28 replies to this topic

[johnholmes]

Cloud 10, on 04 April 2012 - 16:26 , said:

GFS not doing well at the moment,must try harder!

acz6.gif

yes that has to be the worst validation I've seen in a long time. Neither ECMWF nor Met are free from 'wobbles' though as the graph shows a short while ago.

[Cloud 10]

johnholmes, on 11 April 2012 - 19:22 , said:

yes that has to be the worst validation I've seen in a long time. Neither ECMWF nor Met are free from 'wobbles' though as the graph shows a short while ago.

The gfs has "pulled its socks up" over the last week or so.




Interesting to note how poor the models have verified for the southern hemisphere
on the graph,not sure why this is?

[Cloud 10]

Some very unpleasant weather across many parts of the UK today with heavy rain and strong winds
and some pretty cold temperatures all brought about by low pressure moving up from the south,so
how well was this predicted?

Today's actual chart.




The ECM,GEM,GFS and UKMO from six days ago.


ECM> GEM>

GFS> UKMO>



Quite a difficult set-up for the models to get right with a low moving up from the south,but a good performance from
the ECM,GEM and GFS.

The UKMO not bad,although it did overdo the high pressure to the north of us.

[loafer]

Not strictly a model (although models involved), it is worth revisiting the Met's April-June forecast...

"The forecast for average UK rainfall slightly favours drier than average conditions for AprilMayJune as a whole, and also slightly favours April being the driest of the 3 months."

http://www.metoffice...-precip-AMJ.pdf

[Cloud 10]

Quite a decent day across many parts of the UK today thanks to a ridge of high pressure coming in
from the west,although some of us still managed to experience showers!

Today's actual chart.




The ECM,GEM,GFS and UKMO from six days ago.

ECM> GEM>

GFS> UKMO>


A varied performance from the models with the GFS seeming to do the best,whereas the ECM had a rare off day
with it showing a small low over the south which would have delivered a rather different day if it had verified.

[bluearmy]

Just to note that this upcoming change was picked by naefs anomaly charts whilst we we're till in the trough doldrums with no end in sight if you just paid attention to the operational runs.

Not really enough pattern changes since the gefs upgrade in feb to make an informed judgement but one would hope that naefs is now even better than it used to be.

[johnholmes]

The first indications started on the 3 500mb anomaly charts around 10-12 May and have consistently since made this a feature

[bluearmy]

johnholmes, on 19 May 2012 - 08:01 , said:

The first indications started on the 3 500mb anomaly charts around 10-12 May and have consistently since made this a feature

maybe using your method john but i posted the following in the model thread based on naefs output:




Posted 07 May 2012 - 22:58
maybe light at the end of the trough filled tunnel with a sceuro height rise in a couple of weeks. lets hope so, though even if it verifies, no guarantee that the troughing to our west would be far enough away to leave us settled.

Posted 08 May 2012 - 13:10
at least the general rise in heights to our south and east remains consistent on the fi ens modelling. still a couple of weeks away but i would think the NOAA cpc charts should begin to show a change in the 8/14day 500mb pattern as we head through this week.

Posted 10 May 2012 - 21:49
just to say that the differences, run to run, in the reliable models (ecm, gem ukno, gfs) in the day 6/8 timeframe is very noticeable. noaa cpc have had low confidence for several days now. longer range ens still show a 'getting better' period as we approach the last week may. in the meantime, cool and changeable if not unsettled sums it up.

naefs alone isnt enough to make absolute predictions but i will be watching carefully over the next few months to see how reliable a tool it might now be to pick up on pattern changes a fortnight away

[johnholmes]

bluearmy, on 19 May 2012 - 11:15 , said:

naefs alone isnt enough to make absolute predictions but i will be watching carefully over the next few months to see how reliable a tool it might now be to pick up on pattern changes a fortnight away

I understand your caution and I share it but the VERY early results, 10 of them if I am counting correctly, using the 500mb charts and of course looking at longer term teleconnections to make sure most are suggesting similar, is pretty encouraging. What I 'thought' was a good guide is being shown to be one IF with my usual caveat all 3 say similar things consistently.

I should of course add that the predictions they give are for 18000ft up in the atmosphere. The forecaster then has to TRY and decide how this might be at the surface.
40 years ago doing a 24 hour 180000ft prediction was far far easier than the surface prediction. That remains the case today and at day 3, 10 days or further out as well.
Yes I know the model does all the levels but ask yourself why it is so far out even 24 hours out with rainfall totals and where that falls let alone will it snow and also temperatures suffer similarly at times. The 18000ft prediction can be pretty accurate but the surface can be very far from accurate for the same date/time, again at all the time intervals.

Edited by johnholmes, 19 May 2012 - 22:15 .