Model Output Discussion

[Summer Sun]

ECM Joins GFS in Breaking up the deep low, ECM does it a bit slower than GFS

http://www.wetterzen...ics/Recm961.gif

http://www.wetterzen...cs/Recm1201.gif

By Thursday ECM develops a new Low for Scotland.

http://www.wetterzen...cs/Recm1441.gif

http://www.wetterzen...cs/Recm1681.gif

Deep ECM offers hope for the west, plenty of showers for the east though.

http://www.wetterzen...cs/Recm2161.gif

http://www.wetterzen...cs/Recm2401.gif

Edited July 15, 2011 by Gavin D

[Gibby]

GFS tonight shows Low pressure moving in over Scotland tomorrow then hanging around in one shape or form for many days to follow. There would be rain or showers for all areas with just short drier and brighter interludes inbetween. It would be windy and cool too away from the Low centre with temperatures on the low side, especially in the rain. In the lower res end of the run things do very slowly improve but it is all relative as even then winds remain from the North or Northwest with further showers periodically from troughs running through on the breeze and temperatures suppressed to normal levels at best.

UKMO is also very unsettled tonight with Low pressure dominant near Northern and Eastern Britain throughout. There would be plenty of rain or showers and cool temperatures especially in the persistant rain. However, there would be some drier and brighter spells too where it will no doubt feel a little bit warmer if you can get out of the breeze.

ECM is also low pressure dominated with a centre meandering around the UK for two or three days from tomorrow before drifting just to our east where it also hangs around for 3 or 4 days. In essence it means unsettled weather with rain or showers and strong winds at times lasting through the whole of next week. In the final days of the run pressure builds North to the west of Britain but not quite close enough to restrict the UK, especially the east from seeing further showers in a cool North breeze. The west and northwest though could see some lengthy dry spells though by day 9 and 10 albeit a little on the cool side still but with low pressure close to East Anglia on day 10 there would be plenty of heavy showers still in the south and east..

In summary tonight things still look decidedly unsettled with Low pressure shown on all models to last through next week. It seems increasingly likely that hopes for drier weather hinge on a build of pressure North through the Atlantic in a week or so's time moving east enough to cut off the North flow from the Low pressure's over Scandinavia and the near continent. On tonight's output I wouldn't place much money on it happening with my hunch being that of the ridge collapsing with more Low pressure rolling down from the NW in time.

***No report tomorrow as away working in the Cotswolds-back on Sunday or if anything interesting to report tomorrow evening.***

[Lt. Dan]

easy to see how warm the air is now without waiting to see what may happen simply by looking at the dewpoint chart on Net Wx?

the link below takes you to Extra and it shows quite well how much 'warmer' air is already tied into the circulation to the south of the surface centre.

http://www.netweathe...03489270e80f1f2

as promised a page or so back, below is the pdf to help those new to using the 500mb anomaly charts. I know some are unable to access pdf files so it will go into the Guides when I get time as an open file with charts inserted.

500mb charts-how to use 2nd version-15 july 2011.pdf

Hi John

Thanks for this, interesting read. Basically this is the long wave ridge/trough pattern? Whilst the UK sits in a long wave trough we can expect 'unsettled' conditions with the odd transient ridge between the next short wave? Hopefully I've understood that!

[PubliusEnigma]

Next weekend looking almost as bad as this one with another washout on the cards especially for the NE, E and SE :o

Another low tracking very close to the east with rain, cool northerlies, a good chance temps will reach tops of

15oC or less in the rainy areas, weekend after weekend of rainy wet weather. Seems as though the British Summer is

returning to the values we used to see in the 70's and 80's.

The Met O latest 16-30dayer talks of very unsettled first half of August with below average temps, so more of the same

for the next month at least, and then there will be just a week or so of very late summer left..

[bluearmy]

the trend is to keep the troughing close to our east and for it to keep pepping up. is this the ops being over zealous as they tend to be in early fi or will the slightly better ens mean be closer to reality ??

