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Model Output Discussions 12z 01/06/2017


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An unseasonally wet, cool and windy day amidst an underwhelming week of weather does not a summer make. Much as anticipated through the second half of Spring, the hand-over to Summer sees the atm

There have been some strange observations made today, as too often occurs in this thread whatever the time of year, and largely based on the usual knee-jerk response to longer term suggested NWP.

You always seem to jump in on my posts, along with a few others. Why don't you try giving your assessment of the models instead of picking holes in others efforts!

Posted Images

3 hours ago, Weatherlad50 said:

Terrible weather on the way over the next two to three weeks with very cold stormy autumnal weather. I agree that there is likely to be flooding across England. No sign of jet stream moving north. This is going to end up like 2007 wish a washout end of July and rain for the whole of august. Nightmare models for heat lovers like me.

Evening All , WOW this is an amazing outlandish post  ...cold and stormy  autumn weather and like 2007  in the next few weeks:rofl::rofl::rofl:  This is nothing like 2007 , if you look at the big picture Ridge Low , Ridge Low,,,,some rainy spells along with some fine and settled conditions...Now can I have a Chocolate Biscuit:rofl: or perhaps a Chocolate Teapot:rofl:

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Edited by ANYWEATHER
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No significant changes with the anomalies last night so stright on with this morning's gfs.

After a pleasant day today fronts cross the country tomorrow associated with the complex area of low pressure in the Atlantic which is going to influence our weather for a few days.In fact one way or another certainly for the next ten days with high pressure making fleeting appearances in the south.

By 12z Thursday the main trough to the WNW has got itself organized and is fairly close to the Hebrides 975mb with the UK in a showery westerly.

gfs_ptype_slp_eur3_11.thumb.png.2cafdf8a8c70e40390129dc7350ebd75.png

From this point the upper low hangs around to the north west as the surface feature slowly fills with the odd system running around the circulation. So by 12z we have this analysis with transient ridging just exiting the south east and the persistently strong jet ready to transport some more quite shallow systems ENE to to top up the general area of low pressure.

gfs_uv250_natl_23.thumb.png.e3703a77ec4708e4e56f8579d1e79858.pnggfs_ptype_slp_eur3_23.thumb.png.96a7c445e4903dea67cd82d0ffc99317.png

Essentially this remains the situation for next week with the UK under the influence of the low pressure thus a generally unsettled period with showers, perhaps the odd longer period of rain, and of course drier and sunny intervals which will be longer and more inclined in the south where the high pressure may make some fleeting appearances. Temps quite variable around the average. Not what we are all looking for in the beginning of August but perhaps the reality will not be as grim as it looks.

gfs_ptype_slp_eur3_31.thumb.png.bb20bb4f90a7f42efda1cf4966c08b42.pnggfs_ptype_slp_eur3_39.thumb.png.a1985af1e61a8dfc6a17387e8d40e6e7.pnggfs_z500a_natl_40.thumb.png.59183a634b8af635efc7fcc99b20e7b1.png

 

 

Edited by knocker
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Another day of vile output dominated by cool weather, deep areas of low pressure, wind and rain. Looking like a summer of two halfs....except the June monsoon is arriving in July and August instead. Shockingly bad.

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24 minutes ago, Man With Beard said:

No clever ensemble picking from me today, just straightforward advice for anyone thinking of a last-minute UK holiday in the next 10 days. For those unfamiliar with these charts, think blue = drizzle/short showers, light green = moderate rain, darker green + anything else = big umbrella needed.

Tomorrow: Rain

36-574UK.GIF?25-0

Thursday: Rain

63-574UK.GIF?25-0

Friday: Rain (particularly in the west, south+east coasts might miss it)

90-574UK.GIF?25-0

Saturday: Rain (Scotland gets it later)

102-574UK.GIF?25-0

Sunday: Rain

138-574UK.GIF?25-0

Monday: Rain

162-574UK.GIF?25-0

Tuesday: Rain

180-574UK.GIF?25-0

Wednesday: Rain

198-574UK.GIF?25-0

Thursday: Rain

228-574UK.GIF?25-0

Friday: Noah's ark recalled into service

55113-2.jpg?1454685789  

bbc weather says Thursday/Friday will be dry so don't know why charts are showing Rain.

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1 minute ago, 40*C said:

bbc weather says Thursday/Friday will be dry so don't know why charts are showing Rain.

In fairness my Friday chart was an evening chart, and it probably will be dry for many until late in the day (whoopee!!).

Thursday though, not so sure, I think most models see rain on that day, even my trusty model Argepe.

arpegeuk-1-60-0.png?25-06

Also, I think in the current set-up, without any decent heights, showers may pop-up at short notice; the weekend just gone being a case in point.

