Model output discussion - 20th Feb onwards

[Frosty.]

Holy cow Steve wasn't joking, the ukmo 12z at T+144 is a pleasant sight for coldies!

[northwestsnow]

1 minute ago, Frosty. said:

Holy cow Steve wasn't joking, the ukmo 12z at T+144 is a pleasant sight for coldies!

GFS looks decent for the north too frosty

[bobbydog]

24 minutes ago, Steve Murr said:

Whilst im pretty much resigned to no more snow here in our little part of the world - tonights UKMO is very good for areas a bit further North & infact the blocking element on that run is pretty good with a cut off high towards greenland at 144

well, bearing in mind IDO's... optimistic... post above, the UKMO gives us a north-easterly at 144

against the GFS's northerly

questions are; which of these is the better option, which will be right and will either of them actually deliver anything of interest?

[Singularity]

     

Bit of an issue with GFS (left and middle ) compared to UKMO (right). The former powers a deep trough up the right side of Greenland on day 6, and then the whole trough complex tries to move SE toward the UK, which is not very effective and brings us westerlies instead. A chance to escape the notably cold theme - but one with (as far as I gather) little support from recent EC/GloSea5 ensemble guidance. UKMO on the other hand is far more in line, as it takes that deep trough further west, with a more amplified pattern ahead of it. The day 6 chart shows a small low splitting off and preparing to journey SE toward the UK.

That's more like what recent ECM runs have been doing, though this morning's effort wasn't as tidy - but it's notable that the theme remained in place despite the deep trough crashing more into Greenland - in a similar vein to GFS. 

 

 

This could be summed up as GFS not seeing much interference with the trough by the amplified state of the polar jet, as opposed to the 'pulling apart' effect that ECM shows us. UKMO is actually down more of a 'blocked off' path, which is interesting and suggests that no solid conclusions should be drawn with respect to how strong the ridges to the high latitudes are later next week - and as a result, how much cold air is drawn across to the UK from the NE.

An important ECM coming up this evening; if it has a stronger ridge than the morning run, i.e. a move toward UKMO, that'll give me justification to throw GFS out the window. Obviously the other side of the coin applies too - ECM siding with GFS would be bad news for UKMO. 

It has to be said, it's very strange that GFS is seeing the least disruption to that trough, given that it's had the highest amplitude MJO predictions of late. I know the model struggles with scenarios that see a split of low heights, but can it really be that bad?

[Cloud 10]

Interesting extreme FI on the 12z,and looks to be a good coupling between the stratosphere and troposphere,with all the deep cold being forced onto our side of the hemisphere.

 

[Frosty.]

Don't you just love early spring in the uk, the Gfs 12z shows snow during March which would be very nice!

[bluearmy]

The UKMO is more amplified by day 3 than the other output. Forget it's day 6 chart., it promises a snow event at day 5!  it is lacking support though, even at T72

[nick sussex]

6 minutes ago, bluearmy said:

The UKMO is more amplified by day 3 than the other output. Forget it's day 6 chart., it promises a snow event at day 5!  it is lacking support though, even at T72

In the shorter terms NCEP discussions they do mention an unusually large spread of solutions upto Thursday. In the medium term ones the GFS/GEFS criticized for having the worst continuity of all the main models and ensembles over the last few days.

Edited February 28, 2016 by nick sussex

[cyclonic happiness]

Why does there always seem to be snow showing 5 days away?  It never gets any closer.

[Essex winter]

9 minutes ago, cyclonic happiness said:

Why does there always seem to be snow showing 5 days away?  It never gets any closer.

Because we live In the british Isles

[Frosty.]

9 minutes ago, cyclonic happiness said:

Why does there always seem to be snow showing 5 days away?  It never gets any closer.

Don't you just love the thrill of the Chase? Early spring shows more wintry potential from the Gfs 12z alone than December did...something to celebrate!

