Model Output Discussion

[NorthantsSnow]

I must admit the synoptics on offer next week are not too dissimilar to what we saw almost a year ago today prior to last February's easterly outbreak:

http://www.wzkarten3.de/pics/archive/ra/2009/Rrea00120090130.gif

Compare to:

http://www.wzkarten3.de/pics/Rtavn1621.png

Main difference is the blocking looks stronger this time and everything is a little further west, which can only be a good thing.

[cooling climate]

On this basis the very good analysis that has been going on this morning by Dave (TEITS) Nick F and others lends a lot of credence for looking at the model output in FI. There are very good reasons for believing that an easterly is possible by about the second week of Feb or so and no hopecasting on the basis of looking several days out can be levelled at anyone in this respect.

I really do hope that just because some posters myself included saw the very real potential for this

pattern to develope from a week ago are not being tagged as hopecasters just because they could

see what others couldn't.

Edited January 28, 2010 by cooling climate

[bluearmy]

GEFS 06z ens not quite as brilliant as the 00z's. however, the parallel lloks better in FI so the trend continues and the 'easterly' (thats a flow east of N to S) looks pretty solid by T180.

the london ecm temps look pretty impressive with the fi milder solutions dropping out and the clumping cold. also, the mean wind doesnt drop which is important given the possibility of the block being too close.

[kold weather]

Still looking very cold on the models in the longer term, the key difference is models are subtly shifting towards a ESE airflow rather then the deep cold ENE/E airflow that was on some of last nights models.

Still such a pattern could easily evolve into something far colder, if you want to see the perfect example of this just take a look at the last days of Jan 91 and the first 10-15 days of Feb 91 which saw a similar long term evolution.

With the shear size of the upper high I can see a real long battle with the Atlantic coming up, as we've seen occuring ever since the 16th of Jan if the truth be known!

[Guest North Sea Snow Convection]

I really do hope that just because some posters myself included saw the very real potential for this

pattern to develope from a week ago are not being tagged as hopecasters just because they could

see what others couldn't.

It is more to do with stating certainties in the outcome and not acknowledging that other outcomes are possible. That especially applied up to a few days ago. Stating something in absolute terms can come across more intended in hope than in reality.

Data has only really become more favourable towards another round of wintry weather over the last few days. As one good example, look at the thoughts of GP and how they have been evolving and changing over the last days from thoughts of a milder Feb. There were many factors pointing towards milder solutions for Feb, and it was important to acknowledge those.

Even though the patterns look more conduisive to cold now, it is still important to state that any further cold spell is no certainty even now.

Edited January 28, 2010 by North Sea Snow Convection

[nick sussex]

Looking at all the model guidance there is a very strong signal for blocking to the east to try and ridge west however as we often see in these situations the orientation of the high and with it the depth of cold is very uncertain. Again we see a deep trough setting up in the Atlantic and it would help if this was negatively tilted as this would lend itself to shortwaves heading under the block and helping to advect the coldest upper air westwards.

In these situations how far east the trough is will determine the early stages of the easterly. Unfortunately the quickest route to the easterly has receded as the models push the Azores high too far east and don't hold the trough over Europe. So overall then a very good chance of some colder continental air arriving but whether this is snowy or a drier more se flow hard to say at present.

[Frosty.]

With the shear size of the upper high I can see a real long battle with the Atlantic coming up, as we've seen occuring ever since the 16th of Jan if the truth be known!

Fantastic times for model watching coming up, however, I think that mild air will encroach into the far western side of the uk by early next week, maybe across much of scotland by tues/wed with a rapid thaw across the far north with temps recovering to 7 or 8c, england & wales will probably remain in cold air after the N'ly subsides and the E'ly kicks in later next week.

[kold weather]

Yep Frosty there is a real risk of that happening, indeed I wouldn't even be surprised if the milder air makes it across most of the UK before it hopefully gets shunted back. For cold anything upto a SSE flow in an anticyclonic flow is going to be cold at this time of year given how cold Europe it is, however as others have said could quite easily be one of those fairly dry flows, or possibly npt, but I'd be very unhappy if we don't end up with at least some sort of continental flow.

