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Model Output Discussion 29th December - Into mid-Winter.

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3 minutes ago, radiohead said:

12Z GFS rolling out painfully slowly on Meteociel...

This is a good representation of the 12z FIGFSOPEU12_336_1.png

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1 minute ago, swilliam said:

He is talking about the big  snowstorm on the US east coast that the UK model is predicting but the GFS is not - this is what SM is talking about as it has downstream consequences for us.

Right, it still isn't going to make a massive difference to us, it might be the difference between the wet / dry boundary but definitely not any deep cold coming on the back of that.

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13 minutes ago, CreweCold said:

I could have backed it up quite easily had I actually seen the merit of such data collection. However,  I thought it was widely perceived as just 'one of those things' and quite widely accepted as being fact?! 

Even Steve Murr has noted that UKMO vs ECM and GFS combo usually results in a UKMO win when cold is progged and UKMO goes against. The opposite is also true, I've never once seen the UKMO model successfully pick cold out against ECM and GFS consensus.... Ever. 

Going back a bit, admittedly, but 2nd half of Jan 2013... UKMO showed cold, the others didn't and it ended up cold. Don't think UKMO have ever showed cold at 6 days in the last 3 winters but I can't back that up obviously

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6 minutes ago, CreweCold said:

I could have backed it up quite easily had I actually seen the merit of such data collection. However,  I thought it was widely perceived as just 'one of those things' and quite widely accepted as being fact?! 

Even Steve Murr has noted that UKMO vs ECM and GFS combo usually results in a UKMO win when cold is progged and UKMO goes against. The opposite is also true, I've never once seen the UKMO model successfully pick cold out against ECM and GFS consensus.... Ever. 

We'll find out soon enough. Not trying to start an argument but making assumptions based on anecdotal evidence could harm objectivity in the pursuit of weather forecasting. And saying something 'usually' happens is different to 99% of the time and that being a widely accepted fact, if this was true then as I said I am sure the boffins at UKMO would take this into account (maybe they do, I'm happy to stand corrected). I know Steve Murr loves cold and a good cold ramp but there is something in this latest battle royale between the models that creates an interesting uncertainty. Anyway, GFS ensemble panels now out and there are indeed some showing more of the UKMO type solution. 

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Just now, LRD said:

Going back a bit, admittedly, but 2nd half of Jan 2013... UKMO showed cold, the others didn't and it ended up cold. Don't think UKMO have ever showed cold at 6 days in the last 3 winters but I can't back that up obviously

Just to clarify though, The UKMO shows only "potential" cough cough for cold at day 6.

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1 minute ago, mountain shadow said:

Just to clarify though, The UKMO shows only "potential" cough cough for cold at day 6.

Yeah agreed. Not hanging my hat on anything yet

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7 minutes ago, feb1991blizzard said:

Right, it still isn't going to make a massive difference to us, it might be the difference between the wet / dry boundary but definitely not any deep cold coming on the back of that.

Well I believe SM thinks differently but I will let him explain that for himself.

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20 minutes ago, feb1991blizzard said:

Already edited my post accordingly, not dissing him as he is highly qualified, but he is a bit of a maverick, not sure what he meant but no snow is happening in that timeframe I can tell you now.

He's talking about a potential Noreaster snow storm for the east coast of the US. Those American focus tweets are causing no end of confusion.

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2 minutes ago, IDO said:

This is a good representation of the 12z FIGFSOPEU12_336_1.png

GEFS have trended toward the MJO visiting phase 8 and clearly the operational got lazy and just replicated the composite picture ;)

JanENMJOphase8gt1500mb.gif

The response seems way too fast for tropical forcing to be much of a cause though. It could even be the 'circumstantial' placement of a mean trough far enough south that it hangs around, but still far enough north to keep feeding LPs into the Atlantic westerlies. 

This suspicion is bolstered by the fact that ECMF has trended not towards phase 8 but towards further enhanced 6/7 activity in the longer-term (bearing in mind Ventrice has shown some weak Pacific activity taking place there even a this point in time), which produces a 'meh' result for 6 but a phenomenal one for 7. Given that in reality there's a lag time for the response to activity in a given phase, and based on some research papers, it's the 6-7 progression that likely matters more than seeing activity in either phase in isolation.

JanENMJOphase6gt1500mb.gif JanENMJOphase7gt1500mb.gif

Data has gone a bit AWOL in recent times but that of two days ago had phase 6 coming into play 8/9 days from now and phase 7 a few days after that. So even if it's along the right lines we have quite a wait on our hands for tropical forcing to help us out. To get something along the lines of UKMO, feedback forcing from the low Barents-Kara sea ice would need to overcome the Atlantic jet, and who knows, given the lack of much other forcing on the pattern, perhaps the 6-10 day period is the time for such feedbacks to shine. Or perhaps not :unknw::crazy:

 

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1 minute ago, mountain shadow said:

Just to clarify though, The UKMO shows only "potential" cough cough for cold at day 6.

The ecm even shows it is possible in this mornings run lets hope it can follow the uk model we are long overdue..

ECM1-144 (6).gif

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arpegeeur2-0-114.png?12

For what it's worth, ARPEGE supports UKMO with respect to the Russian blocking, but doesn't separate the lows to our N although I'm not sure how much this would impact the ability of the western feature to dig south.

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ANybody spot whats happening on the GEFS, after a few days of predicting N'ly / NW'lies, you can now see the switch back to forecasting Easterlies very slowly taking place (as per Met Office low probability outcome), expect some upgrades in the next 48 hours and some stellar charts to show again for those that like the chase, for those that prefer to know the outcome though, just expect it to be a false dawn and the pattern will flattern again.

