General Model Output Discussion

[MR EXTREMES]

If you're after cold the last thing you want is for the cold block to be 'blasted away'. That would leave us with the jet across us and a potential SW dominated high as a result.

What we need is for the high to stay where it is and for the atlantic to drive slightly further south, re intensifying the cold westward momentum which should hopefully get the heights to rise over Greenland as the high spreads over the far northern latitude.

Looking at the way past events panned out I think we'll start seeing the models trend towards an easterly scenario for next week.

to be totally honest looking at the last couple of days of outputs id say its not likely for a fair while yet.

i also think the block to the east will shift futher from us over time and i see nothing that suggests anychance of a gh building.

although this does not end winter because things can change but my think is it wont be rapid if it does trend towards cold.

:unsure:

[Thundery wintry showers]

If you're after cold the last thing you want is for the cold block to be 'blasted away'. That would leave us with the jet across us and a potential SW dominated high as a result.

What we need is for the high to stay where it is and for the atlantic to drive slightly further south, re intensifying the cold westward momentum which should hopefully get the heights to rise over Greenland as the high spreads over the far northern latitude.

Looking at the way past events panned out I think we'll start seeing the models trend towards an easterly scenario for next week.

Much sense in the above. If the high gets "blasted away" from here there's no certainty that it would leave the door open for northerly outbreaks or even spells of mobile westerlies with polar maritime incursions- it's just as likely that it would sink south and leave us with a Euro High and cloudy drizzly south-westerlies for much of the country. With the polar vortex implied over Greenland from this scenario, I think the latter would be quite likely.

The models show the Atlantic starting to break through but there is no obvious sign of the block fading, just of it being too far east to bring us a full-on easterly. That said, I see no obvious signs of retrogression towards Greenland either, in contrast to some of those blocking forecasts.

[Sawel]

Looking at the verification stats, The UKMO has been performing head and shoulders above the other models at both 120 and 144 hours for this past 7 days.

at 120 hrs the UKMO has verified best for 4 out of this past 7 days, has tied with the ECM once and the ECM has only verified best once and GFS once.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz5.gif

at 144 hrs the UKMO has verified best 5 out of this past 7 days, with the ECM verifying best once and the GFS once.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz6.gif

It's worth noting that the GFS has been performing very poorly for this past 6 days, and the GEM has been pretty dire too.

Edited January 14, 2010 by Sawel

[Thundery wintry showers]

Looking closely, in fact I think there has been very little in it between the UKMO and ECM. What's certainly clear, though, is that the GFS has been struggling and has been nowhere near as good as the Euro models, which supports many of our observations on the GFS struggling to get a grip on the persistence and positioning of northern blocking and attempted breakdowns from the SW.

Interesting to see the UKMO performing very well at T+144. For a long time, T+144 outputs were the UKMO's Achilles heel.

[Just Below Zero]

If you're after cold the last thing you want is for the cold block to be 'blasted away'. That would leave us with the jet across us and a potential SW dominated high as a result.

What we need is for the high to stay where it is and for the atlantic to drive slightly further south, re intensifying the cold westward momentum which should hopefully get the heights to rise over Greenland as the high spreads over the far northern latitude.

Looking at the way past events panned out I think we'll start seeing the models trend towards an easterly scenario for next week.

Totally agree

If you want to see the doctor the best place is in his waiting room ready to be called.

I too am sure the models will start to show the jet slipping south again shortly :blush:

[nick sussex]

Looking at the verification stats, The UKMO has been performing head and shoulders above the other models at both 120 and 144 hours for this past 7 days.

at 120 hrs the UKMO has verified best for 4 out of this past 7 days, has tied with the ECM once and the ECM has only verified best once and GFS once.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz5.gif

at 144 hrs the UKMO has verified best 5 out of this past 7 days, with the ECM verifying best once and the GFS once.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz6.gif

It's worth noting that the GFS has been performing very poorly for this past 6 days, and the GEM has been pretty dire too.

Yes and this shows why the gfs especially with blocking patterns is very poor and often goes from one extreme to the other, either overdoes the block or overdoes the Atlantic.The ukmo 144hrs often gets criticized in here but i can't see why given that its the second best model generally behind the ecm at that timeframe.

[Guest FireStorm]

Out of interest since the GFS started using new data, would that be a reason to GFS performing so poorly?

