639 replies to this topic

[johnholmes]

Just a touch of reality-been away a day or so, for those using comparisons. Take a look at, someone showed a chart in Jan 1947 a day or so ago. Then look 72 hours ahead!

The weather can AND does, as all saw last week, make many of us who profess to be able to forecast it, using whatever method turns us on, look pretty foolish at times.

I have no idea what the NAO, AO, MJO, Startosphereic profiles etc were before the 1947 freeze up started or indeed another winter I 'enjoyed' 1962-63 but the weather does sometimes change very rapidly. Don't be taken in too much by any of us telling you what is going to happen-it might turn out right it might not. But providing folk use charts to illustrate their belief I think its fine, be it a forecast for tomorrow or a month ahead. What probably irks other folk as much as myself are those posts with little if any chart evidence or links to explain their forecast.

For what its worth the 500mb anomaly charts still show pretty much what they have shown over the past 7-10 days for 10-15 days ahead. A strongish westerly flow across the Atlantic into the UK, sometimes, as those of the last 24 hours show, suggesting a flow from about 240 degrees sometimes about 270 degrees. Most of the time with the heights between 534 and 546DM over central UK. This suggests much as we have had over the past 7-10 days.
Really the Met O 6-15 and their 16-30 day outlooks pretty well mirror this and are about as close as any of us are likely to be to what the actual weather will be.

Edited by johnholmes, 19 December 2011 - 14:43 .

[John Cox]

johnholmes, on 19 December 2011 - 14:41 , said:

Just a touch of reality-been away a day or so, for those using comparisons. Take a look at, someone showed a chart in Jan 1947 a day or so ago. Then look 72 hours ahead!

The weather can AND does, as all saw last week, make many of us who profess to be able to forecast it, using whatever method turns us on, look pretty foolish at times.

I have no idea what the NAO, AO, MJO, Startosphereic profiles etc were before the 1947 freeze up started or indeed another winter I 'enjoyed' 1962-63 but the weather does sometimes change very rapidly. Don't be taken in too much by any of us telling you what is going to happen-it might turn out right it might not. But providing folk use charts to illustrate their belief I think its fine, be it a forecast for tomorrow or a month ahead. What probably irks other folk as much as myself are those posts with little if any chart evidence or links to explain their forecast.

For what its worth the 500mb anomaly charts still show pretty much what they have shown over the past 7-10 days for 10-15 days ahead. A strongish westerly flow across the Atlantic into the UK, sometimes, as those of the last 24 hours show, suggesting a flow from about 240 degrees sometimes about 270 degrees. Most of the time with the heights between 534 and 546DM over central UK. This suggests much as we have had over the past 7-10 days.
Really the Met O 6-15 and their 16-30 day outlooks pretty well mirror this and are about as close as any of us are likely to be to what the actual weather will be.

I certainly remember the charts of early Jan 1982 and it was only possible to see about 3 days ahead at the time and no weather nurds like me to exchange views on forums.

The sudden change then and the mystery of not knowing too far ahead made the end result all the more exciting. I do miss those days.

[Jonathan Evans]

Ian Brown, on 19 December 2011 - 12:18 , said:

Well we are now facing up to an intense PV and Uncle Barty;

http://www.wetterzen...s/Rtavn2401.png

Get to here, and it's a long haul back to even the sort of cooler zonality seen lately

It is more sensible to look for short term trends rather than making a statement on a chart that has a very low probability of verifying - same old story every year!

[Frosty039]

A green christmas and new year are more or less guaranteed now with a tropical maritime flow covering at least the south of the uk, again there is a chance of the high to the south building into southern areas and bringing the twin hazards of fog and frost but if the flow remains moderate or fresh from a predominantly sw'ly quarter, it will remain either mild or very mild over christmas with temps of 12-14c possible, probably a bit cooler in the north with a flow from the north atlantic keeping temps nearer to 8-10c for most of the time but the northern third of the uk probably remaining generally unsettled with spells of rain and stronger winds with a few brighter, colder and showery interludes.

[Geordiesnow]

I think cold fans will need to have a bit of paitence regarding the upcoming weather but thankfully with xmas coming up, the weather will probably not be on most peoples minds as much if it was in January or earlier on in the season.

The outlook is not a totally mild dominated outlook, if we can get the jet to buckle then we should see some cooler weather with wintry showers in the NW like what is forecast for Friday however the models are hinting at a Euro high set up and with a fairly strong PV in control then it may be a struggle to get much in the way of cold weather even from the NW as the GFS FI shows.

Still as the most experience members know, the pattern can break down before we know it and thats the only straw I can clutch at the moment.

