Model Output Discussions 12z 03/05/2016

[northwestsnow]

On 5/18/2016 at 22:46, knocker said:

 

Pretty shocking GFS12Z this evening , slow moving trough just to the east brings heaps of rain and then we see a massive greeny high in the longer term and the jet heading south. Hope thats massively wrong because if it isn't i expect to see some serious backtracking in the meto june outlook over the next few days

edit and ukmo 144 looks a bit ropey with LP swinging in from Iceland, totally different to gfs but neither fill me with much joy ..

Edited May 22, 2016 by northwestsnow

[knocker]

Still some doubt over when the low pressure will move away and decay over the weekend and the distribution of the convective, and perhaps longer, outbreaks that may well occur. After that it still looks hunky dory according to GEFs this evening with HP taking over the reins.

 

 

Edited May 22, 2016 by knocker

[Cheshire Freeze]

11 minutes ago, knocker said:

Still some doubt over when the low pressure will move away and decay over the weekend and the distribution of the convective, and perhaps longer, outbreaks that may well occur. After that it still looks hunky dory according to GEFs this evening with HP taking over the reins.

 

 

The centre of that high anomaly is Iceland- my bet would be on a more micro level we'd see LP encroach from the SW in that set up where the jet sneaks underneath the block. Heights stretch across the pole and most of the low anomalies are mid latitude features- pretty much the synoptic opposite of what you'd want to see if you were wanting the foundations of a prolonged summer spell from a hemispheric perspective.

Edited May 22, 2016 by CreweCold

[knocker]

20 minutes ago, CreweCold said:

The centre of that high anomaly is Iceland- my bet would be on a more micro level we'd see LP encroach from the SW in that set up where the jet sneaks underneath the block. Heights stretch across the pole and most of the low anomalies are mid latitude features.

Possibly but I would make two observations. The jet is not necessarily a major player in this and although the stronger anomaly is to the NW that doesn't rule out ridging so the position of the surface high at this range would be up for grabs.. Of course if this sort of set up does materialise it doesn't rule out upper troughs in the southerly quadrant.

Edited May 22, 2016 by knocker

[knocker]

The ecm still running a surface low north from southern France into the southern North Sea which would bring some quite inclement weather the east coast. Early days.

[damianslaw]

Very anticyclonic picture being shown by all models today, with very extensive northern blocking - if this was Dec-Feb cold lovers would be rejoicing in there droves - it would be a bitterly cold outlook, entrenched cold. Alas it isn't, and instead we will have to watch carefully to see how the jet interacts and where frontal/trough activity develops, wherever it does, it will be a slow moving stuck set up, those unfortunate to be sat underneath such feature would see very wet dissapointing conditions. Its difficult to call how things may pan out, the anomalies are showing 'retrogression' of heights to the NW, which would see the east/south east at the vagaries of trough action from the NE, whils the SW would be at the mercy of low pressure pushing in from the SW, the NW would fair best in terms of temperatures, but some chilly nights.

Lets see how the models behave in the coming days, if we continue to see suggestion of heights advecting to our NW, then the suggestions of a very warm start to June would unlikely materialise, conversely with the weak jet forecast we could see strong enough ridge development over the country from such heights meaning a much better chance of warm conditions holding sway, but perhaps not very warm.. 

Overall we have a rather unusual pattern ahead of us if the modesl today are to verify, far from the default westerly pattern, indeed the last 3 months have seen quite a number of non-westerly airstreams.

[Thundery wintry showers]

5 hours ago, reef said:

There's a front stuck over the east of the UK and a keen easterly breeze so it would be disappointingly cool and cloudy for most with that. Western areas would possibly reach the low 20s in any sunshine though.

The current charts remind me of that easterly spell at the start of June 2007. Hopefully that's where any similarities end!

I'm being reminded of June 2007 as well.  I have a nagging feeling that it could develop a similar way (though probably not as extremely wet as in 2007).  I think the nearest ENSO (strong El Nino transitioning towards La Nina) analogue is probably 1998, which featured mostly cloudy wet conditions, apart from a dry sunny August in the south.  

The MJO is forecast to hang around phases 4/5 which are consistent with the projected easterly type.  The composites for phase 6 show an anomalous northerly flow over the British Isles, which is a plausible progression as the high pressure to the north may eventually retrogress towards Greenland.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

In the nearer term, looking bright with scattered showers tomorrow, then cool and grey for most on Tuesday/Wednesday as a front moves in off the North Sea.  The Bank Holiday is looking most likely to have warm sunshine for most, with some scattered thundery showers in central and western areas, although with the winds coming in off the North Sea some low cloud may affect eastern coastal areas at times, and we have to watch for the possibility of a deepening low to the south-east around Bank Holiday Monday.

