Model Output Discussion 14th May 2012 Onwards

[Milhouse]

A slow change from the South as Pressure starts to fall away from the gfs and ecm and ukmo late weekend/earlynext week.....

Although i do wonder what could be brewing looking at the ECM at 240h.

[Alex]

Although i do wonder what could be brewing looking at the ECM at 240h.

The ECM run tonight keeps heights pretty high and perhaps renews heights towards the beginning of June?

[Summer Sun]

The ECM run tonight keeps heights pretty high and perhaps renews heights towards the beginning of June?

This could be what our summer brings higher than average pressure giving the chance of some very hot spells, and thunderstorms

Edited May 22, 2012 by Gavin D

[ribster]

This could be what our summer brings higher than average pressure giving the chance of some very hot spells

Yes indeed 'could', Summer could be a lot of things, it hasn't even started yet, a lot of claptrap in this forum today, records being broken, our athletes running in high 30s heat (yeah, that will be good, lol), summer being the best ever based on a hunch! It's as bad as it gets in winter with the ramping, thank god GP and John are here to give us some proper analysis and objectivity.

[J10]

Does look like the potential for some stormy weather for some southern and south western parts for early next week for a time before that thought looking mostly sunny and warm/ hot [mist/low cloud on some coasts being the only real exception, and even that should be gone for most by Thursday]

As for my summer prediction,

Looking like the hottest summer ever, with an equal chance of the coldest summer ever, or perhaps more controversially somewhere in between.

[damianslaw]

Reliable tiemframe remaining dry sunny and warm for most (very warm in the next 2 days), by the weekend a stiff easterly breeze will certainly take the edge of the temperature, but should prevent cloud build up. In overview the rest of the week looks very good indeed, a very decent spell of summery conditions.

Into next week, the models continue to suggest heights will retrogress NW but with no real oomph in the atlantic trough, any atlantic attack looks like being a weak affair, suggesting either perhaps a showery breakdown with weak frontal assaults from the SW and homegrown convection, or a cooldown with a cool slack northerly/northeasterly airstream.

As I commented a couple of days ago, the synoptics of the last 7 weeks and those being projected for the foreseeable future had they occured at the start of winter would have caused a most brutal one indeed, with easterlies, northeasterlies and northerlies dominating and cyclonic slow moving snowy attacks. Alas it is spring and these non westerly type of synoptics are most likely to occur in April and May - but not necessarily the summer it has to be said. It would be foolish to say the upcoming synoptics will dominate the summer, just like thinking early v wintry synoptics in late nov- dec (think 2010) would dominate the rest of the winter.

[Robbie Garrett]

Just thought I'd like to touch on the fact that 38-39*C was already reached in Spain this year. Possibly 40*C, and that was unseasonably in May. Let's see how the pattern develops, a low hectorpascal high pressure may be what we want (1015-1020mb) is perfect.

[johnholmes]

This could be what our summer brings higher than average pressure giving the chance of some very hot spells, and thunderstorms

well nowt like hopecasting Gavin and a fair dollop of meteorological fantasy as well!

The ECM run tonight keeps heights pretty high and perhaps renews heights towards the beginning of June?

that reminds me of a song some years ago

perhaps, perhaps, perhaps.

perhaps! I should actually stop having a go at others and do a spot of objective model commenting-so here goes?

The main feature I use, within reason, are the 500mb anomaly charts-oh gawd some say and move on quickly-for those of stronger disposition-currently they have one definite message for 7-10 days ahead.

That is that an upper ridge is going to be somewhere wnw-nw of the UK, how far away is a little open to doubt, possibly around the Iceland area. But where does that leave the UK?

Do we get a N'ly with a trough setting up NE/E of the country?

Do we have some kind of NW-SE or even NE-SW trough to the west?

or is it a trough/cut off low south of the UK?

To be honest its very far from clear just which of these 3 alternatives are most likely.

Current outputs suggest something of a mix between the second and third option.

