Jump to content

Archived

This topic is now archived and is closed to further replies.

General Cluster

Model Output Discussion:

Recommended Posts

Rating of models (cold and snow) from 0-10

GFS: 9/10 (9/10 ensembles)

ECWMF: 6/10 (7/10 ensembles)

UKMO: 4/10

GEM: 9/10

GME: 4/10

NOGAPS: 3/10

JMA: 7/10

FI is +48 though.

Share this post


Link to post
Share on other sites

Rating of models (cold and snow) from 0-10

GFS: 9/10 (9/10 ensembles)

ECWMF: 6/10 (7/10 ensembles)

UKMO: 4/10

GEM: 9/10

GME: 4/10

NOGAPS: 3/10

JMA: 7/10

FI is +48 though.

Yes, this is quite evidently going to remain a spell of considerable inter-run flux and uncertainty: the latest UKMO analysis expresses the continuing uncertainties and presently rather low-grade risk of anything profoundly cold developing, noting as follows (abstracted) - -

Days 8-10: Wed to Fri: ".....Temperatures rather cold in many areas, perhaps cold at times in the N/E, and near normal in the W/SW/S...."

Days 10-15: Trend: "....temperatures often a little below normal and perhaps turning cold...." (Rationale / Discussion): ".....the majority of solutions favour low pressure dominating over the Atlantic and a SE'ly weather type across the UK. Whilst this is the favoured solution it is worth noting that a not insignificant minority favour a milder S/SW'ly type and a smaller minority a colder E'ly type. Much of the uncertainty..... stems from developments associated with major cyclogenesis over the W'ern Atlantic during the next few days, the behaviour of pulses of shorter wave forcing round this major vortex in particular accounting for inter-model differences in the rate of frontal progression across the UK early next week (and hence whether the UK ends up in a SE or SW'ly type)".

In other words, we remain at something of a model impasse despite the eventually colder (albeit perhaps not dramatically colder) theme remaining somewhat marginally favoured for now, with any (presently still not significant) snow risk largely cited as probable in NE/E/Central districts. I agree with others who have continued to stress the 'moveable feast' nature of this current period and very evidently, any worthwhile prognosis of what'll happen towards the second half of next week has the caveat of 'low confidence' stamped all over it in big letters.

Share this post


Link to post
Share on other sites

Perhaps a clue that UKMO arent buying it. Looks like they still with SW influence. Cold, yes possible, but the easterly of GSF

UK Outlook for Monday 8 Feb 2010 to Wednesday 17 Feb 2010:

Mainly cloudy with outbreaks of rain, heavy at times with hill snow in the north at first. Brighter conditions with showers, some heavy, in the south and west, then following. The rest of the week remains unsettled with bands of rain spreading in from the southwest and turning to sleet and snow at times across northern, eastern and central parts. Some showers and brighter spells, between these bands of rain, temperatures close to or a little below average in many areas. For the rest of the period there is a large degree of uncertainty in the forecast, but it looks likely that unsettled, rather cold conditions will continue, with rain, sleet and snow at times, temperatures below average with overnight frost and ice.

Updated: 1203 on Wed 3 Feb 2010

Printable view days 1 to 15

Did you expect them to go with a flip the size of GFS immediately?? seems to tie in pefectly with what ian posted yesterday about their thoughts for next week and more importantly, doesnt fit in with raw UKMO output.

incidentally, parallel 06z GFS ens are better than op ens

Share this post


Link to post
Share on other sites

Could you explain what the MJO is, and what phase 8 means please?

Its the Madden Julian Oscillation

Heres a good explanation:

The MaddenJulian oscillation (MJO) is an equatorial traveling pattern of anomalous rainfall that is planetary in scale. The MJO is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean. The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean. The wet phase of enhanced convection and precipitation is followed by a dry phase where thunderstorm activity is suppressed. Each cycle lasts approximately 3060 days. Because of this pattern, The MJO is also known as the 3060 day oscillation, 3060 day wave, or intraseasonal oscillation.

For western Europe the more favourable phases are 7, 8,1 and 2, this is because these phases associated with its movement enhance the chances for northern blocking, although you need other factors working with this.

Share this post


Link to post
Share on other sites
The rest of the week remains unsettled with bands of rain spreading in from the southwest and turning to sleet and snow at times across northern, eastern and central parts.

Sounds like what GEM 00Z is showing for next week heavy rain on monday turning more wintry in northern, eastern and central parts with winds from the continent getting pulled into the mix, sounds a good update to me and could easily go colder for tomorrows update.

The crucial period is around T+72 hrs which can have big knock on effects down the line so next week starting sunday really is a nightmare to forecast and it will change daily.

Share this post


Link to post
Share on other sites
Guest North Sea Snow Convection

Did you expect them to go with a flip the size of GFS immediately?? seems to tie in pefectly with what ian posted yesterday about their thoughts for next week and more importantly, doesnt fit in with raw UKMO output.

incidentally, parallel 06z GFS ens are better than op ens

Yes true, but that update is a distinct edging away from the more favoured colder outcome updates of recent days. Uncertainty has always prevailed yes, but there is a greater emphasis now placed on atlantic intervention than previously - although the hint of colder air to the east still never far away of course . Yesterdays update spoke about ppn 'fizzling out' perhaps before it reached eastern areas

In view of the model oscillations though, this balance can always change. However it puts the latest GFS output into some perspective and a lot of doubt.

