Model Output Discussion 1st January 2014-06z onwards.

[Methuselah]

When you talk about phasing and phased energies what exactly do you mean?

I wish I knew the answer to that one too...How many 'phases' are we talking about? What are 'energies' anyway?

Edited January 3, 2014 by No-Time Toulouse

[shedhead]

If FI always verified as shown, most winters would be 47's or 63's, with most Summers 76's or 95's. 

 

There have been a few occasions that FI charts from GFS have got very close to verifying, Dec 10 probably being one of the best and most recent examples, but finding them is like finding hens teeth tbh.

 

Firstly I think we have to start seeing some consitancy of evolution in FI, that has hardly been the case across the last few days either, but without question the prospects for something colder this month are greater than we saw throughout Dec...more patience is and will be required though imho.

Edited January 3, 2014 by shedhead

[Stuie]

"Phasing" is when 2 low pressure systems merge and become 1.

[Weather Boy]

Well for me the cold upgrade continues as 'suggested'.  This Jan will go one of two ways.  Either we will have real cold/wintry weather dig in or we'll be stuck in the preferred MetO SW'ly regime....no room for halfway house imo.  Steady as she goes as far as I am concerned, we have seen a continued 'improved' cold outlook which IMO could still come sooner rather than later in Jan.  And why not look at what 3 days have done?? 

 

BFTP

 

Not sure I follow your reasoning with respect to the part in bold.  What's wrong with, for example, a far reduced Atlantic with slackish Continental flow, chilly, but mostly dry (and any precipitation rain except on high ground) being a suitable scenario? Or a brisk cold-ish NW flow?

 

It seems to me that there are strong signs of a change from the current Atlantic-overdrive weather we are getting in the semi-reliable, but I'm not getting why you think it's either severe cold and snow or as you were? Can you please explain your reasoning?

[Troubleatmill]

"Phasing" is when 2 low pressure systems merge and become 1.

But is it just a phase they are going through? Edited January 3, 2014 by Arron B

[Stuie]

But is it just a phase they are going through?

Quite probably ;-)

[pureasthedriven]

If FI always verified as shown, most winters would be 47's or 63's, with most Summers 76's or 95's.  There have been a few occasions that FI charts from GFS have got very close to verifying, Dec 10 probably being one of the best and most recent examples, but finding them is like finding hens teeth tbh. Firstly I think we have to start seeing some consitancy of evolution in FI, that has hardly been the case across the last few days either, but without question the prospects for something colder this month are greater than we saw throughout Dec...more patience is and will be required though imho.

After years of model watching I can recall some occasions where GFS has latched onto an idea or pattern in deep FI, only to drop it unceremoniously but then return to something akin nearer the time. Nothing scientific here and I have no exemplar charts to post, but just a thought to add into the mix.

[Methuselah]

"Phasing" is when 2 low pressure systems merge and become 1.

But a low isn't an 'energy' though, is it?

[Stuie]

But a low isn't an 'energy' though, is it?

Erm err.... erm not sure. Plenty of energy in a super low? 

 

Edit: Or is it just a depression? again not sure.

Edited January 3, 2014 by StuieW

[Weather Boy]

But a low isn't an 'energy' though, is it?

 

I've always thought that it was a flow, hence "energy over the top of the high" for example, bringing the weather systems or whatever across.  Therefore a deep low will have a lot of energy as it has a lot of wind (especially) on its flank.

 

But happy to be educated by someone who actually uses the term!

Edited January 3, 2014 by Weather Boy

[Nick L]

I've always thought that it was a flow, hence "energy over the top of the high" for example, bringing the weather systems or whatever across.  Therefore a deep low will have a lot of energy as it has a lot of wind (especially) on its flank.

 

But happy to be educated by someone who actually uses the term!

 

The perils of using terms that have no meteorological definition - nobody seems to know exactly what they mean!

[pureasthedriven]

But a low isn't an 'energy' though, is it?

I'm reading Nick as meaning that, metaphorically, it's the difference between, say, a constant, steady flow in traffic where you just cannot get across the road (phasing) and a break in the flow of traffic to enable you to get across (no phasing). This lack of phasing provides a window for ridging to occur and shove the original troughing out of the way and create at least the opportunity for blocking.Having said that, it's all about where the jet goes isn't it? Jet slackens, splits, weakens, etc, you'll get that clearance of energy. Jet maintains its west-east vigour, status quo. Kennedy's 'it's the economy, stupid' seems to be me to be equally applicable to the jet!

[lassie23]

The GFS wants to set up an easterly come the 17th of January. Heights still unable to form for long over Greenland, so an easterly is our best bet.

[Great Plum]

Well, the 06 GFS op is not an outlier, but definitely one of the colder options...

