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Model Output Discussion - 23rd Jan - 12z onwards


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The GFS 06hrs run is more amplified upstream and we can see the big difference this makes.

 

The key detail is really what orientation the PV will take after this, if this develops more elongated running sw/ne then you have a chance to extend the cold.

 

You need this digging further south over the USA and stretching ne'wards this will help throw a ridge further ne.

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Short answer   The short answer to your question is yes, the presence of low pressure (at higher altitudes, being coincident with very cold upper air), makes the air more unstable, as the gradient i

Welcome to "Celebrity Model Discussion". Let's go out to our reporter, who has managed to corner the miracle man himself, Jesus Christ, for his thoughts: Reporter : Thanks for joining us Jesus, first

If people will insist on analysing the 850mb temperatures every single run here's something to bear in mind when viewing the output for the upcoming period - -6c is a baseline figure to put snow/rain

Posted Images

one thing ive overlooked recently are these

post-2797-0-41035000-1422268174_thumb.gi post-2797-0-68873700-1422268187_thumb.gi

which have consistently refused to make more of the scandi-low atlantic ridge then the recent ecm and current ukmo charts suggest. so and strong northerly blast was never going to be more then a transitory feature.

they also supported the gfs's unsettled northwesterly outlook as opposed to the sweeping northerlies the ecm suggested.

so the potential for something cold and snowy wont be realised (as in a protracted spell). what we are left with is a far more marginal affair. sure there will be snow , especially over higher ground, but its looking unlikely that there will be a decent widespread lowland dumping and any snow we might get looks short lived.

there are hints that after week 1 of february high pressure might build in at least across southern areas, this might settle things down and could herald a milder spell which for many (but not me! :p ) be about as welcome as a zonal spell in week 2 of august would be for heat lovers.

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Snow showers for many of us later Wed and through thurs and even into Friday in the south, becoming less cold from the north on Friday into Saturday then much colder from the north through Sunday into next week, the 6z op has added an extra 24-36 hours to the polar airflow compared to the 0z so the cold spell may last well into next week.

post-4783-0-47981400-1422268704_thumb.pn

post-4783-0-58924000-1422268711_thumb.pn

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There looks to be a front crossing North to South on friday with a fair bit of precip within it, looking at the precip type it shows rain...and slightly warmer 850s. 

Is it possible this could be a snow event??

Early next week could have a substantial snowfall on latest GFS, big uprade for longevity of cold too.

I think at the moment the snow risk is mainly Wed night/Thurs as Friday we see slightly less cold air. The colder air should arrive at the weekend but then big question mark as to what occurs afterwards. Like I say the toppling and return to milder weather is favourite but I wouldn't bet against a massive shift in the output towards a very cold E/NE,ly.

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Within the expected movement of the PV from the Siberian side the GFS doesn't depart from that trend so I wouldn't discount its output. It's merely where it places it that's different from the ECM.

 

I'm not sure we can manage the right cut back in the jet over western Europe but at least you can extend the cold by a few days.

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This is going to be unusual should it occur.

 

I am so used to looking for snow showers from the NE/E but never coming from the cheshire gap.

 

http://www.wetterzentrale.de/pics/Rmgfs813.gif

 

Derbyshire tend to do well in these situations as does Wales.

 

 

 

Not all of Wales i may add....us south eastern areas often miss out as the precipertation fades away over the welsh mountains

Edited by WINTRY WALES
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The GFS 06hrs run is more amplified upstream and we can see the big difference this makes.

 

The key detail is really what orientation the PV will take after this, if this develops more elongated running sw/ne then you have a chance to extend the cold.

 

You need this digging further south over the USA and stretching ne'wards this will help throw a ridge further ne.

 

Yes and at T216 we are not a million miles away from a link up of our ridge to the huge Siberian/Russian block, with slack nothingness between them....that would be the perfect scenario!

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Yes and at T216 we are not a million miles away from a link up of our ridge to the huge Siberian/Russian block, with slack nothingness between them....that would be the perfect scenario!

The main purpose of the Siberian ridge at that point is it holds low heights over southern Europe, if the UK is to extend the cold you don't want a link up at that point because the energy will spill over the top. You need a separate lobe of high pressure thrown ne and need energy then to disrupt from the upstream troughing.

 

Remember bigger isn't always better!!! lol The Siberian high often looks good but its very rare to get that extending sufficiently west.

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Interesting FI....Trying to get some northern blocking after the Northerly.  Teits said this is a possibilty.  Extreme FI looks epic although just for fun at this timeline

Edited by Ali1977
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The main purpose of the Siberian ridge at that point is it holds low heights over southern Europe, if the UK is to extend the cold you don't want a link up at that point because the energy will spill over the top. You need a separate lobe of high pressure thrown ne and need energy then to disrupt from the upstream troughing.

 

Remember bigger isn't always better!!! lol The Siberian high often looks good but its very rare to get that extending sufficiently west.

See what you are saying Nick, I thought a link up would stop lows just spilling over the top and help to 'pull' our heights further north whilst they are developing? a sort of window of opportunity?

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post-4955-0-19902200-1422270501_thumb.gi

Edited by Nicholas B
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From zero to hero, the GFS makes the best of this upcoing cold spell with a stonkingly good run all in all.

