Model Output Discussion

[Lewis]

It's interesting how a few days ago we get the best charts since 1947 etc the mother of all cold spell coming up all getting pushed back and back.

Testis I do hope you do get your beloved easterly before the summer but T240 its all back in F1.

I always find it interesting few people talk about things within T96, we have seen on recent runs nothing is 'nailed' within that time frame.

Cold air can arrive over night with the right synoptics, waiting 10 days for everything to be in place I'm afraid is wishful thing and hope casting.

For the next week the temps are going to be slightly below average with a few cold nights (cira -4c CET zone).

Agreed,

This morning charts are poor in the reliable time frame, the Northerly topples much quicker, the 850's are not as pronounced, and the flow is a lot slacker.

I have been saying all week that we should see what we get in reliable time frame and up until Monday with regards the model output. The next 4-6 days are crucial as to where we end up later in FI (blocking) etc.

I don't think the easterly will happen.. Just waiting now for the 06z to roll out and downgrade the Northerly this week once again, at the rate we are going it'll end up being -5 850's with a 12 hour North Westerly.

[TEITS]

Cold air can arrive over night with the right synoptics, waiting 10 days for everything to be in place I'm afraid is wishful thing and hope casting.

True but under certain synoptic patterns F.I isn't as far out as you think. For example suppose a model run indicates the HP at +168 being in the perfect position but the cold uppers don't arrive until +240. Well if this is the case then this isn't so much of a concern because the cold pool of air has to back W because it doesn't have anywhere else to go. The key is getting the block in the right position and this then being maintained. If this happens then the rest takes care of itself.

[TEITS]

Agreed,

This morning charts are poor in the reliable time frame, the Northerly topples much quicker, the 850's are not as pronounced, and the flow is a lot slacker.

I have been saying all week that we should see what we get in reliable time frame and up until Monday with regards the model output. The next 4-6 days are crucial as to where we end up later in FI (blocking) etc.

I don't think the easterly will happen.. Just waiting now for the 06z to roll out and downgrade the Northerly this week once again, at the rate we are going it'll end up being -5 850's with a 12 hour North Westerly.

Sorry but I strongly disagree. Calling this mornings charts as poor leaves me rather speechless.

A typical N,ly in the UK is a 3-4 day event with upper temps around -8C with snow showers affecting coastal regions. So lets have a look at the ensembles for Cambs.

http://charts.netweather.tv/ensimages/ens.20100128/00/t850Cambridgeshire.png

Very typical of a N,ly.

The only downgrade is the flow in now slack with more of a NW,ly flow rather than a N,ly.

Beyond the N,ly and take note the ensembles don't rise above -5C. Also note how cold the ECM ensembles are.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Sorry but to call this mornings charts as poor means we have either been spoilt or we are misreading the models. Now im not saying the E,ly is nailed but the trend remains excellent.

[Lewis]

Sorry but I strongly disagree. Calling this mornings charts as poor leaves me rather speechless.

A typical N,ly in the UK is a 3-4 day event with upper temps around -8C with snow showers affecting coastal regions. So lets have a look at the ensembles for Cambs.

http://charts.netweather.tv/ensimages/ens.20100128/00/t850Cambridgeshire.png

Very typical of a N,ly.

The only downgrade is the flow in now slack with more of a NW,ly flow rather than a N,ly.

Beyond the N,ly and take note the ensembles don't rise above -5C. Also note how cold the ECM ensembles are.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Sorry but to call this mornings charts as poor means we have either been spoilt or we are misreading the models. Now im not saying the E,ly is nailed but the trend remains excellent.

This mornings models are poor compared to the past few days, if you remember on Monday/Tuesday i was saying that nothing is nailed, i expected a downgrade nearer the time frame of this Northerly, HP much further East, other models all week showing it slightly further West. Flow is much slacker, and even slacker on the current 06z run as it rolls out.

All i'm saying is, nothing is nailed on. 9 times out of 10 it downgrades within reliable time frame, so how can we be so certain and be "over joyed" because some models are showing an easterly T240! I'm sorry but i see it as forecasting/model suicide.