Best not to have too high expectations from the 12z's perhaps

Share this post


Link to post
Share on other sites

Wow very well done snowyowl, you really did go searching for as close to a chart to ECM 00Z T+96 hrs as possible and by the looks of it you really found one very similar that turned out cold :lol:

Share this post


Link to post
Share on other sites

Thankfully the MJO has moved back into phase 7, lets hope it continues through there into phase 8.

http://www.cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.html

Yep good news and still a very strong signal to take it through to phase 8. :lol:

I posted earlier about that Norway SW. Something about how the charts have been showing it behave recently hasn't quite rung true with me.

The models appear as confused as me about it, what's your take on it Nick?

Share this post


Link to post
Share on other sites

We are heading towards something incredible and thats just looking at ECM cold mild battle where cold won out to extremeness these 2 charts say it all 1985 february. :lol: :lol: :o

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850207.gif

http://www.wzkarten.de/pics/Recm961.gif

Good shout. That chart from the 3rd looks remarkably similar!

Share this post


Link to post
Share on other sites

Looking at the 00Z EPS, the GFS ENS mean and indervidual charts etc, I would give a 50% chance of a major shift in the METO GM for the 12Z shift.

I would increase this to 80% to see a much improved ECM which brings in an easterly somewhere between T144 and T200.

I know this brings high expectations from the 12Z but I really do think it's justified.

Share this post


Link to post
Share on other sites

We are heading towards something incredible and thats just looking at ECM cold mild battle where cold won out to extremeness these 2 charts say it all 1985 february. bomb.gifbomb.gifohmy.gif

http://www.wetterzen...00119850207.gif

http://www.wzkarten....ics/Recm961.gif

I don't see very much similarity between those two. The 1985 setup has HP over Scandinavia, with very cold air on its southern flank being directed towards the UK. The 2010 chart has LP over Scandinavia, blocking any particularly cold air reaching the UK.

Looks likely the milder air is likely to win for most of England and Wales, with only for NE of England and Eastern Scotland looking like being particularly cold by the weekend. As for the Met Office further outlook, they've had the possibility of returning cold in the plus 10 day period for about a week now, so if they were accurate, it would be in the 3 to 5 day period by now, which it clearly isn't.

Share this post


Link to post
Share on other sites

Wow very well done snowyowl, you really did go searching for as close to a chart to ECM 00Z T+96 hrs as possible and by the looks of it you really found one very similar that turned out cold :lol:

Good shout. That chart from the 3rd looks remarkably similar!

I remember it. :lol:

If anyone wants to see how mild it got before well.

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850205.gif

http://www.wetterzentrale.de/archive/ra/1985/Rrea00219850205.gif

Share this post


Link to post
Share on other sites
Guest North Sea Snow Convection

Looking at the 00Z EPS, the GFS ENS mean and indervidual charts etc, I would give a 50% chance of a major shift in the METO GM for the 12Z shift.

I would increase this to 80% to see a much improved ECM which brings in an easterly somewhere between T144 and T200.

I know this brings high expectations from the 12Z but I really do think it's justified.

I hope you are right! That Feb 1985 model comparison is a very very good one I think. You are never going to get every detail and nuance exactly the same, but the same general set up applies then as it does now.

Here's to the same outcome!

Share this post


Link to post
Share on other sites

Wow very well done snowyowl, you really did go searching for as close to a chart to ECM 00Z T+96 hrs as possible and by the looks of it you really found one very similar that turned out cold :lol:

Those charts are very different, the 1985 one has 985 low pressure over Russia while today's one has a 1045mb high in the same place.

Share this post


Link to post
Share on other sites

Yep good news and still a very strong signal to take it through to phase 8. :lol:

I posted earlier about that Norway SW. Something about how the charts have been showing it behave recently hasn't quite rung true with me.

The models appear as confused as me about it, what's your take on it Nick?

Yes I've been going on about that shortwave for days, I think I've driven everyone mad with it! In a knife edge pattern that is very important, theres no surprise that the output that weakens it and takes it further east looks the coldest, this allows the stronger ridge sw'wards which then forces the upper trough to swing sending that shortwave se under the ridge later on, this is key because as the next low exits the USA this will run into the upper trough, without the ridge extension the pattern moves east rather than ne and we lose the trough disruption, more importantly its the 72hrs with the track of the shortwave that will either make or break the possibility of getting anywhere close to that GFS 06hrs run.

I'll repost an earlier post from the other thread to highlight the small but hugely significant difference the behaviour of this shortwave makes.

