Model Output Discussion - The Start Of Winter

[Man With Beard]

Michael Ventrice â€@MJVentrice

ENSO + MJO 500H analogs that best match current State. Hello western North American ridge. GOA trough still there pic.twitter.com/Kg49kxCDrI

It's notable that HLB has been a feature of the winter already - on the other side of the pole. If the pattern was switched 180 degrees around the Arctic Circle, we'd already be having considerable cold snaps. The one positive is that this HLB is preventing zonality around the entire NH at our latitude, and it means our air is sourced from slightly further north than in a true zonal pattern, which is contributing to the current slightly cooler pattern.

[IDO]

Yep, tail end of GEFS is sniffing something out for sure. Lots of wild and wonderful versions of increased wave activity being played out. Like you say, is it the start of a trend or a blip?!

 

Yes there are a few, but the vast majority are flat. I would have thought that it would be another week at least before decent FI charts start showing up. However its not set in stone so a subtle move in that direction is always welcome. Matt Hugo's suggested SSW timing:

 

 

  MattHugo81

Signal continues to develop for a sig strat warming wk beginning Mon 22nd...My prediction, a SSW event by 7th Jan 15 http://t.co/lc1Lts5AHS

12/7/14, 6:18 PM

[IDO]

Given the outputs so far this evening theres no backing for the ECM 00hrs run which was very progressive, seeing as these outputs have 12hrs worth of newer data I would be shocked if the ECM 12hrs didn't backtrack.

 

The end result might still be underwhelming at T240hrs but in terms of the possible northerly next weekend perhaps it might at least be less progressive with the low heights piling east and se.

 

You thought it couldn't get worse:

 

D6   GFS for comparison: 

Edited December 7, 2014 by i'm dreaming of...

[Snowman.]

You thought it couldn't get worse:

 

D6 ECM1-144-2.GIF  GFS for comparison: gfs-0-144-2.png

 

Indeed.

 

ECM unusually flat and progressive. GFS amplifed and less progressive.

 

It's a funny game these models play.

[Winter Cold]

You couldnt make it up could you!

 

I suppose the saving grace for coldies is that next weekend is still borderline FI in weather terms, especialy at present as aparrent with the model disagreements. Room for improvements on the amplification still.

 

Friday could still offer some snow on ECM i think? North westerly and cold uppers..

 

Edited December 7, 2014 by Winter Cold

[Mucka]

Not often you see ECM more progressive than GFS.

manana, manana...

 

 

JMA is somewhat better for Northerly reload prospects down the line.

 

Edited December 7, 2014 by Mucka

[nick sussex]

You thought it couldn't get worse:

 

D6 ECM1-144-2.GIF  GFS for comparison: gfs-0-144-2.png

It's better than this mornings 00hrs run which is a start. Further on the Azores high fails to make it into Europe which is at least one positive, upstream is also better with a bit more amplitude.

 

This mornings ECM was a horror show tonights is just a bit blah .

 

It's somewhat of a role reversal because tonights GFS is garbage apart from a slightly longer nw flow it then goes onto to do an ECM 00hrs run horror show upstream, if offered I'd take tonights ECM at T240hrs which at least shows some hope, the GFS is abysmal at that point.

Edited December 7, 2014 by nick sussex

[IDO]

It's better than this mornings 00hrs run which is a start. Further on the Azores high fails to make it into Europe which is at least one positive, upstream is also better with a bit more amplitude.

 

This mornings ECM was a horror show tonights is just a bit blah .

 

I don't know how you can mention ECM and amplitude in the same post and keep a straight face

 

The later parts of the ECM run are flat in our sector:

 

  

 

Pretty much in line with the other models and highlighting the relative confidence in the upcoming couple of weeks for a westerly flow with the odd cooler shot thrown in for the north.

[nick sussex]

I don't know how you can mention ECM and amplitude in the same post and keep a straight face

 

The later parts of the ECM run are flat in our sector:

 

ECM1-168-3.GIF ECM1-216-6.GIF ECM1-240-6.GIF

 

Pretty much in line with the other models and highlighting the relative confidence in the upcoming couple of weeks for a westerly flow with the odd cooler shot thrown in for the north.

I'm keeping a straight face, its irrelevant whats happening over the UK at that point you have to look upstream at the vast difference between the ECM and GFS, the GFS is flat right out to the Pacific at T240hrs. Dismal is being kind to its T240hrs pattern upstream:

[nick sussex]

So the GFS at T240hrs upstream:

 

 

A flat jet all the way from the Pacific to the Atlantic.

 

The ECM:

 

 

Note the troughing digging into the central USA and the high ahead of it.

 

Its for this reason that the GFS IMO is awful for cold whereas the ECM offers some hope.

 

It's for this reason that its best to view the outputs from the NH perspective.

