Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!

[bluearmy]

Looking at the weatherbell ECM data, the majority of the heavier precip in the southern half of uk (where it looks heaviest) is associated with DP's just above zero. When the precip subsides, the DP's drop. I expect it's quite a knife edge situation which is where elevation will assist decent cover. Tomorrow morning is 36/48 hours ahead. If the charts look the same in the morning, a yellow warning will be issued.

too unsure at the moment to do so and a forecast of a wintry mix will suffice until some certainty appears.

[Cheese Rice]

12 hour RAW ppn for the south midlands into the Green is @ 10mm ratio..

just for those 6 hours...

http://en.vedur.is/photos/atlant_evr_urkomuspa/150118_1200_66.png 10 mm

http://en.vedur.is/photos/atlant_evr_urkomuspa/150118_1200_72.png 4mm

A tadge of elevation would be good- Chilters etc

Thankyou for posting the charts

😃

I'm referring to ECM charts on Wunderground which show a mostly none event.

Edited January 18, 2015 by Cheese Rice

[Harsh Climate]

I just can't see snow south of the M4 next tuesday/wednesday. Infact I can't see much low lying accumulations south of the midlands tbh. I think a lot of people are viewing the ECM with south snow tinted glasses on and are hopecasting more than anything..

 

Let's look at tuesday nights action first of all, the slider has a notable mild sector associated with it also in the south the precipitation isn't expected to be too heavy so any evaporative cooling will have little effect. I think transient snowfalls south of the midlands above around 300m..

 

 

I think the second event that arrives wednesday night will be further north than the precipitation chart I have posted shows, but still temperatures a bit too marginal down south ALTHOUGH a little slushy covering is possible around the M4 corridor or just a little south as slightly colder air filters in behind the sliding low.

 

.

 

Here's how I see it.

 

 

With a good 6-9 hours of persistant snowfall I expect 5-10cm in these areas above 50m, with upto 10-15cm above 300m. just away from the highlighted area perhaps 2-3cm.

 

 

I expect generally 2-5cm in the highlighted areas, although above 200m in northern ireland due to the encroaching milder sector. 5-10cm above 300m generally. With perhaps 1-2cm just south of the main warning area. Wednesday nights event shouldn't be as long lasting and intense as tuesday nights event although down towards the south coast/central southern england could be issues with intense rainfall.

Edited January 18, 2015 by Harsh Climate

[dragan]

Certainly a cold to cool week coming up, snow for some, sleet or rain for others. It seems a fairly standard cold snap lasting untill next weekend when the ECM UKMO and GFS state a return to milder south westerlies. I still feel February will provide some low temperatures under a high pressure, just my 'gut' feeling however!!

[BLAST FROM THE PAST]

Good observations being made about the nearer term pattern positive adjustments westward, in accordance with expectations, but intra model suite reactional assumptions continue based on face value observations beyond the end of the week

 

The gist of that post earlier was not definitively predicting a full blown bitter easterly to occur by next weekend or into next week because that is not at all likely to happen so soon - but that the very messy Atlantic phase was destined to continue for some time - and does not have a logical conclusion back to sustained westerlies.

 

I have repeated this in at least two recent posts before today - and the pendulum has already swung back and forwards with westwards, then eastwards, and now westwards Atlantic/European adjustments once again...

 

It is beyond this messy Atlantic phase (and irrespective of any attempted Atlantic incursion) that with the stratospheric profile much better suited in our sector for the first time this winter (displaced vortex on top of earlier junior SSW, plus Mountain Torque interaction as described in detail and within a NW-SE orientated trough disrupting jet stream pattern environment) that further ever more favourable pattern evolvements have a good chance of occuring - and it is at that time, towards months end and into February that any real events from the east conceivably could well come into play.

 

There is uncertainty about the MJO forecasts (some dichotomy between GEFS and ECM forecasts) and in terms of the possible NAO trends I spoke about, we do need more certainty here - but winter has its biggest chance yet to get properly started now than it has done thus far.

 

One step at a time. With a cold week ahead already anyway - there is plenty to watch out for of great interest beyond this time

 

Edit : Ed, yes between course work and writing this I have

Hi Tamara

And what synoptic pattern do you expect from these better signals?

 

BFTP

[bluearmy]

The thing is IDO NCEP expect troughing to become established over the eastern USA, its whether that becomes more amplified to help sharpen up any troughing to the west of the UK.

 

Below is the latest updated NCEP state forecast for New York:

 

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...

