Model Output Discussion - 1st June 2015 12z--------->

[Summer Sun]

Bar the risk of some rain in the far north and west mid week the ECM ens has a lot of dry weather on offer from Monday till the end of its run

 

[bluearmy]

The extended ens means and anomolys are certainly moving in the right direction as ECM tries to edge the anomoly just east of the UK. Naefs shows a high anomoly into the distance but it isn't as marked as ECM.

as summer progresses, the mean dam/slp combo slowly edges further North

[East_England_Stormchaser91]

Anything past 150 hours should be taken not too seriously. Pretty sure what we witnessed yesterday was not picked up on barely any of the models until around 140 hours. Still then, they had the plume going much more northerly.

Devil is in much finer detail. One movement of a system in the short term can alter the situations massively.

[Polar Maritime]

High Pressure again showing to push up into Greenland for around the 21st, As shown on the 18z blocking the Atlantic at least.

 

Edited June 13, 2015 by Polar Maritime

[Tamara]

For the time being at least, until the picture becomes clearer, the "safe money" would be not to over anticipate the arrival of full summer as currently suggested by the GFS - but to take a half way house.

 

Hence that split across the UK looks a best estimate  - at least for the time being.

 

My usual broad-brush weather- on- the- ground approach here -  but temperatures in the shorter term are set to see-saw in complicit obedience to the dogs breakfast of upcoming opposing synoptics to the north and to the south. Coolness especially today, then a warm-up over the next couple of days (courtesy of thundery destabilisation from the continent which will specifically influence the southern half of the UK), coolness returning as the thundery trough departs - and then a probable warm-up again through next week as the pattern adjusts eastwards.

To update on progress

 

The cautious approach remains a reasonable stance for the short to medium term, but the overall trend is slowly but surely getting better for summer on an increasingly more nationwide basis as the low angular momentum cyclical pattern shows signs of finally fading. The result is that cool air flooding into the North Atlantic towards the UK mixes out, with the jet stream over the coming few weeks having less and less tendency to dig as far south as it has repeatedly done, adjusting closer to where many would seasonally hope it to be

 

A cautious approach looks to also have proved to be wise with respects to GEFS AAM/GWO forecasts. Whilst modelling has been largely correct in identifying the overall direction of travel,  it has definitely exhibited an exaggerated low AAM/bias much as suspected and mentioned on here in previous posts.

 

Maybe this is a "behavioural tendency"- driven by long term entrenched background atmospheric responses in the Indian Ocean and Western Pacific?

 

Verification of Phase 1/2 - into 3 GWO orbit is proving a fair bit shallower and faster than the predicted amplitude response was - and proves that the recent kelvin induced convective wave in the Indian Ocean is merely a transitional seasonal response and not some major continuing disconnect with El Nino as might have been suggested

 

http://www.atmos.albany.edu/student/nschiral/research/gwo/gfsgwo_1.png

 

We are not completely there yet, but this is evidence of a very important atmospheric change of response and hopefully good news for prospects with regard to returning to the opening theme of this post about where our summer heads

 

GWO Phase 3 looks good for improving arrangements,with MJO forcing becoming less indeterminate on the atmospheric pattern with time. 

 

Still something of a UK NW/SE split for a little while yet, but with a more coherently sustained Nino atmosphere response gradually starting to take hold, the current extended term ensemble means are a very good reflection of the larger scale pattern changes happening

 

In the 10 day + period, plenty of fine warm weather for many - but still weakening fronts coming SE around the high pressure ridging towards the southern half of the UK from the Azores

 

Cautiously, but with good supporting evidence - in the longer term the Azores mid latitude ridging might reasonably be expected to become more persistent, adjusting very gradually further eastwards to provide a broad belt through the UK into Europe, and therefore be less prone to interruptions from less settled and cool inroads from the north Atlantic

 

Edit later: Not sure why there a debate about high pressure over Greenland, unless one always takes intra model output at face value. Based on the way that the pattern is evolving as described above, the opposite pressure profile seems more likely with the jet stream heading north rather than south. As long as the atmospheric pattern heads in the direction it is, the anomaly charts will be consistent, and from that it becomes possible to discount anything else as unlikely

 

It is also not a good idea to take NAO forecasts at face value either - if, especially in FI, a model reacts to an incorrect signal then the NAO forecast, which reflects that output signal, will also be wrong.

