Model Output Discussion - Stormy Period Inbound...

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SATURDAY JANUARY 10TH 2015.

NEXT UPDATE SUNDAY JANUARY 11TH 2015 08:00

THE CURRENT GENERAL SITUATION A strong Westerly flow will extend to all areas today lasting through tonight before a warm front approaches NW Britain tomorrow.

MODELS-2 WEEK HEADLINE Continuing mostly unsettled with rain or showers at times. Near average temperatures will fall rather cold at times with some snowfall at times on all higher ground.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a very strong Jet Stream being maintained across the UK in the short term. It weakens steadily with time but remains sufficiently dominant to control the weather in what will appear to be a cold zonality spell of weather in a WNW to ESE moving flow close to SW England later.

GFS OPERATIONAL The GFS operational shows a very disturbed week to come with a very strong Westerly airflow blowing across the UK with fronts rushing East in the flow bringing spells of cold and showery weather with snow on hills. A deep Low close to midweek brings a brief spell of less chilly and wet weatehr and severe gales before a general cold and showery pattern develops late this week and next weekend as winds veer slowly North. Then the latter stages of the run are dominated by a pattern reset as the cold ridge collapses and Westerly winds with rain and wintry showers return.

THE GFS PARALLEL RUN The Parallel run is broadly similar in the sequence of events throughout the period with cold zonality the order of the day through the second week as further weaker depressions than of late maintain an Atlantic driven package of weather with the bias towards colder and showery conditions  overriding the short milder interludes with rain.

THE GFS CONTROL The GFS control run too shows the powerful storm in the middle of next week with it's attendant very wet and windy weather. The sequence thereafter remains Atlantic driven with plenty more Low pressure shown crossing East over or to the North of the UK with spells of cold and showery weather with short milder interludes when rain and gales are possible.

THE GFS CLUSTERS The GFS Clusters show a mixed viewpoint this morning with 35% split each between a brief Northerly followed by a toppling ridge or milder Westerly winds returning over the UK with rain at times. There is a 10% cluster which show a direct Northerly while the other 20% show a cold zonality pattern in mostly NW winds.

UKMO UKMO continues to project a very unstable and cold Westerly flow across the UK next week. This type of pattern will deliver cold conditions at the surface with strong Westerly winds and spells of wintry showers for all Northern and Western areas in particular. A new depression midweek would bring a short mild and particularly wet and windy spell before the cold and showery westerly winds sweep back over all areas later.

THE FAX CHARTS The Fax Charts shows a continuing changeable theme surrounding two types of weather. One being mild, windy and occasionally wet weather and the other cold, windy and showery weather with some snow on hills across the North, the latter more likely later next week.

GEM GEM today shows very disturbed weather across the UK through the next 10 days culminating in a pattern change by the end of the run. Through Week 1 as is documented by other models Atlantic Low pressure areas crossing East over or near the UK bring spells of rain, strong winds and variable temperatures, sufficiently cold for snow at times over many hills especially later in the week. Then as we move through next weekend and the start of the second week rising pressure over the Atlantic and then to the North of the UK tilt winds first Northerly and then Easterly and with Low pressure caught up in this colder air some sleet or snow is expected at times across England and Wales in particular..

NAVGEM NAVGEM reflects no end to the Westerly flow with sometimes mild, wet and very windy conditions over the UK mixed with colder periods with showers in between with little change in overall synoptics shown one week from now. It too shows another powerful storm system across the UK midweek exacerbating the unsettled and stormy theme.

ECM ECM this morning also shows a lot of strong Westerly winds with spells of rain and wintry showers to come for all especially across the North. As with all other models it too shows a major storm system midweek with very wet and windy weather for all for a time. Then cold and showery weather returns before a brief cold ridge crosses East next weekend ahead of more Atlantic domination returns from Low pressure North of the UK with rain or wintry showers at times.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart shows a rather chilly prospect under cold zonality this morning with a WNW flow the most likely option with Low pressure to the North and a trough over Europe driving spells of rain followed by colder conditions with wintry showers at times in from the West and NW..

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend this morning remains quite Atlantic driven overall with a brief drier interlude next weekend ahead of returning Atlantic Westerlies soon afterwards.

