Model output discussion - mid January

[feb1991blizzard]

The overnight GEM and NOGAPS ensemble suites show an improved appetite for delivering frigid to us when they previously had very little in terms of sub -5c.

[Summer Sun]

At t168 this morning we have ECM and GFS both showing high pressure close enough to the UK to keep us main dry

UKMO has other ideas with a fairly deep low to the north of Scotland bringing windier conditions and some rain

 

[MP-R]

11 minutes ago, SN0WM4N said:

Snow is also more common in those months than December. Well April anyway.

No it's not...  Easterlies yes, snow no.

[Fourty Point Three Degrees]

People will never learn how to take 10 day long range GFS/ECM outputs with caution and how to not treat them like its 100% gods honest gospel.

[cheese]

15 minutes ago, MP-R said:

No it's not...  Easterlies yes, snow no.

Easterlies can even be warm in late spring, if the continent is heating up. I think May 2008 is a good example of a warm easterly. 

Edited January 27, 2018 by cheese

[bluearmy]

44 minutes ago, feb1991blizzard said:

Does that include the 0z suite?

Yep

given that this invariably trends towards climatology at day 15 (hence the Azores ridge ), this isn’t a bad indicator 

[ICE COLD]

The doom and gloom army are out in force this weekend ?. Funny when there's a potential cold spell round the corner they come out in force . The broad pattern looks the same as it has for the last few days . Off course op runs are gonna change run to run . Look at the ens there is loads going on as we enter Feb. We would do very very well to miss out on some wintry weather that's for sure . 

very cold runs in there . The snow rows up . And the ecm was a milder outlier towards the end . It's all good in the hood . ?

[Nick F]

30 minutes ago, karlos1983 said:

Looking at the gfs anomaly, does suggest expectations for any easterly are really post D10, starting with a High pressure near or over the UK which then goes north and delivers the goods!

 

 

I mentioned last night that I was surprised the GFS on 18z last night was bringing in blocking with the NEly / Ely so soon, given the progression of the MJO wave into western Pacific in early Feb and factoring the lag, so would think 10th-15th timeframe for potential blocking to the N or NE to bed in. Any decent cold incursions before the 10th a bonus and likely driven by the effects of the -EPO ridge amplifying the flow.

There is the caveat that the MJO effects on the northern hemisphere pattern could be dampened in our locale by a strong jet cranked up by intense cold eventually shifting into eastern side of N America perhaps helped by the broadscale negative effects of GLAAM/GWO and/or unfavourable downwelling from the strat. So, as always, there are no guarantees of the cold and snowy nirvana that the GFS has been showing will come off, but February probably the best shot at it that we've had this winter for a nationwide cold spell with nationwide snow potential.

[SLEETY]

17 minutes ago, ICE COLD said:

The doom and gloom army are out in force this weekend ?. Funny when there's a potential cold spell round the corner they come out in force . The broad pattern looks the same as it has for the last few days . Off course op runs are gonna change run to run . Look at the ens there is loads going on as we enter Feb. We would do very very well to miss out on some wintry weather that's for sure . 

very cold runs in there . The snow rows up . And the ecm was a milder outlier towards the end . It's all good in the hood . ?

Yes it always happens,always .The same posters come and post negative comments about the chances of a cold spell happening.

still looks a good chance to me of a cold spell developing soon,looking at the models this morning

 

[MP-R]

59 minutes ago, cheese said:

Easterlies can even be warm in late spring, if the continent is heating up. I think May 2008 is a good example of a warm easterly. 

Absolutely. May 2008 brought a classic warm easterly followed by a chilly one with a northerly source.

[Weathizard]

Bit dismissive just to nonsense people's posts because they have a mild bias, the majority on here have a cold bias and look for any avenue to cold so I find the mild rampers equally useful, gives some balance.

Its all very well looking at ENS suites but they struggle to pick up the spoiler features that always pop up and ruin easterlies, I just cannot see an easterly with the polar vortex still where it is, it requires some serious luck and we never get that.

[karlos1983]

5 minutes ago, Weathizard said:

Bit dismissive just to nonsense people's posts because they have a mild bias, the majority on here have a cold bias and look for any avenue to cold so I find the mild rampers equally useful, gives some balance.

Its all very well looking at ENS suites but they struggle to pick up the spoiler features that always pop up and ruin easterlies, I just cannot see an easterly with the polar vortex still where it is, it requires some serious luck and we never get that.

