Model Output Discussion 18z 28/07/13

[Captain Shortwave]

Good output this morning, good support for the cut off low, including ECM ens

 

 

Uppers remain above average except for a brief period on Friday as a cold front tries to move east.

[Summer Sun]

I hope Lorenzo is right about no SSW to influence winter this winter that really knackered our spring up this year especially March

 

UKMO continues to show pressure rising later this week with the north becoming drier first

 

 

ECM shows a similar pattern later this week

 

 

The SE would continue to see high temperatures else where it would be around average

 

 

As we move into next week its a case of the further north the better it would be with pressure lower in the south it becomes warmer for all again

 

 

ECM ends with uppers around average

 

 

GFS also follows ECM by keeping pressure higher the further north you are http://www.null/ds/gfs.htm

 

 

Apart from Friday when cooler uppers try to push east a continuation of the warmth is the form horse again

 

Edited September 1, 2013 by Summer Sun

[Milhouse]

D

 

Doesn't look too bad for here especially temperature wise, could be looking at above normal temperatures again after the 9th. 

 

Not for the first time this summer the mean only temporarily drops below average.

[Summer Sun]

Here is the latest from Gibby on the models

 

Good morning folks and welcome to meteorological Autumn 2013. Here is the report on the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM along with the Fax Charts, GFS Ensemble review and the Jet Stream forecast for today Sunday September 1st 2013.

 

The General Situation. All models show a Westerly flow over the UK with High pressure to the South and Low to the North. In the South winds will be light today while the North will be blustery. Warm fronts will carry cloud and damp weather to the North today and rather more than damp for the far NW later as wet  weather spreads in here. In the South some bright weather is expected with hazy sunshine and temperatures a little warmer than yesterday. Through the next few days this pattern persists with the best conditions in the South where it will become warm or very warm by midweek, especially in the SE as High pressure migrates to the SE of Britain feeding up warm winds from the South. By midweek though pressure will be falling everywhere and a broad trough will move in from the West on Thursday with some potentially quite heavy and thundery outbreaks of rain or showers in a slack Southerly breezy. Towards the end of the week the trough continues to dominate the weather as it slows down over eastern britain while developing Low pressure along it which relaxes down to the South of the UK for next weekend setting up a cool NE flow with rain or showers at times in the South. Northern areas will see better conditions next weekend as a strong ridge of high pressure builds across these areas.

 

The Fax Charts back up the above text pretty well with a broad trough of low pressure crossing East on Thursday with widespread showers and outbreaks of rain working their way West to east across the UK late in the week with Low pressure forming near Eastern England.

 

GFS then shows a North/South split in the weather for next weekend and the start of the second week as Low pressure to the South of the UK maintains fairly cloudy and unsettled conditions in the South with thundery rain at times while the ridge across the north continues to ensure drier and brighter conditions are likely here in average temperatures for early September. The end of the run shows little change with the axis of low pressure always maintained closest to the SW of Britain with further rain at times which could extend to northern areas too as a trough crosses East and the outer limit of the run.

 

The GFS Ensembles show a lot of spread this morning following the warm phase this week. There are options shown for both cool and warm solutions but many do indicate rain at times for the South too with the North if anything trending to rather less rain as high pressure builds somewhat here. The operational was on the warm side of the crop this morning.

 

The Jet Stream maintains an overall thrust of being positioned just to the North of the UK for much of the time. However, an arm of it is shown in a confused and diffuse state for much of the time over the UK and Europe as the Low to the South of the UK complicates it's usual West to East flow.

 

UKMO would most likely evolve in a continuation of a North/South split in conditions with the South seeing the biggest share of showery conditions as Low pressure to the South on Day 6 looks like it could start to edge back up towards Southern Britain in the days that follow.

 

GEM today keeps low pressure to the SW and later west of the UK, close enough to promote showers across the South and West with the North and NE seeing the driest and brightest conditions in a cool East wind while elsewhere sees average temperatures but a lot of cloud.

 

NAVGEM too has Low pressure over France at the end of next weekend with cool and unsettled weather across the South while the North closer to high pressure to the North stay largely dry and bright with some sunshine in average temperatures. It will be cool in the blustery East or NE wind though everywhere.