Edited January 28, 2010 by Storm Force Lewis

[Weather-history]

Sorry but to call this mornings charts as poor means we have either been spoilt or we are misreading the models. Now im not saying the E,ly is nailed but the trend remains excellent.

Yes, I remember people would have grasped that northerly in previous winters, so poor those winters had been for cold and snow up to that stage.

And the signs are that this winter isn't going down the 1981-82, 1996-97 route at the moment. Winters that went pear-shaped for cold. At this stage for the winter of 1981-82, it had become very mild.

[Cecil Hogmanay Melchett]

Sorry but I strongly disagree. Calling this mornings charts as poor leaves me rather speechless.

A typical N,ly in the UK is a 3-4 day event with upper temps around -8C with snow showers affecting coastal regions. So lets have a look at the ensembles for Cambs.

http://charts.netweather.tv/ensimages/ens.20100128/00/t850Cambridgeshire.png

Very typical of a N,ly.

The only downgrade is the flow in now slack with more of a NW,ly flow rather than a N,ly.

Beyond the N,ly and take note the ensembles don't rise above -5C. Also note how cold the ECM ensembles are.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Sorry but to call this mornings charts as poor means we have either been spoilt or we are misreading the models. Now im not saying the E,ly is nailed but the trend remains excellent.

Some good points Dave but imo the models are trending away from any meaningful Easterly this morning.The key to the whole thing is around T120 to T144 and both Euro models have far to much pressure from the Atlantic on the Atlantic high.meto looks very poor at 144 and i cant for the life of me see anything decent coming from that.ECM FI shows some extensive Northern blocking but even then we have lots of energy around the iceland region preventing the Blocking directly affecting the UK.

So far as the north wind is concerned only NE Scotland looks favourable for snow,the vast majority will be bone dry and cold for 3 days or so but by mon the high has lps rolling over the top which ties in with the meto 3 to 5 dayer with rain pusing in from the NW.

Maybe things will improve over the next day or 2 but thats purely an aspiration.

The gefs ens look very cold but they flip and flop very quickly and im not putting much faith in them.

In short im disappointed with this mornings output,i'll probably get slagged off for saying it but its just my two penneth.

This mornings models are poor compared to the past few days, if you remember on Monday/Tuesday i was saying that nothing is nailed, i expected a downgrade nearer the time frame of this Northerly, HP much further East, other models all week showing it slightly further West. Flow is much slacker, and even slacker on the current 06z run as it rolls out.

All i'm saying is, nothing is nailed on. 9 times out of 10 it downgrades within reliable time frame, so how can we be so certain and be "over joyed" because some models are showing an easterly T240! I'm sorry but i see it as forecasting/model suicide.

thats a very good post lewis and i agree with nearly everything you have wrote.

[TEITS]

This mornings models are poor compared to the past few days, if you remember on Monday/Tuesday i was saying that nothing is nailed, i expected a downgrade nearer the time frame of this Northerly, HP much further East, other models all week showing it slightly further West. Flow is much slacker, and even slacker on the current 06z run as it rolls out.

All i'm saying is, nothing is nailed on. 9 times out of 10 it downgrades within reliable time frame, so how can we be so certain and be "over joyed" because some models are showing an easterly T240! I'm sorry but i see it as forecasting/model suicide.

Well for starters the E,ly isn't at +240 if you look at the GEFS mean.

As for downgrades. Well cast your mind back a few days when the N,ly was replaced by milder W,lys as the HP topples. The GEFS mean at the time was above 0C! Remember how I said I was going to take a break from the models. So you could argue the N,ly has upgraded the cold spell with regards to length.

Nobody is saying the E,ly is nailed. What we are saying is the outlook looks dominated by blocking to the NE but its where this blocking positions itself thats uncertain.

I really wish members would look at the wider picture i.e GEFS mean, SLP mean for UK, Iceland, Oslo. Just using the operationals doesn't give you an accurate respresentation of the models.