[Snowyowl9]

If anyone things the N-ly has been downgraded it has for today but it`s just delayed as this is potent.

http://91.121.93.17/wz/pics/Rmgfs362.gif

http://91.121.93.17/wz/pics/Rmgfs363.gif

http://91.121.93.17/wz/pics/Rmgfs364.gif

As for the E-ly,it`s getting closer.

http://91.121.93.17/pics/Rtavn1681.png

http://91.121.93.17/pics/Rtavn2401.png

Edited January 28, 2010 by Snowyowl9

[nick sussex]

Interestingly this morning NOAA don't like the ECM or GEMs track of that shortwave over in the eastern USA and have gone with the GFS 00hrs and GEFS ensemble mean, also later they include the GEFS and ECM ensemble means for later in the outlook.

Further upstream there is some uncertainty over the Pacific regarding ridge placement this also impacts downstream so still some variability likely in the models for the timebeing.

Edited January 28, 2010 by nick sussex

[Cecil Hogmanay Melchett]

Interestingly this morning NOAA don't like the ECM or GEMs track of that shortwave over in the eastern USA and have gone with the GFS 00hrs and GEFS ensemble mean, also later they include the GEFS and ECM ensemble means for later in the outlook.

Further upstream there is some uncertainty over the Pacific regarding ridge placement this also impacts downstream so still some variability likely in the models for the timebeing.

Thanks for the update nick thats good news because the ecm op as far as im concerned was poor for the UK.

I might be being greeDy but i want the full works,not no high sat around or over the uk,yes it will mean cold but i it wont

mean the cold uppers that a direct E wind will bring.

Any wind sourced from Poland/Ukrain etc will be frigid,those countries are in a deep freeze comparable to 1987

.I know its greedy and maybe unrealistic but id love to get some winds from that direction as that would be absolutely bitter for us.A

We can have all the blocking in the world over Scandy but if the dominant high for us is situated over us our to

our east we simply wont drag the bitter temps west to us.

Edited January 28, 2010 by happy days

[Duane S.]

Yep Frosty there is a real risk of that happening, indeed I wouldn't even be surprised if the milder air makes it across most of the UK before it hopefully gets shunted back. For cold anything upto a SSE flow in an anticyclonic flow is going to be cold at this time of year given how cold Europe it is, however as others have said could quite easily be one of those fairly dry flows, or possibly npt, but I'd be very unhappy if we don't end up with at least some sort of continental flow.

Spot KW, as is often the case.

I would be amazed if we don't end up with SOME form of Easterly flow during February. I see a milder (frustration for some perhaps) interlude after the Northerly finishes with us. After that however I struggle to see HOW that block from the East is NOT going to affect us in some form or another. Details, exact positioning etc leaves us open to a whole myriad of different scenarios but cold will be the one underlying theme.

Worst case scenario, IMO, a cool-cold dry 7 days. Best case scenraio would be a massive perfectly positioned block, with undercutting lows bringing increasing cold 850s and heavy snow for a very prolonged period of time.

[guitarnutter]

Worst case scenario, IMO, a cool-cold dry 7 days. Best case scenraio would be a massive perfectly positioned block, with undercutting lows bringing increasing cold 850s and heavy snow for a very prolonged period of time.

I'll take the second one

A few quite cold members on the ensembles:

[nick sussex]

Thanks for the update nick thats good news because the ecm op as far as im concerned was poor for the UK.

I might be being greeDy but i want the full works,not no high sat around or over the uk,yes it will mean cold but i it wont

mean the cold uppers that a direct E wind will bring.

Any wind sourced from Poland/Ukrain etc will be frigid,those countries are in a deep freeze comparable to 1987

.I know its greedy and maybe unrealistic but id love to get some winds from that direction as that would be absolutely bitter for us.A

We can have all the blocking in the world over Scandy but if the dominant high for us is situated over us our to

our east we simply wont drag the bitter temps west to us.