MY THOUGHTS The strong Jet Stream remains totally in control of the weather across the UK for another week at least. Further marked storm systems, especially the one midweek look like delivering some nasty weather with some disruption from high winds, heavy rainfall and maybe snow too later as it exits away NE by the end of the week. The cold zonal spells which will dominate other times will in themselves bring some snowfall to quite modest levels at times and it will often be quite wintry in the NW. Then once we leave this week and move into next weekend there is some support for the Jet flow to be disrupted as a ridge of High pressure edges into the UK from the West, damping down the wintry showers and allowing a period of drier and frostier type weather. However, almost without exception this looks unlikely to last as the Atlantic bandwagon regroups to the North and NW of the UK with further rain and strong winds alternating with colder showery spells look the most likely option to develop again through the second week. The GEM operaional does fly the flag for the cold fraternity this morning rising pressure sufficiently to create a High pressure cell North of the UK with a cut off cold Low over the UK bringing the risk of snow and cold conditions but this scenario does look rather isolated in an otherwise Atlantic dominated pattern. We are now at the point where the Northern hemisphere has reached it's coldest point and even Westerly winds over the UK can deliver snowfall in places and I wouldn't be surprised if some places even in the South don't at least see something of snowfall over the next week or so, mostly in the form of wintry showers but full of interest nonetheless. However, if it's something rather longer lasting cold rather than fleeting your after then there still seems little overall signs that anything from an European direction is likely antyime soon with as of the rest of the Winter so far North being our best direction to obtain fleeting glimpses of Winter in a mostly NW flow as that old friend the Azores High while being less influential over the upcoming period remains a thorn in the side for anything noteworthy to develop and sustain.

[nick sussex]

Morning all

 

This morning the GEM stands alone in its fightback against the Atlantic, the rest fold like a cheap suit.

 

The ECM is less amplified, both GFS's sing from the same hymn sheet with even less excitement on offer. How you view the outputs will depend on your location and expectations.

 

It's a case of being happy that at least theres a few PM shots on offer or being rather frustrated that we can't even manage a more Arctic based flow with toppling ridge towards Scandi.

 

In terms of some of the differences between the outputs there is still some uncertainty as to events in the eastern USA with stream interactions, and phasing which still gives some room for changes.

 

You'll see that at T240hrs the ECM has removed the PV chunk from ne Canada and moved it eastwards, the problem across both this winter and last is that its been like pulling teeth to actually rid ourselves of the PV in that location, it might get modelled but doesn't verify.

 

There are still some more interesting GEFS within T240hrs and I for one hope that we can see one of these get picked up by the operationals because to be honest whilst the outputs might deliver a little snow they really are the leftovers at the buffet table.

 

If we see some decent cold with non-marginal snow modelled within T144hrs I may get interested but until then I'm going to remain in the underwhelmed camp

Edited January 10, 2015 by nick sussex

[iand61]

BBC forecasts aren't making much of this midweek storm at the moment.

Maybe they think it is either outside the reliable time frame or just not worthy of a mention until nearer the time but all talk seemed to be spells of strong winds up to mid week only and nothing said about the days beyond that.

One things certain though, no changes in models by Monday and it will be creeping into the forecasts as this has the potential to be a serious, life threatening event.

[Frosty.]

From what I can see we will be spending lots of time in polar maritime / arctic air with rapid reloads all the way through FI. The Gfs 00z op run only shows brief milder incursions, it's mostly cold and very unsettled with a risk of sleet and snow, especially in the north and at elevation but a much colder pattern than anything we saw last winter. The winds are going to make the headlines next week, severe conditions at times along with heavy rain, sleet and wet snow..we have it all this morning, rain, hail, sleet, snow, thunder, ice, frost, severe gales to storm force..even a kitchen sink or two.

Edited January 10, 2015 by Frosty.

[JoeShmoe]

Morning all

This morning the GEM stands alone in its fightback against the Atlantic, the rest fold like a cheap suit.

The ECM is less amplified, both GFS's sing from the same hymn sheet with even less excitement on offer. How you view the outputs will depend on your location and expectations.

It's a case of being happy that at least theres a few PM shots on offer or being rather frustrated that we can't even manage a more Arctic based flow with toppling ridge towards Scandi.

In terms of some of the differences between the outputs there is still some uncertainty as to events in the eastern USA with stream interactions, and phasing which still gives some room for changes.

You'll see that at T240hrs the ECM has removed the PV chunk from ne Canada and moved it eastwards, the problem across both this winter and last is that its been like pulling teeth to actually rid ourselves of the PV in that location, it might get modelled but doesn't verify.

