Model Output Discussion - Early October Onwards

[Cheshire Freeze]

GFS 6z carries on where the 0z left off in the high res.......something I advocated a week or so ago with heights retrogressing towards Greenland which is where I think we are headed as we enter November- something which the long rage CFS has advocated for months also. It all goes down the pan in typical low res fashion with the jet seemingly powering up out of nowhere.

Also to add, and something Fred has often pointed out, the signs are good IMO as the GFS high res shows the willingness of the retrograde motion even when synoptics are unfavourable- something which has been prevelent over the past few years.

Edited October 20, 2011 by CreweCold

[Frosty.]

The general view of the latest models is for low pressure to be to the southwest of the uk for most of next week before gradually drifting north as a filling feature and for a large anticyclone to the northeast of the uk with the uk ending up sandwiched between. In the short term, it will become much milder and the southeast looks warm and sunny on sunday at 19c but not as good further north and west with more cloud and some patchy rain but on the mild side. Early next week looks very mild but windy with a strong S'ly airflow and some rain edging up across the uk although northeast britain could have a fine day on monday, the rest of next week looks most unsettled in the west but mild and winds will ease and back SE'ly and the best weather will be further east. Looking at the Gfs 06z, into FI it shows low pressure to the south with the Azores High throwing a ridge across the uk before the atlantic becomes more active and we revert to a normal zonal pattern with temps around average, still no sign of any cold snaps as we go into early november.

[Liam J]

The general view of the latest models is for low pressure to be to the southwest of the uk for most of next week before gradually drifting north as a filling feature and for a large anticyclone to the northeast of the uk with the uk ending up sandwiched between. In the short term, it will become much milder and the southeast looks warm and sunny on sunday at 19c but not as good further north and west with more cloud and some patchy rain but on the mild side. Early next week looks very mild but windy with a strong S'ly airflow and some rain edging up across the uk although northeast britain could have a fine day on monday, the rest of next week looks most unsettled in the west but mild and winds will ease and back SE'ly and the best weather will be further east. Looking at the Gfs 06z, into FI it shows low pressure to the south with the Azores High throwing a ridge across the uk before the atlantic becomes more active and we revert to a normal zonal pattern with temps around average, still no sign of any cold snaps as we go into early november.

Which fits in nicely with the Meto 30 day outlook, It's been quite a while since the Atlantic has been so active for a prolonged period. Strange setup at the start of next week with a deep LP system sitting to the SW and filling in situ, looking mild with air being pulled up from the south and windy with rain at times into next week.

Edited October 20, 2011 by Liam J

[Cheshire Freeze]

Which fits in nicely with the Meto 30 day outlook, It's been quite a while since the Atlantic has been so active for a prolonged period. Strange setup at the start of next week with a deep LP system sitting to the SW and filling in situ, looking mild with air being pulled up from the south and windy with rain at times into next week.

That's the thing, the Atlantic isn't that active. Infact, the Atlantic seems fairly sluggish to me at the moment- sluggish enough to allow pressure to rise to the east. This isn't the norm for the end of October. An active atlantic would see depression after depression running west to east with warm sectors and rain and cool ridges behind before the next depression rolls in. This is a slightly different scenario.

I hasten to add, the only thing which is preventing us from entering a period of unseasonably cold weather in a week's time is the projected heights over Europe.

Edited October 20, 2011 by CreweCold

[Liam J]

That's the thing, the Atlantic isn't that active. Infact, the Atlantic seems fairly sluggish to me at the moment- sluggish enough to allow pressure to rise to the east. This isn't the norm for the end of October. An active atlantic would see depression after depression running west to east with warm sectors and rain and cool ridges behind before the next depression rolls in. This is a slightly different scenario.

I should have elaborated a bit more, i was refering to the low res part of the 6z which is keen to keep us very unsettled in the long range, but obviously the chances of this varifying reduces greatly as the run goes deeper into FI, but we all know that.

I don't take every GFS run as being gospel as there is far to much variation, looking at the 6z runs going back over this week thay have been fairly consistant with an unsettled outlook in the long range, but then again you could pick another GFS run that has possibly shown another scenario in the long term and say the same thing - which one would you go for!

But the general guidance maintains a rather unsettled and mild outlook on the whole, but as ever this is not set in stone and a new trend could emerge in the longer range model outputs.

Edited October 20, 2011 by Liam J

[cyclonic happiness]

Which 6z run are you refering to? The GFS 6z is only just rolling out.

Omg! What is this 'nit pickers anonymus', I obviously meant the 0z, did you really need to point that out?

And reality checks are not needed, i'm quite happy believing what ever I want (just look at the people in charge, they set a great example).