I think we're at that stage of the winter where it would be nice too see some of that very cold upper air advected westwards, you don't get many chances to see upper air close to -15 getting into the UK and in terms of having the cold pooling to draw on its likely that an area of sub -20 850's will be pulled sw into eastern Europe. However as we've seen from the last week it's a major hurdle getting that westwards.

Preferably you need to have the elongated high and low pressure to the south over the Med but equally the high has to set up far enough west initially, thats why the key timeframe for me isn't post 168hrs, its between 120 and 144 hrs, the models generally agree on a deep Atlantic trough, the further west this is the higher the chance of a more favourable outcome.

[cooling climate]

It is more to do with stating certainties in the outcome and not acknowledging that other outcomes are possible. That especially applied up to a few days ago. Stating something in absolute terms can come across more intended in hope than in reality.

Data has only really become more favourable towards another round of wintry weather over the last few days. As one good example, look at the thoughts of GP and how they have been evolving and changing over the last days from thoughts of a milder Feb. There were many factors pointing towards milder solutions for Feb, and it was important to acknowledge those.

Even though the patterns look more conduisive to cold now, it is still important to state that any further cold spell is no certainty even now.

The data was there a week ago, MMW, MJO,convection building over the date line, ridging into the Arctic,

hights moving across the pole and linking with the Siberian high, GLAAM and mountain torques predicted to

rise which you could see on the northern hemisphere charts,hints of fast downward propagation of easterly

winds in the stratosphere together with the warming and also remembering the initial response last year to a

sudden stratosphere warming (MMW)plus looking at the developing circulation pattern in the northern

hemisphere which I kept asking people to look at.

[bluearmy]

I think we're at that stage of the winter where it would be nice too see some of that very cold upper air advected westwards, you don't get many chances to see upper air close to -15 getting into the UK and in terms of having the cold pooling to draw on its likely that an area of sub -20 850's will be pulled sw into eastern Europe. However as we've seen from the last week it's a major hurdle getting that westwards.

Preferably you need to have the elongated high and low pressure to the south over the Med but equally the high has to set up far enough west initially, thats why the key timeframe for me isn't post 168hrs, its between 120 and 144 hrs, the models generally agree on a deep Atlantic trough, the further west this is the higher the chance of a more favourable outcome.

of course nick, those early assessments from NOAA cant take the ECM ens into account as they arent available at that time. the ecm ens via the london meteogram look better than the op so the meto update which has the easterly option with undercutting would seem to indicate that the ecm ens gets there anyway. over the past few days, the ops have seemed a bit progressive but the in the end, the ens take on the overall evolution and timing are repeating. continental flow by day 7 - with some trough disruption off the eastern seabaord, this could be earlier. beyond day 7, the continental flow becomes slowly colder and stronger.

The data was there a week ago, MMW, MJO,convection building over the date line, ridging into the Arctic,

hights moving across the pole and linking with the Siberian high, GLAAM and mountain torques predicted to

rise which you could see on the northern hemisphere charts,hints of fast downward propagation of easterly

winds in the stratosphere together with the warming and also remembering the initial response last year to a

sudden stratosphere warming (MMW)plus looking at the developing circulation pattern in the northern

hemisphere which I kept asking people to look at.

thats all well and good CC, but what about your seaweed !!

[cooling climate]

of course nick, those early assessments from NOAA cant take the ECM ens into account as they arent available at that time. the ecm ens via the london meteogram look better than the op so the meto update which has the easterly option with undercutting would seem to indicate that the ecm ens gets there anyway. over the past few days, the ops have seemed a bit progressive but the in the end, the ens take on the overall evolution and timing are repeating. continental flow by day 7 - with some trough disruption off the eastern seabaord, this could be earlier. beyond day 7, the continental flow becomes slowly colder and stronger.

thats all well and good CC, but what about your seaweed !!

Lol who told you my secret.

Looking at these stratosphere temperatures showing where the warming is I would favor the high to

set up in a very favorable position for both cold and snow.

http://strat-www.met...t=temps&alert=1 http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=town&alert=1

Edited January 28, 2010 by cooling climate

[chionomaniac]

Lol who told you my secret.