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Good to see the mean dropping nicely though...

Happily take the light blue line...

[shedhead]

After years of model watching I can recall some occasions where GFS has latched onto an idea or pattern in deep FI, only to drop it unceremoniously but then return to something akin nearer the time. Nothing scientific here and I have no exemplar charts to post, but just a thought to add into the mix.

Indeed, this has happened on many occasions, as has it latching onto a pattern in FI, then uncerimoniously dropping it and never returning to it.  That highlights the perils involved in even looking at FI for trends, because quite often those trends run for some time in FI but never make it into the low res part of the run..a la carrot, stick and donkey - we never quite get there.

[nick sussex]

When you talk about phasing and phased energies what exactly do you mean?

Phasing I thought was a common term used by forecasters, its very evident in the discussions by NOAA in the USA.

 

Generally I use it to describe two parcels of energy/lower heights/lower pressure merging, so for example upstream the current set up shows a shortwave running ne out of the Gulf merging with low heights and the PV, two separate areas of lower heights merging into one, the definition I've seen is two shortwaves merging into one wave.

 

Theres hardly a day goes by upstream when NOAA aren't talking about phasing issues in terms of timing and how much interaction takes place so for me its a perfectly acceptable term.

 

I've been talking a lot about this over recent days , and have made clear how important it is to keep the trough energy which is over the UK separated from the PV.

[Polar Maritime]

Indeed, this has happened on many occasions, as has it latching onto a pattern in FI, then uncerimoniously dropping it and never returning to it.  That highlights the perils involved in even looking at FI for trends, because quite often those trends run for some time in FI but never make it into the low res part of the run..a la carrot, stick and donkey - we never quite get there.

 

How many other ways can it be explained ? But as far as the models are concerned the trends are there. And that's the interest it gives us during the Winter months, all standard precautions at this time of the year when looking at a pattern change.

[BLAST FROM THE PAST]

Not sure I follow your reasoning with respect to the part in bold.  What's wrong with, for example, a far reduced Atlantic with slackish Continental flow, chilly, but mostly dry (and any precipitation rain except on high ground) being a suitable scenario? Or a brisk cold-ish NW flow?

 

It seems to me that there are strong signs of a change from the current Atlantic-overdrive weather we are getting in the semi-reliable, but I'm not getting why you think it's either severe cold and snow or as you were? Can you please explain your reasoning?

 

Nothing I suppose but the winter has been dominated by extremes around the NH and I think to stop the onslaught we'll get something more 'substantial' initially and I think there's more serious weather to come yet over the coming two weeks.  The slack calm conditions may well come, indeed I have that as a scenario for last 3rd of Jan but my start has gone array a touch as the SW'ly regime has held on for longer but the stormy NY arrived with a bang.  MetO have their strong signal for SW'ly regime for the month ahead [must be taken seriously] so at the moment a slack set up is least fav in my books....not that we'll be right

 

BFTP

Edited January 3, 2014 by BLAST FROM THE PAST

[shedhead]

Phasing I thought was a common term used by forecasters, its very evident in the discussions by NOAA in the USA.

 

Generally I use it to describe two parcels of energy/lower heights/lower pressure merging, so for example upstream the current set up shows a shortwave running ne out of the Gulf merging with low heights and the PV, two separate areas of lower heights merging into one, the definition I've seen is two shortwaves merging into one wave.

 

Theres hardly a day goes by upstream when NOAA aren't talking about phasing issues in terms of timing and how much interaction takes place so for me its a perfectly acceptable term.

 

I've been talking a lot about this over recent days , and have made clear how important it is to keep the trough energy which is over the UK separated from the PV.

It tends to get used more across the other side of the pond Nick, seen it a lot in past NOAA outputs and I would definately describe it as a meteorological term. Anyway that aside, if the latest GFS is to be believed you could well be 'phasing' into shorts and t-shirts down there come next week... Pyrennean snow cover must be starting to suffer by now?

[Polar Maritime]

METO are still on board, in line with the trends we are seeing.

 

18 Jan 2014 to Saturday 1 Feb 2014:

 "Some signals are also emerging for an increasing risk that the weather may undergo a change to colder weather types later this month."

 

And before that...

 

 8 Jan 2014 to Friday 17 Jan 2014:

"Later in the period we may see a slightly higher occurrence of colder interludes between spells of rain leading to an increased risk of frost and icy patches compared to recent weeks."

Edited January 3, 2014 by Polar Maritime

[BLAST FROM THE PAST]

METO are still on board, in line with the trends we are seeing.

 

 "Some signals are also emerging for an increasing risk that the weather may undergo a change to colder weather types later this month."

