Model Output Discussion

[chapmanslade]

I think the models have done really well recently. GFS Op run picked up on the first hint of the pressure rise nearly a week ago with the ensembles following later. Op run seems to be picking up on things much better than other members (as it should)

Certainly a complete pattern change looks likely now

[Lincs Observation]

Afternoon All

well my take on things is this, ive looked at the 850hpa and jet stream patterns for a while now and have been looking for something that will damage the constant southly jet and incur a pattern change, over the last few runs high pressure situated over Corsica seems to be the catalyst of what i have been looking at.

Even though the change is out in FI it is becoming a daily trend, forcing the jet to buckle and start a move northwards. However the jet remains resilient in many of the charts, breaking down then building again, but the high pressure build giving much of southern europe its summer heat is like a expanding balloon, and pulsing more and more NW sooner or later the jet has to be forced up the west coast of the UK or if it strengthens pust it north.

by the end of the last few runs ive seen hints at both, either one could be the start of a pattern change, I would favour the jet running up the west coast and high building in from the SE for a change in fortunes but with such a strong jet pattern its a waiting game.

I do feel that in the next 14-18days we will see a pattern change for a short period of warm settled weather over most of the uk with a good chance of more scattered thunderstorms.

next weeks warmth will be a welcome event but i still think the change is a while away yet, as they say good things come to those who wait.

well thats my take on things and ill see if what i have just written has been on the back of regular members education wish me luck

LO

well here goes, lol into gloat mode................nah not really, but the signs were there in my opinion when i wrote the post above on 30th July, with that increasing high pressure over southern Spain building the jet had to move, and all the rest of what followed and will follow as result of the bulling by the high pressure systems to the south of the jet.

LO

[Snowyowl9]

I would say GFS is being very consistant and would say that is better in this type of spell,and it has started already today warmest day since July 4th.

http://91.121.93.17/pics/Rtavn1441.png

Not showing as far north as the GEM.

http://91.121.93.17/pics/Rgem1441.gif

[Gordon]

I just have a quick question

on the BBC forecast for tomorrow

according to its graphics it has the Rain as far west as Birmingham

yet according to most on here it's mainly eastern England seeing the rain

and seeing the front apparantly clearing through earlier today

I am wondering what the forercast for my area (Coventry) is for tomorrow day & night

any help appreciated

edit : just saw the latest forecast on BBC news and am still none the wiser

is it a case of wait and see ?

Edited August 5, 2009 by Gordon

[Frosty.]

Another good GFS 12z with plenty of high pressure during the next few weeks mostly influencing the southern half of the uk but even the north will see pressure rising at times although low pressure will occasionally break through the top of the high across the northern half of scotland mostly with sun/mon being a good example of this. The main core of the high will shift around and looks like being mostly centred to the south west of the uk but with a strong ridge across the south for much of the period. The later stages of the gfs 12z run look quite autumnal with deep low pressure eventually taking charge as the main high sinks away to the south but the next 10-14 days look generally good in southern areas especially once the thundery rain clears away on friday.

Edited August 5, 2009 by Frosty039

[Snowyowl9]

UKMO is not so good, another 4 sunny days here may just be good enough if it`s as sunny and warm as today.

http://91.121.93.17/pics/Rukm961.gif

Still a weakening front would be coming south from this,not so good for the north.

http://91.121.93.17/pics/Rukm1201.gif

[ANYWEATHER]

I just have a quick question

on the BBC forecast for tomorrow

according to its graphics it has the Rain as far west as Birmingham

Some discrepency as yet as ever with these situations, keeps your eyes in the next 24hrs on the rainfall radar and netweather is my best advice,,,,,hope that helps!

[Gordon]

Some discrepency as yet as ever with these situations, keeps your eyes in the next 24hrs on the rainfall radar and netweather is my best advice,,,,,hope that helps!

Thanks I'll keep a look out

[Cheese Rice]

Thanks I'll keep a look out

The meto warning for thursday sums up the areas that are likley to get rain, but the exact track of the ppn is still undecided. http://www.metoffice.gov.uk/weather/uk/uk_forecast_warnings.html?day=2

[Thundery wintry showers]

My reading of the charts is that UKMO seems to keep it pretty unsettled with the Azores ridge never getting far north enough to be more than a toppler, though it only goes out to T+144. GFS 12Z has the high further south than the 06Z but still far north enough to keep most of England and Wales dry, sunny and reasonably warm (even hot in the south) but with plenty of cloud & drizzle for Scotland and Northern Ireland. Ensembles have the high further south than the control run, and interestingly, support for a brief NW'ly toppler around T+168 which could bring a brief bout of cooler bright showery conditions but could also open the gates for that high to come in a little closer afterwards.

ECMWF just rolling out and I have to say I don't like the look of its T+72 from a dry sunny weather perspective as everything is shifted further south.

[PB22]

Certainly looks like a backwards step tonight in terms of a fine and fairly sunny outlook from the UKMO and now the ECM:

http://www.wzkarten.de/pics/Recm961.html

http://www.wzkarten.de/pics/Recm1201.html

http://www.wzkarten.de/pics/Recm1441.html

http://www.wzkarten.de/pics/Recm1681.html

Most of the rain would always be for the north, but its not looking so clever as it did earlier on.

[Gordon]

The meto warning for thursday sums up the areas that are likley to get rain, but the exact track of the ppn is still undecided. http://www.metoffice.gov.uk/weather/uk/uk_forecast_warnings.html?day=2

well looking at that if that pans out I'll miss the worst of it and may miss it completely bloody hope so otherwise I'll be doing swamp tours in my back garden

[Thundersquall]

At last!!!! Somthing to look forward to after an abysmal July and beginning of August.

It may not last long but this High Pressure cell could easily become stuck over us.

