Model Output Discussion - 1st February Onwards 12z--->

[Frosty.]

A few nice GEFS 12z perturbations tonight have brought me out of hibernation, and for those of us hoping for a colder outlook, these are welcome charts.

[MP-R]

A few nice GEFS 12z perturbations tonight have brought me out of hibernation, and for those of us hoping for a colder outlook, these are welcome charts.

 

and with that arrive the August 2014 synoptics I earlier posted in the Model Moans thread haha. If only!

 

Across the board, the short term does looks very similar to the second two thirds of February 2009 with a very stubborn high only moving about gradually. My take is on more emphasis on cloud and mist with sunny, frosty and/or foggy conditions fewer and further between. This of course depends on the main direction of wind affecting surface conditions. 

[Frosty.]

High pressure looks like being in control during the next few weeks which will be pretty insufferable for those of us hoping for a snowy spell or any sort of weather action but there are signs of a change to generally more unsettled weather by the last week of february on tonight's GEFS 12z mean and also I'm not ruling out the possibility of a colder outbreak from the north after mid month if the main high drifts further west as shown on some of the 12z gefs perturbations.

[Jason M]

Each GFS run that I see has me increasingly thinking 'Bartlett'.

 

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=372&mode=0

 

Of course it differs somewhat from the famous 1988 winter (or rather non winter), but the general thrust of it is the same. Each time pressure subsides its reinforced with a new high pressure cell. Normally, I'd say that this pattern wouldn't persist, but on this occasion I think it might. It could even stretch out into March.

 

One advantage though to this over a full on zonal pattern is that there is a say 10-20% chance of getting a potent cold spell in the last 10 days of Feb. Its unlikely, but slightly more likely than was the case this time last year. I think its worth persevering for another week, but more in hope than expectation.

 

Should the pattern persist I'd imagine temps will slowly rise through the month with some notably warm weather being possible after mid month. High pressure to our SE will inevitably to a southerly element and combined with higher solar input it would be a slow but steady climb into spring. Looking on the bright side, at least this will cut down on the heating bills again!

 

Not quite 'white flag' time yet though. As others have said if the change comes it could appear quickly in the day 7-8 range via retrogression.  March can bring interest but its rare to see a snowy march after a very mild winter!

 

 

Edit: GEFS out to 198 and as expected its UK high all the way. A couple of ptrbs look interesting but they don't develop anything.

Edited February 7, 2015 by Jason M

[Jason M]

This from the GEFS illustrates why its worth waiting a bit longer before throwing the towel in. A minority solution yes, but its possible under this type of situation.

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=11&ech=300&mode=0&carte=0

[summer blizzard]

Gloriously dry..

 

[bluearmy]

I think I'll take a break till the 12z's. Too much potentially going on in what should be a blocked anti cyclonic 10 days or so!

[Eugene]

Well easily the worst spell coming up from friday, not bad until then but the prolonged anticyclonic weather has been downgraded, turning very mild and Springlike from next weekend, those who think this winter has been bad haven't seen anything near that bad for cold.

 

Bluearmy why should it be an anticyclonic 10 days or so?

[knocker]

The GFS this morning reminds me of a carousel with HP/UK the hub with low pressure winging around it to the north on the northern arm of the split jet.

Chart courtesy weatherbell

 

[West is Best]

Well easily the worst spell coming up from friday, not bad until then but the prolonged anticyclonic weather has been downgraded, turning very mild and Springlike from next weekend, those who think this winter has been bad haven't seen anything near that bad for cold.

 

 

Although on the 0z GFS the first anticyclone does depart to north Germany, as suggested, leaving a possibility for some sort of meridional reload. At the moment as you rightly point out the GFS replaces the high pressure with another. 

 

'Springlike' is never likely to go down well but the models do show increasingly mild conditions and given the time of year a fast exit from winter cannot be ruled out. It hasn't been bad though. Two cold snaps with a smattering of brief snow here is certainly an improvement on last winter. And although not technically winter both March and April can still give cold and snow potential. 

[Biggin]

Gloriously dry..

 

Gotta love that 528 Dam near Libya / Tunisia ??

Edited February 8, 2015 by Biggin

[Frosty.]