[A Scottish Winter's Tale]

Polar_ Low, on 19 December 2011 - 17:07 , said:

A green christmas and new year are more or less guaranteed now with a tropical maritime flow covering at least the south of the uk, again there is a chance of the high to the south building into southern areas and bringing the twin hazards of fog and frost but if the flow remains moderate or fresh from a predominantly sw'ly quarter, it will remain either mild or very mild over christmas with temps of 12-14c possible, probably a bit cooler in the north with a flow from the north atlantic keeping temps nearer to 8-10c for most of the time but the northern third of the uk probably remaining generally unsettled with spells of rain and stronger winds with a few brighter, colder and showery interludes.

Not exactly guranteed yet. What I'm hoping for is the timing of events to change. A predicted cold snap on the 23rd to either last longer; be more potent; start at a later date - the cold snap on Boxing Day to start earlier.

I really am praying that we'll still be under relatively cool uppers come Xmas Eve and I would love it if we have some remaining lying snow on the ground come midnight 25th December.

[Frosty039]

A Winter, on 19 December 2011 - 17:13 , said:

Not exactly guranteed yet. What I'm hoping for is the timing of events to change. A predicted cold snap on the 23rd to either last longer; be more potent; start at a later date - the cold snap on Boxing Day to start earlier. I really am praying that we'll still be under relatively cool uppers come Xmas Eve and I would love it if we have some remaining lying snow on the ground come midnight 25th December.

I wouldn't call it a cold snap on the 23rd, temps of 5-7c is not a cold snap, unless you meant the scottish mountains where it will be cold but for most of the uk it's a cool blip following the mild days on wed/thurs and the mild days that follow the 23rd.

[phil n.warks.]

The 12z output so far shows the same outlook as earlier runs, and unfortunately,for those looking for it, nothing seasonal is promised for the Christmas weekend.

The first day of much milder weather is due to spread across the UK on Weds.
http://hw.nwstatic.c.../h850t850eu.png

The Azores high then builds closer to the UK by the end of the week and with persistent low pressure to our North the flow becomes predominately South Westerly with any colder Pm air limited to brief incursions into the far North.

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

The pattern beyond and into the following week on GFS continues with that blocking to our south extending into c.europe as the current european troughing warms out.
Here a Nhemisphere view at T180

http://hw.nwstatic.c...180/npsh500.png

Whilst the pattern overall looks pretty zonal it shows the High pressure very close to the UK that could well bring a colder feel as we pick up a drift off the continent-with some night frosts in some central and se areas.
Places further north and to the far west will likely have more cloud and dampness with a flow more off the Atlantic.

[i'm dreaming of...]

A Winter, on 19 December 2011 - 17:13 , said:

Not exactly guranteed yet. What I'm hoping for is the timing of events to change. A predicted cold snap on the 23rd to either last longer; be more potent; start at a later date - the cold snap on Boxing Day to start earlier.

I really am praying that we'll still be under relatively cool uppers come Xmas Eve and I would love it if we have some remaining lying snow on the ground come midnight 25th December.

There is little in the way of cold, maybe transitional cool in Scotland. The ensembles (GFS) have 100% confidence that by the 30th we will have a HP to our SW and be influenced by relatively mild weather. A week later the HP is slightly further East with above average temps. The end of GFS has no short term route to cold. In fact with the Jetstream way to our North, quite the opposite; aided by two HP's moving in to the picture from the SW and South. (I usually am skeptical of FI but in the current setup the confidence is quite high).

It looks like above average temps for the first half of Jan 2012. Something need to change in the next two weeks or the second half will also be a write off for cold. So effectively six weeks of Winter left...

[Optimus Prime]

i, on 19 December 2011 - 17:44 , said:

It looks like above average temps for the first half of Jan 2012. Something need to change in the next two weeks or the second half will also be a write off for cold. So effectively six weeks of Winter left...

You're looking at models that deal with the weather, not high calculation climate models. Whatever it shows right now for weeks ahead will change. To say we will have the samt type of weather for the next 4 - 6 weeks is taking these comparible low resolution models way too seriously. The ensembles and GFS will not help you beyond 12 days so there is no point looking at them with any degree of confidence past that time frame.

[Swave Snow]

Ian Brown, on 19 December 2011 - 17:53 , said:

Well generally that is true but if we take the projected picture at T240, then broadly speaking such a pattern in terms of the broad synoptics will persist for considerably longer - the METO outlook going up to mid-Jan reflects this.

But to be fair they have chopped and changed a lot recently

Edited by Swave Snow, 19 December 2011 - 17:55 .

[i'm dreaming of...]

Optimus Prime, on 19 December 2011 - 17:50 , said:

You're looking at models that deal with the weather, not high calculation climate models. Whatever it shows right now for weeks ahead will change. To say we will have the samt type of weather for the next 4 - 6 weeks is taking these comparible low resolution models way too seriously. The ensembles and GFS will not help you beyond 12 days so there is no point looking at them with any degree of confidence past that time frame.