Anticyclonic/easterly conditions are suggested for the first week of June by the NOAA 8-14 day anomaly charts so probably a fair amount of warm sunshine for most but cool and cloudy near some North Sea coasts, again, rather like early June 2007.

 

 

 

Edited May 22, 2016 by Thundery wintry showers

[Singularity]

A big problem is the large weakening of the N Atlantic thermal wind (jet stream) due to the much warmer than usual conditions across the Arctic in general. Under such a setup slack lows have a habit of following a boundary line between a hot central/eastern Europe - left to sizzle without the usual westerlies to escort hit airmasses away - and a cooler Atlantic, so placing the UK in the firing line.

With luck, a trough can become quasi-stationary away from the UK and allow for a lengthy fine spell. At the other end of the spectrum is something like 2007, 2012, or 2015 - though an exceptionally cool North Atlantic played a significant role in that last one.

I have often wondered if, with the North Atlantic thermal wind reduced even further, blocking highs could tend to take over our weather from the north - with alternating warm, dry easterlies and cool, showery northerlies.

[knocker]

The EPS anomalies tonight show no evidence of a Greenland high in the 10-15 day period.

Starting with the 6-10 we have a declining trough to the SE, another trough western Atlantic and high pressure northern Scandinavia, So it's still a problem when the unstable weather will clear the UK but still looking towards the end of the BH but at this stage I wouldn't bet the house on it. Thereafter the HP moves west linking rather tenuously with the Azores HP to the south west so effectively for the 10-15 day period we have HP ridging over the UK to an area just east of Iceland with a trough Greenland/western Atlantic. . Ergo a period of dry weather with temps a little above average.

 

 

Edited May 22, 2016 by knocker

[Scorcher]

I can only see very slight similarities to June 2007 in the outlook tonight. In that spell early in the month, high pressure built much more strongly to our north than it is looking likely to do at the moment. In any case that was a very decent month apart from the awful last week in the NW of England anyway. In Manchester we had 12 days above 20C and 7 over 22C, reaching 25C once so it was a pretty decent month overall.

[cheese]

20 minutes ago, Scorcher said:

I can only see very slight similarities to June 2007 in the outlook tonight. In that spell early in the month, high pressure built much more strongly to our north than it is looking likely to do at the moment. In any case that was a very decent month apart from the awful last week in the NW of England anyway. In Manchester we had 12 days above 20C and 7 over 22C, reaching 25C once so it was a pretty decent month overall.

June 2007 is a funny month - it was exceptionally wet, here in Leeds we had close to 300mm of rain with one day having over 80mm (Yorkshire was hit very hard, with Hull in the news quite prominently) - but the month actually started off very nicely, with warm, settled weather. We exceeded 20C 14 times. Average high for the month was 19.1C which is pretty normal. 

It really was only the last week of June 2007 that was terrible. July was a lot worse (appallingly bad actually - not only very wet but also very cool), with August coming out best that summer.

Though it's quite funny that after the exceptionally wet June 2007, just 4 years later in April we would go on to record less than 2mm of rain and 0 days of rain >1mm. 

Edited May 22, 2016 by cheese

[northwestsnow]

Good grief 18z GFS is even worse than the 12z with huge greeny blocking.

For goodness sake is anything srtaightforward in our wretched climate????

[Fourty Point Three Degrees]

so does this mean we can say goodbye to that good spell of summer we were expecting in June and 2007 here we come?

 

[northwestsnow]

1 hour ago, 40*C said:

so does this mean we can say goodbye to that good spell of summer we were expecting in June and 2007 here we come?

 

I wouldn't go as far as that but i see a pretty hefty downgrade to what i was seeing and reading only 48 hours ago.#

It seems its turning into a bit of a dogs dinner with that euro trough really complicating matters and now we are seeing greeny height rises being progged for June, after reading matt hugos update for june and the meto mrf and the longer term NWP it looked nailed on for something decent in june, now its starting to looking really iffy, gfs wants to build massive greenland high for june and a southerly tracking jet, that was not in any script i read.

[knocker]

 

[knocker]

Well the GFS this morning doesn't make for pretty viewing. The anomaly for Sunday shows that the trough in the western Atlantic has reinvigorated the trough to our south west and created a general area of low pressure. Surface wise this translates thus with most of the grot going into France.

It then breaks an upper low from the main area of low pressure to the SW and pops it NE over the UK where it hangs around. Now what will the ecm say I wonder?

[northwestsnow]

Yup, GFS is like a dog with a bone with its dreadful outlook - im guessing there will be some head scratching going on at Exeter this morning, i sincerely hope the talk of high pressure and clement weather is not replaced by high pressure over Greenland and a southerly tracking jet ..