LONG RANGE MODELS AND ENSEMBLES ARE IN GOOD AGREEMENT ABOUT A LARGE

SCALE RIDGE DEVELOPING OVER THE WEST COAST FOR THE END OF THE WEEK

THROUGH THE BEGINNING OF NEXT WEEK. THIS PATTERN OPENS UP THE

EASTERN HALF OF THE COUNTRY TO COLD AIR INTRUSIONS WITH A GENERAL

LARGE SCALE TROUGH ACROSS THE EASTERN HALF OF THE COUNTRY.

 

the size of the east american trough days 8/10 is DEEP.  gonna be some issues with the florida orange crop if that verifies.  as it happens the op is also an outlier is nw europe - no sign of a surface and upper ridge where the op has it.

[The Enforcer]

Well for every forecast showing rain, there's another one showing snow. According to the latest NMM, http://www.meteociel.fr/modeles/wrfnmm.php?ech=54&mode=1&map=0 there is some snow in southern areas between 2am and 2pm on Tuesday and to a more limited extent between 5pm and 12am and then more significantly from 7am Weds until 12pm Thurs, which is the end of the run. This will inevitably change, but it at least demonstrates that snowfall is an option.

 

Is the development of precipitation Wednesday into Thursday being caused by the development of a Low Pressure system that drags in moisture from the channel? If so, this is the same occurrence that put this area in the metoffice red warning zone back in January 2010.

Edited January 18, 2015 by The Enforcer

[Snowy L]

I just can't see snow south of the M4 next tuesday/wednesday. Infact I can't see much low lying accumulations south of the midlands tbh. I think a lot of people are viewing the ECM with south snow tinted glasses on and are hopecasting more than anything..

 

Let's look at tuesday nights action first of all, the slider has a notable mild sector associated with it also in the south the precipitation isn't expected to be too heavy so any evaporative cooling will have little effect. I think transient snowfalls south of the midlands above around 300m..

 

 

I think the second event that arrives wednesday night will be further north than the precipitation chart I have posted shows, but still temperatures a bit too marginal down south ALTHOUGH a little slushy covering is possible around the M4 corridor or just a little south as slightly colder air filters in behind the sliding low.

 

.

 

Here's how I see it.

 

download (1).jpg

 

With a good 6-9 hours of persistant snowfall I expect 5-10cm in these areas above 50m, with upto 10-15cm above 300m. just away from the highlighted area perhaps 2-3cm.

 

download (2).jpg

 

I expect generally 2-5cm in the highlighted areas, although above 200m in northern ireland due to the encroaching milder sector. 5-10cm above 300m generally. With perhaps 1-2cm just south of the main warning area. Wednesday nights event shouldn't be as long lasting and intense as tuesday nights event although down towards the south coast/central southern england could be issues with intense rainfall.

 

That's how I see it too for Tuesday/Tuesday night too

 

 

 

My problem isn't with talk of snow restricted to the North and inland areas and I support that forecast, my concern is the met office thinking no meaningful snow will hit England, Wales and Scotland.

[IDO]

The thing is IDO NCEP expect troughing to become established over the eastern USA, its whether that becomes more amplified to help sharpen up any troughing to the west of the UK.

 

Below is the latest updated NCEP state forecast for New York:

 

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...

LONG RANGE MODELS AND ENSEMBLES ARE IN GOOD AGREEMENT ABOUT A LARGE

SCALE RIDGE DEVELOPING OVER THE WEST COAST FOR THE END OF THE WEEK

THROUGH THE BEGINNING OF NEXT WEEK. THIS PATTERN OPENS UP THE

EASTERN HALF OF THE COUNTRY TO COLD AIR INTRUSIONS WITH A GENERAL

LARGE SCALE TROUGH ACROSS THE EASTERN HALF OF THE COUNTRY.

 

 

As expected the op is a clear outlier:

 

 

 

 

 

The op has the US trough too deep and too cold compared to the mean. 

[bluearmy]

Well for every forecast showing rain, there's another one showing snow. According to the latest NMM, http://www.meteociel.fr/modeles/wrfnmm.php?ech=54&mode=1&map=0 there is some snow in southern areas between 2am and 2pm on Tuesday and to a more limited extent between 5pm and 12am and then more significantly from 7am Weds until 12pm Thurs, which is the end of the run. This will inevitably change, but it at least demonstrates that snowfall is an option.

 

Is the development of precipitation Wednesday into Thursday being caused by the development of a Low Pressure system that drags in moisture from the channel? If so, this is the same occurrence that put this area in the metoffice red warning zone back in January 2010.

 

uppers and thicknesses were much lower then. this is far more marginal and the set up isnt the same. that was a wave in the atlantic which developed and ran into the the mean frigid trough which we had over the country.