Less boring 00z, especially the Ecm 0z, although high pressure initially looks powerful and in full control for most of the week ahead, lowering heights to the northwest bring unsettled and windier spells across the north of the uk with polar maritime influence at times bringing wintry showers across Scotland from time to time later in the week onwards with the high forced further south by south west. I'm happy about that because at this late stage of winter, I don't want to see two weeks or more of benign anticyclonic weather sucking the life out of what little bit of winter we have left, hopefully support will increase for colder and unsettled solutions during the second half of February. :-)

Edited February 8, 2015 by Frosty.

[IDO]

No change from the GEFS mean with HP in charge till D16 apart from around D5, the period where the phasing of the two HP systems occur. This always leaves a small window from some encroachment from the north of the jet:

 

 

It has been signposted by the GEFS for a week and at no time has it ever hinted at this being a pattern changer, just a blip in the HP dominated output. ECM op has made more of this on runs and today it hints at a N/S split with the south more settled from D5 and the north wetter (supported by its mean). This changes the flow to PM and TM alternating with some mild spells amongst the cooler spells. The cyclogenesis of lows running off the PV as they race over the Atlantic block around D4-7 is the cause of the variation in the models. It will be interesting to see which model handled these:

 

 

By D10:  

 

The GEM op this winter has produced a regular output of charts that are out of the blue and today is another case in point:

 

 GEFS Mean: 

 

Not one GEFS member is even close to this and the GEFS mean at D10 for comparison highlights this. FI from the GEFS has HP in charge till D16 and bearing in mind the propensity for the GFS to bring the Atlantic back in, this remains a strong signal:

 

D13:   D16: 

 

So it is possible that the period around D5 may bring the Atlantic closer to the UK, but that has always been on the table with this week's HP edging east easing the robustness of the block. The long wave pattern from the GEFS remains the same after that short wave development, with HP in charge of the UK, though again opportunities for variations within that theme as the Atlantic may encroach the north into FI. If the GEFS are wrong with the northern extent of the HP, then the alternative looks almost certainly like a return to an Atlantic zonal flow with little sign of heights building north of the UK with the PV running across that region. ECM D10 NH profile highlights that:

 

 

The 2m temps from week 2 suggests a return to above average temps for the south:

 

[mushymanrob]

Rob - I'm a great supporter of the NOAA CPC charts but they are generally going to struggle ahead of any pattern change (the ncep ens are generally a bit slow on board) and also they will not show small detail which will be short lived. If yesterday's ECM 12z was to verify, those charts would look pretty well the same. the broad mean pattern remains the same averaged over a 6 day period.

does anyone have yesterday's 12z op mean heights/anoms 6/10 day charts to see how the ECM looked averaged out compared to the gfs? Wonder how different it looked.

 

hi ba

i was going to reply but john has done that far better then i could (after all it was johns lead i was following, ) i guess we all have our favoured data sources,

 

well.... after bleating on about a dirty high for so long, then other members picked up on it, and even the tv graphics started predicting cloud.... i wake up to a frost!

well we will see how this pans out over the next 5 days or so, cloudy or clear (or somewhere in between) was always going to be a close call and reliant on atlantic moisture circulating the high as was previously predicted.

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS

THE CURRENT GENERAL SITUATION A High pressure to the West of Ireland will slip slowly SE towards the tip of SW Ireland tomorrow. A slack North wind will back NW over most areas by tomorrow.

http://www.wetterzentrale.de/pics/Rtavn001.gif

MODELS-2 WEEK HEADLINE A lot of benign and quiet weather is expected across the UK with light winds and plenty of cloud but some sunshine or clear spells with some frosts at night especially in the South. Daytime temperatures close to average. Perhaps a short period of less settled weather next week.

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow moving eat towards Scandinavia from a position just North of the UK. This flow is maintained for a time before it ebbs and flows North and South across the UK from later next week as successive troughs of Low pressure cross East over the UK each time followed by a ridge.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS operational today is very High pressure based, gradually declining the exissting centre away from Britain to the SE early next week and allowing a trough of Low pressure to move East overall areas late in the week, most active over the North where a band of rain and squally winds look likely. The South will quickly become fine again as pressure rises from the SW and all areas then settle into a sustained UK High based weather pattern with the usual issues of chasing cloud amounts and identifying places where frost and fog is likely overnight.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif
 
THE GFS CONTROL The GFS control run differs from the operational today only in as much as it keeps the second High pressure area further South behind the frontal trough that crosses east over all areas later next week. As a result there would be a stronger Westerly flow over all areas through Week 2 with further occasional rain in the North and dry and rather cloudy weather in the South. Temperatures under this regime will be average at worst and rather mild in the sheltered East.