 

ECM finally shows a similar pattern to the rest with the South bearing the focus of the cloud, rain and showers while the North sees the best of the dry and bright conditions with Western Scotland probably seeing the brightest and driest weather with the highest temperatures away from the cool and fresh East or NE flow blowing elsewhere.

 

In Summary today we have unity from all models that a trough of low pressure will replace the fine and dry conditions in the South up until Thursday with rain and showers developing for all for a time. From the weekend as Low pressure develops either close to the East and eventually the South of the UK the weather will become least settled in the South where thundery rain or showers look like continuing for some considerable time. The North looks like there will be a good deal of dry weather developing though onshore winds in the East will keep things cool here while the best weather may end up in the NW of Scotland with some sunshine at times. For the first time for a long period it looks as though if the above outputs verify the Azores High will at long last have lost it's influence over the UK with a more cyclonic pattern for most with High pressure close to the North for a change. The chances are that towards the end of the second week Atlantic depressions may stroll across the Atlantic to extend more unsettled conditions for all by the end of the period hinted at by GEM today.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

 

 

[Milhouse]

A potentially interesting situation emerging for about 7 days time with low pressure being squeezed away to the south of the UK by a two pronged attack by high pressure on both sides. Then we have easterlies setting up across the UK sourced from a long way south.

 

Edited September 1, 2013 by Milhouse

[bluearmy]

.... but if john uses it, its good enough for me! his research came up with some impressive results, so im taking closer eye on them (obviously still learning )

 

and actually, i dont get it, because the anom and op often vary...

 

rob, john uses it as if it shows consistency over three runs then it shows the ops are in consistent agreement on the lw pattern and anomolys in the 6/10 day timeframe.  i agree wholeheartedly with that viewpoint. however, to look at them, run to run and make judgements is useless if the ops are not showing a consistent pattern as they will merely reflect any op flip flopping.  and gavin, we will forgive you your comment on SSW's. just dont do it again 

[Tim Bland]

I hope Lorenzo is right about no SSW to influence winter this winter that really knackered our spring gif

Excuse my ignorance if I'm wrong but you can't forecast a SSW event. Hence why the S is for Sudden. Also A lack of such event doesn't equall a mild or cold winter. Is there going to be a thread opened soon for all the winter forecasts / debate throughout Autumn?

[Southern Storm]

Excuse my ignorance if I'm wrong but you can't forecast a SSW event. Hence why the S is for Sudden. Also A lack of such event doesn't equall a mild or cold winter. Is there going to be a thread opened soon for all the winter forecasts / debate throughout Autumn?

just because something happens suddenly" it doesn't mean you can't forecast it, for example I could forecast a sudden drop of temperature to happen in two days time, not that it will of course!I would also add that the stratosphere is a lot more easy to model than the troposphere, you don't see half as many swings as say the surface pressure charts.But I will agree that you don't need a SSW for cold weather to affect the uk, but it improves our chances a great deal. Edited September 1, 2013 by Thunderman1981

[Polar Maritime]

Hope Lorenzo doesn't mind me copying his detailed thoughts from the regional thread...

 

"Think my prediction about the atmosphere not kicking on until there was a Hurricane from a couple of weeks back is carrying some weight now."

 

A couple of invest in the Atlantic , one with a chance of a tropical depression status in 6 days marries up well with the MJO pulling out of dormancy and the extra tropics being owned by weak Kelvin wave action.

 

MJO kicking through the maritimes is like an ignition paper for upper level divergence, a cheeky wheelspin of African equatorial waves which will ignite tropical season, the following pacific action killing the wave 3 anchor across the hemispher and heralding a more mobile pattern. It's weird writing on the forum where winter north south divide is so very different from summer. The south hanging onto some good ridging and reasonable uppers.

 

One major standout from the dogs breakfast ECM of the scrambled Scandi high for +144 next week is the Greenland Tip.

 

There is a wee hint that what caused the trough disruption of winters past is a good 300 miles further east this year. If this is so and the atmosphere want to ghost this synoptic, without Stratospheric influence, whereby this year is a weak analog, then we are looking at a strongly mobile winter.