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Whilst the above charts may suggest a washout, it is worth remembering that these rain bands will not necessarily be with us day in day out. I am not particularly excited to see cooler temps and unsettled weather but lower resolution charts make it look worse than it probably will be.

For example many areas will see the worst of the rain pass over during the night or early/late hours on various days (subject to timing changes). If it is particularly windy due to a rather deep area of low pressure, you will find rain bands should cross within a few hours. Showers may be likely but again these are usually hit and miss. Just for example Saturday just gone there were a lot of showers moving into the SW yet my location only had 2 brief showers for the whole day with pleasant sunshine in between. Others weren't so lucky - such is the nature of showers.

The Jet has picked up a notch and it's positioning is not helping the Azores high nudge into Europe enough to settle us down again. However there are sometimes posts writing off the whole of August based on 1-2 weeks worth of output that to be honest can change at short notice due to subtle changes in the synoptic patterns.

It will be interesting to see how things progress as we move into August. Fingers crossed we see something more settled again for the kid's holidays :)

 

 

Edited by Chris K
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I'd agree - those charts can be a tad misleading....the SE looks really wet going by those, but looking at the accumulated ppn charts:

Rmgfs120sum.gif
There's only 3-18mm in a large swathe of the SE over a 5 days period - hardly a washout. The northwest however looks particularly grim. Widely 30mm+, up to 70mm in places. Could be flooding risks if those amounts stack up.
 

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19 minutes ago, Chris K said:

Whilst the above charts may suggest a washout, it is worth remembering that these rain bands will not necessarily be with us day in day out. I am not particularly excited to see cooler temps and unsettled weather but lower resolution charts make it look worse than it probably will be.

For example many areas will see the worst of the rain pass over during the night or early/late hours on various days (subject to timing changes). If it is particularly windy due to a rather deep area of low pressure, you will find rain bands should cross within a few hours. Showers may be likely but again these are usually hit and miss. Just for example Saturday just gone there were a lot of showers moving into the SW yet my location only had 2 brief showers for the whole day with pleasant sunshine in between. Others weren't so lucky - such is the nature of showers.

The Jet has picked up a notch and it's positioning is not helping the Azores high nudge into Europe enough to settle us down again. However there are sometimes posts writing off the whole of August based on 1-2 weeks worth of output that to be honest can change at short notice due to subtle changes in the synoptic patterns.

It will be interesting to see how things progress as we move into August. Fingers crossed we see something more settled again for the kid's holidays :)

 

 

Yes fair enough. For instance, we might get lucky with the Friday/Saturday main rain band crossing overnight, leaving most of Friday/Saturday dry-ish especially in southern and eastern areas.

But I think my post demonstrates that not a single location in the UK is guaranteed even one dry day in the next nine, after today. 

Signs of improvements after D10, but given the current situation, it would only take one extra low to cross the Atlantic to scupper that.

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The whole Atlantic right now looks like just one huge over-sized breeding ground for troughs and lows pressures have plenty of room to swing their full weight around. It has to be said - this type of pattern is never in a hurry to clear, although there seems to be a trend for improvement around the 5th.

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1 hour ago, Man With Beard said:

No clever ensemble picking from me today, just straightforward advice for anyone thinking of a last-minute UK holiday in the next 10 days. For those unfamiliar with these charts, think blue = drizzle/short showers, light green = moderate rain, darker green + anything else = big umbrella needed.

Tomorrow: Rain

36-574UK.GIF?25-0

 

High res for the same time tomorrow

aromehd-1-36-0.thumb.png.c98d57ec458712daf5b2a2233a655398.pngnmm_uk1-1-36-0.thumb.png.3ba834758add1a0fa84b423591bbed60.png

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54 minutes ago, Chris K said:

Whilst the above charts may suggest a washout, it is worth remembering that these rain bands will not necessarily be with us day in day out. I am not particularly excited to see cooler temps and unsettled weather but lower resolution charts make it look worse than it probably will be.

For example many areas will see the worst of the rain pass over during the night or early/late hours on various days (subject to timing changes). If it is particularly windy due to a rather deep area of low pressure, you will find rain bands should cross within a few hours. Showers may be likely but again these are usually hit and miss. Just for example Saturday just gone there were a lot of showers moving into the SW yet my location only had 2 brief showers for the whole day with pleasant sunshine in between. Others weren't so lucky - such is the nature of showers.

The Jet has picked up a notch and it's positioning is not helping the Azores high nudge into Europe enough to settle us down again. However there are sometimes posts writing off the whole of August based on 1-2 weeks worth of output that to be honest can change at short notice due to subtle changes in the synoptic patterns.

