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Model Output Discussions 06z 04/11/16


phil nw.

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50 minutes ago, Bristle boy said:

Agreed. Same as almost every Winter. Charts 10 days out seldom come to fruition. Winter will ramp up in the 'usual' way for UK come December. (Gut feeling)

Wouldn't go that far. The models are far from a normal start to December, in fact they're quite meridional given what is now the most westerly time of year. The problem will come from whether we're on the right side of any troughs, which would translate to visually similar conditions at the surface e.g. west-based NAO resulting in a trough to the SW of the UK bringing cloud and rain.

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10 minutes ago, Ali1977 said:

Nice, I like the look of this link - although I can't read Italian - looks like an Easterly signal though.

Onto this run, at 144 there is better WAA into Greenland, hopefully this helps the block that should form to be slightly further North.  We shall see.

The charts speak for themselves but the most important part is the explanation of the temperature anomaly charts, purple is the most intense cold anomaly, followed by blue and then green. Uk remaining warm on those charts until mid december when cooler air nudges the south east, then chillier for all by 23rd.

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4 minutes ago, fergieweather said:

Yes, there's no signal of anything replicating last December...!!

A huge sigh of relief:D 

The models show a much more even playing field between cold, average and mild, something I'm grateful for.:)

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3 minutes ago, Seasonality said:

The charts speak for themselves but the most important part is the explanation of the temperature anomaly charts, purple is the most intense cold anomaly, followed by blue and then green. Uk remaining warm on those charts until mid december when cooler air nudges the south east, then chillier for all by 23rd.

Was similar to the Monday CSFv2 as well. Didn't check if it changed its mind since then.

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1 hour ago, Bristle boy said:

Agreed. Same as almost every Winter. Charts 10 days out seldom come to fruition. Winter will ramp up in the 'usual' way for UK come December. (Gut feeling)

A bit pessimistic there non? Considering that so many teleconnections and indexes are pointing towards a colder than average start to the winter? Even the MO is saying there is a 30% chance of seeing cooler than average temps, 70% chance of average. Perhaps it'll not be 2010, but we'll all see snow falling at some point if not settling? To me all the recent runs are developing a theme and that is blocking and easterly and very little sign of any zonal coming back into play with any strength?

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As others have mentioned, according to the GFS model a low to the SW of the UK could bring cold and unsettled conditions with snow for the higher ground of SW parts of the UK on Monday.

gfs-0-114.png?6 gfs-1-114.png?6 gfs-0-120.png?6 gfs-1-120.png?6 gfs-0-126.png?6 gfs-1-126.png?6 gfs-0-132.png?6 gfs-1-132.png?6

.

 

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Overall im happier with the 06z GFS. The HP over Greenland isn't really moving and the HP in Russia appears at this stage to be retrogressing towards the Greenland HP. Also interestingly a couple of lows towards the channel keep the jet over or just below Spain :) . Anything past around 180h is irrelevant at this stage the short term pattern is absolutely key here!   

definitely looking to see an upgrade on 12h GFS, its tricky for the all the models to forecast when the atmosphere is so out of sync with years gone by (due to a number of factors like sun spot activity etc).  

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Plenty of Northern blocking on this run, it just isn't falling right for the UK by day 9.  It does seems quite a complicated set up so no wonder even the METO aren't sure on the outcome.  The signal for blocking is there though, and surely this is the key moving forward in Dec.  Now we need the severe cold over central Siberia to link with the block and get some retrogression into the mix.

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Nice GFS 06 hrs run in terms of overall pattern but we can see the negative effect of that Russian high pumping so much mild air into Central Europe. At this time of year though as soon as you cut off that mild feed surface temps at least should start falling.

In terms of the continued disagreement between the GFS and ECM US forecasters view the ECM op as an outlier solution not supported by its ensembles. Still concerning though that it continues to churn out that progressive solution. Given the timeframes involved hopefully we'll see a resolution this evening.

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2 hours ago, fergieweather said:

Longer range suites aren't deterministic runs! They merely give broad guidance on trends. Despite mixed signals, temperatures are still more likely to end-up below average overall, based on latest output. There's a long way to go before we can express any real confidence in the synoptics/circulation by later Nov and early Dec. 

 

Morning Ian - 

have you seen the updated Ensembles for the 60N zonal mean- 

We are currently competing against 2009 for date records ( around 8 M/S ) V todays initialised value of around 11 M/S-

However we could be looking at a date record for a reversal of wind - The forecast from 00z is -3 M/S occuring on 28 / 11 - which I think ties the date record....

Heres the ensembles - A pretty HISTORIC image to be fair......

Also worth noting that for Dec 1 assuming the landing zone is circa -10 M/S then thats around 50 M/S less that Dec 15 - thats like comparing a mercedes F1 car with Something like a GOLF GTI hatch!!

IMG_9476.PNG

Steve

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22 minutes ago, MP-R said:

Wouldn't go that far. The models are far from a normal start to December, in fact they're quite meridional given what is now the most westerly time of year. The problem will come from whether we're on the right side of any troughs, which would translate to visually similar conditions at the surface e.g. west-based NAO resulting in a trough to the SW of the UK bringing cloud and rain.

all eyes on heights to our south re west based -NAO and its potential effect o the UK. if heights are low to our south then I wouldn't be too concerned unless its an extreme west based solution and even then, low heights to our south in winter pretty well guarantees a cold surface for the UK 

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6 minutes ago, mb018538 said:

It's also worth mentioning that there a high chance of a tropical depression forming in the Caribbean in the next 5 days (80% likely according to latest forecasts)

 http://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=2

Another ingredient to throw into the melting pot.
 