 

Caveat is that this is just an early autumn read on seeing the trough disruption in FI, and for a good idea ahead we need to see the atmosphere base pattern ( strongly a drop in trough right now ) and shredding of systems... AFTER this MJO phase.. So November 05 12 GWO and MJO will be predictor of winter 13 -14, anything before that has some mighty guesswork. This year a late read, odds on no SSW influence, Brewer Dobson annihalated in summer , ozone transport delayed. at a guess now late feb / march again. with a zonal winter. until the 05th week November cannot tell

 

http://forum.netweather.tv/topic/77270-scotland-regional-discussion16th-july-2013-onwards/page-24#entry277860

[Tamara]

Thanks Lorenzo.

Looks like you will be taking over GP's job during the Autumn/Winter months here on the forum ! Your input/thoughts will be greatly appreciated, as others..

Yes an excellent and very interesting assessment there from lorenzo I have been really struck by the fact that this has been the first summer since 2006 with a prevailing +AO pattern, definitively westerly,with the Azores high returning to the fold, and yet we have continued to see this split energy theme that has characterised recent years under the semi permanent blocked patterns over the arctic.

I think it is noteworthy that the cyclical pattern of trough disruption and energy sinking SE rather than through what became known as the 'corridor of death' has been sustained through this switch from HLB since the late Spring....Of course the biggest test will come when the polar vortex season starts and the jet stream gains proper energy - however with the propensity for tendency towards split energy rather than through the northern branch it makes for a very interesting autumn season as it progresses

So in terms of the here and now and the more immediate further outlook - the EPS members show very good agreement for a repeat of the wider general theme we saw leading up to the August Bank Holiday, with the trough disruption, cut off low, and returning mid latitude ridging from the west.

.

It has been fascinating watching the models converge once again as time has got nearer on this split energy solution after that "dogs breakfast" as I called it of model uncertainty. That is the general macro scale pattern, but in terms of advancement of any plume warmth generated between the cut off low and the downstream ridge retreating over europe there remains uncertainty as part of this increasingly likely rinse and repeat scenario.

A temporary SE/NW split once more seems most probable as the ridge advances and the trough, most likely, ejects into the nearby continent. It brings the potential once more for appreciable rainfall for more southern parts. This is the part which remains with greater uncertainty. There might now be general model agreement for more energy to head SE...but it is still critical how much energy goes SE as to determining the surface conditions that actually verify for the UK. Much the same as was discussed in the lead up to the Bank Holiday - and we know that the Bank Holiday proved a large headache to forecast

So its just now a case of watching the closer pattern detail as time goes on.

Edited September 1, 2013 by Tamara Road

[Yarmy]

Excuse my ignorance if I'm wrong but you can't forecast a SSW event. Hence why the S is for Sudden. Also A lack of such event doesn't equall a mild or cold winter. Is there going to be a thread opened soon for all the winter forecasts / debate throughout Autumn?

 

I've noticed a sort of Godwin's Law on Netweather whereby every thread eventually becomes a discussion about Winter.

Edited September 1, 2013 by Yarmy

[TonyH]

Yeah could rename the site Netwinter.

[bluearmy]

I've noticed a sort of Godwin's Law on Netweather whereby every thread eventually becomes a discussion about Winter.

 

well meteorological summer ended yesterday yarmy so we are now free to look forward .....................   (but you are very close to the truth)

 

lorenzo's regional thread post interesting.  so many different ideas about the upcoming seasons and yet CFS continues to throw out a generally cold theme. but there is no comment on model output so i shall withdraw gracefully .......

[Captain Shortwave]

Whilst the models churn out charts like this

 

 

I'm keeping winter at the back of my mind. Still room in September for some high temperatures, it's only when you reach October that the temperatures really start to fall off a cliff.

Edited September 1, 2013 by Captain shortwave

[pandit-scholar]

Hi all,

Although I know some things about weather and can read the weather models now, I am still learning! Thus in layman terms what is Lorenzo suggesting for this Autumn and Winter please! Thanks

[Dancerwithwings]

Yeah could rename the site Netwinter.

That would be nice !!!! Maybe in about 200 million years when they reckon the uk will situated where the northpole is now

[No Balls Like Snow Balls]

Whilst the models churn out charts like this

 

 

I'm keeping winter at the back of my mind. Still room in September for some high temperatures, it's only when you reach October that the temperatures really start to fall off a cliff.

