Winter 2012 / 2013 Part 2

[michail]

What were the cfs charts showing for 10/11 in september of that year? were they predicting below average temps? Thanks in advance

[syed78]

i must say the 2 forecasts r conflicting met saying below avrage and wsi r saying mild, i'm mor incline to go with the met for the moment and not just because i love cold and snowy weather. By the way guys what's wsi's forecasting record like?

[feb1991blizzard]

What were the cfs charts showing for 10/11 in september of that year? were they predicting below average temps? Thanks in advance

As you can see the height anomalies were pretty accurate for early winter with positive height anomalies over Greenland.

However, the temperature charts certainly were not showing anything like the bitter cold that followed, December chart even shows above average for some parts of the country, the only month that was very accurately predicted on the chart below was feb which came out above average.

It was not until November that the CFS really got a handle on the potent cold of december.

Edited September 28, 2012 by feb1991blizzard

[feb1991blizzard]

i must say the 2 forecasts r conflicting met saying below avrage and wsi r saying mild, i'm mor incline to go with the met for the moment and not just because i love cold and snowy weather. By the way guys what's wsi's forecasting record like?

Bare in mind though that the Met dont actually issue seasonal forecasts and it is just the raw data from their seasonal model (GloSea4) with no human alteration to the data.

[michail]

Cheers feb1991blizzard! so they were accurate with the pressure anomalies, but not so much with the temps. I hope we see a positive change in the next update.

[Polar Maritime]

A weak El Niño may develop in September and October and last until the northern hemisphere winter, according to the World Meteorological Organization’s new El Niño/La Niña Update.

Edited September 28, 2012 by Polar Maritime

[snowstorm445]

Weather Services International are going for a Mild and Wet Autumn / Early winter for western Europe this year

http://www.wsi.com/f...ase-details.htm

WSI predicted cold weather last year before deciding to take a u-turn right at the last minute in favour of a mild winter. They also made no mention of the severe cold spell in Europe in February.

I'm presuming you are a mild lover, given the ?

[feb1991blizzard]

Cheers feb1991blizzard! so they were accurate with the pressure anomalies, but not so much with the temps. I hope we see a positive change in the next update.

Yes although it suprises me that when they are showing huge areas of mean + anomalies of heights to the North that the temperature charts do not reflect the synoptics, although to be fair i havent actually checked them against the actual charts that verified and only against what is percieved to have verified in my head, though the CFS nailed the 09 / 10 winter very well.

Certainly November was zonal and december cold.

[Robbie Garrett]

CFS v2 1 month Showing a mild start for the UK under high pressure for the begging of November. We all know how that panned out in 2010.

Current stuff trending out of the CFS 06z, 12z, and 18z runs (as those are the only ones I've every really viewed, never awake for the 00z) is the following.

1. Early Cold spells, possibly similar to 2010 or worse.
   
2. Very windy/possibly very wet Winter with some very deep and powerful lows
   
3. Europe Very blocked on occasions - perfect Summer synoptic..
   
4. Blocked Atlantic on occasions.
   

It's pretty much hinting at everything on all the signals .. one thing it is going for overall is something quite chilly and cold but wet at the same time.

Edited September 28, 2012 by Robbie Garrett

[gottolovethisweather]

Cheers feb1991blizzard! so they were accurate with the pressure anomalies, but not so much with the temps. I hope we see a positive change in the next update.

I know where you're coming from but you should ask yourself, would that actually make a difference? I am not picking on you specifically, but all newcomers and any less experienced model watchers need to be aware of the danger of doing as suggested. By this I mean, as global climate is ever changing, a simple disturbance/change down the line, be it from within 60 seconds, minutes or hours of that output would result in a completely different model output. So, if the next six CFS runs picked up the same general signal, we might then think it is onto something. However, even then, nothing in meteorology is certain and there will be further complications over time. My advice as ever, is to attempt to look for consistent trends in the charts and ensembles, all of which comes with experience. Right, I've rambled enough so I'll leave the rest to the usual suspects.

[gottolovethisweather]

WSI predicted cold weather last year before deciding to take a u-turn right at the last minute in favour of a mild winter. They also made no mention of the severe cold spell in Europe in February.

Furthermore, if they are to issue a forecast at the start of Autumn (as do a few others), the chances of it being correct, six months down the line is stupendously difficult in my humble opinion.

Take with a large

Edited September 28, 2012 by gottolovethisweather

[A.J]

Solid post Tony, worthy of a thumbs up IMHO,

[AderynCoch]

Can those long-term CFS forecasts ever be considered reliable? They always seem to flip-flop at whim.

[johnholmes]

as both the twp previous posters have suggested the answer is very doubtful for an accurate prediction.

No one has yet solved the problem of seasonal forecasting but its fun seeing the ouputs and slowly probably very slowly the accuracy will improve.

