Model Output - General Discussion

[David-kig]

wooo 00z is good even better then last one for cold sunday -7 blimey - have you seen north sea could freeze 1c omg im gunna faint

the altantic looks to progressive i cnt believe it will just fly it like that mmmm

Edited December 14, 2009 by David-kig

[xerxes]

wooo 00z is good even better then last one for cold sunday -7 blimey - have you seen north sea could freeze 1c omg im gunna faint

Indeed - makes you wonder where we'll be in the run-up to xmas day. The 0z operational certainly keeps a tantalising threat on our doorstep later on. What a week ahead though

[Barometer Obama]

Indeed - makes you wonder where we'll be in the run-up to xmas day. The 0z operational certainly keeps a tantalising threat on our doorstep later on. What a week ahead though

UKMO updated on meteociel looks good. Precipitation for us southerners tuesday night, lets hope its cold enough!

Edited December 14, 2009 by Barometer Obama

[Optimus Prime]

Dew point (the moisture in the air) being one of them. 100% Relative Humidity indicates the Dew Point and air temperature is of equal value. Lower than 99.99% indicates Dew point is lower then the air temperature value. 100% in this country is extremely rare or probably never recorded.

Dew point for the aforementioned date (Tuesday night/Wednesday morning)

Not looking good for the SW...below 0c obviously indicates the Dew (point) is at freezing point. The SW generally between 4c-6c but is to be expected nearer the coast with higher then normal SSTS.

850s (1500 feet atmospheric temperature)

The stuff that's falling out of the sky is of snow right around Britain aside from perhaps the extreme NW Britain.

Convective Potential Available Energy (or CAPE for short)

Not much going on there (more convection around the coast which is to be expected)

2M air temperature. Chilly but perhaps not cold enough for the SW....

Have a look at this chart;

Record snowfall for Britain at a low liying location in the SW. 5 feet (!!!) of snow for the SW and South Wales/N.Ireland. But look at the 850s;

Doesn't look to cold does it?

Anyway there are other factors like Lapse rates/Sea SSTS. I don't think I need to post the SSTS as we should all know the SW at this time of the year has mild seas around it...double figure-ish

[Optimus Prime]

any news on the ukmo and the gfs parrel

+96 hours

+120 hours

+144 hours

Need we say more (about as good as it gets considering the change in climate we're going through)

PS- Wish Steve would get up earlier so all the works done for me :lol:

With regards to the GFS parallel I'm old fashioned and don't bother looking at them.

[PB22]

The 00Z ECM T+96 chart is potentially very cold and snowy for the southeast:

Then by T+120 its time to look north:

Sensational output again this morning.

[David-kig]

+96 hours

+120 hours

+144 hours

Need we say more (about as good as it gets considering the change in climate we're going through)

PS- Wish Steve would get up earlier so all the works done for me

nice run thanks very much 144hour super. gd runs so far ecm plzs dont let us down. has been the best run i think lately for cold and long term.

theres good aggrement it seems with all the main models thankfully with the general pattern looking at that ukmo i tread to think what could happen there very good

[Iceberg]

There is some pretty good model agreement around now.

Short term.

More agreement between GFS, METO and METO forecasts for Tuesday to contain a mixture of rain, sleet and snow, but the models are increasingly moving towards the later two, particularly later in the day as it moves south and west. Areas such as the Cotswolds could see snow snow from this.

The colder weather is still due to move over Wed/Wed night with again an increasing tendency for the rain to turn to sleet and sleet to snow, ECM and METO are a bit more bullish on a slightly more wintry easterly than GFS.

Then very good agreement between 120-144 for the northerly to start spreading considerable snow southwards over this coming weekend, snow depths will be very very large if it comes off as proged.

The above is support by all runs including the Parallel and ECM.

What is also noticable is that the Greenland high is stronger and that the milder weather is finding it more and more difficult to break through, there was good agreement for a mild breakdown on the 22nd on GFS Ensembles yesterday, this looks to have been put back to the 24/25th IMO and will probably go a day or two longer than that, giving many areas a good chance of a snowy chirstmas (or at least snow on the ground).

The LP's coming down in the northerly will be very complicated as the front is extremely active (thundersnow etc), this will form secondary lows and will be a true nightmare to forecast from.

All is All the models are as good as you could wish them to be, probably only light snow this week, but the METO forecasts are increasingly showing snow for tues/wed/thurs and this will continue as we get closer IMO.

[Optimus Prime]

Has anyone seen the latest NWS/NCEP report?

About as accurate as going off with a bent rod and measuring a snowdrift and using your results as a level plateau. But look at how cold December may come in at.

[Iceberg]

nice to see greenland way above average and iceland :lol: even january dont't look bad. march april interesting times ahead signs are there though

which chart is this nt gfs????

This ECM shows it very well. In the early chart look at the flat isobar across the M4 in the south, this shows a sharp front of instability that's stalled.

