Model Output Discussion 18z 28/07/13

[bradymk]

The 6z GEFS control run follows the trend of the op with a much warmer weekend with LP staying further south west. Hoping the 12z suite can build on this, hopes are not that high now though. The 6z control run is v good though compared to recent, better than 6z op aswell which was good.

Edited August 19, 2013 by bradythemole

[Captain Shortwave]

The 6z GEFS control run follows the trend of the op with a much warmer weekend with LP staying further south west. Hoping the 12z suite can build on this, hopes are not that high now though. The 6z control run is v good though compared to recent, better than 6z op aswell which was good.

If anything the control is even better, the warm and dry conditions would still be holding on into Monday, 12C uppers across the whole of the UK pretty much

 

It's hope and that's all it is at the moment. Again we seem to be facing off with the big bad ECM and it's cooler and more unsettled outlook.

Edited August 19, 2013 by Captain shortwave

[East_England_Stormchaser91]

Infact, that GFS is pure eye candy if you are looking for some vicious proper storms! Plus side of it is that anything that develops over France/Low Countries will be supported by higher sst's, which are at their highest around about now if that GFS output remains consistent and the same, some people might need to batten down their hatches and have their cameras ready! Also if that low sits right over the Midlands, some tornadic activity may well be likely.

[bradymk]

If anything the control is even better, the warm and dry conditions would still be holding on into Monday, 12C uppers across the whole of the UK pretty much

 

It's hope and that's all it is at the moment. Again we seem to be facing off with the big bad ECM and it's cooler and more unsettled outlook.

Yes the GFS 6z control is a great run, the op run was good but that is even better. Out to Tuesday and still v warm and dry for most, this is what we want the other models to start showing, and this is what can easily happen if the low stays further SW.

[shedhead]

If anything the control is even better, the warm and dry conditions would still be holding on into Monday, 12C uppers across the whole of the UK pretty much

 

It's hope and that's all it is at the moment. Again we seem to be facing off with the big bad ECM and it's cooler and more unsettled outlook.

Since GFS initially picked up this weeks LP, it has been ECM that has consistently handled the feature best of all, with the former virtually chopping and changing every 6hrs. The detail regarding this weekend remains elusive, but the big picture looks fairly well established, with bands of thundery rain or showers set to push northwards and eventually introduce cooler, fresher weather. The speed and direction we travel thereafter is clearly dependent on exactly how the BH weekend pans out, but the logical conclusion is for the LP to drift slowly east and introduce the west-northwesterly flow currently being advertised by both the big two.

Edited August 19, 2013 by shedhead

[Frosty.]

The GEFS 06z control run is a peach, hot and sultry on thurs/fri with temps of 27-30 celsius across the southern half of the uk and it continues hot and humid with hazy sunshine through the holiday weekend with an increasing risk of thundery showers, early next week is similar and then high pressure builds in again, what could be better?

Edited August 19, 2013 by Frosty039

[shedhead]

The GEFS 06z control run is a peach, hot and sultry on thurs/fri with temps of 27-30 celsius across the southern half of the uk and it continues hot and humid with hazy sunshine through the holiday weekend with an increasing risk of thundery showers, early next week is similar and then high pressure builds in again, what could be better?

It being correct...

[Frosty.]

The GEFS 06z mean is similar to the op and slows everything down, the anticyclone sticks around longer and this delays the shallow thundery trough, those writing off this warm spell as a non event..think again, this could be a very nice surprise at the end of what has been a very good summer overall, if things work out, it will be very warm or hot and sultry on thursday, friday, saturday, sunday and next monday with hazy hot sunshine and an increasing threat of scattered thunderstorms, then next week settling down again with sunny spells and temperatures in the low to mid 70's F.

[Frosty.]

Why this fashion for 'short wave' what's wrong with saying 'low' ?

or trough

[mushymanrob]

Why this fashion for 'short wave' what's wrong with saying 'low' ?

 

thought 'short wave' was the technical term to distinguish between a small are of low pressure and a large one... the larger type often being the 'mother' and the shortwave a smaller area that develops on a straggling cold front. an area of low pressure to me conjurs up an image of a large feature in the north atlantic driving west/swesterlies across us..

 

Fair play, perhaps a lesson in future to perhaps be a little more grounded in our expectations, I know I will. After all, many of us on here are amateur enthusiasts rather than have vast knowledge and experience like yourself.

Still we would have got away with it if it wasn't for those meddling shortwaves

 

im annoyed with myself...i was doubting for a long while the validity of the ops showing a heatwave/hot spell as the anomaly charts didnt support it.... then they began to wobble and appeared to be heading towards supporting what the ops were showing. my liking for heat got the better of me and i gave in and expected the hot spell to be real...