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10 minutes ago, Sawel said:

That's the 12Z stats. The UKMO still verifies better than the GFS long term.

The 00z stats has the UKMO comfortably outperforming the GFS long term.

The other stats I have attached shows the UKMO outperforming the GFS long term at 120 hours since 2007. Each model gets it wrong now and again but over the years, the UKMO is the second best model. The notion that "the UKMO has a poor verification record at 144 hrs" is 10 years out of date.

 

cor_day6_HGT_P500_G2NHX.png

dacz_wave120_NH500mb_day5.png

From those stats, the GEM has been closer to the GFS than the GFS has been to the UKMO over this past year.

Edited by Sawel

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Good grief what happened to the GFS. Very underwhelming output with little pressure rise to the east/ne to force the jet se'wards, the UKMO much better with that pressure rise from Russia, the low has to head se at T168hrs. I really hope the UKMO has called this correct because the GFS is really poor. NCEP should comment on those differences because the UKMO would deliver some snow to the ne seaboard where as the GFS is offshore. Hopefully they trash the GFS output!

This is what NCEP think but this won't include tonights outputs , the State forecasts will cover that later:

AN AREA OF FORECAST UNCERTAINTY IS WITH THE POTENTIAL FOR A SECOND
SURFACE LOW TO DEEPEN OFF THE SOUTHEAST COAST THIS WEEKEND.  THE
BULK OF THE 00Z GUIDANCE IS CURRENTLY IN AGREEMENT WITH DEEPENING
A SYSTEM SOMETIME ON SATURDAY...BUT THEN THERE REMAINS A LOT OF
MODEL SPREAD WITH THE EXACT DEPTH AND TRACK OF THE STORM WHILE IT
QUICKLY LIFTS NORTHWARD SATURDAY NIGHT INTO SUNDAY...WITH THE 00Z
GFS CURRENTLY ON THE WEAKER/EASTERN EDGE OF MODEL SPREAD AND THE
00Z UKMET CURRENTLY REPRESENTING THE STRONGEST/CLOSET TO THE COAST
SIDE OF MODEL SPREAD.  ALSO...MINIMAL CLUSTERING WITH ENSEMBLE
LOWS AND LARGE RUN-TO-RUN MODEL INCONSISTENCIES SUGGESTS THERE IS
STILL A LARGE AMOUNT OF UNCERTAINTY WITH THE POTENTIAL FOR SURFACE
CYCLOGENESIS OFF THE SOUTHEAST COAST THIS WEEKEND.    

 

Edited by nick sussex

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UKMO sticking to its guns only this time it is on our side.

ECM wasn't that far away this morning so there is hope it is ahead of the game again.

I think hoping a 144 chart, that only gives a chance of colder weather, does show how far we crashed after the prospect of our cold wintry spell collapsed but at least it  is something to chase.

IMO we would likely need consecutive lows to disrupt SE against the ridges being thrown up ahead, the first would be the "trigger"to amplify upstream and pull ridging to our NE Westward, hopefully bridging to our North and trapping a trough over Europe but that is now around day 10.

Fortunately we wouldn't have to wait that long for a chance of colder uppers as if we got lucky we would draw in cold N/NW flow the disrupting low - best case scenario the first trigger low does all the work and we quickly transition into NE/E flow but that seems a bit optimistic to me as the pattern could be quickly overridden by the second low but a lot depends on how well the first low triggers increased amplification.

I think more likely we need two attempts with the second low also digging SE and disrupting and forcing WAA/weak ridge NE up toward Scandi with the low undercutting and pulling high pressure W and then it is all about alignment/Strength of any ridge/high to our E/NE and how amplified upstream is to see if we get more undercut from there (la la land at the moment)

So quite a few hurdles to overcome but also far from wishful thinking - just as long as UKMO is on the right track.

 

 

Edited by Mucka

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Generally for the eastern USA the ECM is the best output . The GFS is often too flat and so if the ECM backs the UKMO then you'd expect the GFS to edge towards the Euros.

The GFS often does this slowly almost hoping no one will notice!

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Just now, nick sussex said:

Generally for the eastern USA the ECM is the best output . The GFS is often too flat and so if the ECM backs the UKMO then you'd expect the GFS to edge towards the Euros.

The GFS often does this slowly almost hoping no one will notice!

Usually the morning run when we are all in bed..

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1 hour ago, Sperrin said:

It stomped all over the GFS and ECM when they went full throttle cold in the very recent past.

Is there anyway to discern the 850s from the UKMO output?

The UKMO is a bit stingy with its data but this table should help.

850.png

On meteociel best to go to just the UK view as its easier to work out.

 

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12Z GEFS are a right mess so I would ignore any GEFS means posted. However some members do predict an E,ly via a low pressure tracking SE allowing a ridge of HP to build in the Atlantic towards Iceland with a cold E,ly following. The period im referring to is around +240 though.

Just a reminder to take these with a pinch of salt as you know im not a massive fan of the GEFS!

 

 

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We should know by T120 if the ECM is heading towards the UKMO solution or not. And ECM is very rarely wrong at T120...

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The ECM at T96hrs is closer to the coast with the developing shortwave over the se USA than the GFS and better to the east with the Russian ridge.

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Primmed for a wrap around of height retro- to Scandinavia. .earlier 12zgfs..

Lets see how ecm 12z take evol around 144..??

gfs-0-90-1.png

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