Model Output Discussion - 21st - 28th November

[Cheese Rice]

GFS is shortwave crazy out to the latter part of the run. While Its nice to see sub -5 uppers these shortwaves will either scupper the chances of cold or massively enhance it. While I can't really say what will happen I would advise everyone to look no further than T72 when it comes to the positions of these lows, although the evolution is consistent (High pressure over Canada) the positions of the lows is not.

On a side note- wouldn't it be lovely if that high nudged further east.

Edited November 21, 2011 by Cheese Rice

[Matty M]

Look at the cold locked in over Greenland

If you look @ this image here, you'd be fooled to think we had 'hope' for cold!

[January Snowstorm]

I'll repeat what I said last night, we are in a far better place than we were a week ago.

Matty I think your suffering from Uk-aitis, because these charts are actually very close to being great for Ireland.

A small nudge East in that trough and bitter cold will move down over Ireland

[Cecil Hogmanay Melchett]

The cold air bottled up over greenland is very BAD for the UK.Its feeding an already frigid Arctic and is feeding the jetstream.

The 18z is im afraid another disasterous run for European sking industry and you can see clearly all that mild air being pumped north as far east as western russia by the never ending belt of High pres across southern and central europe.

Might see some flirtations with pm air acorss the north but its slim pickings and the vast maority will see rain.

The bigger picture remains as flat as a pancake

Edited November 21, 2011 by happy days

[Grimsby Snow Lover]

Not a bad run to end the day on really if average to cool weather is your liking. What pleases me the most is that for the first time in a while we have had two gfs runs together that have had cool/coldish FI. Really hope this trend continues now and the ECM comes on board the seasonal train.

[feb1991blizzard]

I know I bang on about it but I do urge folk to make use of the daily output of the 3 500mb anomaly charts.

They are far more reliable and subject to far less chopping and changing than the routine 2x ECMWF and 4x GFS outputs at time scales beyond the T+144 range.

IF and only IF they consistently predict a similar upper air pattern for several days its about 80% if not 90% likely that is how the upper air pattern will turn out.

remember its the UPPER air NOT surface. That is another difficulty, no offence intended, for amateurs to try and 'marry' upper air pattern down to what the surface overall pattern may be. Do not expect the detail hardly ever to be correct at the surface 10 days out-just get a feel for how the pressure pattern will most likely look like. It should for instance tell you pretty clearly the difference between a settled anticyclonic spell and a less settled one as well as a good idea which direction the isobars are going to come from.

Expect more? then expect to be constantly disappointed!

Wholeheartedly agree John but for fans of severe cold and snow like me, which there are a lot of on here, there has not been anything to remotely get excited about in the 8-10 day range the whole of this autumn so therefore we are forced to look at the GFS FI. I have tried to take a back seat and view things with a modicum of realism but havent been posting that much because i dont want to turn this forum into a mauge!

For what its worth i think the GEFS and ECM ensemble suites over the last week have been the most interesting so far but unfortunately that isnt saying much as you would expect them to be trending progressively colder due to the change in seasons.

[January Snowstorm]

The cold air bottled up over greenland is very BAD for the UK.Its feeding an already frigid Arctic and is feeding the jetstream.

The 18z is im afraid another disasterous run for European sking industry

Indeed it is, but the Scottish one could well kick off and is Scotland not nearer to home?!

Edited November 21, 2011 by January Snowstorm

[ZONE 51]

View the 500hpa latest 18z run here..

http://www.weathercharts.org/wetterzentrale-t120-t384.htm#top

[damianslaw]

The cold air bottled up over greenland is very BAD for the UK.Its feeding an already frigid Arctic and is feeding the jetstream.

The 18z is im afraid another disasterous run for European sking industry and you can see clearly all that mild air being pumped north as far east as western russia by the never ending belt of High pres across southern and central europe.

Might see some flirtations with pm air acorss the north but its slim pickings and the vast maority will see rain.

The bigger picture remains as flat as a pancake

Looking on the positive when/if we do see a northwesterly/northerly blast it would be a jolly cold affair thanks to very cold uppers - in some winters northerlies failed to deliver proper cold - I think back to early feb 05 as an example.. but this year watch those cold fronts and troughs sweep rapidly over the country. I'll say it again the outlook is very very standard fare for the time of year - all very normal service.

[ZONE 51]

GFS - 18z

I see the potential for snowfall at around 600-800m across Scotland at the end of the week into the weekend, perhaps falling down to 500m in heavier precipitation?

[nick sussex]

No late night tease from the GFS tonight. The elongation of the troughing to the north isn't good, and a frenzy of shortwaves are likely to make it difficult to tap into the PM air.

Again one of the essentials to an improving pattern that being pressure dropping significantly in central and southern Europe fails to materialize with the Euro high holding on.

[wimblettben]

From what I can see from the models any interesting wet and unsettled weather is only really going to be reserved for Northwestern areas with the bulk of the country still not having much difference in weather conditions that the South has witnessed from the past month and more.