It will be interesting to see how things progress as we move into August. Fingers crossed we see something more settled again for the kid's holidays :)

 

 

does the jet stream determine where the azores high is positioned , or does the azores high dictate where the jet stream flows?....

its true that you cannot write off the whole of august based on the first two weeks of prediced synoptic patterns. but historically, and you only have to go back to the last few summers, once these atlantic trough driven patterns have established and they have 'written off' the rest of august/summer. so whilst it certainly isnt a done deal - it is pretty likely, these troughing patterns are usually hard to shift once in place. ill not place any money on any sustained hot spell emerging, however its one bet id be happy to lose!

Edited by mushymanrob
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3 minutes ago, mushymanrob said:

does the jet stream determine where the azores high is positioned , or does the azores high dictate where the jet stream flows?....

its true that you cannot write off the whole of august based on the first two weeks of prediced synoptic patterns. but historically, and you only have to go back to the last few summers, once these atlantic trough driven patterns have established and they have 'written off' the rest of august/summer. so whilst it certainly isnt a done deal - it is pretty likely, these troughing patterns are usually hard to shift once in place. ill not place any money on any sustained hot spell emerging, however its one bet id be happy to lose!

I agree, as depressing as it is, every time you wake up and see another run of Atlantic trough domination, it's another nail in the coffin of summer. If this was happening in June I'd be less inclined to believe that, but we are in late July now and it's quite feasible this could go on for another 4 weeks- it's happened before in recent years.

That's not to say there won't be a few nice days (and possibly the odd warm/hot day if the troughs stall out west briefly), but the way things are it's very hard to see a prolonged spell of settled weather at the moment.

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27 minutes ago, mushymanrob said:

does the jet stream determine where the azores high is positioned , or does the azores high dictate where the jet stream flows?....

its true that you cannot write off the whole of august based on the first two weeks of prediced synoptic patterns. but historically, and you only have to go back to the last few summers, once these atlantic trough driven patterns have established and they have 'written off' the rest of august/summer. so whilst it certainly isnt a done deal - it is pretty likely, these troughing patterns are usually hard to shift once in place. ill not place any money on any sustained hot spell emerging, however its one bet id be happy to lose!

I won't go into the science of the Jet stream because there are different factors that will affect its strength, flow, direction and angle, but yes my choice of words probably weren't the best linking it to the positioning of the Azores High.

I agree with you and I am well aware of patterns that can set in for a prolonged period of time. However I don't think anyone can definitively say it will go one way or the other. I don't know what others thoughts are, but to me it has felt like we have had a repetitive pattern of High pressure moving from the Azores into Europe for brief periods since the end of May, with the "mini plumes" that came with it for some parts of the country. This seems to be changing now with the trough becoming more dominant and similar to what you said, hopefully it won't become hard to shift. I am only an amateur in terms of interpreting models and I cannot see whether this is perhaps a transitional phase of unsettled weather or a pattern that is likely to last a while. Maybe you know more than me? I can only go on experiences of the past where models have shown a prolonged period of unsettled weather then throws a curveball a week later with a (sometimes completely) different outlook...

Edited by Chris K
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28 minutes ago, mushymanrob said:

does the jet stream determine where the azores high is positioned , or does the azores high dictate where the jet stream flows?....

its true that you cannot write off the whole of august based on the first two weeks of prediced synoptic patterns. but historically, and you only have to go back to the last few summers, once these atlantic trough driven patterns have established and they have 'written off' the rest of august/summer. so whilst it certainly isnt a done deal - it is pretty likely, these troughing patterns are usually hard to shift once in place. ill not place any money on any sustained hot spell emerging, however its one bet id be happy to lose!

Rob - that is the six million dollar question with a lot of model watching.  Which weather system 'causes' another to be in a particular location.  I don't think anyone knows for sure - certainly not me.

Disagree with your second para.  Weather systems and patterns can and do change at any time of the year, sometimes quite unpredictably.  I don't consider that this unsettled spell was modelled at all well until relatively short notice i.e. less than a week.  It started in a very low key way and expanded.  Who's to say that there might be a similar change to settled at some point, maybe even relatively soon.  I totally agree that there is zero signal of that at the moment, but I think it's wrong to make any firm predictions beyond roughly the end of this month.  Had I attempted to do so about a fortnight ago, based on model watching, I'd have been suggesting that we would be sweltering round about now!

I suppose you are referring to history, but you can't seriously be saying that all or even most Augusts end up exactly the same way as they started, if unsettled?

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1 minute ago, Weather Boy said:

Disagree with your second para.  Weather systems and patterns can and do change at any time of the year, sometimes quite unpredictably.  I don't consider that this unsettled spell was modelled at all well until relatively short notice i.e. less than a week.  It started in a very low key way and expanded.  Who's to say that there might be a similar change to settled at some point, maybe even relatively soon.  I totally agree that there is zero signal of that at the moment, but I think it's wrong to make any firm predictions beyond roughly the end of this month.  Had I attempted to do so about a fortnight ago, based on model watching, I'd have been suggesting that we would be sweltering round about now!