Also the kink over ireland just below the 1005.

The next chart 24hrs later shows this kink forming a full on LP system feeding on the instability of the front above and pushing systems back eastwards again.

In a way there is too much instability, but this will probably get toned down and moved Eastwards anyway.

[Iceberg]

that just sounds to good to be true. how much support is there didnt see anything like that on the gfs i dont think.

GFS support it, see below, but with slightly less instability.

The flat line front is from just below the wash to wales here and the isobar kink over west scotland, but considering we are 144-168 out this is very good agreement.

The details will change on every run, but there is good agreement on the instability and the potential for the fronts to stall and for secondary lows to form.

But this coming week looks good to me particularly a line from the wash to Bristol down to say the dorset/devon border.

[West is Best]

Super 0z outputs overnight for cold lovers. Plenty of variety for different people. The ECM is particularly interesting. A week hence things could be distinctly lively.

The great thing on these runs is that this is no short-lived cold spell, so although the details are changing from run to run it is all within a general cold, very cold, setup. A throwback to something we've not really seen for a very long time in this country.

[Frosty.]

The GFS seems to be losing confidence in a mild christmas, compared to yesterday's 00z when it was in fairly bullish mood for a return of milder, unsettled weather type, it now shows the cold block reluctant to give way with more of a battle hinted at. Fantastic GFS, ECM & UKMO 00z for cold fans with a strong outflow of cold Siberian air spreading west during wed and digging in for thurs/fri with snow becoming a problem for travel perhaps by then in eastern areas especially. This is only half the story though, we have a powerful greenland high in development and it will throw strong ridging southwards and a deepening trough due north dropping south by friday bringing the first wave of snow showers to northern scotland. Next weekend and the first half of the following week currently look ARCTIC with heavy snow, gales, drifting, severe frosts.

[TEITS]

Gosh so much to look at this morning it difficult knowing where to begin. Makes a pleasant change because in recent years its only taken me 30 secs to view the models due to the poor output!

Let me begin with the short term i.e Wed-Sat.

Relatively good agreement that snow showers will begin developing from Thurs onwards although the flow, duration, still remain uncertain. The pick of this mornings models for the E,ly is the ECM at +96 with a stunning NE,ly. Even at +120 you would find snow showers continuing in E Anglia. Very difficult to call how much snow is likely to fall and to be honest we shall have to wait until tomorrow or Wed.

Medium term.

Well a Bitter Arctic N,ly is on its way. The cold front that will sweep SE during the weekend looks a very lively chap and could bring some large snowfalls. Ahead of the cold front and some very low temps look likely due to min temps dropping very low. Speaking of cold temps I wouldn't be surprised if some locations drop as low as -15C especially after the cold front has passed through and if clear skies allow for this. Very difficult to be specific for this period because disturbances our bound to develop during this spell.

Longer Term.

Normally under such synoptic patterns if the models suggest a breakdown to milder weather you could add 3 days onto this because normally they are too progressive. However in my opinion I feel the models are backtracking away from a return to milder weather. The potential remains for a snow event to hit the UK from the S although at this stage its uncertain how far N this will go. During some of the classic winters there would be a shortlived less cold spell with regards to upper temps but the surface temps remained cold. Shortly after a return to blocking would occur and so would the bitter airmasses from the N & E. This remains a possibility for us towards xmas and beyond!!

[Methuselah]

Thanks for the heads-up, Dave...Having looked at the fax charts just now, I think that the Northerly Blast is now very, very likely...I remember the late 1960s' winters, when fronts bringing milder air stalled and waved over Eastern/Northern parts - snow to rain/freezing rain to snow again...

Agree about possibly very low o/night minima - especially where cold still air stagnates over the snowfields???

[snowmadchrisuk]

Gosh so much to look at this morning it difficult knowing where to begin. Makes a pleasant change because in recent years its only taken me 30 secs to view the models due to the poor output!

Let me begin with the short term i.e Wed-Sat.

Relatively good agreement that snow showers will begin developing from Thurs onwards although the flow, duration, still remain uncertain. The pick of this mornings models for the E,ly is the ECM at +96 with a stunning NE,ly. Even at +120 you would find snow showers continuing in E Anglia. Very difficult to call how much snow is likely to fall and to be honest we shall have to wait until tomorrow or Wed.

Medium term.

Well a Bitter Arctic N,ly is on its way. The cold front that will sweep SE during the weekend looks a very lively chap and could bring some large snowfalls. Ahead of the cold front and some very low temps look likely due to min temps dropping very low. Speaking of cold temps I wouldn't be surprised if some locations drop as low as -15C especially after the cold front has passed through and if clear skies allow for this. Very difficult to be specific for this period because disturbances our bound to develop during this spell.

Longer Term.

