Model Output Discussion 22/07/12 Onwards.

[Backtrack]

Showery next week, the focus of the showery activity possibly a touch further north than was anticipated yesterday. Longer term, slow changes - possibility that we may see pressure rise to our east and north-east and troughing shift south-west in the Atlantic alllowing for an improvement, drier and warmer conditions to take root in the SE, extending further east and north - but this only a theory at the moment and not substantiated by any model as far as they go.

Hi Stewart. Taking your suggestion of a possible pressure rise over Scandinavia, are you suggesting something like this chart may be within the realms of possibility?

[OldMetMan]

Interesting Met O FAX for 96hrs:

The 120hrs shows the cold front sweeping through quickly as mobility restarts from the Atlantic, so as I see it, there is still a good chance of significant storms ahead of the front, although based on this chart, and the GFS which is comparable, I will admit the thundery activity from France would seem less likely on Friday, although overnight storms originating there may head N/NE overnight Thursday/Friday

However, there is still a certain amount of ambiguity in the short term with all the models as to how amplified the upper flow becomes in the next 2-3 days, especially upstream - if there's a deeper trough near the US coast, I think it would favour sharper troughing to our west with the developing LP to the NW digging further S, the cold front slowing down in its SE motion and thus more hot, thundery air from France becoming involved in the circulation than otherwise would.

I shall watch developments with interest!

[johnholmes]

The Met O Fax when compared to its previous position for Friday shows reasonable movement in the SW of England but hardly any movement elsewhere. Much as one would expect with virtually no gradient across it away from the SW. Way too early to decide what the actual weather may be in the London area on Friday evening. The track of any storms being governed by whatever the upper level winds show, and the latest suggests that IF they do form they could miss the area?

the 500mb trough predicted movement suggests it could be Saturday or even Sunday before its over the London area so London could miss out unless something is triggered by the upper trough itself.

Edited July 24, 2012 by johnholmes

[Glacier Point]

Sorry for going slightly off topic but thanks GP for your honesty...at least you admit things when they dont go to plan(which of course is no fault of yours)...keep up the good work

.. although, hold on .... 00z... any blocking over Greenland gone on operationals within day 7 timeframe. Have the models overcooked this ?

@backtrack - yes, that kind of synoptic pattern could well evolve in the very extended range.

Edited July 24, 2012 by Glacier Point

[Alex]

.. although, hold on .... 00z... any blocking over Greenland gone on operationals within day 7 timeframe. Have the models overcooked this ?

@backtrack - yes, that kind of synoptic pattern could well evolve in the very extended range.

The pattern continues to evolve with the trough becoming shallower and more north. I think the ECM run though is a bit suspect this morning with blocking to our direct north. I get the feeling that the models are lost of where to go next, maybe the slight drop in Angular momentum last week and then sharp rise recently along with a more amplified phase 3 GWO has thrown them off course?

[nick sussex]

High pressure continues to be reluctant to edge ne and we still see that troughing near or over the UK but this still remains a slack feature so its a case of showers and some sunshine in the medium term.

A positive is that those Greenland heights diminish, lets hope that continues.

In the shorter term looking at the fax chart this has moved that front to the nw se quicker and there still remains alot of uncertainty for the Olympics Opening Ceremony.

Looking at the GEFS ensemble maps re precip it seems that at this stage we probably want to see a quicker progression of fronts as most of the ensembles have a clearance behind that precip which is largely shown to just be effecting the far se around the time of the ceremony.

Edited July 24, 2012 by nick sussex

[shedhead]

Certainly something of an improvement on the big two this morning, but to be frank that was not going to be difficult in view of what they've been progging for the last 3 or 4 days. Let's hope we can pull theses troughs thru quickly and pressure can then rebuild, no heatwave required, just something dry and settled will do for most of us I suspect.

[Summer Sun]

All is not lost for next week yet folks, GFS is much better this morning with lower pressure of Greenland, we need this to continue in more runs before we can become more confident

[legritter]

just had a look at todays charts data ,and certainly a lot on offer weatherwise .developements over france still far from certain and even the positioning of any trough that sets up will be crucial with such a mix of types . if there are any new posters about who would like to learn while the iron is hot so to speak ,take yourself away from the computer and look skywards . notice the jet contrails ,how short they are and how quickly they disapear ,then go back on computer and study current charts then have a read about contrails how they form etc .you will learn about temp in upper atmosphere ,moisture levels higher up ,wind directions and loads of other info and also how to do a forecast using this information [an example would be ,thick contrails long lasting with possible rings could point to weather about to get stormy etc ] .have a look at todays MET OFFICE FAX CHARTS COMPARE TODAYS WITH SAY FRIDAYS FORECAST CHART .GOING BACK MORE ON TOPIC looking at northern hemisphere jet i dont think iv seen it so fragmented and completely out of synch .interesting times ahead perhaps cheers legritter

[bluearmy]

watching naefs changing week 2 with the low anomolys nw europe and scandi weaker and the high ones around greenland also weaker. this type of ens driven model will never 'jump' around markedly in fi so this could be an interesting 'first step'. its definitely not an unexpected trend in my view,

[Summer Sun]

This mornings ensembles support a pressure rise into August

Slightly less settle further north

Maybe August could be a half decent month, maybe unsettled at first but getting better during the first full week

[Frosty.]