I see your point, but I think given past experiences over the last few years, we have grounding for our worries about this pattern sticking around for some time. There have been far more spells of prolonged trough domination with a fired up jet stream then there have been prolonged nationwide settled hot spells.

In addition, this is the UK and there is always a bias towards the unsettled unfortunately. Every time we do get a hot spell, what is one of the first things people mention? The breakdown. Past experience has shown that hot settled weather generally doesn't last for very long, whereas we have plenty of past experience of unsettled weather lasting for weeks on end, even in summer.

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57 minutes ago, mushymanrob said:

does the jet stream determine where the azores high is positioned , or does the azores high dictate where the jet stream flows?....

 

If you have a spare hour during heavy showers coming up :)

A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming

https://skepticalscience.com/jetstream-guide.html

Or from Ed

http://www.netweather.tv/index.cgi?action=jetstream-tutorial;sess=

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1 hour ago, Weather Boy said:

Rob - that is the six million dollar question with a lot of model watching.  Which weather system 'causes' another to be in a particular location.  I don't think anyone knows for sure - certainly not me.

Disagree with your second para.  Weather systems and patterns can and do change at any time of the year, sometimes quite unpredictably.  I don't consider that this unsettled spell was modelled at all well until relatively short notice i.e. less than a week.  It started in a very low key way and expanded.  Who's to say that there might be a similar change to settled at some point, maybe even relatively soon.  I totally agree that there is zero signal of that at the moment, but I think it's wrong to make any firm predictions beyond roughly the end of this month.  Had I attempted to do so about a fortnight ago, based on model watching, I'd have been suggesting that we would be sweltering round about now!

I suppose you are referring to history, but you can't seriously be saying that all or even most Augusts end up exactly the same way as they started, if unsettled?

it appears to me though that its the anticyclonic pattern that gets curved balls thrown in to disrupt more then trough dominated patterns.  of course they can change, but recent history shows that we havnt had a decent august (widespread) for many years... in fact wasnt it 07 that after a washout june/july that things picked up?

so no, its not an exact science, as i see it its the laws of probability, and going of recent trends augusts can start unsettled and do remain unsettled..... nobody would like it more then me of this forthcoming trough dominated pattern shifted quickly, but i cannot see it happening.

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19 hours ago, Singularity said:

You may wish to consider putting GFS aside for a while as that might improve moods.

Or maybe not - let's see what ECM does this evening.

As of +120 it's much more similar to the GEM 12z than GFS 12z with the low over by Newfoundland (much deeper with more amplification of jet ahead of it as a result), which suggests a slower progression of the Atlantic troughs may be seen from this new ECM run. This doesn't equate to a finer outcome next week for sure, but it makes it seem more plausible which is a start..........."

 

Actually, from looking at the GFS over the past few days i would say it has also trended (ever so slightly admittedly) towards a slower evolution.  

For the start of next week - the heights over Greenland region have been attenuated as have the low heights in our vicinity moving to what i would describe as a sprawling flabby upper low in comparison to the tighter affair shown for the same time frame.  A comparison of todays 0z/6z at 135/132 illustrates how i feel the GFS has been moving.  The location of this upper low for the start of next week seems to be all over the place but if heights over greenland continue to fall i wonder if it will move ever further North.

  h500slp.thumb.png.c59acb01a138b6754f6b86f5abb25a87.png59774ae6c1557_h500slp2.thumb.png.8b57205bf2b9fafeee80d015190695a8.png

 It will certainly not be high summer over Eng/Wal for the start of next week but just maybe favouring a more showers with sunshine regime rather than a succession of rain bands that i was fearing from the weekends outputs?  Still looking like a poor outlook for Sco/Ire.

Edited by swebby
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5 hours ago, mushymanrob said:

does the jet stream determine where the azores high is positioned , or does the azores high dictate where the jet stream flows?....

i

Mushy

Another point that perhaps is pertinent to your question. I noticed a few days ago that Michael Ventrice said this in a tweet

"Take a look at the amplitude of that North Pacific ridge forecast to build in; completely changes the structure of the North Pacific Jet"

jet.thumb.jpg.9d4cf8b86669ca5e48f7f03f8afba36a.jpg

 

Edited by knocker
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6 hours ago, 40*C said:

The whole Atlantic right now looks like just one huge over-sized breeding ground for troughs and lows pressures have plenty of room to swing their full weight around. It has to be said - this type of pattern is never in a hurry to clear, although there seems to be a trend for improvement around the 5th.

At least it will be mild! seem to be tracking SW/NE, rather than dreaded NW/SE, summer seems over, but sunny days likely 23° days inbetween systems, as long as rainbands timed for the night

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