 

[knocker]

I very much doubt there will be much head scratching apart from next weekend the details of which are somewhat elusive. This morning's GEFS for the 10-15 period continues to be not bad.

Edited May 23, 2016 by knocker

[northwestsnow]

ECm pretty much goes the same way as GFS0z.

Joy.

[knocker]

The ecm this morning is still tracking the low pressure from France north into the North Sea, as it was yesterday, before edging it west and bringing some very inclement weather with it. There certainly is no consensus on drifting the LP east as was the original thinking so at the moment, stress at the moment, the first part of the weekend might be better than the latter part.

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON MONDAY MAY 23RD 2016

THE CURRENT GENERAL SITUATION Pressure is building to the North of the UK with the slack Northerly showery flow gradually weakening as it veers NE over the next few days.

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

CURRENT SNOW FORECAST AND/OR FREEZING LEVEL OVER THE UK The freezing level and snow forecast is now suspended until the beginning of October.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE Some rain or showers at times but plenty of dry and fine weather too especially in the North. Occasionally warm in the South.

THE GFS JET STREAM FORECAST The Jet Stream is expected to feature largely to the South of the UK over the next few weeks. It features in a cyclonic form around Low pressure to the SW later this week this easing out only slowly as a period of slack and poorly defined period of flow seems likely in a week or so and through the second week although what flow there is seems to remain biased to be at a point South of the UK.

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

GFS OPERATIONAL The GFS Operational Run today shows Low pressure forming to the South and SW of the UK and High pressure to the North becoming the driving forces within the UK weather over the coming weeks. The situation develops over the next few days as an easterly flow develops with some reasonably warm conditions especially towards the West but with an increased risk later of thundery showers moving up from the South eventually affecting many areas from the start of next week with only slow changes in the overall patterning then through the second week involving more showers at times but with some dry and bright and potentially warm conditions for many at times as well.

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

http://www.wetterzentrale.de/pics/Rtavn3841.gif

GFS CONTROL RUN The Control Run shows a similar pattern to the synoptics over the first week while the second week leans an influence towards warm and sunny conditions developing with the risk of the occasional thundery shower as High pressure looks more resilient in this run although some insertions of shallow Low pressure looks possible too.

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA The clustering today continues to show some variations in expected conditions across the UK in two weeks ranging from slack pressure with showers to dry and fine weather under High pressure. There is nothing too dramatic shown though within the clustering for the UK so quite average benign conditions would be the most likely patterning.

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 The UKMO model this morning shows the theme of an ENE flow for a time this week before the winds fall light as the pressure pattern slackens always with the risk of some potentially thundery showers at times probably most focused towards the South.

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

THE FAX CHARTS The Fax Charts show High pressure to the North with an Easterly flow developing across the UK. A lot of dry weather for many for a time but later in the week troughs from both the East and South threaten parts of the UK with showers by the end of the week.

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

GEM The theme of GEM shows a week or so of easterly winds with the increasing risk of showers by the weekend before High pressure slowly builds NE into the UK over the Bank Holiday weekend and next week with showers dissolving and conditions becoming sunny and warm for many.

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

NAVGEM NAVGEM keeps slack Low pressure conditions across the UK from later this week, through the weekend and out to the end of the run with a continued risk of showers, some heavy especially in the South but with some warm, dry and bright weather for many too at times.

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

ECM ECM today is not the best of the group this morning if it's fine and settled weather your after as persistent High pressure North of the UK keeps Low pressure albeit weak and slack near to the South with thundery showers at times right out to Day 10 from this morning's run.

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

ECM 10 DAY MEAN (12z) The 10 Day mean Chart from last night shows the UK in almost 'col' conditions between two Low pressure areas East and West and High pressure areas North and South. This often means quite quiet and benign conditions with some warm sunshine mixed with occasional showers.

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

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The theme from the models today seem to lean towards slack pressure being maintained for the foreseeable future meaning light winds and a sunshine and shower mix of weather across the UK with day to day variances hard to predict.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.5 pts with UKMO at 99.4 pts and GFS at 99.2 pts.  At 3 days ECM is leading with 97.3 pts to UKMO's 96.0 pts while GFS lags behind at 95.8 pts. At 5 days ECM leads with 89.0 pts to UKMO at 87.0 pts and GFS at 85.2 pts. Then at 8 Days ECM has the leading spot from GFS with 58.6 pts to 51.4 pts. Finally at Day 10 ECM has the lead from GFS with a score of 38.2 pts to 35.7 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

