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

[Tamara]

Totally agree with you Dave weather can change extremely quickly and I'm thinking wrt Tamara's post yesterday that certain elements are in favour of us it go into a cold spell as we move into feb. May be just a few other things need to go in our favour to complete the jigsaw!!

That was very much what I said this morning - most particularly the second sentence.

 

Besides, the process of making forecast predictions (or just simply attempting explanations and making suggestions as I try to do about the way ahead) are on any level, whether amateur weather enthusiast or professional, never complete and never ending - because the atmosphere and weather patterns never stop moving and are in constant flux.

 

I know since it was becoming apparent through December that patterns were becoming cyclically unfavourable in our Atlantic sector, I have repeatedly been posting about a few of the major issues which have emerged as to why this winter has not been meeting our former expectations (here on net weather at least). On that basis some of the more bullish suggestions for cold every now and then, which have attempted to be well reasoned, have always been tempered against these mitigating and thus far, overriding factors.

 

I think that there are many on here who will have obviously been very frustrated by last winter and this one (so far) in terms of any elusive sustained cold pattern -  but surely have had much to learn from it all. The general quality of experience and knowledge on these threads has grown substantially over the time I have been reading and learning from it myself.

 

That in my opinion is the most important thing  .

[fergieweather]

EURO4 highlighting great uncertainty for Wednesday snowfall.

12z accumulation

Yes indeed. Plus differences between Euro4 and Euro4 Parallel; plus now 18z UKMO-GM. However, Tues night reliably the period with greatest chance of some lower-level snow in parts of south (and Weds AM for SE: UKMO cite 40% probability e.g. Heathrow/Gatwick, but low (30%) likelihood troublesome... Chilterns perhaps at greater chance, especially with 18z GM widening the PPN envelope in SE through colder air). However, forecast remains under constant refinement and the broad theme (snow *mostly* Midlands northwards but some in south) is now where the nitty-gritty detail is being sought-out. Tricky one. Edited January 20, 2015 by fergieweather

[shaky]

Yes indeed. Plus differences between Euro4 and Euro4 Parallel; plus now 18z UKMO-GM. However, Tues night reliably the period with greatest chance of some lower-level snow in parts of south (and Weds AM for SE: UKMO cite 40% probability e.g. Heathrow/Gatwick, but low (30%) likelihood troublesome... Chilterns perhaps at greater chance, especially with 18z GM widening the PPN envelope in SE through colder air). However, forecast remains under constant refinement and the broad theme (snow *mostly* Midlands northwards but some in south) is now where the nitty-gritty detail is being sought-out. Tricky one.

sorry ian could you elaborate further if you dont mind about tomorrow nights snowfall and what those models that you have mentioned are showing!! I've never seen such a difference in the Model output at such a short time frame! ! Gfs has everything east! Euro4 has everything west and ecm has the snowfall slap bang in the midlands! ! What is going on?

[john mac]

Yes indeed. Plus differences between Euro4 and Euro4 Parallel; plus now 18z UKMO-GM. However, Tues night reliably the period with greatest chance of some lower-level snow in parts of south (and Weds AM for SE: UKMO cite 40% probability e.g. Heathrow/Gatwick, but low (30%) likelihood troublesome... Chilterns perhaps at greater chance, especially with 18z GM widening the PPN envelope in SE through colder air). However, forecast remains under constant refinement and the broad theme (snow *mostly* Midlands northwards but some in south) is now where the nitty-gritty detail is being sought-out. Tricky one.

That's does look like it's going to be a cut off low. You can see the potential for more precipitation to be of snow. Also could be a small window for convection off the North Sea. Maybe???

[Trom]

Whilst it's late and so I'm unlikely to derail the thread too much with an off topic post, could I ask why the strat thread is not in the models area of the site?  It seems to me that it would be better pinned next to the MOD thread to make it easier to flick between developments in the strat and trop.  It just seems that it's odd that the strat thread lurks in "Weather Discussion and Chat" rather than "Forecasting Model Discussion".

 

A very minor gripe - I know.  As a relative newcomer to this site I managed to miss the strat thread as I would have never thought of looking for it in its current location.

 

Currently I'm still developing my understanding of both strat and trop modelling but in order to understand some of the posts on both threads you need to be able to cross reference.  For example Tamara's mountain torques have a direct upwards effect on the strat.  Sorry Tamara if I keep mentioning your torques but your explanation of Rossby wave breaking was really helpful in understanding the interaction from trop to strat and suddenly a lot more of your posts make sense to me.