Now I'm off to look at the ehem 06z! (so many pedants, so little time)

[Liam J]

Omg! What is this 'nit pickers anonymus', I obviously meant the 0z, did you really need to point that out?

LOL perhaps you had super powers and could see the 6z run before it had even initiated

[Frosty.]

Which fits in nicely with the Meto 30 day outlook, It's been quite a while since the Atlantic has been so active for a prolonged period. Strange setup at the start of next week with a deep LP system sitting to the SW and filling in situ, looking mild with air being pulled up from the south and windy with rain at times into next week.

Looking further ahead, the Gfs 06z shows a strong euro high which may reduce our chances of an amplified upstream pattern emerging..so as we go well into november there may be higher temps than some experts are anticipating, the euro high could end up being a real spoiler for those hoping for any sort of arctic shot throughout november..I desperately hope i'm wrong.

[Aaron]

People shouldn't be hoping for an arctic shot in November.. winter doesn't start until December.

[Isolated Frost]

People shouldn't be hoping for an arctic shot in November.. winter doesn't start until December.

lol, you should be pleased, average sunshine and temperature - hard to come by in the modern november (apart from 2010).

I fully agree Aaron - we want to bottle that arctic energy up for it too spray on siberia and scandi and build up their cold. not ours- we also dont need waa that much up w greenland as a feature, the feature that's pushing them arctic northerlies and lows east.

[Frosty.]

People shouldn't be hoping for an arctic shot in November.. winter doesn't start until December.

That's like saying people shouldn't be hoping for a warm southerly in april or may because summer doesn't start until 1st June.

The models are showing a very sluggish atlantic in the next few weeks with no clear indication of the jetstream blasting across the uk until sometime in early november and the azores and euro high may have something to say about that.

[Isolated Frost]

That's like saying people shouldn't be hoping for a warm southerly in april or may because summer doesn't start until 1st June.

The models are showing a very sluggish atlantic in the next few weeks with no clear indication of the jetstream blasting across the uk until sometime in early november and the azores and euro high may have something to say about that.

It was a general statement i think that the real cold is more likely in winter official?

[Aaron]

It was a general statement i think that the real cold is more likely in winter official?

Yes that is my point, there has only been one cold November over the past 10 years and before last year most people wouldn't have been looking for wide spread snow in November.

[Isolated Frost]

Yes that is my point, there has only been one cold November over the past 10 years and before last year most people wouldn't have been looking for wide spread snow in November.

Yes - it's always interesting to see a cold snap in autumn or spring - but unless there is serious cold bottled up in the Arctic - or the cold air is deflected by a block or series of lows, then we are simply taking arctic energy which can be potent - but not as potent as possible. It's the case of any cold vs. optimized cold ...

ECM brings in a mixed flow. Southerlies turning to Southeasterlies due to a strong block and lingering trough, and then towards the end, very calm and settled, coolest in the north and west.

Big euro block, strong Azores high and weak atlantic - not personifying autumn, but a calm, warm spell likely, with some frosts on clearer evenings during drier SE'lies.

Generally, GFS flow is very sely/ely (euro block dominating), ECM flow is mixed sely/sly (trough with some influence on block), and the UKMO (only up to +144) gives swly flows generally, as that trough penetrates well into that block.

Interesting model watching to see which wins out.

Edited October 20, 2011 by Isolated Frost

[Bottesford]

Lets keep things on topic folks and just talk about what the models are showing and not what people should/shouldn't be hoping for...

[Paul]

Latest from Michael Fish

[Isolated Frost]

Just as the 12z gfs was beginning to move that low further north than past run, that trough sinks south and rapidly falls. Southerlies and southwesterlies alternating with the low just to the west from Monday to Wednesday, but from Sunday to Monday, the low trickles about a bit and the winds turn southeasterly for a while. But by Wednesday, that Euro block squeezes west, pushes out that trough and burns it out in the bay of biscay. Drier, warmer air should give maxima about 15-17c, and with clearer skies, about 5-7c minima, possibly lower under cooler conditions.

Generally, the low brings cooler air in the form of an rPm airmass - but it's dead when it approaches the stubborn block. Very interesting pattern - so far it looks like Block 1 Atlantic 0, ECM should roll out soon - will be very intriguing. However, the next week is generally a wet week for the west, cloudy and average for much of the nation, with some warmth and clearness possible in the south east, especially later on.

This weekend looks cloudy and wet in the west, and generally slightly milder than usual, especially towards Sunday night/Monday (in which warm southerlies move in).