[Thundery wintry showers]

I think next week is looking rather dubious sunshine wise. A "clean" airflow from west of due north would certainly give us sunshine and showers, but the UKMO FAX charts indicate that there may be a fair number of slow moving fronts around the depression in the North Sea, which would promote cloudier conditions with longer outbreaks of rain in the areas affected by the fronts. I'm also wary of the possibility of the odd shortwave or two coming down from the north-west, which would have the same effect.

Temperatures will be below average whatever happens due to the winds coming down from well within the Arctic Circle, so if we do get much in the way of cloudy wet interludes it will feel distinctly nippy, but if it stays bright and showery for most of the week then it might not feel too cold in the sun and out of the wind.

Next weekend will probably be cloudy, cold and mostly dry as the low pressure looks like being sat out in the North Sea with the cold air at 850hPa being mixed out from the NE creating a more stable air profile.

[PubliusEnigma]

Next weekend will probably be cloudy, cold and mostly dry as the low pressure looks like being sat out in the North Sea with the cold air at 850hPa being mixed out from the NE creating a more stable air profile.

depends it there is an occlusioin wrapped around the low off East Anglia, if there is temps could well be 11-13oC in E Anglia and the south east, in a very chilly NNE wind. THe low looks very slow moving, so a re run of this weekend looks likely however with less dry weather, more rain, and lower temps. in fact the next 10 days look wet almost any day, and when not wet, some very chilly nights and even days under cumulus which flattens out into extensive Stratocumulus.

[johnholmes]

Hi John

Thanks for this, interesting read. Basically this is the long wave ridge/trough pattern? Whilst the UK sits in a long wave trough we can expect 'unsettled' conditions with the odd transient ridge between the next short wave? Hopefully I've understood that!

that is about it briefly;

the position of the upper trough is crucial, over/east=coolish and unsettled, to the west and it means warmer winds from the S-SW, still largely unsettled, depending just where the trough is.

[95 Degrees]

depends it there is an occlusioin wrapped around the low off East Anglia, if there is temps could well be 11-13oC in E Anglia and the south east, in a very chilly NNE wind. THe low looks very slow moving, so a re run of this weekend looks likely however with less dry weather, more rain, and lower temps. in fact the next 10 days look wet almost any day, and when not wet, some very chilly nights and even days under cumulus which flattens out into extensive Stratocumulus.

No need to troll really, the charts look dreadful for the next week but 11-13C? almost impossible in Mid-July, do you have any positive atom in your body, and after the disaster that is the weekend and Monday it's showers rather than all day frontal rain.

[PubliusEnigma]

No need to troll really, the charts look dreadful for the next week but 11-13C? almost impossible in Mid-July, do you have any positive atom in your body, and after the disaster that is the weekend and Monday it's showers rather than all day frontal rain.

I can assure you, I can recall 10oC in July, if you have a nasty Low centred off the Thames estuary with strong north easterlies, driving rain, and evaporative cooling then 11-13oC is certainly possible. If Dry, then you can add a couple of degrees.

Showers maybe in the channel, but I wouldnt want to be in parts of the north west under the wrap around this weekend, it could rain pretty much non stop from Sat lunchime until Monday lunchtime.

that is about it briefly;

the position of the upper trough is crucial, over/east=coolish and unsettled, to the west and it means warmer winds from the S-SW, still largely unsettled, depending just where the trough is.

problem is John, all the models are showing the AzH edging a tad nearer towards the end of july, most probably shunting the trough we've had over or near us since the end of May, into the north sea. The resultant effect is a continuation of the unsettled theme, but with a tendancy for the averages to drop as things turn colder in the coming weeks with northerlies more common. Based on the lastest Ensemble thinking.

Edited July 15, 2011 by PubliusEnigma

[johnholmes]

problem is John, all the models are showing the AzH edging a tad nearer towards the end of july, most probably shunting the trough we've had over or near us since the end of May, into the north sea. The resultant effect is a continuation of the unsettled theme, but with a tendancy for the averages to drop as things turn colder in the coming weeks with northerlies more common. Based on the lastest Ensemble thinking.