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  A few days off from the models and I was hoping that changes towards High pressure based weather with UK wide warm and sunny conditions would greet me this morning but with the odd exception or two I see that is not the case and in fact changes since I last reported on Friday are minimalist in a picture of very slack conditions across the UK with fine and humid weather mixed with the risk of potentially thundery showers at times. The main focus of the weather appears to be High pressure positioned to the North of the UK keeping our risk of warm humid and continental style conditions moving up across at least the South of the UK later this week and looking reluctant to move away thereafter. This means of course an Easterly flow across the UK so west will be best for warmth while Eastern coasts look occasionally cool and cloudy at times with winds off the North Sea. Thundery showers will focus on the South at first but could occur elsewhere too with time. In these slack pressure patterns many areas end up with conditions set fair or better with little in the way of significant rain whereas localities could see some very heavy downpours at times and the devil will be in the detail day to day over the coming weeks. Temperatures shouldn't be a concern and it could feel warm and humid at times away from that East coast. Then if I had to make a judgement on where we go longer term I would favour a slow build of pressure, hopefully from the SW which would be the best direction to bring our best shot at warm and sunny weather and I feel there is a chance of that happening as we enter deeper into June.

Next Update Tuesday May 24th 2016 from 09:00

[Singularity]

 

What a shame to see the MJO collapsing in phase 4 already - a push toward 5 in the final week of May could have helped us out a lot with getting the ridge to behave. Instead we continue to see quite bizarre patterns in the offering, as high-latitude blocking keeps on being  upgraded in the mid-range.

ECM:   GFS: 

A brief but vicious looking dipole pattern has now emerged for 29th May, which given the wind strength is more bad news for the Arctic.Here in the UK, we're lucky to see a ridge close enough to our NE and a weak enough low to the south to allow for warm conditions with little more than a few scattered showers for at least the southern half of the UK.

We then see some quite monstrous blocking across the Arctic from both ECM and GFS - but with significant differences in the orientation. GFS keeps focusing it on the American side of the Arctic, with a peak over Greenland, which is basically the outcome from hell for the Arctic as another strong dipole rages away. ECM is kinder in this regard - but on the other hand, the high pressure is so extensive and 'warm' that prospects are perhaps little better up there. Down here, though, it could make a difference, as ridges from the Azores can join forces with blocking in that position to bring us fine weather while unstable conditions are held to the south - but only if you've not got a residual low wandering about such as the past few ECM runs have gone with. You know the weather patterns are out of kilter when you have a low moving from SE to NW across the country.

As amazing as it sounds, it seems likely to me that the record-early and dramatic breakdown of the polar vortex in early March has combined with a record-warm Earth to set in motion a chain of events in which exceptional imports of warm air into the Arctic promote not just record-breaking Apr-May sea ice melt but also strong height rises in the Arctic. Speculating as to possible causes, I can see the reduced Arctic to mid-latitude thermal gradient playing a role, and/or the warm air imports tending to ride up over colder surface air and then sink down - so raising surface pressure. There are probably other key variables at play too. Perhaps the stretches of open water on the American side are already having significant impacts. All going well, I intend to research this as part of my professional work this week, so that I can speak more definitively on the subject - though I may not be allowed to tell you much on here I'm afraid!

This summer should make for an important case study not only into what actually happens but how well the models handle it all (this is where this thread comes in!), unless of course there is an extreme turnaround in the Arctic weather patterns.

[carinthian]

Nice work again by Gibby. You really put a lot of effort into your presentation. Back in Skipton for a few weeks , so not looking bad here as we avoid those blustery NW winds. Although in Yorkshire, I would say climate wise my location is more in kind to the Northwest of England.  Anyway, Blackpool is a fair bit closer to the Gateway to The Dales than Scarborough. Err , Easterly winds in Scarborough at this time of year... Go west where the sunshine is best..

 C

Edited May 23, 2016 by carinthian

[Polar Maritime]

9 minutes ago, Singularity said:

As amazing as it sounds, it seems likely to me that the record-early and dramatic breakdown of the polar vortex in early March has combined with a record-warm Earth to set in motion a chain of events in which exceptional imports of warm air into the Arctic promote not just record-breaking Apr-May sea ice melt but also strong height rises in the Arctic.

Yes Sing, As you say a very interesting year indeed coming up what with the unknowns involved. And how the models handle these strong anomalies over the Arctic. It's certainly not going to be 'plain sailing' so to speak!

[knocker]

A quick look at the EPS anomalies this morning illustrates pretty well the problems a few days ago with the unstable weather over the BH weekend and when it would clear. Still no definitive answer of course but at Sun. 00 the upper trough is still very adjacent so surface LP remaining influential and although this does eventually clear, as can seen by Thursday, it may not be quick enough to save the holiday. Still time for adjustments of course but you can never be sure which way they will go.

Moving on to the 10-15 period everything still looking hunky dory with ridging up over the UK to Iceland with a trough in the western Atlantic.Ergo dry with temps a little above average.