Fair point In first paragraph.

ENS suites are a guide though for what could be a change in pattern, and looking for depth or longevity of cold as an example, (or heat). As for the PV, it’s been in tatters for most of winter and with any easterly, PV lobes sending energy SE is never a bad thing! 

Interesting times ahead for all enthusiasts I’d say!

Edited January 27, 2018 by karlos1983

[dixonoid]

It seems to me the weekend is the 18z very hungover brother, output always seems to be missing something :-@ when the models go in low res, it's like someone let's down a balloon. I think the easterly is gonna be like Mr deeds butler, but interesting model watching.

[mulzy]

4 minutes ago, Weathizard said:

Bit dismissive just to nonsense people's posts because they have a mild bias, the majority on here have a cold bias and look for any avenue to cold so I find the mild rampers equally useful, gives some balance.

Its all very well looking at ENS suites but they struggle to pick up the spoiler features that always pop up and ruin easterlies, I just cannot see an easterly with the polar vortex still where it is, it requires some serious luck and we never get that.

Indeed.

As I said in my earlier post, we have taken a step back this morning with some rather ordinary NWP output.  Let's see how output pans out from here but definitely no impending freeze on the horizon at the moment.

[Snowman.]

1 hour ago, MP-R said:

No it's not...  Easterlies yes, snow no.

Whoops it was march not April

[Nick F]

I understand the negativity given the model output this morning, but models will often struggle with a pattern change, particularly when the change is still outside the high res timeframes of the models, hence beyond 7 days we get swings between runs showing cold then showing mild then back to cold again, well certainly GFS anyhow. EC op has been fairly persistent as the potential pattern change driven by MJO wave is still likely beyond day 10 anyway. The models often do not latch on to blocking occurring to within 7 days anyway, so I’m not duly concerned until we reach 2nd week of Feb and still no cold spell showing within 7 days!

Edited January 27, 2018 by Nick F

[snowfish1]

10 minutes ago, Nick F said:

I understand the negativity given the model output this morning, but models will often struggle with a pattern change, particularly when the change is still outside the high res timeframes of the models, hence beyond 7 days we get swings between runs showing cold then showing mild then back to cold again, well certainly GFS anyhow. EC op has been fairly persistent as the potential pattern change driven by MJO wave is still likely beyond day 10 anyway. The models often do not latch on to blocking occurring to within 7 days anyway, so I’m not duly concerned until we reach 2nd week of Feb and still no cold spell showing within 7 days!

Amidst the negative posts this one surfaces like a green shoot amongst the dung pile yes output will always change but the trends are still there

Edited January 27, 2018 by snowfish1

[SMU]

As much as the models ( mainly the GFS ) have given a us a bit of a tease I’m afraid the last 2 days have seen a general downgrade of the signal of high pressure over Scandi- we started out with Scandi high from GFS then this gradually morphed into a wedge of heights to the NE swerving the jet to the SW of the UK - last nights control was the highlight-

The problem with a wedge being modelled as opposed to a proper high is that it’s subject to big revisions in location - & we are currently seeing the models gradually ease things away east - favouring the more traditional low heights over Iceland aligned west east not even NW SE - 

This is why also the MJO plots are almost as useless as well- it ceases to amaze me that no one realises they are all the same data depicted in a different way- for example this week everyone got excited over the 00z GFS & GFS - then about 2 hours later someone posts the MJO forecast & that ramps everything up again - even post that the AO means gets churned out as a big indicator - & it euphoria- & everyone thinks that 3 data sources must be adding a lot of credibility - it’s not it’s just 1 GFS data source.

Also personally I’m glad that GSDM website is shutting down because to date all its ever delivered is a lot of useless information that exemplifies the starting point across the globe in terms of what everything is doing but beyond that nothing meaningful in terms of creating a tangable forecast - All I see is a long list of If but & maybes to cover all bases. It might be science based & it all looks very glossy but actually delivers diddly squat.

This winters got 3-4 main weeks left & then it’s over for another year, whist we have been lucky in certain locations the headline figures will be yet again no SSW which makes it what 7-8 years -

probably no deep cold from the continent ( although there is still time ) 

No Greenland high - when was the last time we saw that & an above average winter...