[gottolovethisweather]

Solid post Tony, worthy of a thumbs up IMHO,

[Robbie Garrett]

Can those long-term CFS forecasts ever be considered reliable? They always seem to flip-flop at whim.

Generally good for trends.... that's what I noticed during my forecast for Spring and Summer which eventually became true.

[womble21]

Can those long-term CFS forecasts ever be considered reliable? They always seem to flip-flop at whim.

Well let's hope we don't need our flip-flops this winter....or barbeques!

[TEITS]

Can those long-term CFS forecasts ever be considered reliable? They always seem to flip-flop at whim.

No a waste of time as I shall explain.

If we use the GFS as an example have you noticed that at +6 very little changes between each run and yet if you compared +384 you would see a completely different outcome on each run. This is simply due to the chaos theory where slight changes in the early part of the run become more and more noticeable as the timeframe progresses. These significant changes are most noticeable from around +300 onwards.So the fact the CFS goes to 1074hrs is just laughable.

The chaos theory is one of the biggest problems for computer models which is why ensembles are used.

[Weather-history]

Is anyone hoping for a stormy winter?

January 1993

December 1993

[Aaron]

I'm hoping for a stormy winter.. I love gales, but of course snow is my priority. It would be great if we could get the two combined, 'true' blizzards are rare here.

[I remember Atlantic 252]

on meteociel archives 30-31 Dec 1994 looks like an absolute snowfest for northern UK, but mildish in south

I certainly dont want a stormy winter, means mild, windy here, where as oop norf, usually means snow, I think Leeds is far enough north to get the 2 combined, although a bit of elevation needed

Edited September 29, 2012 by ihatetherain

[A.J]

No a waste of time as I shall explain.

If we use the GFS as an example have you noticed that at +6 very little changes between each run and yet if you compared +384 you would see a completely different outcome on each run. This is simply due to the chaos theory where slight changes in the early part of the run become more and more noticeable as the timeframe progresses. These significant changes are most noticeable from around +300 onwards.So the fact the CFS goes to 1074hrs is just laughable.

The chaos theory is one of the biggest problems for computer models which is why ensembles are used.

I kind of agree with Robbie's post giving some credence to the CFS model for spotting long term trends, but I also find myself agreeing with your points as well!.....and TBH It's reassuring to know that I'm not the only one who believes firmly in the 'chaos theory' aspect of weather forecasting. I think I'll keep things simple this winter by looking at the various short/mid range model output (in particular at timescales of T100 - T240) to get an idea of possible trends (which may well have a decent predictive percentage of accuracy) and keeping tabs on Stratospheric temperatures (again purely for the possible 'knock-in' effect that for example SW can have)

Edited September 29, 2012 by ajpoolshark

[bluearmy]

stormy does infer large variations in uppers over a fairly small area. that doesnt say cold in general. within a generally blocked environment, stormy would be high risk as the deeper the depression the further north it will try and swing which inevitably takes part of the country out of the cold air. also, stormyness promotes mixing of the layers which is another anti snow factor. if you are looking for a cold snowy winter, i'd say stormyness is best left to autumn.

[NorthernRab]

stormy does infer large variations in uppers over a fairly small area. that doesnt say cold in general. within a generally blocked environment, stormy would be high risk as the deeper the depression the further north it will try and swing which inevitably takes part of the country out of the cold air. also, stormyness promotes mixing of the layers which is another anti snow factor. if you are looking for a cold snowy winter, i'd say stormyness is best left to autumn.

Definitely true generally, but from a Highland perspective, the most impressive blizzards are often associated with large storm systems. I've seen Badenoch (the area in which Dalwhinnie and Kingussie lie) looking like a desert the morning after a storm system passed across the country, massive drifts of soft snow which contorted into almost sharp little peaks, all bathed in a weak yellow sunlight, an impressive sight!

In saying that, I'd take blocked conditions, the effects are more lasting!

Case in point:

Edited September 29, 2012 by NorthernRab

[Terminal Moraine]

No a waste of time as I shall explain.

If we use the GFS as an example have you noticed that at +6 very little changes between each run and yet if you compared +384 you would see a completely different outcome on each run. This is simply due to the chaos theory where slight changes in the early part of the run become more and more noticeable as the timeframe progresses. These significant changes are most noticeable from around +300 onwards.So the fact the CFS goes to 1074hrs is just laughable.

The chaos theory is one of the biggest problems for computer models which is why ensembles are used.

I'd agree, TEITS, that the very long range synoptic charts are of very little use for the same reasons you outline above but the long range CFS maps are useful for spotting long term trends. I keep a close eye on these and as far back as early February the overall forecast for the summer (cooler and much wetter than average away from the far north west of Britain) was a consistent theme and proved to be close to the mark.