[Ali1977]

I just can't see snow south of the M4 next tuesday/wednesday. Infact I can't see much low lying accumulations south of the midlands tbh. I think a lot of people are viewing the ECM with south snow tinted glasses on and are hopecasting more than anything..

 

Let's look at tuesday nights action first of all, the slider has a notable mild sector associated with it also in the south the precipitation isn't expected to be too heavy so any evaporative cooling will have little effect. I think transient snowfalls south of the midlands above around 300m..

 

 

I think the second event that arrives wednesday night will be further north than the precipitation chart I have posted shows, but still temperatures a bit too marginal down south ALTHOUGH a little slushy covering is possible around the M4 corridor or just a little south as slightly colder air filters in behind the sliding low.

Good post, but why all this ramping when no Meto backing? Sliders just are not giving much accumulation in areas with uppers, lowers and dp low enough for snow and especially moderate accumulations....except maybe higher ground.

 

.

 

Here's how I see it.

 

download (1).jpg

 

With a good 6-9 hours of persistant snowfall I expect 5-10cm in these areas above 50m, with upto 10-15cm above 300m. just away from the highlighted area perhaps 2-3cm.

 

download (2).jpg

 

I expect generally 2-5cm in the highlighted areas, although above 200m in northern ireland due to the encroaching milder sector. 5-10cm above 300m generally. With perhaps 1-2cm just south of the main warning area. Wednesday nights event shouldn't be as long lasting and intense as tuesday nights event although down towards the south coast/central southern england could be issues with intense rainfall.

[bluearmy]

As expected the op is a clear outlier:

 

EDH100-216.gif EDH101-216.gif

 

ECH100-216.gif ECH101-216 (1).gif

 

The op has the US trough too deep and too cold compared to the mean. 

 

odd IDO, you call it an outlier upstream where it is the same pattern (mean will never be as deep as the op) and yet over nw europe where it is a different pattern, you dont reference ???

[snowking]

I just can't see snow south of the M4 next tuesday/wednesday. Infact I can't see much low lying accumulations south of the midlands tbh. I think a lot of people are viewing the ECM with south snow tinted glasses on and are hopecasting more than anything..

 

 

 

I'm not meaning this to come across in a negative way but perhaps if you have a WxBell subscription and take a look through the ECMWF charts there you will see that nobody is putting on rose-tinted specs, just reporting on what is shown from the 12z det (caveats already publicised)

 

If we take the ECM at face value using the IMO charts we can in fact see that most of the precip (at least anything significant precip wise) is either North of the border in to Scotland, or South of the M62

 

 

This is also reflected on the latest FAX charts, with the 'triple point' indicated pretty close to where the slightly more intense precipitation is noted above:

 

 

Perhaps to further underline the fact that I am not trying to be IMBY in any of my posts in this thread, I have highlighted that the precipitation never quite reaches locations such as mine.

 

Not wanting to sound like a stuck record but this was simply a face value analysis of a single ECMWF run, nothing added, nothing taken away.

 

Of course there will be many interpretations of the will it/won't it snow situation over the next few days, and FWIW my suspicion is that by the time we get closer to the event there will be very little in the way of precipitation around, but to suggest that members are posting hopecasts when they are trying to reflect what is actually presently modelled seems a little out of order to me.

 

SK

Edited January 18, 2015 by snowking

[fergieweather]

That's how I see it too for Tuesday/Tuesday night too

 

 

 

My problem isn't with talk of snow restricted to the North and inland areas and I support that forecast, my concern is the met office thinking no meaningful snow will hit England, Wales and Scotland.

???

No warnings have been issued *because areal (and accumulation) continuity has been totally lacking*. Now we are seeing that manifesting in UKV/UKPP and other output, you can expect Ops Centre to progress things over next day or so. There's been no requirement for early knee-jerking, irrespective of whatever certain people, prone to hyperbole and specious 'analysis', feed the Daily Express.

[nick sussex]

As expected the op is a clear outlier:

 

EDH100-216.gif EDH101-216.gif

 

ECH100-216.gif ECH101-216 (1).gif

 

The op has the US trough too deep and too cold compared to the mean. 

But synoptically in terms of overall pattern its not miles apart. The short De Bilt ensembles in terms of temps give support to the op and theres a colder cluster also by a few degrees. Of course that might be a slack flow surface cold scenario but De Bilt shows majority support upto day ten for no Atlantic encroachment in Holland.

[Snowy L]

???