Edited August 5, 2009 by Thundersquall

[Thundersquall]

Has anyone started a thread for weather forecast for the Bristol International Balloon Fiesta?

The forecast charts from GFS suggest light winds Thursday until Sunday.

[chionomaniac]

Well this evening we see an interesting split between the GFS and the ECM. The GFS suggests a migrating Azores high which could give fine settled weather, with the ECM suggesting the Azores high topples and never quite makes it. Which model do we believe? The recent form suggests the ECM which continues to perform better than the GFS.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz5.html

This is more in line with what the MJO 500hPa anomaly composites suggest.

The MJO is currently orbiting in a weak phase 6/7.

http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.html

The MJO is linked to the pattern of tropical convection which can be analysed by looking at the Outgoing Longwave Radiation (OLR) which shows how much radiation is reflected out to space. When we look at the last three days OLR we see that there is a detached area of convection that has crossed the Pacific Ocean to the west Pacific. There still is a larger area of convection still at the east side of the Pacific however but the western area of convection may still have a knock on effect to the pattern of weather we receive downstream.

Current OLR: http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR/m.3d.html

Previous 3 day OLR: http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR/map.prev3days.gif

Now this may be enough to push the MJO into a similar phase 7 scenario even though the signal is weak. Previously we have seen a weak phase 6 orbit which suggested that the trough covering the UK would regress to the NW and weaken. This is occurring now and a Scandinavian high is building as part of this phase.

So to move onto phase 7 the 500hPa anomaly comparison charts suggest that the trough reasserts itself and if it enters phase 8 this relocates to Scandinavia with an Azores high building but never fully making it to our shores. Now if, and a big if, the MJO stays weak then a watered down version of this may be the end result. I wonder is this where the ECM is heading?

As ever only time will tell how strongly the Azores high is likely to affect us and we should listen to the experience of John Holmes who suggests that the signals are suggesting ridging in our vincinity, but there is always the chance that the Azores high may not ridge NE enough to give us the prolonged settled spell that many of us crave. I hope not.

Phase 7 August H5 MJO

Phase 8 August H5 MJO

c

[mountain shadow]

Has anyone started a thread for weather forecast for the Bristol International Balloon Fiesta?

The forecast charts from GFS suggest light winds Thursday until Sunday.

Had it been the International Fiesta Ballon Bristol's I might have started a thread....

[damianslaw]

A bit of battle looks about to start between the azores high and atlantic jet stream, the former is going to try desperately to ridge northwards over the coming days whilst the jet really isn't wanting to head northwards for a long period it seems. The outcome looks like a bit of a no mans land situation with the south under the influence of the azores high and the north feeling the pressure of the jet and atlantic but to fairly weak effect. If this was May, June or July I'd be backing the azores to win outright, however, as it is August it will be the atlantic who will rule the roost so to speak any temporary ridging of the azores high will get quickly kicked into touch I'm afraid..

[January Snowstorm]

One other point of note is the beeb seem fairly confident of things settling down this wkd.

ECM out on its own even by Saturday.

Still the beeb have been wrong before.....

[chionomaniac]

. When we look at the last three days OLR we see that there is a detached area of convection that has crossed the Pacific Ocean to the west Pacific.

This should read East and the east in the next sentence, west!

Seems like the 18Z GFS is heading towards the ECM.

Edited August 5, 2009 by chionomaniac

[Frosty.]

The overall theme of the GFS 00z can safely be called Anticyclonic, initially, this coming weekend looks ok under a weak ridge. Early next week though, a shallow low moves across the far north bringing wet & breezy conditions to northern areas but even further south it will become more changeable and a bit cooler for a time with a NW'ly breeze before pressure rises strongly by midweek or just after and then high pressure takes total control for the whole of the uk bringing a prolonged spell of sunny and very warm weather, the ukmo 00z also shows the Azores High ready to move across the uk after the middle of next week.

Edited August 6, 2009 by Frosty039

[ANYWEATHER]

Both the big3 models right to the end of a more reliable time frame go for a pressure build ,especially for the south, BUT, it does show to as example on the fax chart here, that it wont stop bands of cloud and some rain even for the south to move across from time to time, so in essence, a brighter outlook further south you go , but still a changeable weather pattern!

[mushymanrob]

tbh i think theres misplaced optimism this morning and yesterday evening, maybe people have been looking at the gfs only which is tending to be promoting pressure build more then the ecm or ukmo.

this mornings 00z is 'better' then yesterdays, but is pretty much on its own. the outlook is for pretty average august weather, which will be better then july, but little chance of a sunny hot spell.

i personally and unscientifically, expect september to produce a drier, settled , sunny spell of weather thatll last into october. nice weather but too late to appreciate fully.

[Gordon]

A little off topic but I see the Met Office have issued warnings and my little part of the west midlands is included

But as that is it's projected western extent hopefully we'll miss most of the heaviest and persistant rain and hopefully the thunder too

I'm praying for a slight more easterly shift and miss it altogether

Here's hoping

[Eugene]

I've got the feeling we aren't home yet regarding a long settled spell, the jet is still pretty strong and has put back HP moving directly over us until later next week.

[Guest North Sea Snow Convection]

Looks like the euros vs the americas atm. Both the GFS and GEM have the emphasis on low pressure being slightly further away from NE areas middle of next week - whilst the euros, UKMO especially, make NE areas in particular look less settled and also rather windy perhaps. Longer term trends though seem to converge with mid latitude high pressure over the UK and the AO isn't negative (gone positive) for the first time this summer. Very similar in trend as 2007 and 2008 which saw a +AO spell in the latter part of the summer. 2006 was the opposite. Interesting pattern trend continuing once again in terms of the jet stream.

Edited August 6, 2009 by North Sea Snow Convection