Model Output Discussion 1200 hrs 30/09/14

[legritter]

well not many posters around tonight ,unless im not updating ,charts are pointing towards a change of sorts and looks like the further outlook could be interesting with much colder air moving south eventually ,but as usual at this range very dicey to predict anything too definate ,but interesting times hopefully will bring a few more posters out from under their Duvet .

[Captain Shortwave]

Looks like that day 8/9 northerly will probably just be a typical PM incursion, perhaps cold enough for snow on the Scottish mountains but that is it.

Before then, I can't get a temperature record for the 31st October, but this would be pushing 20C in the south this Friday

12C isotherm over the south again, as well as tomorrow and Tuesday too.

Beyond that, probably a return to near normal conditions. OPI looks good so lets see how November develops.

[IDO]

GEFS from D6 going with the zonal flow but with the PV on the Siberia side of the hemisphere it won't be a turbo charged westerly flow. So opportunity for transient ridges and troughs. Both ECM and GFS see the toppled ridge around D9:

 

  

 

Though GEM says no to that and is full on zonal (do not believe it): 

 

I think the long wave pattern is now established for week 2, with a more westerly flow, its now time to get timing and energy flow intensity ironed out amongst the models. Determining how much amplification from the slack flow is clearly proving difficult from D8. Also where the PV goes from D10 is also proving an exercise for the GEFS with no clarity at D12: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=300.

 

Its movement is becoming more important, as one thing is clear the GEFS are showing it as developing from its current status over the next 16 days. So as we would expect will become more of the driver of the November weather.

 

Next week looks to have good agreement. Mild, especially for the south; more rain for Scotland (NW) and a reluctant cold front moving south Tuesday/Wednesday. A ridge builds in for Thursday/Friday before the Atlantic moves in with several fronts, associated with a LP system, bringing rain from the west Saturday, Sunday, Monday...

[Barry12]

The next week looks like it will remain mild...

 

but week 2 will change as it always does.

 

Just don't get why people analysis anything over 10 days away, it's a pointless exercise!

Edited October 26, 2014 by Barry95

[Polar Maritime]

Just don't get why people analysis anything over 10 days away, it's a pointless exercise!

 

The Models are used to look at the broader picture out from day 7, Useless for detail, But great for spotting signals/pattern changes. So not at all pointless if used correctly.

[knocker]

A quick look at the Arctic

 

[MR EXTREMES]

Peeps getting too hung up on the detail.

Just look at the lw pattern - if it doesn't look like delivering any colder air to the uk it doesn't matter at this stage of the year. Wrt repeating patterns, we just want to see it happen.

Very true ba and once you see the appearance of heights then there be plenty more to come .

It's progressing nicely ecm was first to pick up but as Steve Murr suggested this happened a lot last year only to fail every time.

But this year totally the opposite to last year.

The outputs are all very much in tune with each other they can't all be wrong.

No vortex sitting over North America dominating our winter progression.

Similar to 09/10 is still my year of choice for this winter.

Edited October 26, 2014 by emotional rollercoaster

[karyo]

Does anybody know which models are used for this NAO forecast?  http://www.atmos.albany.edu/student/macritch/naoindex.png

 

It updates once a day and it shows a much more promising outlook after we pass the current positive NAO spell.

 

Karyo

[chubbyfan]

The next week looks like it will remain mild...

 

but week 2 will change as it always does.

 

Just don't get why people analysis anything over 10 days away, it's a pointless exercise!

its weather model output porn. depending on whatever type of weather folk want to see happen..

 

the long range model runs gives everyone even a small chance to get way overexcited at a model run suggesting hot/cold/sun/rain/snow/gales/thunder/etc,

[knocker]

A quick look at the GEFS anomaly this morning illustrates the continued volatility of the upper pattern into the near future.

 

Not particularly necessary to go into detail as a quick shufty at the charts tells the story. Starting off at T96 ridge UK, trough mid Atlantic, trough eastern seaboard and another ridge western N. America. Very meridional. Ending at T240 with a more zonal flow with flattened heights but a trough Pole/Greenland.mid Atlantic with a ridge to the SW of the UK The chart and jet for t240 perhaps illustrates this. Temps above average. See what the ECM has to say later but I'm not expecting a great difference.

Edited October 27, 2014 by knocker

[terrier]

Well nothing really in the charts this morning westerly based about sums it up. Think we may start to see a change as we move into mid November but that's a long way off yet. Before then more above average temps.

[knocker]

As cs mentioned yesterday some bold temps for Halloween before the rot sets in.

Edited October 27, 2014 by knocker

[Frosty.]

The GFS 00z op run shows another surge of exceptional warmth pumping up from southern europe later this week with some parts of the south & east not far off 70 F on friday which would be remarkable for 31st October (Halloween)..looking further ahead, Bonfire Night also looks to be on the mild side. This run shows bouts of unsettled and windy weather but also settled spells with overnight fog, especially further southeast and on the whole it's a mild run, especially further south.