There are still some more interesting GEFS within T240hrs and I for one hope that we can see one of these get picked up by the operationals because to be honest whilst the outputs might deliver a little snow they really are the leftovers at the buffet table.

If we see some decent cold with non-marginal snow modelled within T144hrs I may get interested but until then I'm going to remain in the underwhelmed camp

Good summary Nick and ties in with what Fergie was saying last night in that the EC clusters continued to show a strong jet and deep depressions right through to the end of the month. Current pattern looks like being maintained for a while it seems with the PV perma rooted in NE Canada

Personally find this far more interesting than last year or weeks of faux cold from stagnant HP cells

Edited January 10, 2015 by JoeShmoe

[IDO]

A very windy week for many upcoming with the well signposted storm beginning to look potentially ominous. The track remains fluid but usually they correct towards Scotland but we may not have a better idea till Monday. 

 

The GEFS are still confident of the zonal pattern continuing till after D12, when the PV over Canada loses it's bite and the flow relaxes. At the moment there is still a good signal late in FI for a disrupted PV with plenty of NH MLB's potential. Too early to say how the UK fits in that. The op. P and Control:

 

 

No clear pattern as you would expect at that range though the Control fits in with my ideas of a slackening westerly flow.

 

From D3-16 London has it's mean 850's below 0c, averaging about -3c. The average at this time of year is about -1c so although nothing very cold it is more seasonal:

 

Aberdeen: 

 

Looking at Aberdeen and again about 2c below the 30 year average so nothing dramatic by any means. It should help the January CET lower as it currently sits at around +3c 

 

No point looking at ECM D10 charts as with the upcoming changes to the current pattern I expect it to do its usual. Looking at the Dutch ens from the 12z run you can see the op and C going the colder route with a small cluster with the main cluster showing just an average set up:

 

 

The 0z and The Control flips to mild (outlier territory). Its a poor trait of the ECM: 

 

The mean ties in with the slackening of the flow with little in the way of blocking by D10:

 

 

As for GEM it is useless in these circumstances as it is worse than ECM with phantom height rises as the PV disrupts.

 

So PM certainly a lot more influential than TM shots over the foreseeable but not much of wintry note south of Birmingham but the usual suspects favoured north of there, though mostly showery rather than heavy frontal dumpings.

Edited January 10, 2015 by i'm dreaming of...

[bluearmy]

Couple of points - looking at the extended eps , getting the trough far enough sw to keep the uk n of the PFJ looks unlikely so Atlantic disturbances in the base and running into the main sceuro trough would provide the best chance of snowfall in the south of the uk. I'd say the pattern pulls far enough southwest to allow that between the 21/23 rd jan. that's outside the higher res ECM eps so could change as it's quite fine detail to take from a mean/anomoly at that range.

Also, de bilt goes warm because of a west euro ridge late on. That doesn't really fit with the mean/anomolys.

Edited January 10, 2015 by bluearmy

[BLAST FROM THE PAST]

A fairly short update - pending some longer term atmospheric uncertainties which will determine whether a colder trend becomes something of greater significance in the longer term or not

 

.

 

There is an impetus just beginning, which I think will be much harder to reverse than we have seen so far

 

 

Hi Tamara

hopefully this time the 'big plan' will come to fruition for everyone's sanity?  I must admit though the spell we are now in and likely to experience next ten days floats my boat enough, especially with a generally getting colder theme.

 

Yes this impetus 'needs' to be the one and of all the ones thus farth is winter imo it wlll be the likely strongest signal for winter.  Jan was signalled to be on mild side generally [using my method but the eastern block being absent] with the shift occurring late Jan [last week as a guestimate of cold pattern emerging with effects of the SW showing]...I think models that show/showed deep cold set up by 20th mark are/were too quick....but the trend is good.  PV to shift to 'our' side of the Atlantic?

 

BFTP

Edited January 10, 2015 by BLAST FROM THE PAST

[Buxton Codge]

A generally very unsettled spell of weather over the next 10 days. Sadly still no sign of any snow for the majority of England for Wales away from higher ground. The 0Z ECM ensembles show the cooling trend.

 

[knocker]

Looking at the extenfed GEFS and EPS mean anomslies.  at T360.

The ECM has the usual Hudson vortex with a trough east of NE Canada. Ridge SW of the UK with the Iceland trough orientated SE over NW Europe. Ridge eastern Pacific. The flow is a tad meridional but up to T288 the cooler 850mb flow is WNW from Canada leading to some negative anomaly temps in the UK These tend to back after that with more influence from the Azores HP. So the synoptic analysis is LP to NW and HP to SW and a lessening of the very unstable westerly flow.