The fact that the 3 500mb versions are far from consistent with themselves and one anohter is probably why the synoptic models at longer time scales T+168 onwards are showing some variability?

Another 2-3 days of their outputs and the start of June should become clearer.

Prior to that then a flow from the east, increasing by the weekend so dry for most and very warm away from the east coast. Even here it should be sunnier than at times over the past 48 hours (for some places that have suffered from a lot of misty cloud at times). As we go into next week then more unsettled for the south with the north staying in the dry and relative warmth for most.

Just how much of a storm threat for those of you wanting such is something you will have to wait for how much if any and where no more than 24 hours before any happening.

I suspect this unsettled weather may spread north for a time before the upper ridge I mentioned some lines above exerts its influence.

Edited May 22, 2012 by johnholmes

[peterf]

cheers John.

[johnholmes]

sorry I forgot to mention in the T+24 time scale, prior to the less warm air and stronger easterly flow, chiefly for tomorrow, local wind covergence along with probable relatively high temperatures and a fairly unstable if dry upper air COULD along the high spots down the spine of the country set of a VERY isolated thunderstorm. Just which part of either the Welsh mountain or Pennine chain I'm not sure.

Look at the Extra predicted skew-t ascents for 12 and 15Z based on the 00z runs tonight for places like Leeds, Manchester, Shawbury perhaps?

[damianslaw]

sorry I forgot to mention in the T+24 time scale, prior to the less warm air and stronger easterly flow, chiefly for tomorrow, local wind covergence along with probable relatively high temperatures and a fairly unstable if dry upper air COULD along the high spots down the spine of the country set of a VERY isolated thunderstorm. Just which part of either the Welsh mountain or Pennine chain I'm not sure.

Look at the Extra predicted skew-t ascents for 12 and 15Z based on the 00z runs tonight for places like Leeds, Manchester, Shawbury perhaps?

Yes some small disturbances could occur over the Pennines tomorrow courtesy of a very weak cold front - this was shown on the BBC forecast tonight. One or two places could see a notable very heavy but shortlived thundery outbreak late afternoon/early eve. Western Pennine regions and welsh mountains could catch a shower or two along with this neck of the woods.. will be interesting to see if any sudden dark clouds appear on the eastern horizon.

[Costa Del Fal]

Excellent GFS 18z thus far maintaining temperatures at least into the low 20s well into next week. High pressure quite firmly anchored to the North/North East however its positioning is a little different to the 12z so looking at the ensembles later may reveal the better picture.

Nevertheless, quite good agreement that at least early next week looks still warm or even very warm with more sunshine but still a slightly higher risk of something a little more unsettled drifting in at times however very little or no signs of the below average temperatures and endless rain as of recent weeks.

Enjoy folks.

EDIT: A Superb 18z GFS with the very warm temperatures lasting even beyond next week however I do feel by then it becomes an outlier as the pressure patterns are a fair bit different to recent runs but who knows it may be onto something. The GFS was the first (from what I saw anyway) to declare this weekend and early next week to be mostly dry and warm.

Edited May 22, 2012 by Blizzards

[Milhouse]

The 18z is a phenomenal run with the Azores high ridging northwards throughout next week to reinforce the high already over the uk. The southern half of the uk then becomes very warm perhaps hot for a time whilst northern parts turn increasingly unsettled

[Derp Patrol]

High pressure looks like it won't go out without a fight, and every time a low comes it gets pushed away. I have a feeling we will see this pattern throughout June - i.e a good month for heat lovers. Next week on the 18Z looks like high pressure wants to stay in control - it looks good for the whole of the UK for a change instead of just us in the SE - so enjoy it while you can up there!