Edited October 27, 2014 by Frosty.

[Ali1977]

The OPI is now pretty certain to be -2c or lower, if this is indicating a colder winter it would be nice to start getting some eye candy from the long range models. The potential colder spells over the next few weeks seem to have dropped off the radar the last few runs.

[Gibby]

Good morning folks. Here's my interpretation of how I see things today.

 

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY OCTOBER 27TH 2014.

 

NEXT UPDATE TUESDAY OCTOBER 28TH 08:00

 

THE CURRENT GENERAL SITUATION. A very mild SSW flow will weaken slowly across the UK over the next 24-48hrs as a cold front near NW Scotland starts to move SE across the UK tomorrow.

 

MODELS-2 WEEK HEADLINE  Mild and changeable with rain and showers at times mostly in the North at first but extending to all areas later. Some short drier and cooler periods are possible too.

 

THE JET STREAM ENSEMBLE FORECAST The Jet Stream blowing SW to NE across the North of Britain at the moment weakens over the coming days before ridging in an undulating pattern later this week at the same time as strengthening strongly. By next weekend the axis of the ridging flow lies over the Atlantic with the UK in a trough with the flow diving South to our West. Later in the run the flow is then shown to simplify in a basic West to East flow close to the UK.

 

GFS. Todays operational run shows the current mild SW flow weakening temporarily midweek before reigniting later as the influence of a mid Atlantic depression takes hold later in the week. After a calm period rain and wind in mild Atlantic air returns by the weekend. Then the trough bringing this weather relaxes SE across the UK bringing a drier and cooler phase back early next week. The longer term charts then show a mobile Westerly flow setting up with deep Low pressure areas crossing West to East over the North delivering spells of rain and showers to all areas in average temperatures and strong winds at times.

 

THE GFS ENSEMBLES.  The GFS Ensembles represent the theme and sequence of events shown by the operational well this morning even out into the longer and less reliable portion of the run.

 

UKMO. UKMO today shows Low pressure to the NW and North taking more and more control of the UK weather with increasingly stronger winds for all and rain for all too at times in a broad Westerly flow with temperatures slowly falling back to more average levels with time.

 

THE FAX CHARTS  The Fax Charts show a trough moving SE across the UK over the next few days ahead of a temporary rise of pressure in colder air over the North. Later in the week troughs are shown to return North and slowly East as Low pressure in mid Atlantic begins to take control in a return of mild SSW winds to all areas.

 

GEM today shows a similar theme already documented within the aforementioned models though the High pressure belt remains a little closer to the South next week. While all areas look like becoming unsettled and windy with rain at times as usual the heaviest rain will still fall more prolifically towards the North and West.

 

NAVGEM NAVGEM too shows a drift towards Low pressure driven weather to the North late this week and next weekend before a strong ridge moves East from the Atlantic towards the UK to start next week.

 

ECM. ECM is also broadly similar in theme with the usettled weekend to come under strong Westerly winds bringing in lower temperatures and quiet weather for a time early next week as an ill defined ridge collapses across the UK. It will be much cooler a week from now with some sunshine by day but fog and frost at night before strong Westerly winds return by Day 10 with rain at times returning to all areas pf the UK later next week.

 

THE ECM ENSEMBLES  The ECM Ensembles today show the theme set by the operational is largely supported within it's ensembles so a period of more unsettled and cooler (not cold) weather is shown with rain at times on a generally westerly flow over next week.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend is still for Atlantic driven weather to continue across the UK though with more risk of some heavy rain at times reaching the South of Britain too wth time in somewhat lower temperatures than of late.

 

MY THOUGHTS  There remains little evidence of anything particularly harsh in weather terms over the coming two weeks. With November arriving later this week it continues to look generally quite mild though probably not as much as currently over the South. Low pressure eventually looks like extending an influence to all parts of the UK by next weekend and an interlude of colder and drier weather with the risk of a couple of nights of frost and fog seem possible as a ridge crosses over from the West towards the middle of next week. However, the predicted Jet stream profile soon pushes the ridge away and Westerly winds return and predominate again through the rest of next week and up to the end of the period. With more of a Westerly element to this phase temperatures will be closer to average rather than above and it could become quite wet and windy at times over all areas but there seems little chance of anything attacking the UK from the North yet nor any large and long term High pressure area situating itself such that we could expect widespread cold weather with frost and fog. So another couple of weeks of generally average weather across the UK seems more than likely and needless to say that the usual areas of the NW who have seen copious rainfall of late will continue to do so but across the vast populous of the UK I don't see any disruptive weather to come yet which will be welcome news for those still recovering from last Winters floods down here in the SW and puts us on a better stead than at this time last year for those fearing a return of flooding returning down here this Winter.