Edited June 13, 2015 by Tamara

[Polar Maritime]

Just look how extensive the blocking is shown to push North over Greenland, Some exceptionally warm Temperatures over the Arctic showing towards the end of the 6z. Leaving the UK under a rather long drawn out cool Northerly flow, With Low Pressure sat just to the N/E of the UK. All subject to change as usual..

 

Edited June 13, 2015 by Polar Maritime

[East_England_Stormchaser91]

Really can't see that northern blocking happening. Doesn't make sense how all of a sudden those heights can just be scooped up like that!!

Expect greens and blues over Greenland on the 12z!

[mushymanrob]

thankfully, theres no anomaly support for the 06z's greenland high, so we must hope its an outlier of a run.  if a greenland high establishes itself now, well, it doesnt look good for anything hot/settled this summer.

 

hold on, im not sure thats true what i said about the anomaly support.



there IS an upward kink over greenland, and a trough to our east , if im reading this right that could suggest the high just off ireland does connect to a greenland ridge?...

hmmm.... not good.

Edited June 13, 2015 by mushymanrob

[johnholmes]

thankfully, theres no anomaly support for the 06z's greenland high, so we must hope its an outlier of a run.  if a greenland high establishes itself now, well, it doesnt look good for anything hot/settled this summer.

 

A Greenland high is unlikely IF the anomaly charts are correct, with +e heights showing west of Alaska this makes it highly unlikely anything but a trough can develop (in the upper air pattern) in the Greenland longitude.

IF the NOAA version starts to tend towards the GFS anomaly idea then it will be time to watch this area but until it does then to me this scenario seems unlikely in the 6-15 day time period.

[summer blizzard]

3 GFS runs and last nights GEM for some kind of northerly around day 9 (2 GFS runs making it a more substantial breakdown).. 

 

[mushymanrob]

A Greenland high is unlikely IF the anomaly charts are correct, with +e heights showing west of Alaska this makes it highly unlikely anything but a trough can develop (in the upper air pattern) in the Greenland longitude.

IF the NOAA version starts to tend towards the GFS anomaly idea then it will be time to watch this area but until it does then to me this scenario seems unlikely in the 6-15 day time period.

 

ive edited my post john, thanks for replying, its an unsettling theme beginning to emerge from the gfs though. and im no expert at understanding the anomaly charts... im just trying!

[BlueHedgehog074]

(Edit: already been beaten to it by others who have covered the anomaly charts well).

I suppose the GFS 06Z shouldn't be totally ignored, as there's always a small chance it could be picking up a new trend. But just like in Winter, strong heights modelled over Greenland can quite often get watered down or taken away closer to the time of verification.

Edited June 13, 2015 by DiagonalRedLine

[johnholmes]

ive edited my post john, thanks for replying, its an unsettling theme beginning to emerge from the gfs though. and im no expert at understanding the anomaly charts... im just trying!

 

I don't think I'm all that expert either mushy although having used them for the past 4 or 5 years I do fel quite confident with them, given my usual cations about them. If we look at how consistent or not GFS has been in the 168h+ period then it is not consistent. If we look at the NOAA anomaly charts at both 6-10 and 8-14 then they are consistent. The ECMWF-GFS version is less so, more especially the GFS one, which probably explains the variability with the synoptic output as well.

I would be surprised to see heights rising to any extent in the 6-12 day time scale, probably even out to 14 -16 days. Could be wrong of course which would not be the first time!

One thing to remember is the anomaly charts are 'averages' and day to day variations can and will occur. However this would tend to rule out marked changes in trough-ridge patterns in the upper air over the period I am discussing, at least in my view.

Edited June 13, 2015 by johnholmes

[summer blizzard]

Does anybody have the full NOAA discussion. They usually give a confidence interval and explain why they back a solution.

[bluearmy]

Good to debate but far too much attention wasted on the outer reaches of a gfs op IMO.

Rob, there is a weak upper greeny ridge on the CPC but I would be more interested in the upper ridge shown over nw Europe together with the high anomoly. Rarely do you see that combo fail to verify.

that should mean the incursions from the depressions running nw to se are shunted further to our East and we should begin to draw ever warmer temps into the block.

[knocker]

I agree with ba that far too much attention is being paid to the GFS ops and the Greenland HP. The ops has it entering the fray around T216 but the ens mean mslp anomaly doesn't agree and more to the point nor does the 500mb anomaly.