Only past 100hrs do the models show the unsettled weather affect more of the country.

Edited November 21, 2011 by wimblettben

[damianslaw]

View the 500hpa latest 18z run here..

http://www.weatherch...20-t384.htm#top

Last post from tonight - yes its way beyond the reliable timeframe - but the run does show alot of polar maritime air over the country as we enter December thanks to more favourable ridging of heights over western atlantic.. as I said all eyes on developments over NE USA and SE Canada in the coming days, whilst the trough may struggle to make much headway eastwards we could end up with it directly over the country enabling the cold polar air to sweep in behind and in such set ups shortwaves and secondary lows can easily appear and hae enough oomph to shove the trough southeastwards which would be a very good direction in helping to lower heights over the continent and enable some proper mid atlantic heights to develop. I do think this is a very plausible pattern for the start of December - will wait and see.

[ZONE 51]

Tuesdays 850s upper temps

Late Thursday (below)

Then Friday afternoon

It looks increasingly likely that high Northern areas will see wintry conditions

Although its a taster, at least its something to be interested in as you never know it might just produce a good snowfall on the high ground, of course the highest risk being the mountains.

(GFS 18z)

Edited November 22, 2011 by ElectricSnowStorm

[BlueHedgehog074]

Summarising the models in the style of a script (this is what happens when that mutli-coloured snowflake gets bored, he hee). ;')

Fred: "Hey, Bob, have you seen the models tonight?"

Bob: "Nah, don't feel like it. The 12Z ECM and 12Z GFS was a big downgrade for cold potential for next week."

Fred: "That may have been so, but they did show potential for snow for Northern areas at least, and still do according to the 18Z GFS. The mountainous areas of Scotland could see a risk of something wintry as early as this Friday, if those snow risk charts are to come true."

Bob: "Well, if you want to know what I think, I don't even think it will be cold. Not one bit. You saw how the Euro high was going to try come back on that run and stall Low Pressures systems further West."

Fred: "Yeah, but they could still change y'know. I mean, okay, fair enough, if you saw the 18Z run, you would see it ain't that keen on totally destroying that High-Pressure to the East, just like with the previous GFS run..."

Example from the 18Z run.

Bob: "Oh... that's just great. That means more mild weather being drawn up from the South and South-West. That just sucks. Why are the models always teasing us like this, eh?"

Fred: "I know it may not be ideal, but there is still potential there for a cold spell to become more widespread in my opinion. Take a look at that wall of High-Pressure systems to the West for example around 159 hours... "

Fred: "Now, if those Highs to the West can keep their strength throughout future runs, then it may provide enough force to get those Lows to travel further East."

Bob: "That would only help, off course, if the Heights to the East become weaker and get knocked further East and South, otherwise those Lows may still hang about too far West and not draw in that much colder air from the North."

Fred: "We do need that JetStream to be in a favourable place, too, to drive those Low Pressure sytems in the right direction."

Bob: "I guess so, but I still don't feel that convinced. Maybe the tallest hills in the far North may get to see some flakey stuff, but nothing else. That 159 hour GFS chart you showed, seems to show rather strong Heights to the East and South-East, and I do feel they may not get knocked about easy."

Fred: "Like I said mate, things can still change."

Bob: "Well, if that yucky 12Z ECM chart doesn't get upgraded, I'm gonna throw a snowball at someone."

Fred: "Ah, but you just said earlier on that you were rather doubtful of a cold spell happening, and besides, the charts ain't showing no snow for your area. Ha ha ha ha haa..."

Bob: "Alright! Come 'ere you!"

Fred: *dashes off and hides on top of a Scottish Montain*

The End!

[weathe20]

Summarising the models in the style of a script (this is what happens when that mutli-coloured snowflake gets bored, he hee). ;')

Fred: "Hey, Bob, have you seen the models tonight?"

Bob: "Nah, don't feel like it. The 12Z ECM and 12Z GFS was a big downgrade for cold potential for next week."

Fred: "That may have been so, but they did show potential for snow for Northern areas at least, and still do according to the 18Z GFS. The mountainous areas of Scotland could see a risk of something wintry as early as this Friday, if those snow risk charts are to come true."

Bob: "Well, if you want to know what I think, I don't even think it will be cold. Not one bit. You saw how the Euro high was going to try come back on that run and stall Low Pressures systems further West."

Fred: "Yeah, but they could still change y'know. I mean, okay, fair enough, if you saw the 18Z run, you would see it ain't that keen on totally destroying that High-Pressure to the East, just like with the previous GFS run..."

Example from the 18Z run.

Bob: "Oh... that's just great. That means more mild weather being drawn up from the South and South-West. That just sucks. Why are the models always teasing us like this, eh?"

Fred: "I know it may not be ideal, but there is still potential there for a cold spell to become more widespread in my opinion. Take a look at that wall of High-Pressure systems to the West for example around 159 hours... "

Fred: "Now, if those Highs to the West can keep their strength throughout future runs, then it may provide enough force to get those Lows to travel further East."