I hardly see the 'as things turn colder....' being really very realistic on 15 July? 10-15 days down the line then more probability but linking that to northerlies and the ensembles is taking it way too far.

Nothing in the 500mb anomaly charts for the next 15 days suggests any spell of northerlies nor in the further out tc's to my eyes. There is a SLIGHT, no more, that the attempts today and yesterday by NOAA, not ECMWF-GFS, to suggest that the +ve area is going to edge further towards the SW of the UK MAY be a probability, about 50:50 I would say at the moment for early August. As to what happens beyond that, if that is what you refer to with your northerlies I have little if any idea.

Edited July 15, 2011 by johnholmes

[PubliusEnigma]

I hardly see the 'as things turn colder....' being really very realistic on 15 July? 10-15 days down the line then more probability but linking that to northerlies and the ensembles is taking it way too far.

Nothing in the 500mb anomaly charts for the next 15 days suggests any spell of northerlies nor in the further out tc's to my eyes. There is a SLIGHT, no more, that the attempts today and yesterday by NOAA, not ECMWF-GFS, to suggest that the +ve area is going to edge further towards the SW of the UK MAY be a probability, about 50:50 I would say at the moment for early August. As to what happens beyond that, if that is what you refer to with your northerlies I have little if any idea.

Sorry, just re-read your post.. Too many commas .. Where I mention the cooler flow it really isnt with us for 8-10 days time, not until next weeks unsettled episode is out of the way..

Edited July 15, 2011 by PubliusEnigma

[johnholmes]

this is what I posted

the position of the upper trough is crucial, over/east=coolish and unsettled, to the west and it means warmer winds from the S-SW, still largely unsettled, depending just where the trough is

You or anyone else is of course entirely free to interpret that as you wish.

What I was trying to get across was the general idea not any specifics about the events you are postulating on. Those are based on GFS and its Ensembles, quite possibly a rather different emphasis there.

[feb1991blizzard]

All models tonight suggest a cold Northerly prevailing almost throughout the runs, if the models are being anywhere near accurate then surely it could be one of the coldest Julys on Record.

[bluearmy]

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

almost there JH. the trough edges east and the upper ridge together with its slp buddy edges closer. this is a chart which has 100% confidence from noaa cpc. also note the upper trough just west of greenland. its a slow old process but we seem to be edging closer to a better spell.

[ANYWEATHER]

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

almost there JH. the trough edges east and the upper ridge together with its slp buddy edges closer. this is a chart which has 100% confidence from noaa cpc. also note the upper trough just west of greenland. its a slow old process but we seem to be edging closer to a better spell.

Sorry Mate, but what forecast is 100%??? If that happens it will be a First!!

[lorenzo]

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 5 ON A SCALE OF

1 TO 5, DUE TO VERY GOOD AGREEMENT AMONG THE MODELS AND TOOLS, DAY TO DAY

CONSISTENCY, AND GOOD CONTINUITY WITH THE PREVIOUS 6 TO 10 DAY OUTLOOK PERIOD.

[Jason T]

Sorry Mate, but what forecast is 100%??? If that happens it will be a First!!

Anything is possible though ...IS it not. As a post stated mother nature finds a way to balance things out,maybe just maybe she over done it and is trying a different angle. Although we do need something pretty strange to happen, Im sticking with this current output (its a start).

Edited July 15, 2011 by silver line

[johnholmes]

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 5 ON A SCALE OF

1 TO 5, DUE TO VERY GOOD AGREEMENT AMONG THE MODELS AND TOOLS, DAY TO DAY

CONSISTENCY, AND GOOD CONTINUITY WITH THE PREVIOUS 6 TO 10 DAY OUTLOOK PERIOD.

you have to remember that, usually, NOAA are understandably talking about their own backyard!