 

We genuinely have some amazing posters on this site.  I'd like to give a little kudos to Gibby, Holmes and Tamara on this thread and Recretos on the strat.  All of you have advanced my understanding more than you know.  Also Ian F has good posts (albeit it's easier to play poker when you know the other player cards but they don't know yours!).

 

Sorry Ian not a dig at all but really just wish we had the detail of the GFS on the other models.  I guess pay up or shut up.

[Timmytour]

Yes indeed. Plus differences between Euro4 and Euro4 Parallel; plus now 18z UKMO-GM. However, Tues night reliably the period with greatest chance of some lower-level snow in parts of south (and Weds AM for SE: UKMO cite 40% probability e.g. Heathrow/Gatwick, but low (30%) likelihood troublesome... Chilterns perhaps at greater chance, especially with 18z GM widening the PPN envelope in SE through colder air). However, forecast remains under constant refinement and the broad theme (snow *mostly* Midlands northwards but some in south) is now where the nitty-gritty detail is being sought-out. Tricky one.

Thanks Ian for the usual informative stuff. But a word of caution....don't go using the phrase "nitty gritty" on TV or radio or you'll have the Political Correct Police after you! http://www.phrases.org.uk/meanings/nitty-gritty.html

[Eskimo]

Could be quite a bit of snow for the Humber on this run, with about 6-7cm. Most snow over the pennines of course. Increased risk of a Humber streamer affecting East Riding and Northern Lincolnshire once the easterly winds kick in with -7C 850's and warm(ish) SST's.

Edited January 20, 2015 by PerfectStorm

[metrosnow]

 

 

 

Not looking brilliant this morning folks, but don't despair. Remember the date everyone. 26th February 2015. Coldies heaven, courtesy of the ever reliable CFS.

Edited January 20, 2015 by metrosnow

[winterof79]

Thanks Ian,

That excellent summary is worth more than a hundred pages of waffle and hope casting you read on here!

No offence intended to any individual but I think we are all guilty of seeing what we want to see and Ian's 'View from the Bridge' is very welcome.

I have to say the MetO has earned it's funding in the last 12 months with mostly superb short, medium and long range forecasting.

Andy

No hopecasting from me.The GEFS remain interesting in to early Feb again this morning,I can't post charts but my post from last night has the links.The HLB not on our side of the Arctic but the PV is split our side due to it.All in the model output.I remain very interested as the GEFS have raised the bar recently.

[Polar Maritime]

Yes the turn of the Month remains of interest this morning, With the GFS showing heights pushing up into Greenland drawing a cold Northerly of sorts.

 

Edited January 20, 2015 by Polar Maritime

[TEITS]

As others have mentioned the signs look promising right at the end of the month beginning of Feb. As I mentioned last night it appears we need to look N rather than E.

 

Just look what happens on the GEFS control from a N Hemisphere perspective. I have chosen this run because the same trend keeps emerging.

 

Note the PV.

http://modeles.meteociel.fr/modeles/gens/runs/2015012000/gensnh-0-1-192.png

 

Watch how we see a split PV

http://modeles.meteociel.fr/modeles/gens/runs/2015012000/gensnh-0-1-228.png

http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-1-252.png?0

 

Look at that cross polar flow!

http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-1-288.png?0

 

I realise I am always promising jam tomorrow! However at least this time im not predicting an Ely lol. Also the period of interest isn't deep F.I and at the moment is consistent in the GFSOP/GEFS control.

 

So at the moment the summary from me is any milder weather appears shortlived before we intially see bursts of NW,lys which could potentially be replaced by a much colder more sustained N,ly.

Edited January 20, 2015 by TEITS

[Eugene]

As others have mentioned the signs look promising right at the end of the month beginning of Feb. As I mentioned last night it appears we need to look N rather than E.

 

Just look what happens on the GEFS control from a N Hemisphere perspective. I have chosen this run because the same trend keeps emerging.

 

Note the PV.

http://modeles.meteociel.fr/modeles/gens/runs/2015012000/gensnh-0-1-192.png

 

Watch how we see a split PV

http://modeles.meteociel.fr/modeles/gens/runs/2015012000/gensnh-0-1-228.png

http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-1-252.png?0

 

Look at that cross polar flow!

http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-1-288.png?0

 

I realise I am always promising jam tomorrow! However at least this time im not predicting an Ely lol. Also the period of interest isn't deep F.I and at the moment is consistent in the GFSOP/GEFS control.