 

The GFS has a more prominent mid Atlantic ridge and a slightly different orientation of the European trough so surface wise the eastern Atlantic is is more influenced by the HP with the LP more to the east leading to benign NW over the UK. Again a noted disruption of the Atlantic train.

 

So certainly an indication of change from the nasty progression of the depressions and no sign of any lengthy cold spells. Rather more the opposite.

Charts courtesy weatherbell.

Edited January 10, 2015 by knocker

[winterof79]

Sorry Knocker but I struggle to understand what your interpretation of the opposite of "no lengthy cold spells"is?

Mine would be lengthy mild spells.

[johnholmes]

A more detailed post than the one I gave last evening.

 

I think it is quite clear that  a colder overall pattern is developing, the anomaly charts, links below, have been reasonably consistent on this over the last 2-3 days. Again similar to their over/post Xmas predicted change, it was the ECMWF-GFS version that first gave this idea. In the 5 years I have made daily notes on the 3 it is usually NOAA at 6-10 sometimes even the 8-14 that picks up pattern changes first. Although it may be a moot point if it is actually a pattern change. To me it is a sufficient shift in the long wave pattern to say it is. Time will tell if it is a major one or a minor one.

 

Above doubt is that the 500mb flow WILL change from its westerly, twitching a touch south and a touch north of to a touch south of west over the past weeks or two, to a quite definite north of west direction. This will mean that ‘most’ of the time fairly cold and relatively deep Polar Maritime air will affect most of the country, at least in the 6-10 day time scale. So far the 8-14 NOAA does not indicate this moving into a more northerly Arctic air mass. There is still no signal for a general height rise Iceland to Greenland for this to look feasible. It may develop but it certainly is not showing yet.

NOAA 6-10 and 8-14, also have a read of the NOAA forecasters assessment, they can give some guide to what the main wave pattern is likely to be in their view. This can sometimes help in giving a bit more guidance for the eastern Atlantic/western Europe area.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

 

ECMWF-GFS output

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

Looking at the synoptic models and those that show this idea out to at least 240h are pretty close to the overall upper pattern. The surface detail, troughs, even the much loved (!) short wave features are not discernible this far out on the anomaly charts but remember it is the upper air that is the major cause of these not the surface, although like much in meteorology there are times when it is not easy to separate one from the other. How much snow, where, when again is for the synoptic models at no more than 72h and more likely 12-24 h to give this detail.

Below is the link on Wetter which gives a quick glimpse of how GFS and ECMWF suggest things may look at 240h

http://www.wetterzentrale.de/topkarten/fsecmeur.html

As you might expect with small features running in this flow then timing is going to be problematical at this time range, hence the differences between the 2 GFS versions and ECMWF, but all 3 really following the idea suggested above.

 

 

Turning to further out than 10 days and we can see how the AO and NAO are looking although they are not drivers but indicators of what the atmosphere is being suggested by the other outputs. The link below show AO, NAO and MJO data (actual and forecast)

http://www.cpc.ncep.noaa.gov/index.php

I tend to mistrust AO, NAO and PNA much after about 7 days, as mentioned they are really only showing what the synoptic models are giving and are as likely to be incorrect at the range of much beyond about 7 days.

Turning to the GFS MJO it currently is in phase 5/6 in reasonable amplitude. The link below shows how this tends to fit in at 500mb in January

http://www.americanwx.com/raleighwx/MJO/MJO.html

Both of them show much as one should expect, that is a 500mb pattern not that far removed from what we have had over the past week or more.

What of its forecast?

This suggests with a lower amplitude but possibly still sufficient to have some effect on northern hemisphere weather edging into phase 7, follow the link above to see what it suggests for the 500mb pattern?

It does suggest a colder upper air pattern with ridging occurring N-E-SE of the UK with –ve heights out west.

That leaves the problem what sort of surface flow might get IF this is correct, and is the upper pattern likely to be that? This is where I leave the stage as I have not enough knowledge to be able to make sensible and constructive suggestions on this. I suspect on balance it may help for the colder spell to be longer than 5-7 days, possibly we MIGHT be looking into 10+ days and of course in that time the feed backs from such a situation will have impacts on how any of the teleconnections will then show.