It does always give more confidence when seeing that kind of comment from them. The long wave length features are such that if its okay over North America it is often, not always, pretty close to being about right for the UK. But as someone has posted and I continually suggest its a forecast and nothing is ever in tablets of stone with forecasts in meteorology, model or human.

But as ba suggests and I also posted there is PERHAPS the first chink of light in something akin to summery conditions in the 12-15 day time frame developing.

[bluearmy]

Sorry Mate, but what forecast is 100%??? If that happens it will be a First!!

the forecast isnt 100%, the confidence of the forecaster in his chart is 100%. as its a mean chart covering a 6 day period, its a lot easier to be confident than picking out the minutiae of the day to day stuff that may occur within the period.

[Jason T]

GOD what do some want... BLOOD, The noaa yes there summary can at times refer to IMBY as JH stated and as BA stated the forecast is not 100% but WHAT output had these changes over the past 10 weeks.

Maybe slight but ITS there.

[ANYWEATHER]

the forecast isnt 100%, the confidence of the forecaster in his chart is 100%. as its a mean chart covering a 6 day period, its a lot easier to be confident than picking out the minutiae of the day to day stuff that may occur within the period.

With ALL respect to you BA, you do have a point, but "NO" forecasts are 100% whether its 24hrs or 168 hrs. We are talking about the weather here, and no right person in there right mind will give a forecast withe a Guarentee or 100%.... :unsure: <_<

[EML Network]

LONG time since I posted here.

I see the usual netweather squabbling still goes on.

IMO that 25th July is a crucial tipping point, for the remainder of the ''summer'' , as is born out by the ensembly's , there does, however seem to be a little more cohesion today, and the general trend leading up to the beginning of August is for a slow and slight increase in overal temperature.

However, going by MET O , and a few other sites it looks to be a short lived affair, and if the 12z GFS comes off, might not happen at all.

In fact the reason for this post today, is to highlight what an abnormal 12z GFS run we have today in comparison to what we have been seeing all week, the HP system that looked for all intensive purposes ''on the cards'' for around the 27th July, seems not to make it to these shores, cut off by a system developing to the East of the UK holding firm, and allowing the winds to transferre from the North

To cut a long story short, IMO were still likely to see a week of dry and reletivley mild weather for the last few days of July, into early August, and that might very well be the last of the warm weather this summer.

Anyone for an Indian...summer that is ??

Edited July 15, 2011 by EML Network

[ANYWEATHER]

LONG time since I posted here.

I see the usual netweather squabbling still goes on.

IMO that 25th July is a crucial tipping point, for the remainder of the ''summer'' , as is born out by the ensembly's , there does, however seem to be a little more cohesion today, and the general trend leading up to the beginning of August is for a slow and slight increase in overal temperature.

However, going by MET O , and a few other sites it looks to be a short lived affair, and if the 12z GFS comes off, might not happen at all.

In fact the reason for this post today, is to highlight what an abnormal 12z GFS run we have today in comparison to what we have been seeing all week, the HP system that looked for all intensive purposes ''on the cards'' for around the 27th July, seems not to make it to these shores, cut off by a system developing over the UK holding firm.

To cut a long story short, IMO were still likely to see a week of dry and reletivley mild weather for the last few days of July, into early August, and that might very well be the last of the warm weather this summer.

Anyone for an Indian...summer that is ??

Gosh, youve put another Spanner in the works....!!!!!

[Thundery wintry showers]

No need to troll really, the charts look dreadful for the next week but 11-13C? almost impossible in Mid-July, do you have any positive atom in your body, and after the disaster that is the weekend and Monday it's showers rather than all day frontal rain.

My take on this is that 11-13C is rather over-egging it, because by next weekend chances are there will be warmer air mixing into the circulation from the north-east. However, if some of the current charts come off then it could be a particularly "driech" story over East Anglia, with the low pressure, relatively stable airmasses passing over the moist North Sea and any slow moving fronts wrapped around the low combining to produce dull damp weather and temperatures most likely held in the region of 13-16C.