[nick sussex]

The ECM doesn't follow the UKMO in terms of the low set up over the UK at T120hrs however to the nw and ne its closer to that than the GFS.

[Essex winter]

7 minutes ago, Frosty. said:

Don't yhae the thrill of the Chcrave.tase? Early spring shows more wintry potential from the Gfs 12z alone than December did...something to celebrate!

Its worth coming on this thread to read your posts alone frosty.you give us all hope for the snow we crave.thanks.

[Frosty.]

1 minute ago, Essex winter said:

Its worth coming on this thread to read your posts alone frosty.you give us all hope for the snow we crave.thanks.

Cheers for that i hope the models are right and we do get some snow during March!

[Guest]

1 hour ago, IDO said:

I hope if we have learnt anything this winter, one thing that should be ingrained is how poor the UKMO T144 charts verify when there is an Atlantic ridge. It nearly always over blows heights in Greenland and not one has come to fruition. The most recent was about a week ago: T144 UKMO:  Actual: 

I am sure one will pop up eventually but I doubt it!

A rinse and repeat next week with not as cold uppers. Then GFS flattens the pattern out after the next Atlantic ridge topples after D8. As GFS is usually progressive re the Atlantic, maybe the topple will be slower than the GFS currently shows. 

As for snow, the fronts on Tuesday and late Thurs/early Friday look like rain, but the PM flow behind them should be wintry on northern hills, but hit and miss. Looks like after next week the MJO may weaken and we lose the better amplification for a while (w2 and w3 March?). So end of March to early April wait for a return for the NW flow and more cold rain for down south.

 

 

There is a lot of disagreement over the MJO amongst the major models. A few do show it weakening, including the UKMO but others like NCEP/GEFS keeps it at a decent amplitude.

Here's the link to NOAA's Climate Prediction Centre and the various models that can be viewed there:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

I have recently been following the daily charts published by Kyle MacRitchie and his work and status seem very impressive. He has a PhD in Atmospheric Science and specialises in studying the MJO, equatorial waves and ENSO and their interaction with the mid latitudes. Here is a link to his charts for today. He shows 4 ensembles and they take the MJO through phase 8 and into phase 1 at decent amplititude around March 14th.  2 members carry on at decent amplitude through to phase 2 around March 20th.  All 4 members keep it in within phase 8/1 for at least the next 3 weeks.

http://www.kylemacritchie.com/real-time-maps/realtime-mjo/

The overall pattern is complicated by the now negative AO, the current stratospheric/tropospheric coupling, the building SSW and the steadily weakening El Nino in the eastern Pacific. This interaction is way beyond my limited knowledge. Tamara, in her excellent post yesterday, provided some insight into these. I believe that the current complexity of these coinciding factors is challenging the experts and the most sophisticated computer models. The next month will provide a huge learning curve to assist future analysis and valuable new input into the models.  

PS  I have tried cutting and pasting charts directly into my posts, tried via saving them in a word document and tried using the NW "insert other media" facility but none of these seem to work I asked NW about this and tried their tip but that did not work either! I have never had this type of problem in my main line of online work. If anyone can advise me what I should do, it would be hugely appreciated. I would much prefer to show charts than merely links all the time..

Edited February 28, 2016 by Guest
spelling

[shane303]

Another week with mainly below average temperatures with all models in agreement a wintry mix for most and some good snowfalls on high ground Why do people seem surprised at snow in March your more likely to get snow in March than any other month. 

Edited February 28, 2016 by shane303

[nick sussex]

Further to BB62/63 and Kyle MacRitchie his MJO forecast was devised after research into the error rates shown by those based on the Wheeler/Hendon.

As with everything in the scientific community theres a debate about which is the better way of forecasting the MJO. The problem with the MJO in strong El Nino years especially is the interference and then you have to add into the mix Kelvin waves.

The MJO from KM does try its best to remove that interference and KW.

[Frosty.]