[Optimus Prime]

The 'Modern' winter has always had lows pushing west to east over the western continent too ensuring high pressure is incontrol in the far east allowing the powerhouse lows to flatten the pattern out. In this case parts of Europe do get cold as the high pulls down northerlies from a modified northern source on the eastern flank but most have it mild or unseasonable mild.

If we had just come out of a typical 'Modern' December which usually entails a cycle between westerlies and inversion highs I'd put a huge bet against that high making it much further west then it currently is. But given how December didn't have an inversion high and how almost all of our cold has come from the continent I get the feeling this won't be our typical breakdown.

Out of interest since the GFS started using new data, would that be a reason to GFS performing so poorly?

Partly because it was released into a synoptically unheard of environment since the 80s. Old GFS would have been the same.

Edited January 14, 2010 by Optimus Prime

[Sawel]

Looking closely, in fact I think there has been very little in it between the UKMO and ECM. What's certainly clear, though, is that the GFS has been struggling and has been nowhere near as good as the Euro models, which supports many of our observations on the GFS struggling to get a grip on the persistence and positioning of northern blocking and attempted breakdowns from the SW.

Interesting to see the UKMO performing very well at T+144. For a long time, T+144 outputs were the UKMO's Achilles heel.

By looking at the archives of how the models have performed from 2001 to present, the UKMO has been performing considerably better at +144 hrs since 2007 it would appear (although I haven't checked every single month). There's very few months since then where it has verified anything other than 2nd best (after the ECM). Whereas before this, it verified second best much less.

I think some people on here are guilty of labelling the UKMO a poor model at +144 based on what it may have been like 5+ years ago.

Hopefully we'll get no more "but the UKMO rarely verifies at +144 hours..." because those stats put that comment to bed.

The archive is here- http://www.emc.ncep.noaa.gov/gmb/STATS/html/monarch6.html

Edited January 14, 2010 by Sawel

[bluearmy]

those graphs show what a poor month the GFS has had in the NH (and the GEM has followed this closely). the ukmo has had a good fortnight, but that came on the back of a poorish 14 days prior to this. over the entire period of that graph, the ecm is 'head and shoulders' above the other output (using your terminology, sawel, which i dont particularly like). interestingly, no model did well at the end of last week which is when our greeny high sank and then ridged northeast. of course, we may be looking too closely at this as our little corner of the hemisphere isnt so important in the grand scheme of things.

[johnholmes]

I think some people on here are guilty of labelling the UKMO a poor model at +144 based on what it may have been like 5+ years ago.

Hopefully we'll get no more "but the UKMO rarely verifies at +144 hours..." because those stats put that comment to bed.

I agree with the two above paragraphs. It has had an unjustified poor label, part due, in the winter, to it not showing what some want it to show, when GFS does!

[Sawel]

Yes and this shows why the gfs especially with blocking patterns is very poor and often goes from one extreme to the other, either overdoes the block or overdoes the Atlantic.The ukmo 144hrs often gets criticized in here but i can't see why given that its the second best model generally behind the ecm at that timeframe.

Yes the unjustified criticisms of the UKMO at +144 hrs always baffled me. There's no doubt the GFS can be pretty shocking at times.

[Shiny_Bottom_1]

Looking at the verification stats, The UKMO has been performing head and shoulders above the other models at both 120 and 144 hours for this past 7 days.

at 120 hrs the UKMO has verified best for 4 out of this past 7 days, has tied with the ECM once and the ECM has only verified best once and GFS once.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz5.gif

at 144 hrs the UKMO has verified best 5 out of this past 7 days, with the ECM verifying best once and the GFS once.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz6.gif

It's worth noting that the GFS has been performing very poorly for this past 6 days, and the GEM has been pretty dire too.

To me, its probably worth noting that the GFS and ECM appear to be quite similar in their success, and the one to watch, is the UKMO.

[nick sussex]

Looking at the gefs ensemble spread upto 180hrs for SLP the main area of spread is near Iceland with very little for the uk and further east, given the set up its safe to say the blocking high will remain over Russia with low pressure unable to cross the meridien. In terms of 850 temps again little spread over the uk and europe. So i think it looks pretty much like a stalemate with the chance that eastern and se areas seeing the coldest of any temps with surface flows occasionally from the Continent, still even with this set up theres a chance of some snow depending on the trajectory of low pressure and the tilt of the trough as fronts try and push eastwards.