Bob: "That would only help, off course, if the Heights to the East become weaker and get knocked further East and South, otherwise those Lows may still hang about too far West and not draw in that much colder air from the North."

Fred: "We do need that JetStream to be in a favourable place, too, to drive those Low Pressure sytems in the right direction."

Bob: "I guess so, but I still don't feel that convinced. Maybe the tallest hills in the far North may get to see some flakey stuff, but nothing else. That 159 hour GFS chart you showed, seems to show rather strong Heights to the East and South-East, and I do feel they may not get knocked about easy."

Fred: "Like I said mate, things can still change."

Bob: "Well, if that yucky 12Z ECM chart doesn't get upgraded, I'm gonna throw a snowball at someone."

Fred: "Ah, but you just said earlier on that you were rather doubtful of a cold spell happening, and besides, the charts ain't showing no snow for your area. Ha ha ha ha haa..."

Bob: "Alright! Come 'ere you!"

Fred: *dashes off and hides on top of a Scottish Montain*

The End!

Great effort.

[BLAST FROM THE PAST]

Hey Bob, the overnighters are looking good again, there's definitely signals for a colder pattern being picked up on!

Fred

[Iceberg]

After a bit of searching and it required it !.

There are tentative signs of a pattern change still as we go into Dec IMO. The ECM ops/ENS has been showing signs of this with a larger pacific ridge off the US west coast, this is 100% needed to provide the upstream amplification. GFS also hints at something similar, although in a different way.

Unlike last year where the High was predominently Greenland based, we probably have a high building and ridging into Scandy begining of December.

The big question for me is will the amplification be strong enough to sustain it giving us a December shot of cold air or will it get blown away.

[bluearmy]

After a bit of searching and it required it !.

There are tentative signs of a pattern change still as we go into Dec IMO. The ECM ops/ENS has been showing signs of this with a larger pacific ridge off the US west coast, this is 100% needed to provide the upstream amplification. GFS also hints at something similar, although in a different way.

Unlike last year where the High was predominently Greenland based, we probably have a high building and ridging into Scandy begining of December.

The big question for me is will the amplification be strong enough to sustain it giving us a December shot of cold air or will it get blown away.

spot on re the possible east pacific ridge

[mountain shadow]

Hey Bob, the overnighters are looking good again, there's definitely signals for a colder pattern being picked up on!

Fred

Colder as in more seasonal, yes. Colder as in the chance of lowland snow, no. Short wave alley continues to scupper any of the real cold flooding south. But yes, a small step forward in the output this morning.

[Iceaxecrampon]

1st -2nd December again on the 00z....!

Not sustained but Low pressure brings a reload on the 4th

High pressure then pushing in from the west.....

[Glacier Point]

After a bit of searching and it required it !.

There are tentative signs of a pattern change still as we go into Dec IMO. The ECM ops/ENS has been showing signs of this with a larger pacific ridge off the US west coast, this is 100% needed to provide the upstream amplification. GFS also hints at something similar, although in a different way.

Unlike last year where the High was predominently Greenland based, we probably have a high building and ridging into Scandy begining of December.

The big question for me is will the amplification be strong enough to sustain it giving us a December shot of cold air or will it get blown away.

.. I have that ridge on the analogue package..

Note the position of the mean trough there, smack bang over the UK. I suspect we will see waxing and waning of the ridge to our north east throughout December as the jet oscillates in strength. Still no indication of high latitude blocking for another month at least given the polar westerlies, and no sign of the necessary surge in tropical forcing until perhaps late December.

Meantime, the model bias in terms of forecasting a -NAO has shown up again, with the pattern looking flatter as we hit the short to medium range.

[shedhead]

Still nothing on the overnight runs to get exited about re cold/N blocking, at least not if you don't live where sheep outnumber humans by 1000 to 1. As others have said, look at the big picture provided by the 500mb anomoly charts rather than chasing every hint of cold offered up by the models every 6-12hrs, otherwise it will drive you barmy before Winter even starts. I know this to be fact, because the big pink hippo driving the bakers van on the frozen lake in the kitchen told me!

Edited November 22, 2011 by shedhead

[Frosty.]

All the real cold is well into FI on the Gfs 00z but there is plenty of cool zoneality before then and friday this week looks like the coldest day for a while nationwide with wintry showers across northern scotland but then turning briefly milder through the weekend as a vigorous low spreads east, cooler weather following with showers which would be wintry on hills of northern britain but too windy for frost, next week gradually shows colder air pushing southeast with snow falling to lower levels in the north and the run ends with rather cold air covering the uk.

[wolvesfan]

Morning all,

Theres a bit more agreement with ECM,GFS on this mornings output.i think in the overall pattern things are pretty set until we get something to change this.the devil is in the detail for the shorter term but the colder polar air staying with us from t126 onwards.things could be better but they could also be a lot worse as the big euro high never too far from our shores.

Edited November 22, 2011 by wolvesfan