We will be very very lucky if things work in our favour now..

just for a moment think of every single excited outlook / forecast & model run since the last week of November - & there has been hundreds from all quarters NOT 1 SINGLE DAY OF THIS WINTER HAS RECORDED A NEGATIVE NAO

Edited January 27, 2018 by Steve Murr

[bobbydog]

as @Nick F says above- there's no point worrying about individual runs whilst there's still so much inter-run inconsistency. take the 00z and 06z runs as an example-

both at the same timeframe (10 days) and huge differences. ensembles and trends are the best guide until we get consistency at closer timescales.

meanwhile,

[summer blizzard]

If it is positives one looks for then the models do show two things..

1) The vortex remains under assault from the Pacific (perhaps also Siberia) side. 

2) Pressure does remain relatively high to our south meaning that a few dead fronts and wind are the order of the day rather than any raging zonality. 

Unfortunately our despondency here stems from people wanting things to happen too quickly since the vortex disruption sends too much energy to Canada. It may be that we have to go through an unsettled period to get a vortex shift into Siberia before we can look to anything meaninful. 

At any rate, there are worse places to be in a weeks time than this.. 

[bluearmy]

2 minutes ago, Steve Murr said:

As much as the models ( mainly the GFS ) have given a us a bit of a tease I’m afraid the last 2 days have seen a general downgrade of the signal of high pressure over Scandi- we started out with Scandi high from GFS then this gradually morphed into a wedge of heights to the NE swerving the jet to the SW of the UK - last nights control was the highlight-

The problem with a wedge being modelled as opposed to a proper high is that it’s subject to big revisions in location - & we are currently seeing the models gradually ease things away east - favouring the more traditional low heights over Iceland aligned west east not even NW SE - 

This is why also the MJO plots are almost as useless as well- it ceases to amaze me that no one realises they are all the same data depicted in a different way- for example this week everyone got excited over the 00z GFS & GFS - then about 2 hours later someone posts the MJO forecast & that ramps everything up again - even post that the AO means gets churned out as a big indicator - & it euphoria- & everyone thinks that 3 data sources must be adding a lot of credibility - it’s not it’s just 1 GFS data source.

Also personally I’m glad that GSDM website is shutting down because to date all its ever delivered is a lot of useless information that exemplifies the starting point across the globe in terms of what everything is doing but beyond that nothing meaningful in terms of creating a tangable forecast - All I see is a long list of If but & maybes to cover all bases. It might be science based & it all looks very glossy but actually delivers diddly squat.

This winters got 3-4 main weeks left & then it’s over for another year, whist we have been lucky in certain locations the headline figures will be yet again no SSW which makes it what 7-8 years -

probably no deep cold from the continent ( although there is still time ) 

No Greenland high - when was the last time we saw that & an above average winter...

We will be very very lucky if things work in our favour now..

I think the issue with the MJO plots is the lag re patterns establishing this side of the NH. There must be a good 5 to 7 days to get the patten over the east Atlantic reflective of the MJO analogue. the models are showing a trop that seems pre disposed to amplification at the moment. But seems tough for this to sustain with the Canadian vortex spewing out pulses of low heights every few days. the fact that we know glosea and ec 46 are both ridgy to our east by mid Feb is notable. Anything before that remains unreliable and given the range, those tools are always suspect. I think the end of last jan saw us chasing a scandi ridge as the strat vortex showed a sudden drop to almost ssw territory. We aren’t in the same place this season stratwise but we are still chasing the scandi ridge! 

[East_England_Stormchaser91]

It's that persistent cold pooling over Canada yet again that's throwing the constant curveball at us. It's barely moved all winter. 

I'm sorry, but the idea of eastern Pacific ridging only diverts the polar vortex to sit very stubbornly over NE Canada as the jet becomes rampant and digs down SE over the states and roars up the US east coast. I'd be more confident of us getting the cold with a Siberian placed main PV. The Azores high has also made sure of us missing out on easterly/northeasterly shots too. Unless we see that Canadian vortex removed and low heights over the Azores too, any chance of a classic spell will start to wane. 

As we approach solar minimum, I'm getting confident however that we will see something terrific maybe in one of the next few up and coming winters. 

[Tamara]

The MJO continues to be referred to too often as a stand-alone product.

Various analyses over a considerable period of time have tried to emphasise that the catalyst for change that does indeed come from the tropics in terms of organised macro scale deep thunderstorm development (the MJO) is just the initiation process. Albeit an important initiation trigger

.