This could be good or bad for us.....the good outcome would be the storm tracks upto the arctic and pumps warmer air in the arctic therefore strengthens the blocking or it could track west and strengthen the jet therefore displacing any early blocking!

defiantly one to watch!  

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19 minutes ago, Frosty. said:

A huge sigh of relief:D 

The models show a much more even playing field between cold, average and mild, something I'm grateful for.:)

Yes, all pretty average-looking fare in latest 15d ensembles. No signs of any exceptional mildness (as per 2015) nor pronounced cold (as per 2010). ENS median currently trends generally a touch below average out to 1 Dec.

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1 hour ago, Singularity said:

Just one part of the puzzle, but one thing I've noticed in the GFS output is that over the past week, the strength of the 'tail' in the vortex at 30 hPa as it undergoes a split has been increased, plus the pace of the split has been slowed a little. It just so happens that this tail extends across the far-N. Atlantic to Canada. So that could be interfering with the process of stopping troughs from making trips from N. America to Siberia via the Atlantic. To overcome that we'll need tropical forcing of a nature that supports strong amplification of the mid-Atlantic ridge. This could well be on the way... but the signals are far from clear.

This seems a very plausible explanation - something the seasonals might not capture. Yes, the disruption and the almost reversal signature but not the micro detail. The warming coming off the Russian ridge is maybe good for longer term but has actually produced a Yin Yang pattern which keeps Atlantic feed in shorter term. The best route, from historical, is for the 'bulge' to be from central Canadian Arctic and thus 'tail' sweeping on a westward trajectory through Siberia to Europe.

On another note - if @fergieweather is about - any possibility you can post a link (as previously) when/if the MedCOF make public the seasonal outlook.

f84209aca46165865c73fb77a3be3efb.png

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A pretty impressive set up beyond day 10, lets see what the GEFS say.  huge low over Southern Europe, and Huge high to the N/NE - if you want a good start to winter this would be a great run.  Just one run though, and looking at what Ian F has just wrote above this one may have little support for now.  

It doesn't actually bring the anything special in just yet - and the high doesn't hold onto Greenland moving too far west.

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3 minutes ago, fergieweather said:

Yes, all pretty average-looking fare in latest 15d ensembles. No signs of any exceptional mildness (as per 2015) nor pronounced cold (as per 2010). ENS median currently trends generally a touch below average out to 1 Dec.

All pretty standard fair then Ian for late autumn early winter. Hopefully the glosea model will continue with its blocking theme into Dec. But as ever we could be on the wrong side of any blocking bringing just slightly below temps for Dec. All looks very standard at moment. Don't think that Russian high is helping matters regarding our tiny island. 

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9 minutes ago, Grimers said:

The ECMWF model shows a low to the SW of the UK bringing cold and unsettled conditions to SW parts of the UK on Sunday.

ECM1-96.GIF?16-12 ECM0-96.GIF?16-12

Was looking at that, keeps the 'colder' upper air temperatures on its northern flank, however it's quite hard to see what's happening when the frames are every 24 hours. Snow for the midlands? 
 

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So much discussion on the distant future, we seem to have forgotten the present. The latest GFS is very, very interesting for a cold scenario. By T192, it is clear that a southerly jet is getting established, and we could end up with northern heights getting locked in:

gfs-0-192.png?6

Yes, indeed:

gfs-0-312.png?6

All we'd need is this pattern to stick and it will go cold by the start of December - possibly deeply cold.

Not a bad match for the NOAA 8-14 dayer:

814day.03.gif

ECM ensembles to D13 not an exact match but has that low towards Iberia.

ec-ens_nat_gh500mean_gh500std_thk500mean

And think about it. Experience tells us that low in Iberia will eventually exit, but only one way - east, not west. And it can't do that without drawing winds from the E / NE at some point.

Once we get the low stuck down in Iberia, I think it is absolutely odds on that we will go cold at some point.

I'll lay it on the line - if the GFS 06Z evolution is correct to T192, I expect we will get some days in the D12-D20 period with a sub-zero CET.

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9 minutes ago, ShaftsburySnow said:

This could be good or bad for us.....the good outcome would be the storm tracks upto the arctic and pumps warmer air in the arctic therefore strengthens the blocking or it could track west and strengthen the jet therefore displacing any early blocking!

defiantly one to watch!  

Why would tracking west cause a strengthening of the jet?

I would expect a track east/northeast would strenghten the jet.

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2 minutes ago, PerfectStorm said:

Was looking at that, keeps the 'colder' upper air temperatures on its northern flank, however it's quite hard to see what's happening when the frames are every 24 hours. Snow for the midlands? 
 

Yes, I would agree, if the low is slightly further N than shown.

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14 minutes ago, bluearmy said:

all eyes on heights to our south re west based -NAO and its potential effect o the UK. if heights are low to our south then I wouldn't be too concerned unless its an extreme west based solution and even then, low heights to our south in winter pretty well guarantees a cold surface for the UK 

Exactly. Either way, below average temperatures would result. Just how wintry conditions will be, which is always hard to determine, will be the question. I'm sure it was February 2010 which ended up with a west-based NAO and resulted in a cold month but as equally damp as wintry.

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Aye. It looks (from all that's been posted so far, today) that the Beeb were quite justified in ending their latest weekly forecast at the coming weekend..The more runs we see, the more confusing things appear to become: a far cry from this time last year!:good:

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