The latest models are telling us that we should make the most of the current hot and sunny weather as it looks like turning cooler and more unsettled by the weekend, and the further north in the uk it will turn unsettled sooner. The Gfs 06z shows a persistent low pressure feature stagnating over the top of the uk for several days which will mean a lot of heavy showers which will be slow moving, so a possible return of the recent floods if low pressure sets up home over the uk, the pressure pattern looks like being very slow to change so it could be a prolonged unsettled spell similar to what we have mostly had so far this summer, there is a little light at the end of the tunnel with the 6z showing another summery spell before mid august but the current hot sun and clear blue skies is not going to last and the ecm 00z shows a similar outcome to the gfs with a sluggish looking trough becoming entrenched over the uk for the whole of next week.

[Gavin P]

Here's my 8-10 day model based video musing:

http://www.gavsweathervids.com/

Overall I think the models are pretty clear that we're going back to cool and unsettled (not the deluge of June and most of July probably, but unsettled) from the weekend and into next week.

[Frosty.]

Here's my 8-10 day model based video musing:

http://www.gavsweathervids.com/

Overall I think the models are pretty clear that we're going back to cool and unsettled (not the deluge of June and most of July probably, but unsettled) from the weekend and into next week.

Here's my 8-10 day model based video musing:

http://www.gavsweathervids.com/

Overall I think the models are pretty clear that we're going back to cool and unsettled (not the deluge of June and most of July probably, but unsettled) from the weekend and into next week.

There would be deluges if the Gfs 06z verified although it probably won't end up being as bad as the 6z is painting it but the 6z is looking very cyclonic next week with hardly any breeze to move the heavy slow moving and probably thundery downpours that would surely result, the only hope is the main part of the trough is further north so that southern areas will be closer to the ridge/high over france but it looks very dodgy from friday onwards in most of the uk and then all areas beyond friday based on the latest output.

Edited July 24, 2012 by Frosty039

[Gavin P]

Yes true. I was talking more about those huge, autumnal areas of low pressure pushing through that we've seen a lot of through June and July

Byt yes, of course the showers could be pretty intense.

[Buzzit]

Just a thought on the GFS 6z, interesting how the 500mb temps for London around Sunday / Monday on the op and control are at the very bottom end of the ensembles, and have been for a few runs now. While the overall trend is the same, there is less impact from the low pressure to the North in the short term.

Edited July 24, 2012 by Buzzit

[camiscool]

Is that good for hot weather ledders?

[Panayiotis]

This arctic oscillation chart is very worrying for those of you who love anti cyclonic weather patterns:

http://www.cpc.ncep....ndex_ensm.shtml

It does look like it drops but after that it rises back to the point it is now, so it doesnt look that bad.

[chionomaniac]

This arctic oscillation chart is very worrying for those of you who love anti cyclonic weather patterns:

http://www.cpc.ncep....ndex_ensm.shtml

I think that you need more to look at the NAO forecasts, Ledders. The NAO has recently gone positive for the first time since May.

The NAO ensemble forecasts dip negative again followed by uncertaintity - very much in line with the models.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao_index_ensm.shtml

Edited July 24, 2012 by chionomaniac

[Cecil Hogmanay Melchett]

A very suspect pattern to be honest as it would encourage more north westerly winds probably mate and as the UKMO suggested that there would be marginally better conditions for the south though nowhere is immune of catching a shower next week.

Looks to be going positive i was under the impression thats a good thing as far as ummer weather is concerned?

[Alex]

Cheers chino for the info my friend.

AO and NAO aren't drivers of the weather though from what I understand they are merely levels of pressure differences in various areas, so are bound to change. The main drivers are things like MJO, angular momentum and GWO etc.

[chionomaniac]

AO and NAO aren't drivers of the weather though from what I understand they are merely levels of pressure differences in various areas, so are bound to change. The main drivers are things like MJO, angular momentum and GWO etc.

And to add to this, the forecasts of the AO, NAO, are the forecasts of the pressure differentials which then give us an idea of where the ridges and troughs may lie.

[Weather Wizard]

Very weird 12z from the GFS. It has a low moving east!!!

I think the outlook from Sunday onwards is very uncertain

[Cloud 10]

And a suggested mid Atlantic ridge pattern as the average pressure pattern for August - note this may be subject to change:

http://www.cpc.ncep....bz700e3Mon.html

Looks like some northern blocking showing up for November/December.

Edited July 24, 2012 by Cloud 10

[Backtrack]

.. although, hold on .... 00z... any blocking over Greenland gone on operationals within day 7 timeframe. Have the models overcooked this ?

@backtrack - yes, that kind of synoptic pattern could well evolve in the very extended range.

Wow awesome, would love a repeat of late May, although in August, it'll obviously be hotter.

Judging by what you're suggesting, you're going for a settled, above average 2nd half to August?

Good to see the models supporting a pressure drop over Greenland again, perhaps meaning the jet could well swing back North again in the near future. I can't help but think this may be the last we see of heat this summer though, August's have a tenancy not to deliver!