Sorry, that's all I had to go on. At this time I was just commenting on the FI by GFS and as there was close to 100% confidence by the ensembles at Day 8 I therefore extrapolated that, confidence at +384 would be of relative significance.

[phil n.warks.]

I have had to remove a couple of posts which were not discussing the model outputs.
If you have want to talk C.E.T. comparisons with other months/winters please take them to the appropiate threads.

[Frosty039]

i, on 19 December 2011 - 17:44 , said:

It looks like above average temps for the first half of Jan 2012. Something need to change in the next two weeks or the second half will also be a write off for cold. So effectively six weeks of Winter left...

Oh my god what a depressing post, writing off over 40 days of winter.

There is no doubt we are entering a phase with a sw/ne angled jet with high pressure to the south or southwest and maybe eventually the southeast and lows pushing east to the north of the BI so it will be a mild christmas but you can't write off the first half of jan as confidence in the model output drops away significantly by the start of the new year.

[stewfox]

Alex, on 19 December 2011 - 12:40 , said:

What is concerning about this model discussion is that like the summer where everyone was waiting for a ridge to develop to our east. The same is happening this winter with the SSW. I'm not saying it will or won't happen! But even if it does as some have pointed out, it doesn't directly mean a big Greenland high and extreme cold! My advice would be to take a look at trends developing and particularly whether a ridge is likely to develop to our west/northwest, other factors also need to be considered.

Does seem to be more of a herd mentaility

Wait for the stratosphere to warm up and then we get a pro longed cold snap due to start by 15th Jan,all things being equal. Dismiss the next 3/4 weeks..

Might as well just close up shop for 4 weeks.

Since when did back ground signals 'dictate' the model outcome at T384 as a majority seem to suggest now ?

Edited by stewfox, 19 December 2011 - 18:43 .

[Gavin D]

ECM tonight for the festive weekend

Christmas Eve

http://www.wetterzen...cs/Recm1201.gif

Christmas Day

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



Dry, settled and temperatures around 7 to 10c I would think.

[phil n.warks.]

Polar_ Low, on 19 December 2011 - 18:37 , said:

Oh my god what a depressing post, writing off over 40 days of winter.

There is no doubt we are entering a phase with a sw/ne angled jet with high pressure to the south or southwest and maybe eventually the southeast and lows pushing east to the north of the BI so it will be a mild christmas but you can't write off the first half of jan as confidence in the model output drops away significantly by the start of the new year.

Hi Karl,

Indeed the placement of the surface features,especially the High can make a considerable difference to the surface conditions.

We will have to see what the other output says but on the GFS the trend seems to build that High close to the SE.
Warks Ens
.
http://hw.nwstatic.c...arwickshire.png

The mean after a rise falls back towards 0c --so not especially mild considering the pattern at first glance.

Edited by phil n.warks., 19 December 2011 - 18:50 .

[Frosty039]

phil n.warks., on 19 December 2011 - 18:45 , said:

Hi Karl, Indeed the placement of the surface features,especially the High can make a considerable difference to the surface conditions. We will have to see what the other output says but on the GFS the trend seems to build that High close to the SE. Warks Ens .http://hw.nwstatic.co.uk/ensimages/ens.20111219/12/t850Warwickshire.png http://hw.nwstatic.c...arwickshire.png The mean after a rise falls back towards 0c --so not especially mild considering the pattern at first glance.

Hi phil,

Yes the placement of the high is far from being resolved yet and I noticed on the canadian ensemble model this morning that the high builds across the whole of the uk in FI bringing frosty and foggy weather, so there are still lots of options but the xmas weekend will at least be mildish with Tm air flowing around the top of the high, let's hope we get a cold anticyclonic spell after christmas instead of mild and rather cloudy with sw'ly winds.

[snow drift]

Ian Brown, on 19 December 2011 - 17:33 , said:

As I've said before, we can extend our outlook beyond the so called reliable timeframe where zonality is concerned, I think we can accept that this time with the High pressure surge from the South, that we are going to end up where the 06z and now the 12z puts us at around T240.

Ian, you have given extended outlooks for awhile now and looking back, there was no mention of the snow that some areas have seen just recently. If you look at the models and what they are currently showing, one can make assumptions but as you well know things can and do change quickly. I think it fool hardy to believe that due to the surge of pressure from the south, that we will end up with what the models are suggesting for 10 days time. So much depends on where this pressure goes to what will be the outcome in the longer term.

[mountain shadow]

Certainly no sign of a prolonged Bartlett on tonights ECM, full of promise at T+168 with an Arctic high possibly linking with an Atlantic ridge. ECM ensembles may show some prpoer cold solutions.