin is true in this case.

It has been quite dry lately and the precipitation showing on the 06z isn't anything to be worried about. The heavier stuff looks to stay comfortably out to sea as well.

[stewfox]

10 minutes ago, jvenge said:

It has been quite dry lately and the precipitation showing on the 06z isn't anything to be worried about. The heavier stuff looks to stay comfortably out to sea as well.

?? Its been raining here on and off last 4 days, ground very soggy.

Last thing we want is the GFS 6Z to verify 24/12

[Man With Beard]

Many GEFS 06Z members still not giving up the ghost on a D5/D6 easterly...surely not?

   

[jvenge]

1 minute ago, stewfox said:

?? Its been raining here on and off last 4 days, ground very soggy.

Last thing we want is the GFS 6Z to verify 24/12

What's December at? I thought it had been very dry in the UK?

What to say. Looking at the model output, there just isn't that much from that particular weather event. It doesn't hang around long, the rainfall amounts show as quite low as well.

[Summer Sun]

JAMSTEC has now updated for December

Surface air temp anomaly is slightly above average for Dec to Feb though slightly below for NI and RIO

Precipitation anomaly is slightly above average

[nick sussex]

To use a roulette analogy we're down to our last few quid, we've gambled nearly all the Christmas money and are now left with piling what we have left on one number!

Ordinarily at this point I would be throwing the towel in however theres just enough uncertainty both upstream and the exact placement of high pressure to the east to warrant keeping the towel until tonight.

The movement of the PV to the north is effected by what happens over in the USA, that's not to say its going to suddenly find some festive spirit and clear off! However its the modelling of the pattern over in the eastern USA which could either help or hinder our chances of getting some energy going se towards Iberia. Currently there are differences with the handling and amplitude of shortwave energy reaching the east coast, these have a knock on effect into the Atlantic.

I think current odds do favour a battle and then the PV winning out but don't discount yet that we might see more energy heading se.

[Interitus]

4 hours ago, fergieweather said:

Hi Steve: not sure which models you mean (missing the stratospheric trend), but GloSea5 certainly didn't. Here's snapshot of output from way back in late October (hence not latest modelling, which I can't show). Red is forecast mean; blue the hindcast mean. Note much weaker period foreseen during Nov; then marked uptick in 10hPa zonal winds (most members heading above average) during December. This signal was repeated and strengthened each run thereafter. UKMO were confident on the turnaround in SPV that has now unfolded, and GloSea5 timing for this was actually good. So it's incorrect to suggest UKMO missed this: quite the opposite; they were ahead of the game. 

 

....and black the reality from the GEOS-5 FP analysis (dashed line = forecast)

OK, but not amazing.

 

[warrenb]

2 minutes ago, Interitus said:

....and black the reality from the GEOS-5 FP analysis (dashed line = forecast)

OK, but not amazing.

 

Really ?

I think as a forecast from October that is pretty blinking good.

[Interitus]

Just now, warrenb said:

Really ?

I think as a forecast from October that is pretty blinking good.

What do you base that opinion on?

[Ravelin]

Since it's 'quiet time' between models runs I have a question. On the GFS ensembles graphs, the bit at the bottom "risk of snow" with the pretty snowflakes, just how is it calculated? A percentage of the ensembles at that time who have precipitation at the location and a suitable 850s temp?

[warrenb]

1 minute ago, Interitus said:

What do you base that opinion on?

That fact that no forecast will ever exactly match the actual and forecasts at that distance are for the trends, which I think it has picked up very well.

[Interitus]

4 minutes ago, warrenb said:

That fact that no forecast will ever exactly match the actual and forecasts at that distance are for the trends, which I think it has picked up very well.

So it's not based on much then? Sorry, the stratosphere is eminently more predictable than the troposphere and the scatter in the ensemble forecast doesn't appear to be much improvement on climatology. Interestingly the actual values were outside the ensemble envelope from early in the forecast.

[bluearmy]

11 minutes ago, Interitus said:

What do you base that opinion on?

Don't suppose you have any other Long range models strat forecasts for that timescale to compare? I don't think that predicting low zonal flow for November is much of a wow but the fairly quick uptick in December could be seen to be a pretty good call if other models weren't showing such a thing.

[warrenb]

1 minute ago, Interitus said:

So it's not based on much then? Sorry, the stratosphere is eminently more predictable than the troposphere and the scatter in the ensemble forecast doesn't appear to be much improvement on climatology. Interestingly the actual values were outside the ensemble envelope from early in the forecast.

Well I apologise you want the train to run on the tracks.

[feb1991blizzard]

Surely the most important thing here is what are the Strat forecasts for the next month or so suggesting.

[jvenge]

50 minutes ago, Summer Sun said:

JAMSTEC has now updated for December

Surface air temp anomaly is slightly above average for Dec to Feb though slightly below for NI and RIO

Precipitation anomaly is slightly above average

Europe for the month to date. Hmmmmmm. Not buying it :-)

 

[feb1991blizzard]

9 minutes ago, jvenge said:

Europe for the month to date. Hmmmmmm. Not buying it :-)

 

Nope nor me - That other chart saying above average over 3 months for nearly all Eaurope, Russia and Siberia, these temperature LR charts annoy me because I'm all for Long range forecasting but they give credence to the 'LR models are all useless' brigade.

[bluearmy]

Can we just agree that a mean temp anomoly that is for more than a month is going to be pretty worthless anyway ??

if you can see the individual monthlies within the period then you can make an analysis of sorts but even that is fraught with likely issues. 

 

[jvenge]

Just now, bluearmy said:

Can we just agree that a mean temp anomoly that is for more than a month is going to be pretty worthless anyway ??

if you can see the individual monthlies within the period then you can make an analysis of sorts but even that is fraught with likely issues. 

 

Oh yeah, but something fairly special would need to happen to get the view mentioned, just considering the first half of the month.

That's before we even talk about how an anomaly is arrived at. Take my country. It's showing as no anomaly, but most people would consider it a colder than usual December. 4 days of mild (+8 higher than usual), some not quite as low night time lows, lower day time highs, etc, skewed it a lot.

 

[AGAL]

49 minutes ago, nick sussex said:

To use a roulette analogy we're down to our last few quid, we've gambled nearly all the Christmas money and are now left with piling what we have left on one number!

Ordinarily at this point I would be throwing the towel in however theres just enough uncertainty both upstream and the exact placement of high pressure to the east to warrant keeping the towel until tonight.

The movement of the PV to the north is effected by what happens over in the USA, that's not to say its going to suddenly find some festive spirit and clear off! However its the modelling of the pattern over in the eastern USA which could either help or hinder our chances of getting some energy going se towards Iberia. Currently there are differences with the handling and amplitude of shortwave energy reaching the east coast, these have a knock on effect into the Atlantic.

I think current odds do favour a battle and then the PV winning out but don't discount yet that we might see more energy heading se.

Ah but what currency are we dealing in Human Emotions I would suggest. If so then we are all in serious debt

[feb1991blizzard]

4 minutes ago, bluearmy said:

Can we just agree that a mean temp anomoly that is for more than a month is going to be pretty worthless anyway ??

if you can see the individual monthlies within the period then you can make an analysis of sorts but even that is fraught with likely issues. 

 

Yep!  -  ive learned that off Gavin P on his videos, if I had a quid for the amount of times he says 'I'm not sure I agree with the temps if the heights verify', I would be very rich.