Model Output Discussion - 23rd Jan - 12z onwards

[Mucka]

JMA backing ECM with having the shortwave further East

 

 

and FI a big improvement on recent efforts.

 

Edited January 28, 2015 by Mucka

[bluearmy]

And this ECM op also has a very very cold Siberian high by day 7. Quite a few of the op runs have had this feature. if upstream is overplayed , this won't take much encouragement to become a player.

Is that based on the current ECM run?? if so a very very early judgement

Nope, it's based on all the op output today Marcus. (And u are in the sweet spot on that ECM op run)

[Banbury]

 

Kink in the Isobars show a disturbance running down the UK, plenty of cold air around for the ppn to be snow, I'd have thought

[Day 10]

192

[Banbury]

And this ECM op also has a very very cold Siberian high by day 7. Quite a few of the op runs have had this feature. if upstream is overplayed , this won't take much encouragement to become a player.

Nope, it's based on all the op output today Marcus. (And u are in the sweet spot on that ECM op run)

Cheers Blue

I probably have rose tinted specs on lol, thought it was all looking good for many ?

[TSNWK]

192

Toppled.....

[nick sussex]

If the upstream pattern on the ECM T192hrs and movement of the PV doesn't deliver some tasty charts following I would be shocked. Given where the outputs were a few days ago theres been some positive changes for cold potential.

[Severe Siberian icy blast]

Whilst it looks it may topple , the low pressure exiting the vortex to our northwest is held back between the time frames t144/168 , may be able to ridge North actually on the latter frames , but idealy we want a negative tilt to the trough rather than a positive one .

[Mucka]

Latest Euro 4 looks good for NW England.

 

 

But forecasts rain for Friday.

 

JMA is quite an interesting run all around and other than the obvious snow chances later it also has a little feature zip down the Western side of England and then across the SW Friday though uppers would be marginal

 

[Geordiesnow]

Must admit, whilst the detail for us looked alright on the ECM, I was slightly concerned about how less of an amplified ridge there was although it has recovered, I would rather the safer UKMO run personally mind, does have more potential in my eye.

[nick sussex]

Shame the ECM flattened the pattern out, with a bit more upstream amplitude that shortwave would have ejected further west. At T192hrs I thought we might get something better. Less overblown PV and I think we'd have seen some nice end.

[snowice]

Latest Euro 4 looks good for NW England.

 

 

But forecasts rain for Friday.

 

JMA is quite an interesting run all around and other than the obvious snow chances later it also has a little feature zip down the Western side of England and then across the SW Friday though uppers would be marginal

 

I would take the euro4 with a pinch of salt.It showed Snow in my location all day today still waiting?

[Mucka]

I would take the euro4 with a pinch of salt.It showed Snow in my location all day today still waiting?

 

Yeah even hi res ppn models need to be taken with a pinch of salt and remember what we currently see is a representation of shower activity over six hours not persistent ppn at that time point.

Edited January 28, 2015 by Mucka

[nick sussex]

It's hard to complain too much about the ECM, its cold right upto T240hrs, it almost delivers a good snow event at T216hrs. Considering a few days back it wanted rid of the cold much earlier we have seen across the outputs an effort to extend the cold.

 

Normally its the reverse so lots to be cheerful about this evening.

[snowice]

Yeah even hi res ppn models need to be taken with a pinch of salt and remember what we currently see is a representation of shower activity over six hours not persistent ppn at that time point.

You would think with all the super computers they would be able to get a more accurate picture of snow PPN.I suppose that's the nature of model watching.

[Iceberg]

if you combine the movements of EC and GFS re the building blocks, the chances of a very potent easterly at Day 10-12 look pretty good.

I well remember a few folks talking about this spell being a few days, then 5-7 days, now it looks good for a 10 day cold spell going from the models, with the potential for another week or 2 added onto that imho.

[Mark Neal.]

Anyone able to post some ECM precipitation charts if possible for Sun-Tues? Would be appreciated if at all possible to do so.

[nick sussex]

I should add re the ECM if it phases the northern and southern stream jets sooner then the shortwave which develops off the eastern USA will do so further west, this will tug the PV further nw then even if you get the blown up PV it will be further west which down stream will see a better picture.

 

 

These upstream interactions between northern and southern stream are difficult to handle for the NWP, commonly NCEP will discuss the uncertainty when theres the suggestion this might take place.

 

In terms of which outputs are likely to be right or wrong at T144hrs this comes down to the handling of a shortwave at T96hrs in the USA, the GFS/ECM are flatter and weaker with this, the result is the low to the west of the UK at T120hrs is further east, also less sharp so less WAA going ne, you'll note the most amplified solutions are the UKMO with the GEM very amplified.

Edited January 28, 2015 by nick sussex

[Nouska]

Anyone able to post some ECM precipitation charts if possible for Sun-Tues? Would be appreciated if at all possible to do so.

 

Here's the precip charts - just change the time stamp from the 120 in the link - available in six hourly increments.

 

http://brunnur.vedur.is/kort/ecm0125/2015/01/28/12/ecm0125_nat_msl_t850_6urk_2015012812_120.jpg

[damianslaw]

Third day in a row the ECM shows high pressure ridging in from the azores later next week and in towards Scandinavia. GFS showing an eventual similar evolution but at a much longer time frame.

 

Certainly nothing in the charts to suggest a swift return to strong westerlies/southwesterlies. Increasing signs that we will see more influence from high pressure, something we haven't seen for a long while.. and if we maintain a split jet with further amplification and a weakened PV then we could easily pull in more of a colder continental influence with heights building towards the north.

[bluearmy]

If anyone wants a good indication of how difficult it is to know what's likely just three to four days away in any detail, look at the three fax charts T96/T84/T72.

All issued within the last 24 hours and all different. Not for the first time, the T72 is closer to the T96 than the more recent T84!

.

Edited January 28, 2015 by bluearmy

[nick sussex]

Looking at the Duty Forecasters USA map for day 5 both the GFS and ECM 12hrs operational runs look too flat upstream:

 

Both the ECM and GFS have that low you can see over the eastern USA already offshore and weaker, the closest match for his map out of the major models is tonights UKMO, and if you take that forward to T144hrs his view supports the UKMO in terms of the low at the base of that troughing:

 

Day 5:

 

 

Day 6:

 

 

 

 

 

[weather eater]

If anyone wants a good indication of how difficult it is to know what's likely just three to four days away in any detail, look at the three fax charts T96/T84/T72.

All issued within the last 24 hours and all different. Not for the first time, the T72 is closer to the T96 than the more recent T84!

image.jpg.

image.jpg

image.jpg

You can see that in the BBC forecasts , they are not that far off now casting such is the MO uncertainty.

[TSNWK]

You can see that in the BBC forecasts , they are not that far off now casting such is the MO uncertainty.

Would the occluded front over the south east oh the 72hr fax produce snow? I can never work perception types on a fax chart..

Edited January 28, 2015 by TSNWK

[bluearmy]

Would the occluded front over the south east oh the 72hr fax produce snow? I can never work perception types on a fax chart..

Maybe but it will probably be gone tomorrow morning!