 

but we DO have 2-4 days , maybe 5 if we are lucky, where it will be warm, or even very warm/hot, the sun is still strong so IF we can dodge any cloud thurs-sat will still be very nice. but the lengthy spell that some runs predicted (the gfs being the main culprit, maybe though thats due to 4 runs a day), where we had the 10c upper for most if not all of the run from weds onwards (plus a lengthy bit with the 15c upper over the south). has gone.

 

so unless things alter quite radically, we are in for some nice warm sunny weather after wednesday, then itll break down with showers,thunder, rain at some point between saturday and tuesday. the atlantic is expected to return afterwards as the ops and anoms suggest in some form.

[A.J]

 

thought 'short wave' was the technical term to distinguish between a small are of low pressure and a large one... the larger type often being the 'mother' and the shortwave a smaller area that develops on a straggling cold front. an area of low pressure to me conjurs up an image of a large feature in the north atlantic driving west/swesterlies across us..

 

 

im annoyed with myself...i was doubting for a long while the validity of the ops showing a heatwave/hot spell as the anomaly charts didnt support it.... then they began to wobble and appeared to be heading towards supporting what the ops were showing. my liking for heat got the better of me and i gave in and expected the hot spell to be real...

 

but we DO have 2-4 days , maybe 5 if we are lucky, where it will be warm, or even very warm/hot, the sun is still strong so IF we can dodge any cloud thurs-sat will still be very nice. but the lengthy spell that some runs predicted (the gfs being the main culprit, maybe though thats due to 4 runs a day), where we had the 10c upper for most if not all of the run from weds onwards (plus a lengthy bit with the 15c upper over the south). has gone.

 

so unless things alter quite radically, we are in for some nice warm sunny weather after wednesday, then itll break down with showers,thunder, rain at some point between saturday and tuesday. the atlantic is expected to return afterwards as the ops and anoms suggest in some form.

Hi Rob, just thought I'd post up in aid to clear up any confusion to members, by definition a shortwave is an embedded kink in the trough/ridge pattern. Its length scale is much smaller than that of longwaves.

 

I think the term is used excessively and incorrectly on the forum, and IMO, the feature in the south west approaches this weekend is a cut-off Low pressure system as it contains its own closed circulation denoted by the SLP charts and not just a kink in the pattern

 

A good example of the different low pressure associated synoptic patterns can be found below

 

 

and within the learners area of the NW forum is an excellent thread on troughs

 

http://forum.netweather.tv/topic/61917-troughs/

Edited August 19, 2013 by ajpoolshark

[mushymanrob]

Hi Rob, just thought I'd post up in aid to clear up any confusion to members, by definition a shortwave is an embedded kink in the trough/ridge pattern. Its length scale is much smaller than that of longwaves.

 

I think the term is used excessively and incorrectly on the forum, and IMO, the feature in the south west approaches this weekend is a cut-off Low pressure system as it contains its own closed circulation denoted by the SLP charts and not just a kink in the pattern

 

A good example of the different low pressure associated synoptic patterns can be found below

 

13.jpg

 

and within the learners area of the NW forum is an excellent thread on troughs

 

http://forum.netweather.tv/topic/61917-troughs/

 

ahh thanks, so i was kind of right, but not in applying it to the expected feature on saturday...

 

wasnt wednesdays originally a real 'shortwave'? it did start life as a wave on the cold front but became detatched from it.

[Methuselah]

Personally, I do not much like the term 'shortwave' at all...When ah were a lud, we had polar lows, heat lows, wave depressions and secondary depressions - in which, the necessary information is contained within the name. But, what is a 'shortwave' - anything that happens to make a mockery of an individual's forecast?

[Buzzit]

Personally, I do not much like the term 'shortwave' at all...When ah were a lud, we had polar lows, heat lows, wave depressions and secondary depressions - in which, the necessary information is contained within the name. But, what is a 'shortwave' - anything that happens to make a mockery of an individual's forecast?

That is why if I refer to a shortwave I always call it a "pesky shortwave" as it is interfering with my forecast output

[bradymk]

Anyone know the credibility/rating of the NASA model on meteociel, never realised it was there, took a sneek peak and its quite different to the other models

[johnholmes]

 

This goes some way to explaining why the 850hPa temperatures are not extremely warm on Friday. The air originates around 700hPa at 55N today. The temperature there is -2C. +15C of warming by dry adiabatic descent and you have the resulting +13C 850hPa temperatures expected on Friday. This is not a long draw continental feed, even at the surface. It's modified mid/high latitude maritime air.