Edited January 28, 2010 by THE EYE IN THE SKY

[Weather-history]

.meto looks very poor at 144 and i cant for the life of me see anything decent coming from that.

Bit hard, when UKMO only goes out to 144hrs. GFS looks poor at 144hr by the way, taking a snapshot.

[NorthantsSnow]

The easterly on the 00z GFS doesn't look very strong. Reminds me of a stab at an easterly we had a year or two ago that was virtually useless in the south for snow.

[TEITS]

You also claimed on your last post, that this current cold spell would be mainly dry for you, does that mean your going to keep looking for armegeddon in the models every run? I think it's a waste of time, and no doubt we'll be having this convosation again in 3 weeks time.

Lets enjoy what we have now.

Lewis even if there was a blizzard raging outside I would still be looking at F.I. I don't just view the models for what weather we may experience. I also view the models because I like to challenge myself against them from a forecasting perspective.

At the moment its charts like these that fasinate me.

http://www.wetterzentrale.de/pics/Rtavn1501.png

[cooling climate]

Well for starters the E,ly isn't at +240 if you look at the GEFS mean.

I really wish members would look at the wider picture i.e GEFS mean, SLP mean for UK, Iceland, Oslo. Just using the operationals doesn't give you an accurate respresentation of the models.

Yep quite agree, including the northern hemisphere charts. The high to the northeast is the dominant

force and it is this that is dictating the pattern. IE where shortwaves and lows move etc, also on the

t150 northern hemisphere charts the Siberian high is pulling much colder air into its circulation.

[Duane S.]

All i'm saying is, nothing is nailed on. 9 times out of 10 it downgrades within reliable time frame, so how can we be so certain and be "over joyed" because some models are showing an easterly T240! I'm sorry but i see it as forecasting/model suicide.

??? 9 out of 10 WHAT downgrades exactly?? We've had good Northerly runs showing on the charts, average Northerly runs shown on the charts and poor ones before the rather average looking event itself. If we take the poor runs (and there were plenty) in the lead up to this Northerly, then it has been upgraded, surely?

It's not about believing, TO THE LETTER, the awesome Easterly runs that have cropped up from time to time of late, it's about being objective and seeing whether or not signals support it. They do. Hence my recent posts saying yes it's likely we will pick up a continental feed (i.e. an Easterly of some description) but not as quick as some would like. Patience will likel be required but with a bit of luck it will all be worth it.

I can't beleive some are already talkking about it being a 'dry easterly'. I wish I was able to be able to predict the exact PPN levels of something occuring in 10-14 days time, very impressive. The old addage of get it in place first and the snow will come needs to be applied here I think.

[TEITS]

Yep quite agree, including the northern hemisphere charts. The high to the northeast is the dominant

force and it is this that is dictating the pattern. IE where shortwaves and lows move etc, also on the

t150 northern hemisphere charts the Siberian high is pulling much colder air into its circulation.

Charts like these are oozing potential.

http://www.wetterzentrale.de/pics/Rtavn1681.png

I couldn't give a monkeys what the rest of the run does as the 06Z so far is incredible.

The only concern we should have at the moment is getting charts like above within +72.

Edited January 28, 2010 by THE EYE IN THE SKY

[chionomaniac]

For me it is all to do with the building blocks and they are all being put into place when the Scandi trough fades. Any Greenland troughing is likely to retrogress westwards as a burst of negative mean zonal winds enter the troposphere. This will allow height rises from the Arctic and Atlantic to merge forming a block from Greenland to Scandinavia in about 10 days time.

[Lewis]

??? 9 out of 10 WHAT downgrades exactly?? We've had good Northerly runs showing on the charts, average Northerly runs shown on the charts and poor ones before the rather average looking event itself. If we take the poor runs (and there were plenty) in the lead up to this Northerly, then it has been upgraded, surely?