[Summer Sun]

High pressure dominates for the foreseeable future on GFS

http://www.jp2webdes...o.uk/ds/gfs.htm

UKMO

Slightly more unsettled the parts of the north may remain settled

http://www.jp2webdes....uk/ds/ukmo.htm

ECM

Follows UKMO's path in bringing unsettled weather our way next week

http://www.null/ds/ecm.htm

Ensembles

So if its warm weather you like GFS is the pick this morning with high pressure dominating for the foreseeable future

Edited May 23, 2012 by Gavin D

[Glacier Point]

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

.. a lot of dry members there, the operational tending towards being a wetter outlier.

With the GFS ensemble mean looking like this..

http://raleighwx.americanwx.com/models/gfsensemble/00zENS11-15day500mbHeightAnomalyNH.gif

(anomalous ridge setting up west of Greenland in the Canadian Maritime, low pressure in the Atlantic) some potentential here for a genuine hot spell to come in the day 10+ timeframe with a ridge breaking in from the SW and re-setting the block over the UK / Scandinavia.

[Thundery wintry showers]

Some deviation between the model outputs this morning, but the ECMWF has abandoned its "retrogression" scenario so I think we can relegate that to the dustbin with reasonable confidence.

Subtle changes for the weekend with the enhanced easterly flow pushed further south (this was already becoming evident on yesterday's runs) and switched to more of an east to south-easterly. This means that the cooler, moister airmasses from north of due east don't quite reach us, and the GFS outputs suggest humidity staying surprisingly low over the North Sea- on this basis I won't expect much in the way of cloud in eastern areas, though it will turn a bit cooler. The main complication will instead be a few thundery showers coming into the south-west, particularly on Saturday night and into Sunday.

Into early next week GFS and ECMWF keep a shallow high over Britain which would mean a continuation of warm sunshine but also increased chance of thundery showers breaking out towards the south. UKMO has a rather different outlook with the low pressure close by to the SW and east to south-easterlies on its northern flank, which might mean more rain/showers towards the SW and more chance of low cloud towards the NE. The ECMWF has shown the Atlantic pushing in towards the end of next week for a couple of runs now, and this is a possibility, but there's also a fair chance that it could be too progressive with an Atlantic trough/Euro high setup also entirely feasible (consistent with Stewart's above post)- the latter is often associated with hot spells.

[Robbie Garrett]

Slightly cooler if not wetter week next week.

July is looking really nice with 30* for most of the month, possible 33*C in sme places up to the 17th July. with 40*C not a problem in southern france, northern spain.

29-30*C in Scotland, 34*C + easily reached in London/Kent. Rainfall does seem to be quite high, I guess it could mean a very stormy hot July. Not sure what the CFS is going on about with temperatures like that and rainfall that it's showing.

Overall June could be pretty unsettled and thundery, but warmer than of late. The fact you have 20-24*C 850hpa sitting over Spain worries me, that if the high/lows position right.... that air will stream up towards the UK and you have yourself a August 2003 again.

[A.J]

The CFS model output is to taken with a very large pinch of salt...It's main function (certainly on this forum) is to pick out possible (not probable) trends & pattern changes.....to pick out specifics such a temperatures etc is, with the greatest respect, fraught with danger & liable to be very inaccurate....Again, no disrespect to the previous poster, but I felt it needed to brought to the attention of thread readers, especially members learning about meteorology otherwise confusion could easily reign if CFS output pans out to be inaccurate.......For reasonably accurate modelling out to T192 GFS, UKMO & ECMWF are the models of choice, and again out into the realms of FI for possible pattern changes/trends these are the models of choice

[Robbie Garrett]

The CFS model output is to taken with a very large pinch of salt...It's main function (certainly on this forum) is to pick out possible (not probable) trends & pattern changes.....to pick out specifics such a temperatures etc is, with the greatest respect, fraught with danger & liable to be very inaccurate....Again, no disrespect to the previous poster, but I felt it needed to brought to the attention of thread readers, especially members learning about meteorology otherwise confusion could easily reign if CFS output pans out to be inaccurate.......For reasonably accurate modelling out to T192 GFS, UKMO & ECMWF are the models of choice, and again out into the realms of FI for possible pattern changes/trends these are the models of choice

However, CFS indicated about 1-2 months ago a dry spell happening about now, into June. It also predicted the washout April, May from January/February. Give it some credit, because it has picked out trends not accurate forecasts. I am not saying using it as a forecast, but it's the same as GFS, UKMO and ECMWF which was not even accurate 3hours ahead this winter, for example it was meant to snow heavily in the west counties but London got blasted during rush hour.