 

If this were to verify (it won't of course but let's face it, it's intriguing to see it getting shown by an op run), Dec 2010 comparisons will not be so outlandish for what would follow on a few days on from this...

 

post-5114-0-53418900-1422270472_thumb.gi

 

 

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The issue going forward is what happens after the PV reforms and where it sets up. Theres a strong signal for the Siberian side to move west, given this the only way to sustain cold is for it to set up more favourably. So in the two images you'll see the difference this can make for the UK in terms of where the jet will go and subsequently where any cold gets directed.

 

I'm not sure whether we can really get enough jet cut back to direct the coldest air into the UK but probably a better chance of at least extending the cold for a few days.

 

So below is the unfavourable PV location:

 

post-1206-0-51264800-1422271001_thumb.jp

 

This one shows what could happen if the PV sets up much more sw/ne:

 

post-1206-0-26043100-1422270982_thumb.jp

Edited by nick sussex
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Akin to mid-month Met office blocking........watch this space.....

 

 


From zero to hero, the GFS makes the best of this upcoing cold spell with a stonkingly good run all in all.

 

If this were to verify (it won't of course but let's face it, it's intriguing to see it getting shown by an op run), Dec 2010 comparisons will not be so outlandish for what would follow on a few days on from this...

 

attachicon.gifRtavn3841.gif

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The issue going forward is what happens after the PV reforms and where it sets up. Theres a strong signal for the Siberian side to move west, given this the only way to sustain cold is for it to set up more favourably. So in the two images you'll see the difference this can make for the UK in terms of where the jet will go and subsequently where any cold gets directed.

 

I'm not sure whether we can really get enough jet cut back to direct the coldest air into the UK but probably a better chance of at least extending the cold for a few days.

 

So below is the unfavourable PV location:

 

attachicon.gifna1.jpg

 

This one shows what could happen if the PV sets up much more sw/ne:

 

attachicon.gifna2.jpg

Something akin to pert 7 of the 6z GEFS?

 

gensnh-7-1-264.png

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With all the chopping and changing in the models such as 0z and 6z it is important to keep reminding ourselves that fi is fi= unreliable time frame- whether it's showing the jet stream roaring through us from the west or a raging northerly, if it's after 72- 96 hours and changing from one run to the next then as the pros have constantly said we cannot take these charts as gospel- I do believe at some point we will be rewarded for our patience though & hopefully 1-0 to the net weather February forecast come a months time:-)

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With all the chopping and changing in the models such as 0z and 6z it is important to keep reminding ourselves that fi is fi= unreliable time frame- whether it's showing the jet stream roaring through us from the west or a raging northerly, if it's after 72- 96 hours and changing from one run to the next then as the pros have constantly said we cannot take these charts as gospel- I do believe at some point we will be rewarded for our patience though & hopefully 1-0 to the net weather February forecast come a months time:-)

I refer you to my earlier post -

 

 

Posted Today, 08:45

I think that we could do with a model forum discussing output up to t120z only - would save a lot of disputes

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I refer you to my earlier post -

 

 

Posted Today, 08:45

I think that we could do with a model forum discussing output up to t120z only - would save a lot of disputes

 

 

Think the main issue with that would be most people are looking for trends or figuring out what happens further down the line, up to t120 we could just watch the news and see? maybe i'm wrong but think that is why in most situations people start looking at the end or further on rather that what is infront of them? myself included  :cc_confused:

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Yes a great GFS 06Z but I await the ECM later on today and also the next run of the GFS will be interesting, if the high in mid Atlantic intensifies at 141 hours out on the later runs then we're in business but it's a big if at the moment.

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Well i,m certainly liking current charts ,plenty of wintry possibilitys and i,m sure that many surprises will and can pop up with little warning .some are looking for the breakdown Again ,this is out at least untill next week and currently is not certain ,this cold period could get extended day by day .in fact todays 06 gfs run shows exactly that ,we need to enjoy this cold period and tonights charts could even be more mouthwatering .Fax charts i,m sure will change very quickly in this set up which is on the way ,cheers  :cold:

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Got to say, I have to go against the grain here and say the GFS 06Z is a poor run, it really is, very little snowfall on this run in the medium term unlike the UKMO and even the ECM runs are showing, too deep of a low which is too close to us which just mixes out the cold uppers thus temps are too mild(5C).

 

Longer term its better but I believe that as much as I believe the ECM op FI run because we all know it will change from run tor run although the ECM FI has probably got more chance to be right seeing as it got more support but its by no means a foregone conclusion because a little change in the short term will change the medium to longer term, that is always the case in model watching hence forecasting longer term patterns is always a challenge.

 

Its an output which is interesting but not a one where its nerve shredding because its not the coldest charts you will ever see and detail wise they are far from perfect, in some respects its kind of nothing to lose type of thing and no doubt we will still see further detail changes whilst the main trend is always there of a half hearted ridge with a fairly strong North/NW'ly flow(albeit not in terms of temperatures).

 

Edit: I'm on about about the medium term regarding the GFS, short term with that cold blast and longer term with lengthening any cold is not bad indeed.

Edited by Geordiesnow
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Still lovely looking charts this Morning, I have a good feeling about this one, and have feeling february is going to be a good one! (Thats it ive said it)

 

Obviously things can still change so am not getting over excited just yet, overall been very good model watching of recent with the start of this spell on wednesday!

 

Hope the 12z will show goodness!

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