 

 

 

[johnholmes]

oddly enough the GFS Nick posts about is almost spot on at 500mb, if that is the inference, to the anomaly charts, and they have been thus over the Pacific for days and days. Some variation in the Atlantic sector which is the cause of the rather less than mild westerly flow the UK is under much of the time with temporary NW'ern shots as minor upper troughs bring surface features along in this basic westerly upper flow. Not much sign of any major change in the next 2 weeks or so.

Edited December 7, 2014 by johnholmes

[IDO]

I'm keeping a straight face, its irrelevant whats happening over the UK at that point you have to look upstream at the vast difference between the ECM and GFS, the GFS is flat right out to the Pacific at T240hrs. Dismal is being kind to its T240hrs pattern upstream:

 

I wasn't having a dig, just highlighting that any amplification after D7 on the ECM, bearing in mind it's recent performances should be ignored and that in a few runs it will be more like the flatter GFS.

 

The last five ECM D6 height bias' for the 12z clearly show how it is totally failing with the pattern:

 

 

Thats at D6, I can imagine the statistical bias at D10! Of course none of the models are covering themselves in glory at the moment at that range.

Edited December 7, 2014 by i'm dreaming of...

[Smiler1709]

Again a lot of people taking each and every run as a cert, the models have downgraded in the last 24 hours but in 24hours time they could be upgrading again, so much uncertainty at the moment and the reliable is about 4 days so lots of change to come. Loving these frosty nights though

[nick sussex]

I wasn't having a dig, just highlighting that ant amplification after D7 on the ECM, bearing in mind it's recent performances should be ignored and that in a few runs it will be more like the flatter GFS.

 

The last five ECM D6 height bias' for the 12z clearly show how it is totally failing with the pattern:

 

NOAA_NWS_NCEP_WPC_MODEL_DIAGNOSTIC_-_INTERACTIVE_MODEL_BIAS_PAGE 4.jpg

 

Thats at D6, I can imagine the statistical bias at D10! Of course none of the models are covering themselves in glory at the moment.

I'm not disputing the ECM's recent poor performance but basically if I was offered the ECM T240hrs output I'd take it . The cycle in recent weeks seems to be the following:

 

Longer range starts off flat, then the models add too much amplification then they become flatter but not as flat as their original view. I doubt however that the GFS T240hrs will verify as theres flat and then really flat!!!

[snowice]

I don't know how you can mention ECM and amplitude in the same post and keep a straight face

The later parts of the ECM run are flat in our sector:

ECM1-168-3.GIF ECM1-216-6.GIF ECM1-240-6.GIF

Pretty much in line with the other models and highlighting the relative confidence in the upcoming couple of weeks for a westerly flow with the odd cooler shot thrown in for the north.

How can you say that about the westerly flow when the ecm had no support also just see country file forecast and there is deep uncertainty past this Thursday?The track of the low pressure to the north is not nailed it will probably track further south so all in all no certainty past t96hrs. Edited December 7, 2014 by snowice

[Jason M]

The trouble with ECM is that we don't see the ensembles so context is always lacking. By day's 8,9,10 the one run we see is of no use whatsoever (IMHO of course :-) ).

GFS has its weaknesses but at least we see 22 runs each time. Ie opp run, control and 20 ensemble members. This is really why people talk about ecm chopping and changing at this range. Any model would do the same, it's just that there is less focus on each GFS opp run as within 45 mins we can see the ensembles in full. Thereby if it's an outlier we either ignore it or treat it with more caution.

Edited December 7, 2014 by Jason M

[blizzard81]

Much happier with the 12z ECM compared to it's 00z run. The main thing I notice is the build in pressure

to our east days 8 to 10. We need this to verify and hope it gets some backing from the ensembles.

We need some consistency now from the ECM ops and I am looking for the build in pressure to

our east to increase more and more with each run.

[ukpaul]

The trouble with ECM is that we don't see the ensembles so context is always lacking. By day's 8,9,10 the one run we see is of no use whatsoever (IMHO of course :-) ).

GFS has its weaknesses but at least we see 22 runs each time. Ie opp run, control and 20 ensemble members. This is really why people talk about ecm chopping and changing at this range. Any model would do the same, it's just that there is less focus on each GFS opp run as within 45 mins we can see the ensembles in full. Thereby if it's an outlier we either ignore it or treat it with more caution.

 

For De Bilt the 00z was the warmest at the latter end of the run and, if I was forced to make a choice, I would bet that the 12z is similar.

[Jason M]

How can you say that about the westerly flow when the ecm had no support also just see country file forecast and there is deep uncertainty past this Thursday?The track of the low pressure to the north is not nailed it will probably track further south so all in all no certainty past t96hrs.

Whilst the exact details re the northerly will change (for better or worse) these changes are not likely to impact much on what happens after. We can see this by looking at the GEFS as some have more pronounced northerlies than others but they all flatten the flow and shunt the cold air East. It's possible that something could just come out of know where, but very unlikely. It's really day 10 plus we need to look at.