Normally under such synoptic patterns if the models suggest a breakdown to milder weather you could add 3 days onto this because normally they are too progressive. However in my opinion I feel the models are backtracking away from a return to milder weather. The potential remains for a snow event to hit the UK from the S although at this stage its uncertain how far N this will go. During some of the classic winters there would be a shortlived less cold spell with regards to upper temps but the surface temps remained cold. Shortly after a return to blocking would occur and so would the bitter airmasses from the N & E. This remains a possibility for us towards xmas and beyond!!

Also worth mentioning rain turning to snow tomorrow , all the models are now predicting this and as the band tends to stall this also could see at least a dusting of Snow in many areas right down as far as Bristol.

[Optimus Prime]

Just look how far hat easterly spread out...

Nothing compared to 1947 where the easterly blew from the continent over the UK through the atlantic and onto the eastern seaboard of the USA.

Edited December 14, 2009 by Optimus Prime

[TEITS]

Also worth mentioning rain turning to snow tomorrow , all the models are now predicting this and as the band tends to stall this also could see at least a dusting of Snow in many areas right down as far as Bristol.

Just shows how much there is to take in as I didn't check about tomorrow.

Your right though because there is a risk of snow tomorrow.

http://charts.netweather.tv/gfsimages/gfs.20091214/00/36/prectypeuktopo.png

[phil nw.]

Some good posts this morning giving excellent summaries of the models.

An Easterly followed by a Arctic Northerly at the weekend.

Many places will have had snow by early next week.

Cold air now filtering towards us and should be established over the UK by midweek.

Here`s the latest Fax.

A long fetch Easterly flow from USSR.should feel bitter.

Then by T144hrs. we have the Northerly coming

http://www.wetterzen...cs/Rukm1441.gif

http://www.wetterzen...s/Rtavn1441.png

http://www.wetterzen...cs/Recm1441.gif

http://www.wetterzen...cs/Rgem1441.gif

Excellent output for cold and snow lovers.

Edited December 14, 2009 by phil n.warks.

[Eugene]

Arctic northerlies are brilliant for severe hard frosts, i think -10C or lower will be easily reached in the midlands this weekend

I also think the models are going to struggle big time with the atlantic breakdown next week, the greenland high hasn't properly formed yet and i'm sure modelling up there isnt that great so i expect large changes to occur once we get the deep cold established.

[TEITS]

I know I should be concentrating on the short term but out of habit im still checking the longer term prospects.

Quiet a shift in the ECM ensembles compared to yesterday and the ECM OP was very much on the mild side of the mean at +240.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Less keen on a return to mild which is the trend the GFS Ops have shown for the last 2 runs.

[Thundery wintry showers]

Well, at least nobody seems to be screaming "downgrades" today! In fact, as I suspected, the models have started to tone up this easterly a little as we get nearer the time, as quite often happens with easterlies that get within the reliable timeframe. Chances of snow events towards the southeast even before that, but in particular overnight Thursday/Friday looks a good bet for a fairly widespread snow cover for eastern districts.

The subsequent northerly is still too far out to firm up details but still looks very promising for cold/snow lovers.

[Frosty.]

Well, at least nobody seems to be screaming "downgrades" today! In fact, as I suspected, the models have started to tone up this easterly a little as we get nearer the time, as quite often happens with easterlies that get within the reliable timeframe. Chances of snow events towards the southeast even before that, but in particular overnight Thursday/Friday looks a good bet for a fairly widespread snow cover for eastern districts.

The subsequent northerly is still too far out to firm up details but still looks very promising for cold/snow lovers.

Agreed TWS,

The Northerly looks very promising for the end of the week on all the models, in fact, it looks like a savage beast but it's still 4-5 days away so it might be a different story when the time comes. The E'ly is nailed though with enough confidence in the 2-3 day range to confirm a strong and increasingly bitter outflow of siberian air which could cause disruptive snowfalls by thurs into friday and then it's time for the Arctic to show it's teeth from the weekend and possibly much of next week.

Edited December 14, 2009 by Frosty039

[snowmadchrisuk]

Well, at least nobody seems to be screaming "downgrades" today! In fact, as I suspected, the models have started to tone up this easterly a little as we get nearer the time, as quite often happens with easterlies that get within the reliable timeframe. Chances of snow events towards the southeast even before that, but in particular overnight Thursday/Friday looks a good bet for a fairly widespread snow cover for eastern districts.

The subsequent northerly is still too far out to firm up details but still looks very promising for cold/snow lovers.

The 6z is downgrading Wednesday , 850's only -1 or -2 and maxes of +3 - +6 It was showing as staying below freezing all day.

[TEITS]

I might be jumping the gun here but to me it looks as though the 06Z GFS is upgrading this E,ly.

http://www.wetterzentrale.de/pics/Rtavn841.png

Seems less progressive than the 0Z which might mean the duration of the E,ly is longer.