No warnings have been issued *because areal (and accumulation) continuity has been totally lacking*. Now we are seeing that manifesting in UKV/UKPP and other output, you can expect Ops Centre to progress things over next day or so. There's been no requirement for early knee-jerking, irrespective of whatever certain people, prone to hyperbole and specious 'analysis', feed the Daily Express.

 

Ok thanks for explaining.

[chionomaniac]

odd IDO, you call it an outlier upstream where it is the same pattern (mean will never be as deep as the op) and yet over nw europe where it is a different pattern, you dont reference ???

Yes one would think that the first place to look would be over the BI where a weak positive anomaly is replaced with possible negative tilted negative anomaly!

Edited January 18, 2015 by chionomaniac

[IDO]

odd IDO, you call it an outlier upstream where it is the same pattern (mean will never be as deep as the op) and yet over nw europe where it is a different pattern, you dont reference ???

 

Up till T168 the mean and op are relatively representative. It is subsequent to that the US trough is over egged and I assume the algorithms went into overdrive distorting the downstream (UK) synoptic based on that deep op US trough. The computer models are highly volatile when there is a mistake upstream therefore the further away from the error the more significant the outlier; so although the long wave pattern in the US is similar op to mean, the over doing of that trough will have a knock on effect downstream hence the op and mean in the UK being vastly different. IMO.

 

Yes one would think that the  first place to look would be over the BI wheree weak positive anomaly is replaced with possible negative tilted negative anomaly!

 

I would argue that it is the upstream errors that has directly influenced the UK anomaly discrepancy.

[bluearmy]

the way the ecm ens mean and anomoly are shaping up, we may be doing this all again in about 10 days time though at the moment, it doesnt look to be such a sharp trough but a more general nw european one. (entire uk briefly gets north of the mean jet around day 10) that may even more difficult to pin down re detail !  eps extended continue with the cold zonal theme with the broad euro low anomolys maintained whilst the lowest are just nw of the uk. that looks to be a set up promoting runners into the base of the trough though thats what the upcoming set up appeared to be initially. rinse and repeat ??

[bluearmy]

Up till T168 the mean and op are relatively representative. It is subsequent to that the US trough is over egged and I assume the algorithms went into overdrive distorting the downstream (UK) synoptic based on that deep op US trough. The computer models are highly volatile when there is a mistake upstream therefore the further away from the error the more significant the outlier; so although the long wave pattern in the US is similar op to mean, the over doing of that trough will have a knock on effect downstream hence the op and mean in the UK being vastly different. IMO.

 

 

I would argue that it is the upstream errors that has directly influenced the UK anomaly discrepancy.

 

im a  bit confused - how can upstream over the states affect nw europe at the same time ??  there has to be a time lag - surely ?? 

[chionomaniac]

Up till T168 the mean and op are relatively representative. It is subsequent to that the US trough is over egged and I assume the algorithms went into overdrive distorting the downstream (UK) synoptic based on that deep op US trough. The computer models are highly volatile when there is a mistake upstream therefore the further away from the error the more significant the outlier; so although the long wave pattern in the US is similar op to mean, the over doing of that trough will have a knock on effect downstream hence the op and mean in the UK being vastly different. IMO.

 

 

I would argue that it is the upstream errors that has directly influenced the UK anomaly discrepancy.

I would argue that if it were the other way around and the op was cold outlier that it is highly likely that the upstream pattern wouldn't get a look in, in your post. After all, in your original post you didn't mention how the upstream pattern would affect the UK and the UK is the bit of the NH that the posters on this forum are interested in!

Edited January 18, 2015 by chionomaniac

[Yarmy]

the size of the east american trough days 8/10 is DEEP.  gonna be some issues with the florida orange crop if that verifies.  as it happens the op is also an outlier is nw europe - no sign of a surface and upper ridge where the op has it.

Sell, Mortimer! SELL!

(Apologies mods, couldn't resist ;-) )

[mulzy]

ECM ensembles look better in the short term but worse in the long term (as far as sustained cold weather is concerned) - I don't like the day 10 chart.  Rather positive NAO with the Russian block = UK Westerlies.  Let's hope for better tomorrow morning...

 

However, the De Bilt ensembles show significant variance after day 7.

 

Edited January 18, 2015 by mulzy

[SMU]

Now we are homing in on the Slider I would say the following counties are probably already out of the game

 

Suffolk, Norfolk, Lincs, Yorkshire (E ), Northumberland,Tyne & Wear, east Lothian-

 

On the cusp ( obviously eastern portions )

 

Kent,Essex,Cambridgeshire & Rutland...

 

S

Edited January 18, 2015 by Steve Murr

[Nick L]

This isn't the "will it snow in...." thread folks.