[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Again though, this run shows us nothing without the other 21 members. If Ens mean is down on the 18z I'm happy.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Looks like GFS is saying no again. That position at t90is unsaveable.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Both the high pressure in the atlantic and the shortwave are further north. Which way will it go?

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

No it makes no difference and that’s the point about the MO, the dynamics are so difficult, all the models and the human forecasters are struggling, its that knife edge.

Sorry, but if a model has to be 24 hours out to make the right decision then it is absolutely useless. I've never come across a model changing its mind less than 72 hours away. 3 days is understandable, 1 day is just pathetic.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Whichever model is right if any, no model will lose credibility, again reference the first point.

That I would think depends on how long the wrong one waits to change its tune. If for example the GFS waits until 24 hours away to change to cold then it should correctly lose a lot of respect. Though I doubt it will come to that, by Saturday we should know.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Could the GFS have a problem with handling the recent SSW

Putting a truckload of low pressures in the exact place where the vortex has split would suggest that it is.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

NOGAPS looks good, we just have to win this lottery another 40 times and the cold will be here

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

I don't think any of the models will be embarrassed if they are wrong.due to the SSW ...the models are all having a tough time.which was spoken about a week ago by mr fergusson and mr Hugo.tommorow morning is huge

Agreed, but there's a bit of a difference between having a tough time and placing the vortex in exactly the place it's least likely to be (what 18z is doing). I guess I can't criticise it until ensembles come out, but I'd be surprised if it wasn't one of the milder or maybe even the mildest member from 144-192.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Not harsh at all.There's no point in running a model out to 10-14 days if it can't even nail 72 hrs. The UKMO have acknowledged this which is why we only see to 144 (this also backed up by Ian F)

To be fair as much as I hate the GFS at the moment it is the best at picking up trends. It picked up this ridge of high pressure to our North about 10 days beforehand.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

By T156 the Polar Vortex is pretty much in full swing. Given what Chio, GP and others have been saying that WILL NOT happen, Strat forecasts/current are absolutely fantastic, to see the PV suddenly rev up like that suggests there's something wrong with the GFS run.

The decider lies very early on with that shortwave to the South of Iceland, every other model sends that shortwave SE allowing heights to build into Greenland and the following cold we get plunged into. What do we have?

ECM + Ensembles - GO

UKMO - GO

GEM - GO

NOGAPS - GO

MOGREPS - GO

BOM - GO

JMA - NO

Along with any others I've missed out. Massive support AGAINST the GFS at this stage. If it proves to be correct, then I think can throw away every single other model/forecasting technique we currently use.

Dan where do you get the MOGREPS data from? It's the one I trust the most after it got December spot on.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

GFS picked the initial trend up for this weekend as well. I've gone from slightly worried to being concerned, that's 3 poor 12z runs.

I'll settle for a short lived cold spell, IF The weekend produces.

But it had a lot of support from it's ensemble members for this weekend. It's almost on it's own with this ridiculous idea to push the shortwave North despite the jet going south. As long as the vast majority of the ensembles keep things cold (as they are currently doing), the operational can do whatever it wants.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Greenland closed off at t114, I believe that's a new record. That's got to be the worst run so far.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Good consistency from the ECM, similar to the 00z.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

looks same as gfs at+96hrs

It's to the east of Iceland on the ECM, west of Iceland on the GFS. Imo the most important thing for cold is the speed of that shortwave, and it's looking quicker on ECM.

Edit: Also just noticed that the GFS shortwave has a supporting one to it's northeast which is probably why it ended up moving Northeast.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

I don't know how we can tell, the Vortex was shredded in 2009/2010, December 2010 and there was no SSW.

December 2010

Very minor warmings in November 2010 prevented the vortex from properly forming. I'm pretty sure there was an SSW in winter of 2009/10 in January.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

In timely fashion - this exact question has been sent earlier today to Exeter for comment.

May I ask what has been causing the sudden ridge of high pressure almost completely stopping the jet in its tracks? Would be very surprised if it isn't at least an indirect affect of the SSW.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

As long as the ensembles say otherwise, I'm not concerned. For example the ensembles were actually warmer on the 18z run yesterday than the 06z run today, yet we went crazy over the 18z because of 1 member and were disappointed by the 06z because of 1 member. Far too much importance is placed on the operational at t96+

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Anyone else annoyed that we are the block that allows Spain and North Africa to get snow on the 12z lol. Absolutely dreadful run long term, improvement for the weekend though.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Could the high pressure be strong enough to stop those 2 lows from linking?

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

Even if it does fail later, some positive news - at t96-120 the lows in the Atlantic are much better alligned (vertical instead of diagonal on the 06z), suggests high pressure standing its ground a bit more.

[Winter Model Discussion 12Z 09/01/13> The hunt for cold ?]

GFS going shortwave crazy again... That area under Southern Greenland is the ultimate high pressure repellent, it's been a conveyer belt for shortwaves all winter.

[Winter Model Discussion 18Z 8/1/13. The hunt for cold (is closer).]

And now GFS does what it does best and revert to zonal when it doesn't know what's going on. I'm pretty sure that will be one of the milder ensembles at t144 onwards.

[Stratosphere Temperature Watch 2012/2013]

The PNA is starting to get a few members on the positive side now, and in the positive phase we see lower pressure over the North Pacific and Aleutian Islands. This tends to be a precursor for increased stratopheric wave-1 activity. I have no idea how reliable wave amplitude forecasts are, but ECM is going to a big rise in wave-1 in 7-10 days:

[Stratosphere Temperature Watch 2012/2013]

Yes those are both great thanks

[Stratosphere Temperature Watch 2012/2013]

http://www.cpc.ncep....here/strat_a_f/

Thanks, but I'm looking for lower than 70mb