 

I really like this kind of data, can you give me a link please or is your link only available to you in your web site-thank you if it is possible

[johnholmes]

Hi Rob, just thought I'd post up in aid to clear up any confusion to members, by definition a shortwave is an embedded kink in the trough/ridge pattern. Its length scale is much smaller than that of longwaves.

 

I think the term is used excessively and incorrectly on the forum, and IMO, the feature in the south west approaches this weekend is a cut-off Low pressure system as it contains its own closed circulation denoted by the SLP charts and not just a kink in the pattern

 

A good example of the different low pressure associated synoptic patterns can be found below

 

13.jpg

 

and within the learners area of the NW forum is an excellent thread on troughs

 

http://forum.netweather.tv/topic/61917-troughs/

 

thanks for that AJ I was going to make a post much the same as you. It has a specific usage in meteorology, on here it gets used far too often for whatever reason.

[Buzzit]

I really like this kind of data, can you give me a link please or is your link only available to you in your web site-thank you if it is possible

JH Use this link to compute your own Trajectories http://ready.arl.noaa.gov/hypub-bin/trajtype.pl

 

- It is not too difficult - I just did the one graphic below - just follow through the requirements - enter your lattitude etc and away you go ! (you can do backwards forwards and many different types of synoptic output) (Select from the GFS 192hrs fcst, Global, pressure)

 

 

 

Edited August 19, 2013 by Buzzit

[johnholmes]

JH Use this link to compute your own Trajectories http://ready.arl.noaa.gov/hypub-bin/trajtype.pl

 

- It is not too difficult - I just did the one graphic below - just follow through the requirements - enter your lattitude etc and away you go ! (you can do backwards forwards and many different types of synoptic output) (Select from the GFS 192hrs fcst, Global, pressure)

 

19192_trj001.gif

thanks for that B-very clever, I did one for here and it started, not yet found out what height, southern Greenland, must spend a bit of time trying things out-thanks again - John

[bradymk]

GFS 12z continuing the improvement, hoping it is on to something.

[Captain Shortwave]

The GFS has shifted the jet a few hundred miles south compared to previous outputs. It just about gets away with it and gives the cut off low to the south west.

 

Not sure what to say about the UKMO, it looks quite similar to this mornings ECM

Edit it's ok-ish, still get a cut off low which helps keep the pattern more settled than the ECM

At least both of these models show a quick return to settled conditions after the breakdown (whenever that happens)

Edited August 19, 2013 by Captain shortwave

[Cecil Hogmanay Melchett]

Warm and lovely this week a brief unsettled spell as pressure falls over the weekend and then the azores high moving back in looks a reasonable assertion based on the 12z's.

Very useable weather for the majority of the UK.

Interstingly gfs introduces a 'mini plume' for the South east as air sourced from the south east clips that corner brining some very warm conditions with temps in the high twenties,possibly one last hurrah to a beautiful summer.

actually touching THIRTY on gfs 12z,phew!!

Edited August 19, 2013 by happy days

[Frosty.]

A stunning GFS 12z operational run in the high res, following on nicely from the 6z, the 12z builds on the idea of a more prolonged hot & humid spell, starting on thursday and continuing through friday, saturday, sunday and crucially, Bank Holiday monday, temperatures soaring into the high 20's to low 30's celsius, especially the further south/se you are but all areas getting a good warm up during the second half of this week, the very warm spell will start on thursday with increasing amounts of sunshine but the pattern at the end of the week looks rather plume like with a growing threat of T-Storms and heavy showers, isolated at first but tending to become more widespread as the holiday weekend goes on, some areas getting deluges while others bask in hot hazy sunshine, this sluggish stagnant very warm and muggy spell lasts into the early part of next week on this run, just like the 6z, hopefully the 12z gefs mean will have the same support as the 6z did, what a bonus to this great summer if this verifies.

Edited August 19, 2013 by Frosty039

[The PIT]

Yes a possible unpleasant weekend coming up once more. Hopefully this will all change in the next few days and we will just have temps in a low 20's and a nice fresh breeze. At the end of the day it all depends on where that low ends up.

[Captain Shortwave]

Well the GFS ensemble is completely different even by day 6

 

06Z run

The mean temperature has dropped in the day 6-8 range by a good 2-4C

I'm sorry guys, I just can't see the GFS op verifying, as much as I want it too. The models are shifting to the ECM solution. I just hope that after the blip we will get over the bank holiday weekend that high pressure builds back in quickly without any cool/cold northerlies

Edited August 19, 2013 by Captain shortwave