 

So at the moment the summary from me is any milder weather appears shortlived before we intially see bursts of NW,lys which could potentially be replaced by a much colder more sustained N,ly.

 

That chart is a thing of beauty, absolutely mouthwatering.

 

I dare to say maybe the russian high retreating eastwards is a blessing in disguise.

[mountain shadow]

Yes the turn of the Month remains of interest this morning, With the GFS showing heights pushing up into Greenland drawing a cold Northerly of sorts.

 

The problem there of courseis the PV segment over Greenland. As wwe get closer to T+0 shortwave energy will appear cutting of the Northerly quickly

[IDO]

There is a very small cluster of GEFS in FI showing some sort of Atlantic heights but I would expect that in a pattern where the PV is mobile and there is phasing between each low from the NW. I suspect that is just background noise and until it's signal grows I suggest it will remain that. Though because of these baby troughs we will see the jet slip south so I would be hopeful of a colder zonal flow again, favouring the NW/W coasts and high ground for wintry weather.

 

The means at D13 and D16:   

 

The MJO loses its drive for the next week as it goes into the COD but maybe returning in phase 5:

 

 

 

However it is not all doom and gloom. With another episode of strat warming moving towards the reliable (for the strat that is) there must be a chance that the cumulative effect on the PV will this time be more effective for some real HLB'ing. This spell of wedges of highs were always going to struggle longevity wise. So enough to maintain the interest in the medium term despite the Met's obvious caution re a Major SSW.

 

So it looks like we will have at least a week of zonality after this cold spell as more energy spills from the Siberian vortex towards the NE Canadian one, balancing it up. At D10 none of the models suggest that either vortex will become the more dominant and that is why I don't expect anything like last year's raging zonal onslaught. In the shorter term hopefully snow for some in the next 36 hours.

Edited January 20, 2015 by i'm dreaming of...

[bluearmy]

Couple of points

A) my analysis of the ec32 for day 24+ wasn't good (note to self not to do this when you're trying to get to bed)

Anomolys to the south and over Europe in general are on the high side.

B) the background noise on a coldish trough n Europe as head through the later stages of week 2 getting very loud. Anomolys on gefs in good support now. ECM mean due shortly though this held the lowest a bit further west.

Either way, if this theme continues, plenty of wintry looking output on view over the next week though with low heights on meteociel, these always look colder than they actually are! the phrase of choice could soon become 'secondary features'!

[BlueHedgehog074]

Looking at the models and it looks as though the next few days will remain chilly. Some of those who are after wintry weather could be in for a snowy treat today. The band of precipitation over Wales and Ireland will slowly move East throughout the day in response to an area of Low Pressure out West tracking East/South-East. The precipitation falling as sleet and snow over the hills, although some of it could extend to lower levels at times, particularly over the South of Northern England and into the Midlands, where the front engages with the cold air over the UK. This being helped out by the fact that the front should reach these areas during the evening and night period. But snow possible for Wales earlier on today, too. The models do show a wedge of less-cold 850 hPa temperatures associated with the system, so possible some places, especially those with elevation below 100 meters could just see more in the way of rain or sleet instead. Where snow does fall, some accumulations are possible, most especially over the hills and peaks. It's then possible the wintry precipitation over central or Eastern areas (if it does make it far enough to the East) could become showery tomorrow with perhaps some brighter spells showing up for places during the afternoon. Some frost and icy conditions possible for places where skies clear overnight. Thursday looking to be another chilly day, but should be mostly dry and bright for most as the models show a shallow wedge of High Pressure over the UK linking up from the Azores and Scandinavian High Pressure systems.

(quick example from the GFS)

The odd isolated shower could be possible, though, towards the South-East with perhaps the odd showery piece of precipitation towards the far North-West. The weather then looks as though it will turn milder for most during Friday. A Low Pressure system from the Atlantic looks to try to beat up the Scandinavian block and break through further East with Westerly or South-Westerly winds returning. This likely to be associated with a spell of rain and hill snow spreading West to East through the British Isles.

While their doesn't look to be any real stormy conditions around this week, it looks as though it could provide some varied weather for places, and apart from Friday, staying mostly on the chilly side with wintry weather for some places. And some frost and/or fog at night.

[Timmytour]

 

 

 

Not looking brilliant this morning folks, but don't despair. Remember the date everyone. 26th February 2015. Coldies heaven, courtesy of the ever reliable CFS.