[IDO]

How can you say that about the westerly flow when the ecm had no support also just see country file forecast and there is deep uncertainty past this Thursday?The track of the low pressure to the north is not nailed it will probably track further south so all in all no certainty past t96hrs.

Hi, lots of uncertainty re the track of that low, but in the great scheme of things it will make only subtle differences to the bigger picture. That's what I was referring to, not the short wave developments. That is of course IMO.

[ANYWEATHER]

As always there is a call time on the models after xamount of time. I think T+120 from gfs and ecm look very good for a continuation of cold, indeed, at that time frame it will be interesting to see what happens then, as some very interesting weather will be on the cards..!

[OldMetMan]

With the major Atlantic storm in the process of brewing up, it's interesting to see how the models are handling developments following on from that. It is tempting to think that such a major upper trough as will develop with this massive low will cause some sort of knock-on effect in the amplitude of the flow, at least in our part of the hemisphere (I have said as much in previous posts) yet there is currently no such indication in model output.

Given the time it took the models to firm up this new storm, I might be forgiven for thinking that future upstream developments might be a bit suspect.

Here's the GFS at T144:

By this stage, there is still a substantial upper trough associated with the deep low, but upstream there seems to be little energy emerging out of the US/Canada. So on the face of it, there seems little to stop the progression of long waves as depicted by the models, well the GFS specifically,

However, I am intrigued by the presence of a small but persistent upper high cell over Greenland, that has been there for a couple of days. It's like it's waiting to link up with its larger cousin ridge to the S, and complete an upper ridge block in the mid/western Atlantic. Such a ridge seems possible with the trough further E.

Even now, the 500mb pattern, as shown above, shows troughing SE out of the US, so what I am suggesting is the possibility of a more amplified flow within a week, with the major vortex associated with this new storm actually hanging about longer than shown, maybe filling and slowly sinking SE. While this is going on, it means the presence of the cold air over us lasting much longer, maybe with small disturbances joining it from the NW. Within such an air mass, of course, there would exist a snow risk almost anywhere.

I say all the above because a) I trust the GFS in this situation less than I usually do and b) the T144+ development just looks wrong to me.

I shall give it a few days to see of there are any substantial changes in model output but for now, I am thinking that the cold air might be around longer than is currently expected.

[marksiwnc]

With the major Atlantic storm in the process of brewing up, it's interesting to see how the models are handling developments following on from that. It is tempting to think that such a major upper trough as will develop with this massive low will cause some sort of knock-on effect in the amplitude of the flow, at least in our part of the hemisphere (I have said as much in previous posts) yet there is currently no such indication in model output.Given the time it took the models to firm up this new storm, I might be forgiven for thinking that future upstream developments might be a bit suspect.Here's the GFS at T144:gfsnh-0-144071214.pngBy this stage, there is still a substantial upper trough associated with the deep low, but upstream there seems to be little energy emerging out of the US/Canada. So on the face of it, there seems little to stop the progression of long waves as depicted by the models, well the GFS specifically,However, I am intrigued by the presence of a small but persistent upper high cell over Greenland, that has been there for a couple of days. It's like it's waiting to link up with its larger cousin ridge to the S, and complete an upper ridge block in the mid/western Atlantic. Such a ridge seems possible with the trough further E.hemi1_00hr071214.pngEven now, the 500mb pattern, as shown above, shows troughing SE out of the US, so what I am suggesting is the possibility of a more amplified flow within a week, with the major vortex associated with this new storm actually hanging about longer than shown, maybe filling and slowly sinking SE. While this is going on, it means the presence of the cold air over us lasting much longer, maybe with small disturbances joining it from the NW. Within such an air mass, of course, there would exist a snow risk almost anywhere.I say all the above because a) I trust the GFS in this situation less than I usually do and b) the T144+ development just looks wrong to me.I shall give it a few days to see of there are any substantial changes in model output but for now, I am thinking that the cold air might be around longer than is currently expected.

Excellent examination of what could be the future and I hope your right. I wonder what would be ian fergie s comment on this?

[IDO]

^^^ Hi

 

I said a few days ago the reason why I thought we would not get a meridional flow was due to the Asian/Pacific jet firing up. It is on turbo settings from D0 to D16:

 

 

 

So the pattern is very flat in that arena and there is no slack in the system. The US west coast will take a pounding from that jet and it will split, but the jet does eventually make it's way to the UK, and that relentless pounding keeps the pattern mobile preventing any chance of amplification lasting too long.

 

We have the Russian high to the east and the US ridge to the west with the Azores directing the jet towards the East; in layman's terms it is hard to squeeze another HLB in the Atlantic with no slack in the system (Asia/Pacific). So IMO this will dictate our medium term outlook.

[OldMetMan]

Excellent examination of what could be the future and I hope your right. I wonder what would be ian fergie s comment on this?

Thank you Mark. I doubt if there is much to support any such development in the current output. I have certainly seen similar happening on past occasions but, as they say, each situation is unique in some way. Anyway, here's hoping!