Charts courtesy weatherbell

Edited June 13, 2015 by knocker

[mushymanrob]

I don't think I'm all that expert either mushy although having used them for the past 4 or 5 years I do fel quite confident with them, given my usual cations about them. If we look at how consistent or not GFS has been in the 168h+ period then it is not consistent. If we look at the NOAA anomaly charts at both 6-10 and 8-14 then they are consistent. The ECMWF-GFS version is less so, more especially the GFS one, which probably explains the variability with the synoptic output as well.

I would be surprised to see heights rising to any extent in the 6-12 day time scale, probably even out to 14 -16 days. Could be wrong of course which would not be the first time!

One thing to remember is the anomaly charts are 'averages' and day to day variations can and will occur. However this would tend to rule out marked changes in trough-ridge patterns in the upper air over the period I am discussing, at least in my view.

 

 

Good to debate but far too much attention wasted on the outer reaches of a gfs op IMO.

Rob, there is a weak upper greeny ridge on the CPC but I would be more interested in the upper ridge shown over nw Europe together with the high anomoly. Rarely do you see that combo fail to verify.

that should mean the incursions from the depressions running nw to se are shunted further to our East and we should begin to draw ever warmer temps into the block.

 

cheers for the comments jh/ba oh and knocker! i guess im panicing abit, looking too hard at a possible spoiler as to what i think could be a great summer. sometimes of course the gfs in fi does pick up on a new trend, but im happy with the points made and until/unless the anomaly charts change, or are wrong, ill try not to get too flustered! lol

[Scorcher]

Subtle signs of Greenland blocking which if verifying could scupper late June early July warmth and can be very persistent once In place.....a reversed slug in Summer.

To the here an now an temps of 17 today in London....NE winds drizzle cloud and suppressed temps aren't doing my garden any good...Liven up flaming June

 

There are barely any signs of it though...only the odd GFS run is showing it in FI. This happens every year in this thread- people see the slightest hint of a Greenland high in FI and there are fears of a 2007 repeat. Northern blocking just hasn't happened for any length of time for several summers now.

Edited June 13, 2015 by Scorcher

[Summer Sun]

There are barely any signs of it though...only the odd GFS run is showing it in FI. This happens every year in this thread- people see the slightest hint of a Greenland high in FI and there are fears of a 2007 repeat. Northern blocking just hasn't happened for any length of time for several summer nows.

 

I may be wrong, but isn't the NAO going negative a sign that northern blocking could occur?

 

 

No sign of it going negative currently

[bluearmy]

With a big n Atlantic high In the offing just to our west, a Subdued NAO is pretty certain

Edited June 13, 2015 by bluearmy

[DR(S)NO]

There are barely any signs of it though...only the odd GFS run is showing it in FI. This happens every year in this thread- people see the slightest hint of a Greenland high in FI and there are fears of a 2007 repeat. Northern blocking just hasn't happened for any length of time for several summer nows.

Indeed Scorcher...FI is FI ...and that doesn't matter which side of the debate we come from...or what season we are talking about.

Of course,just because it hasn't happened for several summers , it doesn't mean it won't happen this Summer

[johnholmes]

Does anybody have the full NOAA discussion. They usually give a confidence interval and explain why they back a solution.

 

not today or tomorrow as its a weekend but this link usually has their thoughts on it

http://www.cpc.noaa.gov/products/predictions/610day/fxus06.html

[Mapantz]

I may be wrong, but isn't the NAO going negative a sign that northern blocking could occur?

 

 

No sign of it going negative currently

Isn't it -ve already?

[Milhouse]

Its going to be a very nice week with warm westerlies for much of it bringing bright or sunny spells and quite decent temperatures. But the way the models are looking next weekend is a bit concerning. High pressure looks like its stuck over Russia, and not going anywhere in a hurry so its acting as a block forcing low pressure south into Europe, meaning more northwesterlies for the UK.

 

If the blocking high could shift westwards more over Scandinavia then the next time we get an Azores ridge we would be in a much better situation to transfer high pressure to the east of the UK. And right on cue the GFS 12z in FI is showing what i mean.

[Alex]

A subdued NAO if we get a negative NAO summer is in trouble

You couldn't be more wrong if you tried. A UK high could well force the NAO to negative. How many more times do members have to say? The NAO is literally the difference in pressure in the North Atlantic between Iceland and the Azores. Yes of course a negative NAO may indicate troughing in the wrong area for us but it may also indicate favourable blocking too.