That's the 78/79 evolution we're looking for!

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY JANUARY 20TH 2015.

NEXT UPDATE WEDNESDAY JANUARY 21ST 2015 08:00

THE CURRENT GENERAL SITUATION A weakening occlusion will move erratically East across England and wales later today, tonight and tomorrow with slack winds following tomorrow.

MODELS-2 WEEK HEADLINE Changeable with rain at times and some snow on Northern hills. Occasional frosts at night with temperatures in general becoming close to average for late January.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows the flow flattening over the coming days as the trough over Europe lifts out steadily. The Jet Stream then looks like steadily strengthening somewhat on West to East flow just to the South of the UK and Eastward through Europe.

GFS OPERATIONAL The GFS operational today shows the end of the cold and slightly wintry period by the weekend as more progressive Westerly winds cross the UK from the West. Temperatures will still fluctuate up and down somewhat as successive cold fronts cross over each bringing their own version of cloud and rain and in the clearer spells there will be some night frosts at times and snow on Northern hills will also occur at times. High pressure to the South of the UK may keep the heaviest rain away here especially next week.

THE GFS CONTROL The GFS control run is very similar in sequence of events over the whole period with less cold air filtering across the UK at the weekend but with some clearer intervals under ridges of High pressure still giving rise to frost at times by night especially over the South. In the second weel cold zonality takes much firmer command with some intervention of very cold Northerly winds with widespread wintry showers across all of the UK at tomes and sharp frosts at night.

THE GFS CLUSTERS The GFS Clusters today look like siding with cold polar maritime air across the UK in the latter half of the output with a much as 60% of the clusters suporting synoptics delivering cold zonality conditions with rain or wintry showers at times in quite strong WNW winds.

UKMO UKMO this morning shows less cold Westerly winds well ensconced across the UK at the weekend with occasional weakening troughs crossing East in the flow bringing occasional outbreaks of rain, especially in the North with clearer spells in between with slight night frosts in places.

THE FAX CHARTS The Fax Charts continue to illustrate trough disruption over the coming days with stark complexities near to Southern England over the next 72 hours delivering a mix of rain and snow in places. The pattern then shows Westerly winds driving further troughs East and SE across the UK at the weekend bringing temporarily less cold air and rain for a time before a chilly NW flow returns at the latter end of the weekend.

GEM GEM today shows early trough disruption over the next 36-48 hours as cloud, rain, sleet and snow in places slides SE. Through the weekend milder conditions spread East over the UK as repeated cold fronts cross East and SE across the UK then and beyond. High pressure not far to the South and SW of the UK will limit rain amounts here but permit some night frosts in the wake of cooler air behind each front.

NAVGEM NAVGEM too shows milder westerly winds becoming established next week as the disrupting troughs pattern we have currently flattens. Some rain from occasional troughs spreading east over most areas will bring all areas occasional rain with brighter and fresher conditions perhaps with some frost at night in between.

ECM ECM this morning too shifts cld air out of the way on Friday as troughs spread across from the West with rain for all. A colder, brighter weekend with some frost at night seems possible before rinse and repeat patterns of troughs moving across from the West bring further outbreaks of rain followed by brighter and drier conditions. Things look like turning more deinitively unsettled under an active Westerly flow late in the period

ECM 10 DAY MEAN The ECM 10 Day Mean Chart is trending towards a more flat pattern as the trough over Europe lifts out somewhat. This allows a push of milder Westerly winds across the UK under Low pressure to the North and High to the SW with rain at times and nearer to average temperatures more likely though still with occasional interventions from the NW with more widespread wintry showers at times and frosts by night.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The main trend continues to illustrate milder Westerly winds displacing the cold pool across the UK currently.

MY THOUGHTS There seems irretrievable evidence to suggest anything other than the fact that the current cold spell will be dead in the water by the weekend as the trough over Europe lifts out and milder Atlantic Westerly winds push the cold pool of air across the UK at the moment away East over Europe. After the next 24 hours or so when a few could see some snowfall the next troughs on Friday looks a mostly all rain affair as Westerly winds begin to take command. With High pressure migrating close to the South and SW at times amounts of rain look far from huge across the South at least and with clearer, fresher conditions spilling down over the UK behind each trough some night time slight frost is still possible in places. With time the models suggest that the Jet Stream will fire up into a stronger tone later with deeper Low pressure areas to the North and NE and bringing more deeply unsettled conditions with gales and heavy rain at times as well as spells of wintry showers and cold zonal conditions again become likely. Once again it's the Azores High and Jet alignment in unison with this feature plus synoptics across the Greenland plateau and NW Atlantic in general that has not allowed the High to ridge sufficiently North over the Atlantic to cut off the supply of milder air constantly attempting to dislodge the UK cold from the West and it was inevitable that eventually the cold pool would become dislodged from this direction. Looking ahead and for those looking for future cold it once again looks like we are going to have to continue to look North or NW for polar incursions of air rather than anything from Europe as there remains too much strength in High pressure poorly aligned for sustained UK cold to the SW and a Jet Stream that refuses to weaken or lie down sufficiently across the Atlantic.