THE GFS CLUSTERS The GFS Clusters today show an 85% chance of High pressure being close to the SW or South of the UK with mild Westerly winds across the North with rain at times. The South would be largely dry and fine with patchy frosts at night. There is a 15% cluster which offer a cold zonality NW type pattern with the High much further to the SW and Low pressure over the Baltic states creating a cold NW flow for the British Isles

 

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO UKMO this morning shows High pressure drifting slowly East away from the UK next week with slack winds and benign conditions expected. Later in the wind winds strengthen from the NW as Low pressure moves East to the NW  bringing an active trough East with a band of rain for all towards next weekend.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts this morning show High pressure slowly migrating East into Europe from Southern Britain next week but holding influence under slack winds then with plenty of cloud cover and patchy overnight frosts and fogs by night the likely weather features for most

http://www.weathercharts.org/ukmomslp.htm#t120.

GEM GEM shows a more mobile evolution developing later next week and beyond as the High pressure currently covering the UK moves away East into Europe and declines. The marked trough other models show is well supported here too later next week but is only the precursor to a more windy, unsettled and eventually colder period again as Low pressure eventually slips SE down the North Sea with cold NW or North winds likely by or soon after Day 10 with wintry weather developing for many.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM is more High pressure orientated than GEM with the end of week trough weaker and less influential to the South before a rise of pressure next weekends restores fine and benign conditions across the UK again at the end of the run with only the far NW open to cloud and light rain in SW winds.

http://www.wetterzentrale.de/pics/Rnvg1681.gif.

ECM ECM shows a slightly more changeable pattern following the weak trough later next week with all areas falling under relatively mild Westerly winds and occasional rainfall this chiefly across the North. The High pressure is held close to but always to the South bringing the South too under mild Atlantic air with less risk of overnight frosts and fogs from this position.

 http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN The 10 Day Mean this morning maintains the prospect that pressure is biased lower to the North of the UK and higher to the South and SW. This maintains the likelihood of rather cloudy weather at times with at least a little rain, biased again towards the North while the South closest to High pressure stays dry the longest and sees the best of any sunny spells and any patchy night frost and fog in relatively mild conditions.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The long term trend today remains for High pressure to be in relative control likely positioned to the South of the UK with generally Westerly winds blowing at least across the |north of the UK

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.6 pts followed by UKM at 97.0 pts and GFS at 96.3. At 5 days ECM just about leads the field at 90.1 pts over UKMO at 89.3 pts and GFS at 87.3. At 8 days GFS takes over with 63.3 pts over ECM's 62.1 pts. Then at Day 10 ECM regains superiority at 46.6 pts over GFS at 45.3.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.png

MY THOUGHTS Not a lot to report this morning especially if it's a quick return to winter your looking for with only GEM flying that flag with an operational that looks like bringing wintry weather back down from the North at the Day 10 point. Elsewhere it's much as before with High pressure looking dominant over or close to the South, steering all rain bearing systems well to the North of the UK for the most part. However, at the junction of the demise of our current High pressure later next week a trough of low pressure and attendant rainfall is expected for all albeit brief before High pressure restores command to the South or SW. All ensemble data biases this setup of High to the South or SW and Low to the North longer term with Westerly winds looking likely to be the favourite option likely to verify after next week. This means that temperatures by day would recover fully to average or above rather than the half-hearted less cold conditions the South are likely to experience in the coming week. Frosts would become less common for all under any Westerly drift and with the High proximity close to the South any significant rainfall will likely mostly affect the far North where it could become windy at times too. Having said all that this is not the only option with a smattering of members suggesting cold zonality under NW winds and even some ECM members not discounting such a thing either. What no model shows leaving the GEM model aside is any High Level blocking and to that means it looks like any sort of blast from the East can be fully discounted within the next 14 days with any hope at all of cold likely from the North on a transitory NW breeze. It looks like the February saying of 'February filldyke' is unlikely to verify this year with the month shaping up to be a very dry one for the majority.

Issued at 08:30 Sunday February 8th 2015

[johnholmes]

I honestly cannot see anything in any model output I can get hold of that one could give any suggestion of any marked deep cold arriving in the next 2 weeks or so. What happens beyond then is not my area but I would be very surprised if any deep cold shows in the time scale I have mentioned.