Looking at these stratosphere temperatures showing where the warming is I would favor the high to

set up in a very favorable position for both cold and snow.

http://strat-www.met...t=temps&alert=1 http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=town&alert=1

The high will only set up in the right place if the displacement of the vortex sets up in a good area which indications now suggest that this could occur - this wasn't the case a couple of days ago. Those warmer temperatures do not quite show the whole picture, cc.

[TEITS]

These AO ensembles keep tumbling.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

Key dates for me based on the model output is 4th Feb, 6-7th Feb. If the output remains unchanged then around 4th feb is when we pull in a colder SE,ly. However by around the 6-7th Feb could be the time when the Siberian express arrives.

[BLAST FROM THE PAST]

Interesting you say that Fred.

I was just thinking to myself that normally the GFS has a tendancy of underestimating blocking. Yet here we are with the GFS/GEFS being very bullish with regards to blocking.

I wiah the ECM would stop messing around though!

Indeed Dave I said that it would be end of the week when we would see the models showing the cold blocking evolution, they showed it two days ago which surprised me and then backtracked a wee bit yesterday, now we should see advancement again. I think in early part of the runs everything is too far east and I think we will see this over4 next day or two. T120 is FI.

BFTP

Edited January 28, 2010 by BLAST FROM THE PAST

[SP1986]

As I said yesterday Dave, it means nowt (negative AO) unless the NAO joins it because that would aid a prolonged continental spell, if thwe NAO ensembles take the neutral ground as they have done it will very quickly shunt any easterly into a southeasterly flow and will lose to some of its umph. It would still be fairly cold, but more like 2001 cold rather than 2009-10 cold.

Nick (Sussex), you say at this stage of the winter you want deep easterlies - are you not happy with what has been so far this winter

[guitarnutter]

These AO ensembles keep tumbling.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

They've already had to change the scale, will they have to again!? Already one member going below -6!

Edited January 28, 2010 by guitarnutter

[Frosty.]

These AO ensembles keep tumbling.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

Key dates for me based on the model output is 4th Feb, 6-7th Feb. If the output remains unchanged then around 4th feb is when we pull in a colder SE,ly. However by around the 6-7th Feb could be the time when the Siberian express arrives.

As kold said earlier, it would be very disappointing if we don't at least get some type of continental flow out of this upcoming spell but I think it will happen because the siberian high looks unstoppable this time even though it's still around a week away from impacting on the uk. Let's hope the siberian tiger is let out of it's cage during the next few weeks and provide some real bite for the last month of official winter.

Edited January 28, 2010 by Frosty039

[chionomaniac]

As I said yesterday Dave, it means nowt (negative AO) unless the NAO joins it because that would aid a prolonged continental spell, if thwe NAO ensembles take the neutral ground as they have done it will very quickly shunt any easterly into a southeasterly flow and will lose to some of its umph. It would still be fairly cold, but more like 2001 cold rather than 2009-10 cold.

Nick (Sussex), you say at this stage of the winter you want deep easterlies - are you not happy with what has been so far this winter

I would expect the NAO to go negative in about 10 days time rather than just average as it is presently. The trend is in the right direction.

I agree that it is the NAO that I would rather see negative as well, but preferably both.

[nick sussex]

As I said yesterday Dave, it means nowt (negative AO) unless the NAO joins it because that would aid a prolonged continental spell, if thwe NAO ensembles take the neutral ground as they have done it will very quickly shunt any easterly into a southeasterly flow and will lose to some of its umph. It would still be fairly cold, but more like 2001 cold rather than 2009-10 cold.

Nick (Sussex), you say at this stage of the winter you want deep easterlies - are you not happy with what has been so far this winter

The winter here has been very good and for you in the UK, I was merely making the point that theres very few chances in the UK to get some very cold upper air so it would be nice to see this happen, the likely cold pooling to the east doesn't happen often so thats really what I was alluding to.