[Gibby]

 

 

 

Not looking brilliant this morning folks, but don't despair. Remember the date everyone. 26th February 2015. Coldies heaven, courtesy of the ever reliable CFS.

There's an education for all in that chart. That's the dream scenario which more or less guarantees a sustained cold and wintry period nationwide. Notice the absence of any significant Azores High allowing the Jet flow to be displaced miles South from it's regular position over the Atlantic.

Edited January 20, 2015 by Gibby

[Anti-Mild]

I'm feeling discouraged this morning. I had expected a decent cold spell this week, but it is fizzling out with barely a whimper.  It just seems that if the weather gods can find a tiny mild spanner to throw in the winter works of the British Isles, then they always find a way! 

 

Moving forward, February is usually the least mobile month, and there are tentative signs of something juicy from the North, although I reckon that the NE will ultimately provide the interest for coldies. 

[BLAST FROM THE PAST]

The mild sector on Friday looks pretty transient but signals the change ahead as we move on into the next round of winter.  Wales and Midlands look like enjoying this evening first though and its cold until Friday, but then warms up a touch.  Now where do we look from there.  Well imo the GFS in deep FI is showing very interesting developments end of month into Feb.  Yes its FI but the signs of deep troughing NW Europe and Atlantic ridging with nnw/n flow with deep lows and sub lows has been ongoing theme.  Winter isn't over....I think its just begun!  Anyone else feeling the love? 

 

Not the detail, its the theme

BFTP

Edited January 20, 2015 by BLAST FROM THE PAST

[winterof79]

A dynamic situation today  for today through to Wednesday highlighted by the fluctuating EURO04 output for 12z tomorrow

 

Tues 00z for Wed 12z

 

 

Mon  18z for Wed 12z

 

Mon 12z for Wed 12z

 

 

I think the warnings will be out for Midlands and Central Northern England also Pennine spine and North Wales.

Edited January 20, 2015 by winterof79

[Captain Shortwave]

So the models pretty much in agreement for it to remain cold today through to Thursday. Friday looks less cold as a series of fronts sweep through. These clearing Friday night to leave a cool and fresh weekend with temperatures a little below normal accompanied by night frosts and a few wintry showers in the north west.

 

Into the first half of next week, it does look like the Azores high will ridge in closer, alongside this more Atlantic weather systems will sweep eastwards but will stay north of the UK. The south might stay mostly dry with any rain being on the light side. Temperatures near normal.

 

In the second half of the week, it does look like a more meaningful Atlantic attack will begin with the jet sinking southwards, this will bring more widespread rain and strong winds.

 

Now with this in mind I guess there are two options on the table here. The first is we see a successful split in the tropospheric vortex which may allow a ridge to build in the Atlantic and allow a northerly down. The other is we enter a very unsettled period of weather as Atlantic systems continue to push through the UK. The GFS at the moment keen on the first, but I remain rather wary of this as the models have a habit of trying to clear low heights from our north west which never really materialises within the reliable timeframe. A lot of interest developing relating to the strotosphere and MJO again, lets see how it pans out.

 

Anyway lets enjoy the last few days of cold weather and the potential snow it can bring.

Edited January 20, 2015 by Captain shortwave

[Paul_1978]

BFTP - yes indeed. No reason to be downhearted. Feb is often our "best" month. 8th Feb 1991?

8th Feb is still THREE WEEKS AWAY yet, a long time in weather.

You never know, we might go out with a a bang, and there's still a lot of winter left yet!

http://youtu.be/Hd6DuebHliY

Edited January 20, 2015 by Paul_1978

[bluearmy]

Extended eps continue with the euro trough with lowest anomoly over the uk

More sign of mid Atlantic ridging and dare i say it, a NH profile beginning to reflect the strat forecast.