[bluearmy]

I honestly cannot see anything in any model output I can get hold of that one could give any suggestion of any marked deep cold arriving in the next 2 weeks or so. What happens beyond then is not my area but I would be very surprised if any deep cold shows in the time scale I have mentioned.

At the moment I agree john - the only caveat being that upstream n America may pull back west a bit which could retrogress the whole set up in week 2.

[knocker]

Regarding upstream.

 

From GFS: after huge Arctic Blast No. 1 on Sat/Sun, pattern retrogresses w/even colder air.

 

AnimGIF:

 

http://weather.graphics/gfs_2015020800_t850a_noram.gif â€¦

[bluearmy]

Regarding upstream.

 

From GFS: after huge Arctic Blast No. 1 on Sat/Sun, pattern retrogresses w/even colder air.

 

AnimGIF:

 

http://weather.graphics/gfs_2015020800_t850a_noram.gif â€¦

Anyone wanting to know what the extend ECM eps are looking like over the past few runs - the naefs anomolys are representative.

[Hotspur62]

Must admit things are looking less and less promising now for a cold spell second half of the month but GEM is just an example of what could happen 10/11 days from now. I appreciate this is unlikely but at t+240 the models have got things wrong before and will do in the future. Mother Nature has a way of bringing surprises and history tells us that March can bring us cold spells. March 2013 ring any bells??

 

As I have said before some members have just been disappointed and frustrated as it is back to back winters that have failed to deliver 1 nationwide snowy and cold spell and as a result have thrown the towel in from a cold perspective. Premature I think and history tells us that.

 

We just need Vortex to move towards Siberia and even in this happens in 14 days time that is still only 22nd Feb. Lets just enjoy the next 10 days with a bit of frost hopefully and pleasant sunny days. After that, lets just see.

[legritter]

 I,d like to speak to a manager please ,  I,m sorry sir he,s at a meeting ,can i help  YES you can ,These high pressure cells are completely in the wrong place get a grip Model .Good job its only the weather and still hopefully time for some good charts, Gem later in its output Tantalising ,and the atlantic showing signs of waking up a little ,lets see where we go from here ,cheers 

[polar vortex]

I think any chance of a potent and newsworthy cold spell in mid to long range depends on the strength of the MJO signal.

If we see a strong  signal which pushes heights well into Alaska and the Arctic then we are likely to see a trop response 

with a much more amplified pattern over the Arctic and a much greater chance of a very cold Arctic outbreak.

 

The 06z gfs run coming out at the moment for instance shows much stronger ridging into these areas so it wil be interesting 

to see where this run takes us.

My money would be on for a stronger MJO response to what the models are showing and thus a greater likelyhood of a 

very cold spell in the last week of Feb.

[Dorset_Weather]

I honestly cannot see anything in any model output I can get hold of that one could give any suggestion of any marked deep cold arriving in the next 2 weeks or so. What happens beyond then is not my area but I would be very surprised if any deep cold shows in the time scale I have mentioned.

But this it always the case, has been the last two cold spells we have had recently, Due to the anomalies not picking up on a change as quickly as there raw model data because there MEANS and smooth out any quick changes to a more of an average.

You can't say with any confidence there will be no cold within the next two weeks. What always happens is everyone will start getting excited about a possible cold spell in 7-8 days time, you spend the next two days warning people to be cautious as nothing is showing in the anomalies, then the anomalies start showing a cooler trend as more raw data starts to come on board, after the usual two day lag of the anomalies smoothing the pattern change you then start to confirm a cooling trend.

So I would expect the anomalies to not show a quick change to cold unless at least half the raw model data was showing this before, your very good with pattern changes John but the patten between you and the anomalies is a very predictable one that we have seen many times.

I love reading your very informative posts and your much more knowledgeable that me but I wish you would treat the anomalies as means instead of trying to make some sort of certain forcast two weeks in advance.

80% of the time the anomalies will be right as the UK weather is very average and anomalies always show the average, they have no chance of picking up a quick pattern change unless all the raw data jumps to cold all at once then they would but again they would just be showing the average.

[bluearmy]

The ECM MEAN anomolys picked every colder period thus far this winter at two weeks. The signal weakish to begin with but firming up quickly to show the euro troughing. The gefs less successful.

[knocker]

And they are not showing any signs of a cold spell at the moment.