So enjoy the colder spell and keep your fingers crossed that in that time some snow may fall on you, enjoy any frosty mornings and see what old man weather actually does. He may well make a complete fool of me but never mind.

[Captain Shortwave]

Seems to me the key is to develop as deep a Euro trough as possible over the coming weekend as this will help re-enforce future spells of cooler weather down the line. So eyes on Thursdays storm and the pattern beyond this point.

The GFS (P) still has the storm

 

A decent colder northerly develops for next weekend brining snow showers to coastal areas exposed to the north/north westerly wind

 

No doubt about temperatures falling a little below average from Friday onwards (calling that as temperatures oscillate around the average mark until that point). Just a question of how cold and how dominant the colder spells are as opposed to milder TM incursions.

 

The operational makes less of the storm and the following colder spell before developing a more settled pattern in low resolution.

Edited January 10, 2015 by Captain shortwave

[knocker]

Sorry Knocker but I struggle to understand what your interpretation of the opposite of "no lengthy cold spells"is?

Mine would be lengthy mild spells.

 

Short cold spells?

[Winter Cold]

Morning everyone.

 

Well I came in here and just read the updates, and expected a horror show when i went to view the models. A few posts have mentioned a step away from cold. I was delighted then when i viewed the ECM, which out of 11 frames has 10 of them with the UK in sub zero uppers, and a lot of days where its -6 to -8!!!!!  Its still looking excellent for snow chances for a lot of the country next week, even if you do work on the assumption of Birminghan north. A few examples:

 

 

 

Also, running through GFS, that spends a lot of time with a blue picture for the UK on 850 view throughout the run aswelll!

 

Lots of chances this week for snow id have thought looking at the charts on offer. Chin up everyone

Edited January 10, 2015 by Winter Cold

[knocker]

Speaking entirely from a personal perspective I think the track and depth of the mid week depression far more important than a few snow flakes.

[Banbury]

http://modeles.meteociel.fr/modeles/gfs/runs/2015011006/gfsnh-0-168.png?6

 

Disturbance in the NW running down the UK

 

http://expert-images.weatheronline.co.uk/daten/proficharts/en/2015/01/10/basis06/ukuk/rart/15011706_2_1006.gif

 

Ends up with wintry ppn IMBY

 

JFF of course

[h2005__uk__]

Speaking entirely from a personal perspective I think the track and depth of the mid week depression far more important than a few snow flakes.

 

Agreed. It'd be more useful (and meteorologically interesting) to focus on that for now.

[kev238]

Indeed

The gfs parallel has exceptionally strong wind gusts for a large portion of England and Wales with some white shading indicating gusts upwards of 80-90 mph. Yet the focus seems to be on the chance of a frost or two and the chance of a fleeting snow shower

The old gfs paints a less severe- given the parallel takes over on the 14th ( the day the Storm arrives on these shores) it will be interesting to see which is correct

[Banbury]

The title of this thread suggest the storm can be discussed as well as any wintry potential. Perhaps there should be a separate discussion

[TonyH]

Models have moved away from last nights colder solutions shown especially by GEM. Looks like there's too much energy in the jet to allow any significant pm incursions.

Fairly typical westerly pattern for the foreseeable unless we get help from a SSW or wave 2.

Next Friday to Saturday a most untypical westerly with fairly widespread wintry showers and some longer spells of rain, sleet or snow:

Edited January 10, 2015 by TonyH

[Polar Maritime]

As long as it's Model related, Anything is open to discussion in here come rain or shine..  

Edited January 10, 2015 by Polar Maritime

[IDO]

Yes it appears the storm timing has now been resolved on the GEFS. It should be over us between T114 and T120. The intensity can be measured by the mean and it would appear that it will be severe:

 

 

As for its track, the GEFS have differences: 

 

However the  eye tracking through Scotland with the gale force winds on its S/SW edges.

 

Further out on the 06z there is little change as the charts continue to show potential but no sign of blocking or sustained cold right out till D14. Op and P at  D16:

 

Edited January 10, 2015 by i'm dreaming of...

[Dancerwithwings]

I'm on the understanding that as long as it's model related you can post whatever you like and nothing has any importance over any other whether it's wind or snow.

 

The GEM for the last few days now as the low further south.

 

Edited January 10, 2015 by Dancerwithwings

[TonyH]

Agreed. It'd be more useful (and meteorologically interesting) to focus on that for now.

Well I think a dual focus on snow chances as well as the storm is possible