Luckily with them 2 charts the very warm temps stay in mainland Europe. The south of England would experiance heavy rain.

[Summer Sun]

Luckily with them 2 charts the very warm temps stay in mainland Europe. The south of England would experiance heavy rain.

 

Yep the north could well be the place to be for a time as it avoids the rain GFS shows only the southern coast and south west getting rain with temperatures around the mid 20's, away from the SW it looks light on Sunday

 

 

Monday (not tomorrow) is a different story heavy rain for the south and again the north is the best place to be as it avoids the rain

 

 

Head into France and the summer heat continues with temperatures pushing 30c

Edited September 1, 2013 by Summer Sun

[stewfox]

Hi all,

Although I know some things about weather and can read the weather models now, I am still learning! Thus in layman terms what is Lorenzo suggesting for this Autumn and Winter please! Thanks

 

This is a output model thread. The link to Autumn discussion is here

 

http://forum.netweather.tv/forum/1-weather-discussion-and-chat/

 

If you want to keep your supply of Prozac in hand, it really is far too early to worry about winter any 'forecast' at this time, waste of time but that my view.

 

Models are suggesting in the foreseeable (T140/T168) some nice warm weather for early September.

Edited September 1, 2013 by stewfox

[No Balls Like Snow Balls]

Hi all,Although I know some things about weather and can read the weather models now, I am still learning! Thus in layman terms what is Lorenzo suggesting for this Autumn and Winter please! Thanks

The met office don't do long range forecasts for a very good reason and that is cos they quite often end up wrong. And they are the people in the know. Edited September 1, 2013 by No balls like Snow Balls

[pandit-scholar]

This is a output model thread. The link to Autumn discussion is here

http://forum.netweather.tv/forum/1-weather-discussion-and-chat/

If you want to keep your supply of Prozac in hand, it really is far too early to worry about winter any 'forecast' at this time, waste of time but that my view.

Models are suggesting in the foreseeable (T140/T168) some nice warm weather for early September.

Thanks! I know it is always difficult to forecast the weather, even a few days ahead, but it is always interesting to know the long range forecasts. I agree, anything can happen between now and winter to turn it to either a very mild or very cold winter (the black swan theory is especially relevant here). Edited September 1, 2013 by pandit-scholar

[johnholmes]

Thanks! I know it is always difficult to forecast the weather, even a few days ahead, but it is always interesting to know the long range forecasts. I agree, anything can happen between now and winter to turn it to either a very mild or very cold winter (the black swan theory is especially relevant here).

You may find the thread one poster by the name of chio runs from the end of September a help. He will give lots of links for reading and also explanations of what he is talking about. The 2012-13 link is somewhere on the site if you would like to start by reading his first post from last September-well worth reading.

[Cloud 10]

You may find the thread one poster by the name of chio runs from the end of September a help. He will give lots of links for reading and also explanations of what he is talking about. The 2012-13 link is somewhere on the site if you would like to start by reading his first post from last September-well worth reading.

 

Here is the link to the 2012-2013 stratosphere thread.

 

http://forum.netweather.tv/topic/74587-stratosphere-temperature-watch-20122013/

 

An interesting read for sure!

[East_England_Stormchaser91]

Regarding things happening between now and winter.

It does not matter really at all on what happens now or in December to predict what we may get further on into the proper winter months. Look at earlier this year with cars being buried under 15ft snowdrifts. In December 2012, nobody predicted it at all when we was under a strong PV with a very active jet giving us a washout and after we thought the opportunity for the 'beast from the East' had gone completely. This is the weather, and as we know, it can be very abrupt and change before your eyes can believe it. The most reliable way of indicating what will happen this winter is simply just to wait and see! 

I for one can't wait, and I hope we do get some memorable events, but I would definitely not call anything at all just yet on how cold/warm it may be, that is hard enough to do even a few weeks out, let alone a few months!

[Summer Sun]

The met office don't do long range forecasts for a very good reason and that is cos they quite often end up wrong. And they are the people in the know.

 

They do produce LRF's still but they don't make them public like they did with the summer forecast a few years back which proved to be the final one issued

 

There seasonal forecast's are now available under the contingency planners forecast's http://forum.netweather.tv/topic/75389-met-office-contingency-planners-forecasts/?p=2777313