It's not about believing, TO THE LETTER, the awesome Easterly runs that have cropped up from time to time of late, it's about being objective and seeing whether or not signals support it. They do. Hence my recent posts saying yes it's likely we will pick up a continental feed (i.e. an Easterly of some description) but not as quick as some would like. Patience will likel be required but with a bit of luck it will all be worth it.

I can't beleive some are already talkking about it being a 'dry easterly'. I wish I was able to be able to predict the exact PPN levels of something occuring in 10-14 days time, very impressive. The old addage of get it in place first and the snow will come needs to be applied here I think.

Sorry.., this Northerly has had its upgrades, but more downgrades. It's clear that this northerly has being downgraded, both potency, and the strength of the flow...

Edited January 28, 2010 by Storm Force Lewis

[Tom D]

For me the 06z op shows exactly what we must expect now - a bit of milder weather before any potential easterly comes through. It could well be that we see a couple of the mildest days since the beginning of December, however at +180 as TEITS says there is A LOT of potential for mid February there.

Even at +174 cold continental air starts oozing into the southeast, and the position of the southern high looks good still.

Edited January 28, 2010 by Tommyd1258

[TEITS]

This will allow height rises from the Arctic and Atlantic to merge forming a block from Greenland to Scandinavia in about 10 days time.

Morning CH.

Yes the GEFS has been very keen in what you describe. Also historically if we look at some of the archives this has sometimes been the case.

This is going to be a very bitter run!

http://www.wetterzentrale.de/pics/Rtavn2401.png

Edited January 28, 2010 by THE EYE IN THE SKY

[Osbourne One-Nil]

I really wish members would look at the wider picture

DO you not think that perhaps you could be accused of looking so hard for easterlies that you sometimes disregard other scenarios?

I come in peace by the way!

[chionomaniac]

Sorry.., this Northerly has had its upgrades, but more downgrades. It's clear that this northerly has being downgraded, both potency, and the strength of the flow...

The last time I looked Lewis it hadn't even occurred yet!

[Lewis]

DO you not think that perhaps you could be accused of looking so hard for easterlies that you sometimes disregard other scenarios?

I come in peace by the way!

Thank you, finally a level headed post.

We should just take the models as they come.

Heres your Easterly TEITS T+252

Edited January 28, 2010 by Storm Force Lewis

[Southender]

Niiiiiiccee, ice baby!

Edited January 28, 2010 by LeighShrimper

[cooling climate]

For me it is all to do with the building blocks and they are all being put into place when the Scandi trough fades. Any Greenland troughing is likely to retrogress westwards as a burst of negative mean zonal winds enter the troposphere. This will allow height rises from the Arctic and Atlantic to merge forming a block from Greenland to Scandinavia in about 10 days time.

Yes they are both one and the same what I mean by that is the Siberian high is moving westwards

because of these downward propagating easterlies.

We see these easterlies in their physical form as the high shunting everything westwards, this is

what I mean when I say the high is the dominant force it is this high( easterlies that are dictating the

pattern).

[TEITS]

DO you not think that perhaps you could be accused of looking so hard for easterlies that you sometimes disregard other scenarios?

I come in peace by the way!

Yes.

The 06Z is a good example of what I was on about earlier. If we can get +168 at +72 then the rest will take care of itself i.e cold pools backing W, snowfall.

[chionomaniac]

Morning CH.

Yes the GEFS has been very keen in what you describe. Also historically if we look at some of the archives this has sometimes been the case.

This is going to be a very bitter run!

http://www.wetterzentrale.de/pics/Rtavn2401.png

Yes, The polar vortex has been highly erratic this year and the positioning as the effects of the recent strat warming will continue to produce classic old time synoptics. It is not the case that this time if the PV rests over Greenland that it is going to stay there as the propagating zonal winds will try and prevent that.

[The Weather Dragon]

I have rarely seen such an extensive cold pool over Central Europe as is projected in GFS 06z FI - This pool has escaped direct from the Artic - I think now that some sort of Easterly is on the cards - it's a matter of fine tuning

Edited January 28, 2010 by Jonathan Evans