[knocker]

There are no major differences between the ECM and GEFFs on the evolution of the 500mb anomaly. Looking further ahead with the ECM it would appear much of the same with a fairly static trough eastern Pacific and little sign of amplification in N. America, nor indeed with the PV. Perhaps more influence from the HP to the east and south.

Edited October 27, 2014 by knocker

[terrier]

The OPI is now pretty certain to be -2c or lower, if this is indicating a colder winter it would be nice to start getting some eye candy from the long range models. The potential colder spells over the next few weeks seem to have dropped off the radar the last few runs.

personally I think too many hopes are been pinned on the opi. Think November at the moment is looking above average according to the mets outlook. And there is nothing today in the output suggesting anything but westerly flow.

[MR EXTREMES]

flip flop models the gfs and ecm remove heights around greenland but this was always in the latter parts of the model runs anyway id be very suprised if they dont flip back towards the idea of the last few days runs.

 

heights in northern america or should i say not the same set up over there as last november vortex still held on the siberian side of the pole which is a good base point moving forwards.

 

the jma has not totally thrown the idea of a more cooler colder chance although no signs of a sustained cool/cold.

and some warm air being pumped up towards greenland and iceland but the jma is trying to pull down a arctic air source.

 

the jet going south which is nice to see 

 

gefs in it latter outputs removes the above average temps and brings them to a more normal level.

but once again shows a nice swath of warmth pumping up towards greenland area but looks like failing this time round.

 

and the jet to is plunging south 

 

ecm looks good for an evolution as the axis is better with heights from the azores into the america trying to get a northerly flow going on our side.

its a progression in the right direction.

i expect there be more frost forecast into november and things becoming more average temp wise perhaps slightly below for the north.

[Frosty.]

I think on balance, the Ecm 00z op eventually becomes rather colder than the gfs 0z beyond this week with a higher risk of frost and fog and also offers an olive branch of hope for a polar maritime incursion beyond T+240 hours but what both models have in common is a very warm start to this week with temps of 18-20c across southern uk, a bit cooler midweek but then turning very warm again, especially friday with next weekend turning cooler and fresher from the west and then that increased risk of frosty nights with fog, night & morning before the atlantic fires up later next week.

[Frosty.]

The GEFS 06z mean shows a very mild, windy and unsettled end to this week with low pressure in control, into next week there is a noticeable drop in temperatures and a gradual improvement from the west as our low pushes away northeast and at the same time, an atlantic ridge builds across the uk. Then looking further ahead it's a northwest / southeast split with the nw generally unsettled and atlantic driven whereas the south and more especially the southeast becomes more strongly influenced by continental anticyclonic conditions with fine and generally benign weather bringing an increasing fog risk and slight frosts. The general theme is for frequently rebuilding high pressure to the east / southeast and persistent lower heights to the north  / northwest as we go further into november.

Edited October 27, 2014 by Frosty.

[Paul]

Latest video forecast from Jo - including some new 850hpa graphics - turning chillier this week for a time, but still no blues nearby though!

 

 

http://www.netweather.tv/index.cgi?action=news;storyid=6252;sess=

[Barry12]

Some interest in FI on the GFS 12z, but not much!

 

Edited October 27, 2014 by Barry95

[Ali1977]

GEFS 12z have some much better FI charts, some good northerlies

[Frosty.]

A few nice cold charts from the GFS 12z op run in FI, eventually a cold high with frosty nights and crisp chilly days. now just imagine if that atlantic high ridging up to the west on the first chart wasn't toppling SE, imagine it was ridging straight up to greenland because then we would get our first wintry snap with snow showers so there is some interest for coldies. I will be very glad to see the back of all the unseasonable warmth this autumn and change it for something more normal for november with cold incursions instead of mild mush most of the time, I think it's time we had a marked change, maybe early / mid november will bring it.

Edited October 27, 2014 by Frosty.

[Altohumorous]

I don't really get the frequent mention of "the jet going south". Looks to me clearly that the jet is oscillating north and south and mostly in a pattern whereby it is north of us, or close to us at best. Hence we are not getting any cold incursions simply because of the positioning of the oscillation pattern, despite the ongoing promise in other terms (vortex etc).

Last winter we had the jet more to the south of us but in any case there were not the other factors necessary for any significant cold to hit us and then the vortex took over. So far, if we can judge anything from the start of november, it looks like a long waiting game for the broader patterns to shift the jet and then just hope the vortex doesn't move as well to its typical location.

Even with no vortex nearby, and cold becoming established regularly in NE Europe, the troughs keep pushing right up into the far northeast, with heights tending to either sink into the SE half of Europe, or ridge to there. Thus the "cold becoming established early" often spoken about in northeast Europe is not of any benefit, and simply not able to remain there. I presume this is a jet factor, oscillating north and south in that area.