[chionomaniac]

Interesting MJO forecasts.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

Most of these seem to suggesting the MJO stalling and fading in phase 2 with the resultant pattern Atlantic to Iceland based trough. Meridional pattern slowly replaced by a more zonal one?

[summer blizzard]

It is certainly interesting to note the differences between the models in the latter time frame.

Up to day 5 we see agreement on a ridge building over eastern Europe causing the low to stall to the SW. The differences are apparent afterward however as the ECWMF has the high sinking while the GFS moves it NW. The GEM model goes the whole hog here and has a northerly by day 10.

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Ensembles weirdly indicate the 12z to be a mild outlier however i have no idea whether that indicates greater retrogression or sinkage.

In summary, the model divide continues.

[Isolated Frost]

It is certainly interesting to note the differences between the models in the latter time frame.

Up to day 5 we see agreement on a ridge building over eastern Europe causing the low to stall to the SW. The differences are apparent afterward however as the ECWMF has the high sinking while the GFS moves it NW. The GEM model goes the whole hog here and has a northerly by day 10.

http://www.wetterzen..._London_ens.png

Ensembles weirdly indicate the 12z to be a mild outlier however i have no idea whether that indicates greater retrogression or sinkage.

In summary, the model divide continues.

The ECM 00z has the high remaining and strengthening?

[I remember Atlantic 252]

hope GFS is wrong, gives an absolute washout Sunday, meto to issue weather warning most likely

[Isolated Frost]

hope GFS is wrong, gives an absolute washout Sunday, meto to issue weather warning most likely

Maybe over certain parts of Ireland, W Scotland, Wales and the SW England/Midlands. Not most of the UK. Also, not much precipitation with the original low. As the break off low emerges from the sw, I'd imagine a lot of precipitation coming with that, especially in southern England.

[summer blizzard]

The ECM 00z has the high remaining and strengthening?

I should have said pushed east, the ECWMF pushed the high east between days 5 and 10 while the GFS moved NW.

ECWMF12z coming out, definitely less progressive than the the ECWMF0z.

Like the breakdowns in winter, it seems that the high seems to force the models to back off a few days.

[Gibby]

Good evening everyone. Here's my take on the way the 12zs of GFS, UKMO and ECM look tonight.

GFS tonight shows low pressure developing to the West of the UK as pressure builds over Europe. A very mild SW then South to Southeast airflow strengthens over the weekend pulling warm air North from Europe over the UK. With rain from the start at times in the NW this will lessen over the next 24hrs before a more coherent band moves slowly East into Western Coastal counties of England, Wales and Scotland on Sunday, moving slowly east. Winds too become strong with gales over coasts and hills in the West on Monday. From Tuesday through to Friday low pressure fills and moves South backing winds off towards the east. Further rain would occur at times but gradually become confined to the far SW by the end of the week with dry if rather cloudy weather for most then with relatively mild weather maintained with air from Southern Europe. In FI High pressure to the NE gives fair conditions for most before Low pressure coming around the top of an Atlantic High brings more unsettled conditions at least to the North. At the end of the run a cold NW flow with a few Northern wintry showers is shown before on the final day a cold and frosty high pressure centres over the UK.

The GFS Ensembles for London tonight shows the operational as a mild outlier from the 27th to the 2nd with most members keeping 850's near to the long term average after the mild hump of the next few days. The 25th is programmed as a wet day with scattered rain thereafter through the run. In Aberdeen the same general pattern emerges with the operational going from a warm outlier on the 29th to a cold one on the 4th. As per usual for Aberdeen rainfall could occur at some point at anytime through the run.

UKMO shows a warm Southerly flow developing with Low pressure close to the west of the UK bringing rain to Western regions pushing slowly east and turning more showery as the Low fills to the Northwest later in the run. Temperatures would remain on the mild side of normal as shown.

ECM also shows a large High pressure block forming over Europe with a warm Southerly flow over NW Europe as well as the UK but for us with Low pressure close to the West a stronger Southerly flow would have active troughs embedded in it giving heavy and possibly thundery pulses of rain especially in the West with brighter and more showery weather inbetween. Towards the end of the run a more mobile Westerly flow looks like possibly developing as Low pressures take a more Northerly track with troughs moving more West to East as High pressure over Europe begins to collapse.

In Summary the pattern remains unchanged tonight. The main thing the models are struggling is the extent eastwards of rain late in the weekend and next week. If it stays West then the east would become very mild or rather warm if windy and rather cloudy while things are more guaranteed to be wet in the West with gales possible though still technically mild. In the long term several outcomes are possible but at this range nothing resembling low temperatures are on offer tonight except in the deepest FI of GFS.

[kold weather]

Right, time to close this thread!

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