Interesting, considering I F's posts recently

 

BFTP

[Mucka]

Edit: I see there have been posts discussing "phasing" of energy while I wrote my post below and I describe it in much the same way as Nick. We can clearly see separation of low pressure areas on the pressure charts. Here at 144 ECM we can see a ridge separates the the low just NW of the UK and the disrupting trough SW of Greenland but by 168 the low to the West has "caught up" with our low and the energy has "phased" leaving a slack trough to our North.

 

 

End Edit:

 

 

 

Disappointing ECM ensembles this morning with the cold cluster all but disappearing and more mild options with the mean actually rising from mid month, no short cut to cold there but without seeing the postage stamps it is hard to know exactly what is going on though I suspect the many are going for a phasing of the trough around the mid term giving a flatter pattern and SW winds similar to the Op.

 

 

 

 

So not great news there but even if ECM Op verified it does not preclude the possibility of colder conditions later in the month of course.

 

This mornings GFS Op runs do not phase that energy over the UK. GFS 00z/06z 144/168

 

 

Resulting in a strong ridge being built toward the Arctic high

 

 

This reinforces the Arctic high which forces the jet North instead of allowing it to push through Scandinavia

 

If we look at UKMO at 144 we can see it has the faster exiting trough as GFS Op runs and looks unlikely to phase energy in the same way as ECM.

 

UKMO/GFS/ECM

 

 

GFS ensembles should be largely ignored for the time being as only around 30% of the perturbations look like following the Op and other models regarding the way the Atlantic ridge is likely to form with cut off weak high to the N/NE so if the majority are likely wrong from 120h there is really no sense in trying to figure out 240h+ charts.

 

I think Nick S already talked about the phasing of energy in ECM hence his despondency but the ECM is only one model even with its own ensembles seemingly backing it.

GFS, GEM and UKMO all disagree with the phasing of this energy over the UK and thus all offer descent potential for a slow decent to colder conditions as we head into the second half of Jan.

 

GEM 144 no phasing.

 

 

GEM 186h strong ridge North (as with GFS)

 

 

Day 10 pressure dropping over Europe much more amplified to the West, colder weather likely inbound

 

 

So overall I think we are at a crossroads regarding how quickly a potential cold spell could develop. GFS, GEM and UKMO it could start around mid month - ECM you could likely add another week and then we can't be sure of potential.

 

Final word is that the possible strat warming later in Jan is a bit of a red herring in the context of developments over the next week or so and I think that is what Chino was alluding to the other day. Look for how the models deal with the Atlantic ridge, possible weak cut off high and whether they phase the energy over the UK - all of that is hanging on fine margins and developments should be quite quick since we are only looking out to day 5 through to day 7/8

Edited January 3, 2014 by Mucka

[Cecil Hogmanay Melchett]

METO are still on board.

 

 "Some signals are also emerging for an increasing risk that the weather may undergo a change to colder weather types later this month."

 

Interesting, considering I F's posts recently

 

BFTP

Yes,i was expecting a downgrade today Fred-i guess there are conflicting signals (not suprising considering the timeframe involved),maybe Mogreps is pointing towards something decent?

Time will tell...

[Day10]

It tends to get used more across the other side of the pond Nick, seen it a lot in past NOAA outputs and I would definately describe it as a meteorological term. Anyway that aside, if the latest GFS is to be believed you could well be 'phasing' into shorts and t-shirts down there come next week... Pyrennean snow cover must be starting to suffer by now?

Pyrénées, enroute BCN 30/12/13. Taken from the office window

[nick sussex]

It tends to get used more across the other side of the pond Nick, seen it a lot in past NOAA outputs and I would definately describe it as a meteorological term. Anyway that aside, if the latest GFS is to be believed you could well be 'phasing' into shorts and t-shirts down there come next week... Pyrennean snow cover must be starting to suffer by now?

Yes you're right re the USA it's very common over there, perhaps JH and Forecaster would supply me with the UKMO term for the American phasing, a term has to be used by the UKMO because its a very common synoptic situation.

 

Regarding some of the terms NOAA use, the recent addition was bombogenesis! that made me laugh, anyway I've been using the term phasing for years on here and am quite comfortable with it, I think its quite explanatory really.

 

Regarding the Pyrenees yes its turned very slushy and mild here now,  drizzly and underwhelming, some heavy snow though is expected tomorrow as it turns briefly colder. Overall though its been an excellent season, it seems strange to say that with all the mild muck but there was a lot of snow end of November, then sunny skies for nearly three weeks but with low dew points, no warm rain which is the real scurge of ski resorts.

 

More snow over Xmas, its just the last few days which has turned slushy, next week could turn warm but as long as its dry the resorts should be okay.

Edited January 3, 2014 by nick sussex