However, it still requires successful propagation of the added westerly wind burst (amplifying) anomalies that accompany the passage of MJO convection though the tropics, into the extra tropical mid and higher latitudes to facilitate widespread hemispheric pattern change. Its necessary to understand the lag times of frictional torque in the tropics > that lead mountain torque in the extra tropics - and then try to assimilate those conclusions as to when NWP might be impacted in the mid and higher latitudes

There is then the question of how strong +ve mountain torque engagement perturbs the troposphere/stratosphere boundary.

Claims persist that too much is made about La Nina being a sole influence on the atmosphere, when of course it isn't. An E/QBO phase derives importance in terms of its ability to heighten efficiency of transfer of ozone from the tropical stratosphere to the polar stratosphere via an enhanced Brewer-Dobson circulation -

  http://www.ccpo.odu.edu/SEES/ozone/class/Chap_6/6_3.htm

 An enhanced BDC can help keep the polar vortex more unstable than under the W/QBO phase when it is generally less pronounced and the polar vortex strength is assisted by natural momentum gyre. We all know of how solar phasing has influences, not least how even moderate geomagnetic activity such as ushered in this winter, despite being in a descending phase, can still influence the height of the tropopause. Plus incidentally, because solar related geomagnetic activity influences the Ferrel cell, it augments the strength of the same sub tropical ridges that are a natural product of La Nina as derived by stronger than average easterly trade winds.

So while we need to be aware of the complex jigsaw of factors, lets realise that many of them come back to the same common denominators that decide tropospheric momentum between the tropics and extra tropics. On that basis, one can return to the starting point of catalyst for MJO pattern change, and analyse the probabilities related to how the atmosphere may, or may not co-operate with poleward +AAM anomaly transfer into the extra tropics.

The ENSO state plays a pivotal role here in terms of its base state because it tells you whether it is pre-disposed to low angular momentum inertia c/o higher easterly trade winds across the tropics that underpin sub tropical ridges and in our sector help support an +NAO, or whether greater westerly momentum added from tropical MJO forcing can help reduce the strength of those easterlies in the tropics and in turn, with time, also reduces the compensated strength of polar jet westerlies that blow at our latitude and inhibit development of blocking at higher latitudes.

That last paragraph/ sentence in a nutshell puts us where we are with the NWP modelling.  Over the last few days we have seen an increasing smorgasbord of solutions served up related to both assessed amplitude, strength and timing of poleward +AAM anomaly transport induced by a robust passage of tropical forcing to the Western Pacific.

The strength of these westerlies (deep orange anomalies) in the tropics are now showing up impressively on the GEFS plot - and angular momentum tendency is on a re-surge from depressed La Nina territory.

The last sight I had yesterday of frictional torque engagement of these on WDT (just before it was pulled!) reflected the GEFS plots and showed a very robust +ve upward tendency. On the way towards scrubbing out the considerable easterly wind legacy of recent La Nina forcing. However we have to factor in the lag times for poleward momentum transport and the existing La Nina surfeit in the extra tropics in terms of managing expectations for engaging changes within NWP

If ever there was a time to clamour for AAM atmospheric budget updates it is now, to anticipate the extra tropical +ve mountain torque reaction and gauge possible strength of amplification as these wave eddies propagate to our latitudes

On the basis of these complex equations, best not get hung up on the usual NWP upgrade/downgrade roundabout and enjoy the ride instead. I think that things may well keep getting more and more interesting.

That is of course, if one is able to control instinctive reactions to intra day model suite variations - of which there will undoubtably be more to come

Edit: That latest post from Steve Murr unfortunately exemplifies the type of baseless and unhelpful reaction that does this thread no good whatsoever. Its the weather- deal with personal frustration and inability to cope through a less tribal aspect.

 

Edited January 27, 2018 by Tamara

[karlos1983]

Some suffer from double standards imo on this forum I’m afraid.

 

Anyway, Nick F has kind of hit the nail on the head imo with the Models struggling in the low res to have any consistency, some patience required., S4lancia also made a good point earlier on. It’s feasible we miss out, just! But we’ve got a good shot in February for a decent cold spell.

Will we get there or not, still not a single person on this forum can be sure either way. 

Ps we can see from De Bilt ens that the ECM was a mild outlier, and the control a stonker!!

 

Edited January 27, 2018 by karlos1983
Typo

[Gowon]

Total fantasy but Pert 20 is what most people on here are after.. This would be epic - check it out 

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=20&mode=0&carte=1