This is a modelling discussion, not a weather forecast topic. I myself and anyone else can post what they are showing, regardless if it goes to 3,000,000 hours ahead..... it's what the forum topic is for!!??

I am not an idiot, to the point where I think the CFS will show temperatures of 29*C on Thursday 26th July 2012, I just posted what could be expected in July IMHO......

Edited May 23, 2012 by Robbie Garrett

[A.J]

Being a member of the NW team, I am very aware of what this topic is for, so I don't need to be reminded, thank you!

By all means make posts on CFS output, there's nothing wrong with that, but perhaps adjust your posting style so that it's clear what the particular model output represent (ie pattern changes etc etc) otherwise again, for newbies, confusion can reign...It might just be me, but sometimes it seems that your posts on CFS output come across as you consider it the most likey eventuality..Agreed, the CFS has picked out some accurate trends recently, that's what it's there for, but I can also recount numerous times when its output has been way off the mark....Like I said, no disrespect intended......Infact, just wondering about the possibilities of a specific thread for long range modelling (if it's not been already done?) ....I do find that particular model output fascinating and it would be a shame if quality member inputs get lost in this thread....What do you think?

Anyhoos, on that note, I'll bow out of the discussion to avoid going off on further tangents

[Alex]

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

.. a lot of dry members there, the operational tending towards being a wetter outlier.

With the GFS ensemble mean looking like this..

http://raleighwx.americanwx.com/models/gfsensemble/00zENS11-15day500mbHeightAnomalyNH.gif

(anomalous ridge setting up west of Greenland in the Canadian Maritime, low pressure in the Atlantic) some potentential here for a genuine hot spell to come in the day 10+ timeframe with a ridge breaking in from the SW and re-setting the block over the UK / Scandinavia.

This setup has been showing on a couple of runs on the GFS recently, unfortunaely the 06z attempts to push everything more east and my worry is that we could miss the boat on this one! Hope not! Do any teleconnections back up the trend Stewart? I realise that angular momentum has been rather steady recently albeit a slight increase and the MJO is looking distinctly phase 8 for a while yet.

[phil nw.]

http://www.knmi.nl/e...agse/index.html

.. a lot of dry members there, the operational tending towards being a wetter outlier.

With the GFS ensemble mean looking like this..

http://raleighwx.ame...htAnomalyNH.gif

(anomalous ridge setting up west of Greenland in the Canadian Maritime, low pressure in the Atlantic) some potentential here for a genuine hot spell to come in the day 10+ timeframe with a ridge breaking in from the SW and re-setting the block over the UK / Scandinavia.

Yes and going by the temps. so far this week Stuart we are already in a hot spell and the medium term looks very Summery as you suggest.

The mean hts from the 00z GFS/ECM runs certainly underline the sypnotic outlook for days 8-10

Northern European Heights and the core of an Atlantic trough out towards the E.Seaboard.

Wrt to the CFS -no issue with people posting/discussing this model but it is longer range and therefore, by inference, less reliable.

They are likely to change just as frequently as the daily runs so newer members bear this in mind when viewing these charts.I don`t see the merit in reffering to these on a frequent basis.

[Deluxe]

What are people's thoughts regarding GFS 06z? Worse than ECM and Met Office charts in the mid-term, and way off the mark with regards to the 18z and 00z runs. Is it on to something, or is it likely to be an outlier? I'm inclined to think the latter, but that might be my preference for a high pressure dominated summer clouding my thoughts!

[The Northern Ramper]

I read a few months ago that the 6z had the lowest verification stats of the four runs.