The crucial part of the output and really what opens up the route to cold is at 72hrs. If you look at the UKMO 00hrs for T-72hrs

http://www.meteociel.fr/modeles/ukmo2.php?nh=&ech=72&carte=1021

Then compare it to the GFS 06hrs run at 66hrs

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=66&mode=0

Notice the difference, how the UKMO leaves a trail of residual energy, this causes a pull like effect on the trough and brings this closer together with more energy later, this is why its absolutely crucial that theres a clean break by the shortwave se'wards.

This very small global difference magnifies down the line like a domino effect, tonight you'll know by this timeframe whether to reach for the prozac or not!

Share this post


Link to post
Share on other sites

This degree of uncertainty is unprecedented in the internet era. It’s a guessing game right now. Having glanced over the model outputs, it still looks 50:50 to me. The evolution to cold is fraught with danger. However, it is often these risky situations that go on to lead to some of the biggest snowfalls. I’m sure some of the great snowstorms of the past e.g. Feb 1978 and Dec 1978 were equally as difficult to forecast. A more predictable transition to long lasting cold like in Feb 86, whilst very cold, was also very dry. To get decent widespread snow events, an Atlantic influence is usually required.

IF the cold air can get established across the UK, the ingredients seem to be in place for an attack from the Atlantic, giving the potential for widespread heavy snow. Things appear to be so finely balanced that I wouldn’t rule anything out just yet.

From a neutral viewpoint, this period of model watching has been fascinating. Even though I'm not in the UK, I would love to see the cold air win out. A decent blast of cold air would surely be the icing on the cake for this winter; firmly cementing it as the best winter in a generation.

Share this post


Link to post
Share on other sites
Guest North Sea Snow Convection

I hope we are not seeing the GFS reeling out the next ice age by 4.15pm and at the same time the UKMO is coming out showing the shortwaves butting into the UK with south westerlies once again!

Just as well I have some chores out and about around that time!biggrin.gif

Share this post


Link to post
Share on other sites
I hope we are not seeing the GFS reeling out the next ice age by 4.15pm and at the same time the UKMO is coming out showing the shortwaves butting into the UK with south westerlies once again!

lol yep another good GFS 12Z tonight similar to 00Z i think a pretty poor UKMO 12Z but slightly better than 00Z and a slightly better ECM 12Z is my opinion tonight of course by tomorrow they`ll all be in agreement which way will it be :rolleyes:

I know where my money is :)

Yes Altostratus you are quite correct to get the best snowfalls in the UK especially down here we need some kind at atlantic intervention thats why i was surprised at North Sea Snow Convections post from earlier as the UKMO update sounded good for this like on GEM 00Z of course i`m going for a colder drier outlook next week :)

Im amazed you being in egypt that you're interested in our weather, can't see too many people from here being that interested in egypts weather, maybe you are from the UK originally and moved there hence the interest.

Share this post


Link to post
Share on other sites

In my humble opinion i cant see anything to stop the low in the atlantic pushing into the uk after the weekend.Looking at a combination of ecm ,ukmo and the fax charts there seems little to stop the momentum.Gfs threw everyone a curve ball this morning but i expect it to be more ion line with the other models come 4-00 pm.hope im wrong mind you. :rolleyes:

Share this post


Link to post
Share on other sites

So the question is, is the GFS now the model of the day or is it just suffering from the usual GFS up and down?

I am really confused I don't believe an easterly is necessarily the end product, but it's quite clear that a southwesterly is very shaky in the model outputs.

Share this post


Link to post
Share on other sites

So the question is, is the GFS now the model of the day or is it just suffering from the usual GFS up and down?

I am really confused I don't believe an easterly is necessarily the end product, but it's quite clear that a southwesterly is very shaky in the model outputs.

There's a message on 'the other weather forum' that moderately critical data was missing plus that there was low data on the 06z GFS run. Or was that also mentioned here and I missed it?

Share this post


Link to post
Share on other sites
So the question is, is the GFS now the model of the day or is it just suffering from the usual GFS up and down? I am really confused I don't believe an easterly is necessarily the end product, but it's quite clear that a southwesterly is very shaky in the model outputs.
Missing data aside, I would say only look at it to get idea of next 24-36 hours because of issue over Scandinavian SW. Beyond that and who could back any of them based on the last week's changeable output. TEITS's wait and see approach may be necessary not just for next few hours, I guess, but perhaps even for next couple of days just to see what may pan out over the weekend. Low confidence you bet!

Especially so, given remarks by Chionomaniac just now in Stratospheric thread.

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.

  • Showers in the north and west again ahead of a hot end to the week

    A weather front will bring showery rain to western and northern regions today, as those further southeast enjoy warm sunny spells. Heat then starts to build for the end of the week with 35c on the cards in the southeast. Read the full update here

    Netweather forecasts
    Netweather forecasts
    Latest weather updates from Netweather

    Heat building - But not before a northwestern soaking

    The weather has thrown up two things to focus on during the coming hours and days. First the rain across the north and especially northwest of the UK, with some heavy, persistent downpours today in western Scotland in particular. Second, the build of heat later this week from the south, with temperatures forecast to rise into the mid-thirties, for some at least, by Friday. Read the full update here

    Netweather forecasts
    Netweather forecasts
    Latest weather updates from Netweather
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...