Edited January 14, 2010 by nick sussex

[bluearmy]

I agree with the two above paragraphs. It has had an unjustified poor label, part due, in the winter, to it not showing what some want it to show, when GFS does!

john, i made a post some while back re UKMO T144 output which didnt get a response. maybe it was a bit manic at the time. my anecdotal impression is that UKMO T144 often looks like an ens mean chart as it isnt keen to over deepen shortwaves nor 'blow up' highs at this range. does this give it an advantage when the stats are done to see how far it is out on pressure readings compared to GFS et all. after all, we know how GFS overdoes central pressure on shortwaves at this mid range.

oh and shiny bottom - you need to look at those charts again if you think GFS and ECM are similar.

Edited January 14, 2010 by bluearmy

[PB22]

In my eyes, the trend from 12Z output so far has drifted even further away from any potential easterly for next week, and the Atlantic looks set to have an increasing influence over our weather. The available model output so far is consistent in wanting raise pressure over Iberia between T+120 and T+144 and this trend has been consistent over the last couple of days. Given the ECM ensembles for London this morning, one would expect ECM to trend in the same direction later on. Having said all that, the deep cold air is never too far to our east (indeed, the east may remain rather chilly next week), and it wouldn't take too much of a shift for the proper cold air to come further west.

[Sawel]

those graphs show what a poor month the GFS has had in the NH (and the GEM has followed this closely). the ukmo has had a good fortnight, but that came on the back of a poorish 14 days prior to this. over the entire period of that graph, the ecm is 'head and shoulders' above the other output (using your terminology, sawel, which i dont particularly like). interestingly, no model did well at the end of last week which is when our greeny high sank and then ridged northeast. of course, we may be looking too closely at this as our little corner of the hemisphere isnt so important in the grand scheme of things.

Well for a model to verifiy best 5 out of this past 7 times would indicate that it is performing "head and shoulders..." would it not? I used 7 days at it is an indication of how each model is performing at the moment.

The ECM over the longer distance is, and always will be the king of the models at both +120 and 144 hours.

Didn't the NOAA come out and say that the GFS doesn't perform as well as the ECM due to the "initialisation of data" or something like that? I'm not sure what they meant.

[karyo]

I agree that the GFS is characterised by large swings in its output! However, no matter which of the models is best, they all look unfavourable for any cold outbreak! The met office further outlook will be milder tomorrow, unless the 12z ECM saves the day.

I would be happy with more of a high pressure influence (with surface cold). This would limit the rise of the CET.

At the moment though, the Atlantic is gaining the upper hand and what looked like a mild blip over the weekend, now looks like the beginning of a mild period.

Karyo

[nick sussex]

I wonder if the mods would consider re-instating the names at the bottom of the thread now that the snow groupies have left! Not trying to offend them but you know turn up at the first whiff of snow, stay for the snow and don't suffer like the rest of us through all the more humdrum times when the output isn't the most exciting!

[Frosty.]

Compared to the forecasts yesterday, the weekend is now looking milder with 6-8c covering the uk and lots of rain and strong winds, rapid thawing and probably a risk of flooding..goodbye cold weather. :blush:

[The PIT]

Very interesting GFS this evening. Okay the cold doesn't make it but I'm just impressed how the high to the North east hangs on in there, before finally being shunted away. Even then its sneaking back over the top in deep fI trying to join with the Greenie high.

In previous years the Atlantic would have ripped it apart and had it for breakfast. Gives me the impression it would only take a slight weakening of the jet for it too push back west.

[snow drift]

I wonder if the mods would consider re-instating the names at the bottom of the thread now that the snow groupies have left! Not trying to offend them but you know turn up at the first whiff of snow, stay for the snow and don't suffer like the rest of us through all the more humdrum times when the output isn't the most exciting!

We are still here Nick. Silently observing. Not until the magical weekend in April, Grand national weekend, Masters weekend and some times F A Cup semis weekend do I then switch off to weather.

[cooling climate]

I know it is in FI but the amount of blocking(-AO)showing up over the Arctic on the northern hemisphere charts

must bode well for another potent cold spell down the line.

I would expect this to become an increasing feature again over the coming days, the best that winter has to

offer is still to come.

[dallas]

It seems all the rain that's modeled for the weekend will give provide a clean sheet (so to speak) Then we might see the PV start to edge more into Northern Europe

[karyo]

None of the 12z ensembles bring any cold upper air for next week: http://www.netweather.tv/index.cgi?action=ensviewer;sess=

And these are for London, which is the most likely to benefit from any east/southeasterly flow!

What a turnaround from yesterday!

Karyo