The Ecm 12z shows colder air becoming entrenched during the second half of the week ahead which continues throughout next weekend and into next week too with a wintry mix and overnight frosts with icy patches.. more like winter than early spring for sure!

[phil nw.]

A return of the polar north westerlies mid week following a milder Tuesday.

If we view the charts for Wednesday the fax at T72hrs reflects the UK raw output and they are pretty well matched at day 3

As we would expect all 3 models are very similar at that range.

Quite a cold blast from the north/northwest behind Wednesday's low as uppers around -5c head south east.Snowfall though does look reserved for mainly higher levels if we take GFS as the measure.

Looking a bit further on there are certainly differences by day 6.UKMO wants to prolong the Atlantic ridge,GFS and ECM both look to to topple it towards the UK with GFS quicker to do this.It could well be that GFS is a little too fast to flatten the pattern into westerlies at that point with ECM the more likely result.

The idea of the Azores high ridging in towards the UK though is hinted at in week 2 in the earlier ens.and is again showing in the 12z gefs.

 

Edited February 28, 2016 by phil nw.

[Gael_Force]

32 minutes ago, nick sussex said:

Further to BB62/63 and Kyle MacRitchie his MJO forecast was devised after research into the error rates shown by those based on the Wheeler/Hendon.

As with everything in the scientific community theres a debate about which is the better way of forecasting the MJO. The problem with the MJO in strong El Nino years especially is the interference and then you have to add into the mix Kelvin waves.

The MJO from KM does try its best to remove that interference and KW.

The McRitchie MJO forecast is just based on 4 ensembles from the CFS: you can see the NCEP favours amplified progression on the daily plots so fair to assume their CFS will be similar. Question is; are they right in the face of all the rest of the models returning to the circle of death.

[ANYWEATHER]

Evening folks.... As we step into Spring , the Winter Phantom comes out and gives us the coldest blast of the season! An Artic blast mid week , across some relatively mild seas ,produces some pyrotechnics .

[nick sussex]

22 minutes ago, Gael_Force said:

The McRitchie MJO forecast is just based on 4 ensembles from the CFS: you can see the NCEP favours amplified progression on the daily plots so fair to assume their CFS will be similar. Question is; are they right in the face of all the rest of the models returning to the circle of death.

The CFS differs from the GFS though, I think a different type of filtering is used. And the CFS hasn't even reached phase 7 going off its current plot compared to the GFS/GEFS.

I suppose the logical extension here could be that the normal dynamical model forecasts are including too much El Nino interference or the CFS is totally wrong.

[Weather Observer]

This winter has knocked the stuffing out of cold and snow fans, with a few redoubtable posters excepted. Charts currently on offer suggest to me more than a glimmer of hope. If we can't get one overnight snow event in the south in early March from Synoptics like this I will have to admit that my old bones aren't what they were. Usual caveats about lack of Artic cold and 192 hours apply.

Some of us will wake up to a surprise snowy Spring sunrise.

[bluearmy]

an observation on the latest eps - those 'unlikely' gfs fi runs playing with a scandi high and an easterly feed have approx 30% support as we head through week 2. signs on the mean/anomoly charts of the jet becoming flat south of us and undercutting a generally blocked area to our north and northeast.

[knocker]

Two comments regarding tonight's 6-10 anomalies. Any suggestion regarding the demise of the Canadian PV has been greatly exaggerated and the downstream pattern remains as it has been with mid Atlantic ridge and trough to the east of the UK running south into Europe. Ergo no change to the previous ten day forecast of NW flow, perhaps veering nearer north, with periods of wet and wintry weather interspersed with drier spells with temps in general below average.

In the 10-15 period the ridge continues to move east thus bringing the UK within it's sphere of influence but the orientation is not universally agreed and with the trough in the western Atlantic edging east (more noticeable on the EPS) the strength and duration of it's influence best left a wee while.

Edited February 28, 2016 by knocker